The urinary system consists of the kidneys, ureters, urinary bladder, and urethra. The kidneys filter the blood to remove wastes and produce urine. The basic functional unit of the kidneys is the nephron, which filters blood in the glomerulus and reabsorbs and secretes substances through specialized tubules. Urine is stored in the bladder and expelled through the urethra.
The document discusses renal physiology and the urinary system. It contains the following key points:
1. The urinary system includes the kidneys, ureters, bladder, and urethra. The kidneys contain nephrons which filter blood to form urine.
2. The kidneys regulate fluid volume, electrolyte and acid-base balance, and remove waste. Nephrons contain a renal corpuscle for filtration and a tubule for reabsorption and secretion.
3. The proximal convoluted tubule reabsorbs the majority of filtered sodium, water, and other electrolytes using active transport mechanisms like sodium-glucose co-transport. This maintains electrolyte and fluid balance
1. Renal blood flow is tightly regulated to maintain a constant rate of around 1200 mL/min despite wide changes in blood pressure, through mechanisms like autoregulation and tubuloglomerular feedback.
2. The kidneys receive a high blood flow of around 20-30% of cardiac output despite their small size, and oxygen consumption in the kidneys is very high, second only to the heart.
3. Blood enters the kidneys through the renal artery and is distributed through a branching network of arteries before entering the glomerular capillaries and surrounding the nephron tubules, with the renal veins collecting the blood and returning it to circulation.
The document summarizes the histology of the kidney. It describes the major structures of the kidney including the cortex, medulla, nephrons, renal corpuscles, glomerular filtration, renal tubules, and collecting system. It explains that the kidney filters blood to produce urine using nephrons as the functional unit, which contain a renal corpuscle for filtration and renal tubules for reabsorption and secretion.
The Urinary System consists of paired kidneys, ureters, a urinary bladder, and a urethra. The kidneys filter waste from the blood to produce urine. Urine travels from the kidneys down the ureters into the bladder, where it is stored until excretion through the urethra. The main functions of the Urinary System are to filter the blood, regulate water and electrolyte balance, and dispose of nitrogenous wastes.
Nephron (The Guyton and Hall physiology)Maryam Fida
Structural and Functional unit of kidney is called nephron.
There are about 1.3 million nephron in each kidney.
New nephrons can not be regenerated by kidneys.
Functioning nephrons decrease about 10 % every 10 years at the age of 40.
At the age of 80, there are 40 % of functioning nephrons as compared to 40 yrs.
It is formed by two parts.
1. GLOMERULUS
2. BOWMAN’S CAPSULE
1- Glomerulus:
It consists of tuft of glomerular capillaries.
There is anastomosing & branching network of glomerular capillaries.
Glomerular capillaries have high hydrostatic pressure (nearly 60 mm Hg) as compared with other capillaries.
Glomerulus is surrounded by a membranous cover called Bowman’s capsule.
Each glomerulus is about 0.2 mm in diameter.
Glomerulus and Bowman’s capsule together constitute renal corpuscle.
Each renal tubule is divided into various part as they have different functions.
i- Proximal convulated tubule.
It is continuation of Bowman’s capsule.
ii- Loop of Henle. It is continuation of prox. conv. tubule.
* Loop of Henle has three parts.
a- descending limb,
b- u turn or bend in medulla and
c- ascending limb.
Ascending limb has initial thin segment followed by thick segment.
At the end of thick ascending limb, there is short segment called macula densa, which plays important role in controlling functions of nephron.
The document summarizes the structure and function of the renal (urinary) system. It describes the key components of the system including the kidneys, ureters, bladder, and urethra. It then discusses the functional units of the kidneys called nephrons and their role in filtering blood and regulating water and electrolyte balance through glomerular filtration, tubular reabsorption and secretion processes. Specifically, it explains how nephrons use active transport mechanisms like the sodium-potassium pump to reabsorb filtered materials and maintain blood pressure and pH levels.
The document describes the anatomy of the renal system. It discusses the anatomy of the kidneys, including their location, relationships with other structures, internal structures like the cortex and medulla, vasculature, innervation, and lymphatic drainage. It also describes the anatomy of the ureters, including their course and vascular supply. Finally, it summarizes the anatomy of the suprarenal glands, including their location, vascular supply, and relationships with the kidneys.
The urinary system consists of the kidneys, ureters, urinary bladder, and urethra. The kidneys contain millions of nephrons, which are the functional units that filter blood to form urine. Each nephron includes a renal corpuscle, proximal convoluted tubule, loop of Henle, distal convoluted tubule and collecting duct. The ureters carry urine from the kidneys to the bladder. The bladder stores urine until emptying via the urethra.
The document discusses renal physiology and the urinary system. It contains the following key points:
1. The urinary system includes the kidneys, ureters, bladder, and urethra. The kidneys contain nephrons which filter blood to form urine.
2. The kidneys regulate fluid volume, electrolyte and acid-base balance, and remove waste. Nephrons contain a renal corpuscle for filtration and a tubule for reabsorption and secretion.
3. The proximal convoluted tubule reabsorbs the majority of filtered sodium, water, and other electrolytes using active transport mechanisms like sodium-glucose co-transport. This maintains electrolyte and fluid balance
1. Renal blood flow is tightly regulated to maintain a constant rate of around 1200 mL/min despite wide changes in blood pressure, through mechanisms like autoregulation and tubuloglomerular feedback.
2. The kidneys receive a high blood flow of around 20-30% of cardiac output despite their small size, and oxygen consumption in the kidneys is very high, second only to the heart.
3. Blood enters the kidneys through the renal artery and is distributed through a branching network of arteries before entering the glomerular capillaries and surrounding the nephron tubules, with the renal veins collecting the blood and returning it to circulation.
The document summarizes the histology of the kidney. It describes the major structures of the kidney including the cortex, medulla, nephrons, renal corpuscles, glomerular filtration, renal tubules, and collecting system. It explains that the kidney filters blood to produce urine using nephrons as the functional unit, which contain a renal corpuscle for filtration and renal tubules for reabsorption and secretion.
The Urinary System consists of paired kidneys, ureters, a urinary bladder, and a urethra. The kidneys filter waste from the blood to produce urine. Urine travels from the kidneys down the ureters into the bladder, where it is stored until excretion through the urethra. The main functions of the Urinary System are to filter the blood, regulate water and electrolyte balance, and dispose of nitrogenous wastes.
Nephron (The Guyton and Hall physiology)Maryam Fida
Structural and Functional unit of kidney is called nephron.
There are about 1.3 million nephron in each kidney.
New nephrons can not be regenerated by kidneys.
Functioning nephrons decrease about 10 % every 10 years at the age of 40.
At the age of 80, there are 40 % of functioning nephrons as compared to 40 yrs.
It is formed by two parts.
1. GLOMERULUS
2. BOWMAN’S CAPSULE
1- Glomerulus:
It consists of tuft of glomerular capillaries.
There is anastomosing & branching network of glomerular capillaries.
Glomerular capillaries have high hydrostatic pressure (nearly 60 mm Hg) as compared with other capillaries.
Glomerulus is surrounded by a membranous cover called Bowman’s capsule.
Each glomerulus is about 0.2 mm in diameter.
Glomerulus and Bowman’s capsule together constitute renal corpuscle.
Each renal tubule is divided into various part as they have different functions.
i- Proximal convulated tubule.
It is continuation of Bowman’s capsule.
ii- Loop of Henle. It is continuation of prox. conv. tubule.
* Loop of Henle has three parts.
a- descending limb,
b- u turn or bend in medulla and
c- ascending limb.
Ascending limb has initial thin segment followed by thick segment.
At the end of thick ascending limb, there is short segment called macula densa, which plays important role in controlling functions of nephron.
The document summarizes the structure and function of the renal (urinary) system. It describes the key components of the system including the kidneys, ureters, bladder, and urethra. It then discusses the functional units of the kidneys called nephrons and their role in filtering blood and regulating water and electrolyte balance through glomerular filtration, tubular reabsorption and secretion processes. Specifically, it explains how nephrons use active transport mechanisms like the sodium-potassium pump to reabsorb filtered materials and maintain blood pressure and pH levels.
The document describes the anatomy of the renal system. It discusses the anatomy of the kidneys, including their location, relationships with other structures, internal structures like the cortex and medulla, vasculature, innervation, and lymphatic drainage. It also describes the anatomy of the ureters, including their course and vascular supply. Finally, it summarizes the anatomy of the suprarenal glands, including their location, vascular supply, and relationships with the kidneys.
The urinary system consists of the kidneys, ureters, urinary bladder, and urethra. The kidneys contain millions of nephrons, which are the functional units that filter blood to form urine. Each nephron includes a renal corpuscle, proximal convoluted tubule, loop of Henle, distal convoluted tubule and collecting duct. The ureters carry urine from the kidneys to the bladder. The bladder stores urine until emptying via the urethra.
The basics of autoregulation of Gloemrular filtration rate. This ppt deals with basic renal physiology, tubuloglomerular feedback, myogenic reflex, juxtaglomerular apparatus and renin angiotensin aldosterone system in brief. P.S.- The ppt has animations so kindly view in slide/presentation mode
The renal system consists of the kidneys and urinary bladder. The kidneys play a vital role in maintaining fluid balance and composition in the body, regulating the internal environment. The kidneys are composed of nephrons which filter blood, reabsorbing necessary substances and secreting waste products to produce urine. Urine is stored in the bladder and emptied during micturition.
The urinary system consists of two kidneys, two ureters, one urinary bladder, and one urethra. The kidneys filter wastes from the blood and regulate fluid and electrolyte balance. Each kidney contains over a million nephrons, the functional units that filter blood in the glomerulus and reabsorb useful substances along the renal tubules. The kidneys secrete urine that travels through ureters to the bladder, where it is temporarily stored then expelled through the urethra. The urinary system plays critical roles in homeostasis by filtering wastes and regulating water, electrolyte, and acid-base balance.
The kidneys are paired organs located in the abdominal cavity. Each kidney has an outer renal cortex and inner renal medulla. Within these regions are over 1 million microscopic filtration units called nephrons. Nephrons contain a renal corpuscle for blood filtration and a renal tubule for fluid processing. Processed fluid drains into collecting ducts and exits the kidneys as urine through the ureters. The kidneys are supplied with blood from the renal arteries and are surrounded by protective layers of tissue.
The urinary system consists of the kidneys, ureters, urinary bladder, and urethra. The kidneys filter waste from the blood to produce urine. Each kidney contains approximately 1 million nephrons, the functional units that filter blood. The kidneys regulate fluid and mineral balance, produce hormones, and remove wastes from the body. When the kidneys fail to function, renal replacement therapies such as hemodialysis, peritoneal dialysis, or kidney transplantation are needed.
The kidneys are paired retroperitoneal organs located on the posterior abdominal wall. Each kidney has an outer renal cortex and inner renal medulla divided into renal pyramids. The kidneys receive blood supply from the renal arteries which branch into segmental and lobar arteries before branching further. Blood exits via interlobar, arcuate and interlobular veins into the renal veins which drain into the inferior vena cava. The kidneys are surrounded by fibrous capsules and perirenal fat and have anterior relations to other abdominal organs and posterior relations to the vertebral column and muscles.
The kidney is bean-shaped and located retroperitoneally. It contains nephrons which filter blood to form urine. Each nephron contains a glomerulus for blood filtration and a tubule for urine transport. The kidneys also contain collecting ducts which drain urine from nephrons into the renal pelvis. Urine exits each kidney via the ureter and is stored in the bladder before exiting the body through the urethra.
The document summarizes key aspects of pancreatic function and disease. It discusses how the pancreas secretes enzymes and fluid to aid digestion. The two major hormones that regulate secretion are secretin and cholecystokinin. Acute pancreatitis can result from factors like gallstones, alcohol use, or hypertriglyceridemia and involves inflammation and damage to pancreatic tissue that can spread systemically. Chronic pancreatitis is characterized by irreversible pancreatic damage and can be caused by long-term alcohol use, genetic mutations, or recurrent acute pancreatitis. Laboratory tests of pancreatic enzymes and hormone stimulation help diagnose pancreatic disorders.
The urinary system consists of the kidneys, ureters, urinary bladder and urethra. The kidneys filter the blood to remove wastes and produce urine. The nephron is the functional unit of the kidney that filters blood and forms urine. Urine passes from the kidneys through the ureters into the bladder, and is then emptied through the urethra. Urine formation involves glomerular filtration, tubular reabsorption and secretion, and a countercurrent mechanism in the kidney. The urinary system regulates water and electrolyte balance and removes nitrogenous wastes from the body.
The liver is the largest gland in the body located under the right rib cage. It is divided into four lobes and has two surfaces - a diaphragmatic surface and a visceral surface. The porta hepatis contains the hepatic artery, portal vein and hepatic ducts. Blood flows into the liver through the hepatic artery and portal vein and exits through the hepatic veins. The gallbladder stores and concentrates bile produced by the liver. The biliary system consists of the hepatic ducts, cystic duct, common hepatic duct, gallbladder and common bile duct which empties into the duodenum.
Micturition is the process of urinating that involves two main steps - the bladder filling with urine until tension triggers the micturition reflex, causing the bladder to empty. This reflex is controlled by the spinal cord but can be inhibited or facilitated by the brain. The urinary bladder stores urine and empties through contraction of the detrusor muscle. Urine enters the bladder via the ureters and exits through the urethra. The micturition reflex maintains control of urination but damage to nerves can cause abnormalities like an atonic bladder with no control or an automatic bladder that empties without brain input.
The document provides an overview of the urinary system and its components. It describes the nephron as the functional unit of the kidney, including the glomerulus, proximal and distal convoluted tubules, and loop of Henle. It also discusses podocytes forming filtration slits in the renal corpuscle and mesangial cells cleaning the filter. Finally, it briefly mentions the collecting ducts, ureter, and transitional epithelia of the urinary bladder.
The document summarizes the histology of the liver. It describes the liver's location, vascular supply from the hepatic portal vein and hepatic artery, and histological structure. The liver structure consists of connective tissue capsule, trabeculae that branch into the interior, and reticular fibers that support endothelial cells lining hepatic sinusoids. The liver parenchyma is organized into thousands of hepatic lobules centered around a central vein and containing hepatocytes radiating in plates.
This document discusses renal physiology, including renal blood flow, oxygen consumption, regulation of blood flow, glomerular filtration, and factors affecting glomerular filtration rate (GFR). Some key points:
- Renal blood flow is approximately 1/4 of cardiac output, or 1200 ml/min. Blood flow to the cortex is higher than to the medulla.
- Glomerular filtration is determined by the net filtration pressure and filtration coefficient. Forces increasing filtration are glomerular hydrostatic pressure and oncotic pressure in Bowman's space. Forces decreasing filtration are plasma oncotic pressure and hydrostatic pressure in Bowman's space.
- GFR is regulated through autoregulation mechanisms like tub
The kidney has several important functions including regulating blood pressure, fluid balance, and blood pH. The basic structural and functional unit of the kidney is the nephron, which filters blood to form urine. Each nephron contains a glomerulus for blood filtration and tubules (proximal tubule, loop of Henle, distal tubule, collecting duct) for reabsorption and secretion. Filtration occurs due to blood pressure gradients, with most filtrate reabsorbed along the nephron. The kidneys also produce hormones like renin, prostaglandins, and erythropoietin to help regulate blood pressure, red blood cell production, and other processes.
The urinary system consists of the kidneys, ureters, bladder, and urethra. The kidneys filter the blood to remove wastes and produce urine. The functional unit of the kidney is the nephron, which contains the glomerulus that filters the blood and Bowman's capsule. The kidneys regulate fluid balance and blood pressure through hormones like antidiuretic hormone and renin. The bladder stores urine and its transitional epithelium and rugae allow it to expand as it fills. The urethra then carries urine from the bladder out of the body.
The document discusses the functions of the juxtaglomerular apparatus and hormonal control in the urinary system. It describes the juxtaglomerular apparatus as a specialized structure located where the distal tubule contacts the renal corpuscle. It regulates renal functions through the renin-angiotensin-aldosterone system and vasopressin response to osmolarity levels which control water retention and excretion. These systems work together to maintain fluid and electrolyte balance.
The nervous system can be divided into the central nervous system (CNS) and peripheral nervous system (PNS). The CNS consists of the brain and spinal cord and is responsible for integrating sensory information and coordinating motor commands. The PNS has two parts - the cerebrospinal part made up of cranial and spinal nerves, and the autonomic nervous system. There are two main cell types in the nervous system - neurons, which transmit signals, and neuroglia, which provide support and insulation. The autonomic nervous system has two divisions - the parasympathetic and sympathetic systems, which work in opposition to activate "rest and digest" and "fight or flight" responses respectively.
This document provides an overview of kidney function and regulation as well as methods for studying renal function. It discusses three components of autoregulation of the kidneys: tubuloglomerular feedback, glomerulotubular balance, and pressure diuresis. It also summarizes the role of the kidneys in regulating osmolarity and volume, sodium regulation, potassium regulation, and calcium regulation. Finally, it outlines various methods for studying renal function, including determining clearance rates and the use of microperfusion and patch-clamp techniques.
The urinary system functions to filter waste from the blood and regulate fluid levels. The kidneys contain nephrons, which are the functional filtering units. Each nephron contains a renal corpuscle with glomerulus for blood filtration, and a renal tubule for reabsorption and secretion. Filtrate passes through the glomerulus and along the tubule, where it is modified before collection in the ureters and storage in the bladder for excretion. The juxtaglomerular apparatus regulates blood pressure and fluid balance.
The urinary system consists of the kidneys, ureters, urinary bladder, and urethra. The kidneys filter the blood and produce urine, which travels through the ureters into the bladder. When the bladder fills, urine is excreted through the urethra. The kidneys regulate water and ion levels in the blood and remove wastes via specialized nephrons that filter the blood, reabsorb necessary components, and produce urine for excretion.
The basics of autoregulation of Gloemrular filtration rate. This ppt deals with basic renal physiology, tubuloglomerular feedback, myogenic reflex, juxtaglomerular apparatus and renin angiotensin aldosterone system in brief. P.S.- The ppt has animations so kindly view in slide/presentation mode
The renal system consists of the kidneys and urinary bladder. The kidneys play a vital role in maintaining fluid balance and composition in the body, regulating the internal environment. The kidneys are composed of nephrons which filter blood, reabsorbing necessary substances and secreting waste products to produce urine. Urine is stored in the bladder and emptied during micturition.
The urinary system consists of two kidneys, two ureters, one urinary bladder, and one urethra. The kidneys filter wastes from the blood and regulate fluid and electrolyte balance. Each kidney contains over a million nephrons, the functional units that filter blood in the glomerulus and reabsorb useful substances along the renal tubules. The kidneys secrete urine that travels through ureters to the bladder, where it is temporarily stored then expelled through the urethra. The urinary system plays critical roles in homeostasis by filtering wastes and regulating water, electrolyte, and acid-base balance.
The kidneys are paired organs located in the abdominal cavity. Each kidney has an outer renal cortex and inner renal medulla. Within these regions are over 1 million microscopic filtration units called nephrons. Nephrons contain a renal corpuscle for blood filtration and a renal tubule for fluid processing. Processed fluid drains into collecting ducts and exits the kidneys as urine through the ureters. The kidneys are supplied with blood from the renal arteries and are surrounded by protective layers of tissue.
The urinary system consists of the kidneys, ureters, urinary bladder, and urethra. The kidneys filter waste from the blood to produce urine. Each kidney contains approximately 1 million nephrons, the functional units that filter blood. The kidneys regulate fluid and mineral balance, produce hormones, and remove wastes from the body. When the kidneys fail to function, renal replacement therapies such as hemodialysis, peritoneal dialysis, or kidney transplantation are needed.
The kidneys are paired retroperitoneal organs located on the posterior abdominal wall. Each kidney has an outer renal cortex and inner renal medulla divided into renal pyramids. The kidneys receive blood supply from the renal arteries which branch into segmental and lobar arteries before branching further. Blood exits via interlobar, arcuate and interlobular veins into the renal veins which drain into the inferior vena cava. The kidneys are surrounded by fibrous capsules and perirenal fat and have anterior relations to other abdominal organs and posterior relations to the vertebral column and muscles.
The kidney is bean-shaped and located retroperitoneally. It contains nephrons which filter blood to form urine. Each nephron contains a glomerulus for blood filtration and a tubule for urine transport. The kidneys also contain collecting ducts which drain urine from nephrons into the renal pelvis. Urine exits each kidney via the ureter and is stored in the bladder before exiting the body through the urethra.
The document summarizes key aspects of pancreatic function and disease. It discusses how the pancreas secretes enzymes and fluid to aid digestion. The two major hormones that regulate secretion are secretin and cholecystokinin. Acute pancreatitis can result from factors like gallstones, alcohol use, or hypertriglyceridemia and involves inflammation and damage to pancreatic tissue that can spread systemically. Chronic pancreatitis is characterized by irreversible pancreatic damage and can be caused by long-term alcohol use, genetic mutations, or recurrent acute pancreatitis. Laboratory tests of pancreatic enzymes and hormone stimulation help diagnose pancreatic disorders.
The urinary system consists of the kidneys, ureters, urinary bladder and urethra. The kidneys filter the blood to remove wastes and produce urine. The nephron is the functional unit of the kidney that filters blood and forms urine. Urine passes from the kidneys through the ureters into the bladder, and is then emptied through the urethra. Urine formation involves glomerular filtration, tubular reabsorption and secretion, and a countercurrent mechanism in the kidney. The urinary system regulates water and electrolyte balance and removes nitrogenous wastes from the body.
The liver is the largest gland in the body located under the right rib cage. It is divided into four lobes and has two surfaces - a diaphragmatic surface and a visceral surface. The porta hepatis contains the hepatic artery, portal vein and hepatic ducts. Blood flows into the liver through the hepatic artery and portal vein and exits through the hepatic veins. The gallbladder stores and concentrates bile produced by the liver. The biliary system consists of the hepatic ducts, cystic duct, common hepatic duct, gallbladder and common bile duct which empties into the duodenum.
Micturition is the process of urinating that involves two main steps - the bladder filling with urine until tension triggers the micturition reflex, causing the bladder to empty. This reflex is controlled by the spinal cord but can be inhibited or facilitated by the brain. The urinary bladder stores urine and empties through contraction of the detrusor muscle. Urine enters the bladder via the ureters and exits through the urethra. The micturition reflex maintains control of urination but damage to nerves can cause abnormalities like an atonic bladder with no control or an automatic bladder that empties without brain input.
The document provides an overview of the urinary system and its components. It describes the nephron as the functional unit of the kidney, including the glomerulus, proximal and distal convoluted tubules, and loop of Henle. It also discusses podocytes forming filtration slits in the renal corpuscle and mesangial cells cleaning the filter. Finally, it briefly mentions the collecting ducts, ureter, and transitional epithelia of the urinary bladder.
The document summarizes the histology of the liver. It describes the liver's location, vascular supply from the hepatic portal vein and hepatic artery, and histological structure. The liver structure consists of connective tissue capsule, trabeculae that branch into the interior, and reticular fibers that support endothelial cells lining hepatic sinusoids. The liver parenchyma is organized into thousands of hepatic lobules centered around a central vein and containing hepatocytes radiating in plates.
This document discusses renal physiology, including renal blood flow, oxygen consumption, regulation of blood flow, glomerular filtration, and factors affecting glomerular filtration rate (GFR). Some key points:
- Renal blood flow is approximately 1/4 of cardiac output, or 1200 ml/min. Blood flow to the cortex is higher than to the medulla.
- Glomerular filtration is determined by the net filtration pressure and filtration coefficient. Forces increasing filtration are glomerular hydrostatic pressure and oncotic pressure in Bowman's space. Forces decreasing filtration are plasma oncotic pressure and hydrostatic pressure in Bowman's space.
- GFR is regulated through autoregulation mechanisms like tub
The kidney has several important functions including regulating blood pressure, fluid balance, and blood pH. The basic structural and functional unit of the kidney is the nephron, which filters blood to form urine. Each nephron contains a glomerulus for blood filtration and tubules (proximal tubule, loop of Henle, distal tubule, collecting duct) for reabsorption and secretion. Filtration occurs due to blood pressure gradients, with most filtrate reabsorbed along the nephron. The kidneys also produce hormones like renin, prostaglandins, and erythropoietin to help regulate blood pressure, red blood cell production, and other processes.
The urinary system consists of the kidneys, ureters, bladder, and urethra. The kidneys filter the blood to remove wastes and produce urine. The functional unit of the kidney is the nephron, which contains the glomerulus that filters the blood and Bowman's capsule. The kidneys regulate fluid balance and blood pressure through hormones like antidiuretic hormone and renin. The bladder stores urine and its transitional epithelium and rugae allow it to expand as it fills. The urethra then carries urine from the bladder out of the body.
The document discusses the functions of the juxtaglomerular apparatus and hormonal control in the urinary system. It describes the juxtaglomerular apparatus as a specialized structure located where the distal tubule contacts the renal corpuscle. It regulates renal functions through the renin-angiotensin-aldosterone system and vasopressin response to osmolarity levels which control water retention and excretion. These systems work together to maintain fluid and electrolyte balance.
The nervous system can be divided into the central nervous system (CNS) and peripheral nervous system (PNS). The CNS consists of the brain and spinal cord and is responsible for integrating sensory information and coordinating motor commands. The PNS has two parts - the cerebrospinal part made up of cranial and spinal nerves, and the autonomic nervous system. There are two main cell types in the nervous system - neurons, which transmit signals, and neuroglia, which provide support and insulation. The autonomic nervous system has two divisions - the parasympathetic and sympathetic systems, which work in opposition to activate "rest and digest" and "fight or flight" responses respectively.
This document provides an overview of kidney function and regulation as well as methods for studying renal function. It discusses three components of autoregulation of the kidneys: tubuloglomerular feedback, glomerulotubular balance, and pressure diuresis. It also summarizes the role of the kidneys in regulating osmolarity and volume, sodium regulation, potassium regulation, and calcium regulation. Finally, it outlines various methods for studying renal function, including determining clearance rates and the use of microperfusion and patch-clamp techniques.
The urinary system functions to filter waste from the blood and regulate fluid levels. The kidneys contain nephrons, which are the functional filtering units. Each nephron contains a renal corpuscle with glomerulus for blood filtration, and a renal tubule for reabsorption and secretion. Filtrate passes through the glomerulus and along the tubule, where it is modified before collection in the ureters and storage in the bladder for excretion. The juxtaglomerular apparatus regulates blood pressure and fluid balance.
The urinary system consists of the kidneys, ureters, urinary bladder, and urethra. The kidneys filter the blood and produce urine, which travels through the ureters into the bladder. When the bladder fills, urine is excreted through the urethra. The kidneys regulate water and ion levels in the blood and remove wastes via specialized nephrons that filter the blood, reabsorb necessary components, and produce urine for excretion.
The urinary system consists of the kidneys, ureters, bladder, and urethra. The kidneys filter the blood to form urine and are located retroperitoneally near the waist. Each kidney contains around 1 million nephrons, the functional filtering units. Nephrons have a glomerulus for blood filtration and a renal tubule for modifying the filtrate. Filtration occurs across the glomerular membrane due to starling forces and is regulated to maintain homeostasis. The modified filtrate becomes urine and is transported through the ureters to the bladder for storage and eventual excretion.
The kidneys filter 180 liters of blood daily, regulating water, electrolyte, acid-base balance and excreting wastes. Each kidney contains about 1 million nephrons, each with a renal corpuscle that filters blood and renal tubule that modifies the filtrate into urine. The nephron is composed of a glomerulus for blood filtration, Bowman's capsule, proximal tubule, loop of Henle, distal tubule and collecting duct. Specialized cells regulate filtration, reabsorption and secretion to produce concentrated urine.
The kidneys filter 180 liters of blood daily, regulating water, electrolyte, acid-base balance and excreting wastes. Each kidney contains about 1 million nephrons, each with a renal corpuscle that filters blood and renal tubule that modifies the filtrate into urine. The nephron is composed of a glomerulus for blood filtration, Bowman's capsule, proximal tubule, loop of Henle, distal tubule and collecting duct. Specialized cells in different nephron segments reabsorb essential molecules while selectively excreting wastes to produce urine, which travels through the urinary tract for excretion from the body.
The urinary system maintains homeostasis by filtering the blood and producing urine. It is composed of the kidneys, ureters, urinary bladder, and urethra. The kidneys filter waste from the blood to produce urine, which travels through the ureters to the bladder. The bladder stores urine until urination, when it is expelled through the urethra. Together these organs excrete waste from the body while regulating water balance and electrolyte levels in tissues and blood.
The urinary system includes the kidneys, ureters, urinary bladder, and urethra. The kidneys filter waste from the blood to produce urine. Each kidney contains approximately 1 million nephrons, the functional units that filter the blood. Urine passes from the nephrons through the renal medulla and pelvis into the ureters. The ureters carry urine from the kidneys to the urinary bladder, where it is stored until excretion through the urethra.
The urinary system, also known as the renal system or urinary tract, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, control levels of electrolytes and metabolites, and regulate blood pH.
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The document provides an overview of the urinary system anatomy and function. It lists the main organs of the urinary system as the kidneys, ureters, bladder, and urethra. It describes the location of the kidneys and discusses the nephrons as the functional units of the kidney. It also summarizes key processes in the nephron including filtration, reabsorption, and concentration of urine.
This document provides an overview of the renal (urinary) system, including its organs and their functions. It describes the internal and microscopic anatomy of the kidneys, including the structures within the kidneys like the renal capsule, renal fascia, and nephrons. It explains the structures and functions of nephrons, including glomerular filtration, reabsorption, and regulation of electrolytes and pH. It also discusses common kidney problems like kidney stones and their treatment options. Overall, the document concisely summarizes the key anatomical structures and physiological functions of the urinary system.
Urinary system
a) Anatomy and physiology of urinary system
b) Formation of urine
c) Renin Angiotensin system – Juxtaglomerular apparatus - acid base Balance
d) Clearance tests and micturition
The urinary system removes waste from the body via the kidneys, ureters, bladder, and urethra. The kidneys filter blood to form urine via nephrons, which consist of a renal corpuscle and renal tubule. Urine passes from nephrons to the renal pelvis and ureters into the bladder, then exits via the urethra. The kidneys also regulate electrolytes and blood pressure by producing hormones like erythropoietin and renin.
The urinary system removes waste from the body via the kidneys, ureters, bladder, and urethra. The kidneys filter blood to form urine via nephrons, which consist of a renal corpuscle and renal tubule. Urine passes from nephrons to the renal pelvis and ureters into the bladder, then exits via the urethra. The kidneys also regulate electrolytes and blood pressure by producing hormones like erythropoietin and renin.
The kidneys are two bean-shaped organs located on either side of the spine. They perform several important functions such as regulating blood composition, removing waste and toxins from the body through urine, regulating blood pressure, and maintaining calcium levels. The kidneys contain over a million nephrons which filter the blood and make changes to regulate its composition. The kidneys have an outer cortex containing nephrons and blood vessels, and a inner medulla containing renal pyramids and collecting ducts which drain into the renal pelvis and ureters that carry urine to the bladder.
The document summarizes the structure and function of the urinary system. It describes how the kidneys filter waste from the bloodstream and regulate fluid and electrolyte balance through millions of nephrons. Urine is transported from the kidneys to the bladder via ureters. The bladder stores urine temporarily before it is emptied through the urethra. Together, these organs work to eliminate waste from the body while maintaining homeostasis.
The document summarizes renal physiology and kidney function. The kidney maintains homeostasis by precisely regulating the balance of water, electrolytes, and other substances in the body through filtration, reabsorption, and secretion. Key functions include regulating fluid volume and composition, electrolyte levels, and excretion of wastes while conserving essential nutrients. These processes occur along the functional units of the kidney called nephrons.
The urinary system consists of paired kidneys, ureters, a urinary bladder, and a urethra. The kidneys filter the blood to remove wastes and excess water, which are collected in the bladder via the ureters. When full, the bladder contracts to expel urine through the urethra. Each kidney contains millions of nephrons, the functional units that filter the blood, reabsorb necessary molecules, and secrete wastes into the urine. The collected urine is concentrated in the kidneys before exiting through the ureters into the bladder for storage and eventual expulsion.
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Local Advanced Lung Cancer: Artificial Intelligence, Synergetics, Complex Sys...Oleg Kshivets
Overall life span (LS) was 1671.7±1721.6 days and cumulative 5YS reached 62.4%, 10 years – 50.4%, 20 years – 44.6%. 94 LCP lived more than 5 years without cancer (LS=2958.6±1723.6 days), 22 – more than 10 years (LS=5571±1841.8 days). 67 LCP died because of LC (LS=471.9±344 days). AT significantly improved 5YS (68% vs. 53.7%) (P=0.028 by log-rank test). Cox modeling displayed that 5YS of LCP significantly depended on: N0-N12, T3-4, blood cell circuit, cell ratio factors (ratio between cancer cells-CC and blood cells subpopulations), LC cell dynamics, recalcification time, heparin tolerance, prothrombin index, protein, AT, procedure type (P=0.000-0.031). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and N0-12 (rank=1), thrombocytes/CC (rank=2), segmented neutrophils/CC (3), eosinophils/CC (4), erythrocytes/CC (5), healthy cells/CC (6), lymphocytes/CC (7), stick neutrophils/CC (8), leucocytes/CC (9), monocytes/CC (10). Correct prediction of 5YS was 100% by neural networks computing (error=0.000; area under ROC curve=1.0).
Cell Therapy Expansion and Challenges in Autoimmune DiseaseHealth Advances
There is increasing confidence that cell therapies will soon play a role in the treatment of autoimmune disorders, but the extent of this impact remains to be seen. Early readouts on autologous CAR-Ts in lupus are encouraging, but manufacturing and cost limitations are likely to restrict access to highly refractory patients. Allogeneic CAR-Ts have the potential to broaden access to earlier lines of treatment due to their inherent cost benefits, however they will need to demonstrate comparable or improved efficacy to established modalities.
In addition to infrastructure and capacity constraints, CAR-Ts face a very different risk-benefit dynamic in autoimmune compared to oncology, highlighting the need for tolerable therapies with low adverse event risk. CAR-NK and Treg-based therapies are also being developed in certain autoimmune disorders and may demonstrate favorable safety profiles. Several novel non-cell therapies such as bispecific antibodies, nanobodies, and RNAi drugs, may also offer future alternative competitive solutions with variable value propositions.
Widespread adoption of cell therapies will not only require strong efficacy and safety data, but also adapted pricing and access strategies. At oncology-based price points, CAR-Ts are unlikely to achieve broad market access in autoimmune disorders, with eligible patient populations that are potentially orders of magnitude greater than the number of currently addressable cancer patients. Developers have made strides towards reducing cell therapy COGS while improving manufacturing efficiency, but payors will inevitably restrict access until more sustainable pricing is achieved.
Despite these headwinds, industry leaders and investors remain confident that cell therapies are poised to address significant unmet need in patients suffering from autoimmune disorders. However, the extent of this impact on the treatment landscape remains to be seen, as the industry rapidly approaches an inflection point.
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These lecture slides, by Dr Sidra Arshad, offer a quick overview of the physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar lead (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
6. Describe the flow of current around the heart during the cardiac cycle
7. Discuss the placement and polarity of the leads of electrocardiograph
8. Describe the normal electrocardiograms recorded from the limb leads and explain the physiological basis of the different records that are obtained
9. Define mean electrical vector (axis) of the heart and give the normal range
10. Define the mean QRS vector
11. Describe the axes of leads (hexagonal reference system)
12. Comprehend the vectorial analysis of the normal ECG
13. Determine the mean electrical axis of the ventricular QRS and appreciate the mean axis deviation
14. Explain the concepts of current of injury, J point, and their significance
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. Chapter 3, Cardiology Explained, https://www.ncbi.nlm.nih.gov/books/NBK2214/
7. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
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Integrating Ayurveda into Parkinson’s Management: A Holistic ApproachAyurveda ForAll
Explore the benefits of combining Ayurveda with conventional Parkinson's treatments. Learn how a holistic approach can manage symptoms, enhance well-being, and balance body energies. Discover the steps to safely integrate Ayurvedic practices into your Parkinson’s care plan, including expert guidance on diet, herbal remedies, and lifestyle modifications.
share - Lions, tigers, AI and health misinformation, oh my!.pptxTina Purnat
• Pitfalls and pivots needed to use AI effectively in public health
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- Video recording of this lecture in English language: https://youtu.be/kqbnxVAZs-0
- Video recording of this lecture in Arabic language: https://youtu.be/SINlygW1Mpc
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
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2. 2
Organs of The
Urinary System
Adrenal gland
Kidney
Ureter
Urinary bladder
Urethra
Renal artery and vein
The urinary bladder stores urine prior to micturition, the urethra expels urine
from the bladder, the ureters bring
urine to the bladder. But the function of the kidneys is NOT to make urine, it
is to maintain homeostasis of the
blood: excreting wastes, keeping nutrients, maintaining electrolytes, acid
base balance, and other things.
3. 3
Structure of the Kidney
Pyramid
Cortex Ureter
Renal pelvis
Calyx
Renal
column
Medulla
}
Papilla
The kidney is composed of several layers and is covered with a fibrous
capsule, the renal capsule. The outer layer of the kidney is the cortex. It
contains the major (upper) portion of the nephrons. The middle layer of the
kidney is the medulla. It is composed of the triangular shaped pyramids and
the renal columns. The pyramids contain the collecting tubules and loops of
Henle, the lower portion of the nephrons. These tubules run nearly parallel to
one another and give the pyramids a grain which leads to their points or
papillae. The renal columns are regions between the pyramids in which
blood vessels run to and from the cortex. The papilla of each pyramid
projects into a funnel-shaped area known as the calyx. The calyces (plural of
calyx) collect the urine released from the papillae and allow it to drain into a
large area known as the renal pelvis and then into the ureter.
5. 5
Kidney
Vascularization
Renal vein
Renal
artery
Lobar artery
and vein
Interlobar artery
and vein
Arcuate artery
and vein
Interlobular artery
and vein
12
3
4
5
Segmental artery
The blood supply of the kidney is paramount in its function. The two kidneys
receive between 15 and 20% of the body's systemic blood flow at rest. The
renal artery branches into lobar and then interlobar arteries. These pass
through the renal columns toward the cortex. Arcuate arteries branch into
the cortex and lead to interlobular arteries which distribute the blood evenly
throughout the cortex to the afferent arterioles which serve the nephrons.
Blood flow leaving the nephrons returns by veins of the corresponding
names.
6. 6
Normal Human
Kidney
Renal cyst
Fetal lobules
Here is a normal adult kidney. The capsule has been removed and a pattern
of fetal lobules still persists, as it sometimes does. The hilus at the mid left
contains some adipose tissue. At the lower right is a smooth-surfaced, small,
clear fluid-filled simple renal cyst. Such cysts occur either singly or scattered
around the renal parenchyma and are not uncommon in adults. Only when
cysts are large and extensive do they have the potential to interfere with
kidney structure and function.
7. 7
Kidney Section
cortex pyramid Renal columncalyx
In a sectioned human kidney can easily be seen the regions shown in
previous slides. Much of the hilus (notch) of the kidney is filled with the fat,
the yellowish tissue.
8. 8
Medulla
Cortex
Nephrons: Functional Units of the Kidneys
The Nephron: - The nephrons are the functional units of the kidney, i.e.
individually and collectively they perform the functions of the kidney. Use this
unlabeled nephron diagram to label and describe its various functions.
9. 9
Functional Nephron Diagram
Structure and Function of the Nephron
Blood flow from
Interlobular art.
Afferent
arteriole
visceral layer
parietal layer
}capsular space
Bowman’s
capsule
distal convoluted
tubule
proximal convoluted
tubule
loop
of
Henle
asc.
limbdesc.
limb
glomerulus
Vasa recta
1
2
2 2
2
2
3 3
Efferent
arteriole
Glu
a.a.
NaCl
H2O
H2O
H2O
NaClNaCl
NaCl
NaCl H+
NH4+
Cl-
K+
Medulla
Cortex
Hypertonic Hypertonic
1 = Filtration -
Pressure forces
water and
dissolved
substances
from
glomerular
blood into
Bowman=s
capsule.
Amounts to 125
ml/min.
2 = Reabsorption -
The return of
substances from
the filtrate to the
blood and
interstitial fluid.
Water by osmosis;
NaCl, glucose, and
amino acids by
active transport
3 = Secretion - The active release of
substances by the tubular lining cells into
the nephron tubule. (A) Gets rid of
toxins and residues, (B) electrolyte
balance, mostly releasing K+, (C) acid
base balance by releasing H+, NH4
+.
HCO3
-
Cl-
Peritubular cap
Vascular
pole
DCT location in
Juxtaglomerular
Apparatus
The nephrons are the functional units of the kidney. They consist of a
number of specific parts which we will
discuss. Nephrons are microscopic, and there are up to a million in your two
kidneys. This diagram
summarizes the parts and functions of the nephrons. We will elucidate each.
See also [Nephron Diagram]
[Bare Nephron] [Functional Nephron] [Test Nephron]
10. 10
glomerulus
Efferent
arteriole
Afferent arteriole
Structure of the Nephron: the Glomerulus
Capillary tuft with
fenestrated
capillaries
Capillary tuft with
fenestrated
capillaries
Each nephron is served with blood by the afferent arteriole. This vessel
brings blood into a capillary tuft called the glomerulus. Blood leaving the
glomerulus flows into the efferent arteriole.
11. 11
glomerulus
Efferent
arteriole
Afferent
arteriole Parietal layer
Visceral layer
Capsular space
}Bowman’s
capsule
Structure of the Nephron: Bowman’s Capsule
A capillary tuft differs from a capillary bed in that it does not perfuse a tissue
like a capillary bed does. Instead this capillary tuft is a condensed mass of
capillaries which allows substances to escape by filtration. The capillaries of
this tuft are surrounded by specialized cells which form the inner (visceral)
layer of Bowman's capsule. The parietal layer is composed of simple
squamous cells with tight junctions that form an outer wall which contains the
filtrate.
12. 12
glomerulus
Efferent
arteriole
Afferent
arteriole
Bowman’s
capsule
Proximal
convoluted
tubule
Distal
convoluted
tubule
Loop of Henle
Descending limb Ascending limb
Collecting tube
(duct)
Structure of the Nephron: Tubules
The Bowman's capsule opens into the proximal convoluted tubule which
leads to the loop of Henle. The loop of Henle has a descending limb
which passes into the medulla, recurves, and becomes the ascending limb
which leads back up to the distal convoluted tubule in the cortex. Most
human nephrons are termed cortical nephrons because their corpuscles are
located in the mid to outer cortex and their loops of Henle are very short and
pass only into the outer medulla. But a small portion are called
juxtamedullary nephrons and their loops travel deep into the inner
medulla. These nephrons are important in concentrating the urine by
increasing the amount of water reabsorbed. Distal convoluted tubules lead
into collecting tubules and ducts which pass through the medullary pyramids
to the papillae. See [Orientation of the Nephron] diagram.
14. 14
Nephron Vasculature
Cortical Nephron
Juxtamedullary nephron
Cortex
Medulla
Peritubular
capillaries
Vasa recta
Convoluted
tubules
Convoluted
tubules
Collecting tube
Loop of Henle
Loop of Henle
Long-looped
nephrons are a
small minority in
human kidneys,
but they are
important in
concentrating the
urine.
Long-looped
nephrons are a
small minority in
human kidneys,
but they are
important in
concentrating the
urine.
Cortical nephrons have short loops of Henle which barely enter the medulla.
Longer loops which dip much further into the medulla belong to
juxtamedullary nephrons. These nephrons are important for concentrating
the urine by absorbing extra water.
15. 15
glomerulus
Efferent
arteriole
Afferent
arteriole
Bowman’s
capsule
Proximal
convoluted
tubule
Distal convoluted
tubule
Loop
of
Henle
Ascending limb
Collecting tube
Descending limb
Vasa recta
Peritubular
capillaries
11
Cortex
Medulla
Step 1: Filtration
Step 1 in urine formation, Filtration - Fluid pressure forces water and
dissolved substances out of the blood into Bowman's capsule. Filtration
averages 125 ml/min for your two kidneys. This amounts to about 180 Liters
per day. Since we urinate an average of 1500 ml per day, more than 99%
must be returned to the blood. Filtration involves the small molecules: water,
electrolytes, urea, glucose, amino acids. It does not involve the blood
proteins or cells. The large amount of filtration is the result of the porous
glomerular membrane and filtration slits in the visceral layer of Bowman's
capsule.
16. 16
1. Filtration
Filtration – Hydrostatic pressure (blood pressure) forces
water and dissolved substances out of the glomerular blood
into Bowman’s capsule.
H2O, glucose, amino acids, electrolytes, wastes
Averages 125 ml/min for both kidneys 180 liters/day
The vast majority of the filtrate must be taken back!
Filtration is a product of the blood pressure and the nature of the fenestrated
capillaries which make up the glomerulus.
17. 17
The Glomerulus and Bowman’s Capsule
Fenestrated
capillaries
Outer
parietal layer
of Bowman’s
capsule
Inner
visceral layer
of Bowman’s
capsule
Podocyte
pedicels
Filtration slits
The capillaries of the glomerulus are surrounded by specialized cells which
form the inner (visceral) layer of Bowman's capsule. (See Figures 26.7 and
26.8)These specialized cells are called podocytes (foot cells) because they
have processes called pedicels which interdigitate or interlace producing
openings called filtration slits. The capillaries are fenestrated in order to
allow a large amount of filtration. The outer (parietal) layer of Bowman's
capsule consists of epithelial cells with tight junctions and serves to contain
the filtrate in the capsular space.
18. 18
The Filtration Membrane
Fenestration
Endothelial cell Basement membranes
Water, ions, and
small molecules in
glomerular plasma
Podocyte
Filtration slits
Filtrate in
capsular space
The filtration membrane is a double layered membrane composed of the
endothelial cells of the capillary wall juxtaposed with the podocytes of the
visceral layer of Bowman’s capsule. Substances make their way through the
capillary fenestrations, then through the combined basement membranes of
capillary and podocyte cells, and through the filtration slits into the capsular
space.
19. 19
Step 2: Reabsorption
H2O - osmosis
NaCl - active transport
Glucose, amino acids - active co-transport
Reabsorption – the return of substances from
filtrate in the nephron tubule to the blood or
interstitial fluid.
Step 2, Reabsorption - The return of substances from the filtrate to the blood and
interstitial fluid. The major substances reabsorbed are water, NaCl, glucose, and
amino acids. Some of the urea, together with other salts are also reabsorbed.
20. 20
Locations of Reabsorption
glomerulus
Efferent
arteriole
Afferent
arteriole
Bowman’s
capsule
Proximal
convoluted
tubule
Distal convoluted
tubule
Loop
of
Henle
Ascending limb
Collecting tube
Descending limb
Vasa recta
Peritubular
capillaries
22
22 22 22
22
Reabsorption occurs in each of these areas for various substances and to
various degrees: Most reabsorption occurs in the PCT (Proximal
Convoluted Tubule), but reabsorption of water also occurs from the
descending limb of the Loop of Henle, reabsorption of salt from the
ascending limb and the DCT (Distal Convoluted Tubule), and more water
from the Collecting Duct.
21. 21
Reabsorption
from Proximal Convoluted Tubule
NaCl
B) NaCl – active transport of either Na+ or Cl-, pulls
water along.
Glucose
C) 100% of glucose and amino acid transported -
occurs in PCT by active co-transport.
H2O
A) H20 – pulled by osmosis into hypertonic blood.
65% occurs in PCT
Water is reabsorbed by osmosis. Entering the proximal convoluted tubule the
filtrate is very dilute compared to the blood. 65% of water reabsorption occurs from
the PCT as a result of this osmotic gradient.
22. 22
Reabsorption from Loop of Henle
PCT DCT
Descending limb Ascending limb
Active reabsorption of NaCl from the ascending limb
causes osmosis of H2O from the descending limb by
making the medulla hypertonic.
NaClH2O
Hypertonic medulla
As the filtrate enters the descending limb of the loop of Henle, especially in
juxtamedullary nephrons with long loops, it is exposed to increasingly hypertonic
medulla. This pulls at least another 20% of absorbable water out of the filtrate.
Reabsorption in this area is termed obligatory because it must occur due to the
osmolarity of the surrounding interstitial fluid.
23. 23
The Counter-Current Mechanisms
1) The counter-current multiplier – increases the
amount of H2O reabsorbed because of opposite
movement in the two limbs of the loop of Henle.
The Countercurrent Multiplier - This mechanism works in the loop of Henle to
increase water reabsorbed from the descending limb as a result of salt
reabsorbed from the ascending limb. The term countercurrent comes from
the fact that fluid is moving in opposite directions in the two limbs of the loop.
This magnifies the effect of transport from one limb on transport from the
other limb. The same principle is at work in heat exchangers used in
industry.
24. 24
The Counter-Current Multiplier
Descending limb
Hypertonic medulla
NaCl absorbed from
the ascending limb
pulls more water from
the descending limb
than it would if their
fluid were passing in
the same direction.
H2O NaCl
Ascending limb
The nephron tubule is
impermeable to water from the
thin segment of the ascending
limb to the collecting tube, thus
preventing reabsorbed water
from escaping into the urine.
The nephron tubule is
impermeable to water from the
thin segment of the ascending
limb to the collecting tube, thus
preventing reabsorbed water
from escaping into the urine.
As the filtrate enters the thin segment of the ascending limb the tubule
becomes impermeable to water. Otherwise it might actually diffuse back into
the tubule as the osmotic gradient reverses
25. 25
The Counter-Current Mechanisms
1) The counter-current multiplier – increases the
amount of H2O reabsorbed because of opposite
movement in the two limbs of the loop of Henle.
2) The countercurrent exchange of salt –
increases the reabsorption of H2O by retaining
NaCl in the medulla.
The countercurrent exchange of salt in the vasa recta. The vasa recta has
descending and ascending limbs too. Blood flowing into the medulla in the
descending limb picks up salt from the hypertonic medulla. As the
surrounding medullary fluid becomes more and more salty toward the papilla
the gradient increases and more and more salt is picked up by the
descending vasa recta limb. But as the blood heads back up to the cortex in
the ascending limb of the vasa recta, the interstitial fluid becomes less and
less salty. This causes the gradient to reverse and salt diffuses back out of
the vasa recta into the medulla. This helps to conserve salt and keep the
medulla hypertonic.
26. 26
Countercurrent Exchange of Salt
Descending limb
Vasa recta
Ascending limb
NaCl More
hypertonic
Less
hypertonic
NaCl
2) NaCl is
released
back into
the medulla
from the
ascending
limb of the
vasa recta.
2) NaCl is
released
back into
the medulla
from the
ascending
limb of the
vasa recta.
Outer medulla
Inner medulla
This mechanism recycles the salt and keeps
the deep medulla hypertonic
This mechanism recycles the salt and keeps
the deep medulla hypertonic
1) NaCl is
picked up by
the
descending
limb of the
vasa recta.
1) NaCl is
picked up by
the
descending
limb of the
vasa recta.
1) NaCl is picked up by the descending limb of the vasa recta. 2) NaCl is
released into the medulla by the
ascending limb of the vasa recta. This mechanism recycles the salt and
keeps the deep medulla hypertonic.
From the ascending limb of Henle’s loop through the distal convoluted tubule
the nephron is impermeable to
water. This prevents the reabsorbed water from being lost to the urine.
27. 27
Reabsorption of NaCl from DCT
PCT DCT
Descending limb Ascending limb
Reabsorption of NaCl from the distal convoluted tubule
is controlled by aldosterone from the adrenal cortex.
22
NaCl
Reabsorption of salt continues into the DCT under the control of the
hormone aldosterone. Aldosterone is one of a group of hormones from the
adrenal cortex called mineralcorticoids which regulate salt levels in the body.
28. 28
Facultative Reabsorption
of Water from the
Collecting Tube
DCT
Ascending limb
of Henle’s loop
Collecting tube
Hypertonic medulla
From the ascending limb
through the DCT the
tubule is nearly
impermeable to water,
thus little water moves
back into the filtrate.
From the ascending limb
through the DCT the
tubule is nearly
impermeable to water,
thus little water moves
back into the filtrate.
As filtrate in
the collecting
tube passes
through the
hypertonic
medulla water
reabsorption
again takes
place under
control of ADH
As filtrate in
the collecting
tube passes
through the
hypertonic
medulla water
reabsorption
again takes
place under
control of ADH
NaCl H2O
22
Anti-diuretic
Hormone (ADH)
from the posterior
pituitary makes the
collecting tube
permeable to
water.
When the filtrate, now nearly urine, passes through the medulla again in the
collecting tubule it is once again exposed to the hypertonicity of the deep
medulla. This has the potential to pull more water out by osmosis. But
reabsorption of water from the collecting tubule is facultative because it is
under control of the hormone ADH.
29. 29
Facultative Reabsorption of Water:
The ADH Mechanism
Blood
Osmolarity
Hypothalamus Posterior
Pituitary
Anti-Diuretic Hormone
Increased H2O
reabsorption from
the collecting tube
Negative feedback can
turn off ADH secretion
Drinking plain water dilutes the blood and turns off ADH secretion. To
avoid loss of water to urine drink isotonic saline solution (e.g. Gatorade)
Drinking plain water dilutes the blood and turns off ADH secretion. To
avoid loss of water to urine drink isotonic saline solution (e.g. Gatorade)
2o stimulus is decreased
blood volume and
pressure.
2o stimulus is decreased
blood volume and
pressure.
Reabsorption in the collecting tubule is controlled by a hormone from the
posterior pituitary gland known as ADH, anti-diuretic hormone. Actually
this hormone is released by nerve fibers coming from the hypothalamus
and stored in the pituitary. ADH is then released into the blood on command
of the hypothalamus. The hypothalamus responds to high blood osmolarity.
Increased osmolarity results from water loss and dehydration from sweating,
vomiting and the like, and from simply not taking in enough replacement
water. ADH allows water to be reabsorbed from the collecting tubule and not
leave the body with the urine. The water is reabsorbed by osmosis due to
medullary hypertonicity. Lack of ADH causes the production of a large
amount of dilute urine, a condition called diabetes insipidus.
30. 30
Step 3: Secretion
Secretion is the active release of substances into the
nephron tubule by the tubular lining cells.
Secretion is the release by active transport of substances into the filtrate. It
is accomplished by the tubular lining cells. The substances released are
usually derived from the blood in the peritubular capillaries. Actually
secretion has already been going on but it is the third process we consider. It
begins in the proximal convoluted tubule and continues in the distal
convoluted tubule and the collecting tube. It is done for three purposes:
1) to release any residues from toxins and drugs which haven't bee filtered;
2) to establish electrolyte balance. Since positive ions, namely sodium, are
reabsorbed, positive ions must be secreted in exchange. The first choice is
potassium, K+. In addition negative ions will be managed. This usually
means chloride, Cl-, will either be secreted or will diffuse down its
electrochemical gradient. Other anions may be available for release such as
sulfate, but certain ions will never be secreted. For example, bicarbonate will
always be retained to help manage the buffering capacity of blood.
3) acid - base balance. Usually this means getting rid of acid. The first
choice for this is H+. Hydrogen ions are derived from the reaction of carbon
dioxide and water, just as they are in the rbc and in stomach lining cells. The
reaction yields carbonic acid which dissociates into H+
and HCO3
-
as you've
already learned. The bicarbonate produced is retained for the buffer (as
mentioned above) and exchanged for chloride, called the chloride shift.
32. 32
Secreted Substances
Secretion is the active release of substances into the
nephron tubule by the tubular lining cells.
Toxins and drug residues.
Electrolyte balance: K+ exchanged for Na+
Acid-base balance: H+ , NH4
+
Cl- exchanged for HCO3
-
H+ are obtained from reaction of CO2 and water.
Bicarbonate ions are always kept in exchange for chloride.
H+ are obtained from reaction of CO2 and water.
Bicarbonate ions are always kept in exchange for chloride.
Hydrogen ions can be secreted during moderately acidic conditions, but
when you have more severe acidity they reach their limit, called the tubular
maximum. At that point they neutralize some of the H+
with NH2
and NH3
groups derived from certain amino acids. The result is ammonium ions, NH4
+
which are secreted during these more strongly acidic conditions. During
extreme acidity they can also secrete phosphoric acid.
Since the hydrogen ions and ammonium ions are also cations, less
potassium is secreted during acidic conditions as well. Since conserving
potassium may be important for many people, consuming liquids which are
acidic as well as contain potassium are important in supplying the needed
potassium and encouraging it to be retained by the body. Citrus juice,
although containing potassium, does not acidify the blood greatly, but
cranberry juice, grape juice, watermelon etc. work well. Cranberry juice also
acidifies the urine which can help discourage bacteria and some types of
kidney stones. Cranberry juice also reduces the adherence of bacteria onto
the walls of the urinary tract thus reducing urinary tract infections.
33. 33
Secreted
substances are
derived from the
blood and interstitial
fluid.
Conc.
gradient
Filtrate
A.T.
Tubular lining cells obtain substances for secretion which have diffused into
interstitial fluid from blood in the peritubular capillaries. Secretion is an active
process requiring ATP use by the tubular cells.
34. 34
Histology of the Nephron
Visceral layer podocytes
Capillary endothelium
Parietal layer
Proximal convoluted tubule
Loop of Henle thin segment cells
Thick segment and distal
convoluted tubule
Collecting duct cells
Proximal tubule cells have abundant mitochondria and microvilli for
extensive reabsorption and secretion. Thin
segment cells in descending limb are modified simple squamous epithelium
for reabsorption of water by
osmosis. Thick segment ascending limb and DCT cells are similar to PCT
but have fewer microvilli and
mitocondria - they also allow secretion and reabsorption but not as much as
in PCT. Collecting duct cells are
cuboidal and allow minor amounts of secretion and absorption.
35. 35
Red indicates the afferent arteriole where it enters the
glomerulus at the vascular pole. Yellow arrow indicates the
opening of the Bowman's capsuleBowman's capsule into the proximal
convoluted tubule.
Glomerular Structures
This is an unusual view of the glomerulus in which the actual afferent
arteriole can be seen. On the other side of the glomerulus is the opening
into the Proximal Convoluted Tubule (PCT). Also a small section of the
macula densa cells, mentioned in a later slide, is visible.
36. 36
Detailed Glomerular Structure
Detailed Glomerular Structure
Distal
convoluted
tubule
capillariesCapsular space
Visceral
layer
podocytes Parietal layer
of Bowman’s
Capsule
A detailed view of the glomerulus reveals the detailed structure of the
capillaries, Bowman’s capsule, podocytes, distal tubule and macula densa
cells.
37. 37
proximal convoluted tubule
with brush border
distal
convoluted
tubule
Convoluted Tubules
Note the structural difference between the cells of the proximal and distal
tubules. Proximal tubule cells are much more active in reabsorption and
secretion and are thicker and with brush border (microvilli) for surface area.
Distal cells are less active and are therefore thinner.
38. 38
Renal Medulla
Collecting
ducts
Vasa recta
In the medulla, the collecting tubes (ducts) and loops of Henle run parallel with one
another as they travel through the pyramids. Therefore these tubules appear
elongated when compared with those in the cortex. Also seen in the medulla are the
blood vessels of the vasa recta which surround the long loops of Henle from the
juxtamedullary nephrons.
39. 39
The macula densa (black) monitors the distal tubular fluid salt
concentration so that the juxtaglomerular apparatus can control
the filtration rate (via tubuloglomerular feedback).
The Macula Densa
Distal
convoluted
tubule
Glomerulus
The macula densa is a group of cells which are part of the distal convoluted
tubule where it comes into contact with the glomerulus at the juxta-
glomerular apparatus.
40. 40
Autoregulation:
(a.k.a. tubuloglomerular feedback)
Autoregulation of Glomerular Pressure and GFR –
mechanisms centered in the juxtaglomerular
apparatus which act to maintain normal glomerular
filtration rate and glomerular blood pressure.
The juxtaglomerular apparatus is a site where
the distal convoluted tubule, afferent arteriole,
and efferent arteriole of the nephron contact one
another.
41. 41
The Juxtaglomerular Apparatus (JGA)
PCT
Bowman’s capsule
Efferent
arteriole
Afferent arteriole
Macula
densa
cells
Juxtaglomerular
cells
Two types of cells are important in
the JGA: macula densa cells of the
distal convoluted tubule…
Two types of cells are important in
the JGA: macula densa cells of the
distal convoluted tubule…
Figure 26.7
… and juxtaglomerular cells
which surround both arterioles.
… and juxtaglomerular cells
which surround both arterioles.
Distal
convoluted
tubule
The juxtaglomerular apparatus is a place where the distal convoluted tubule
lies close to the glomerulus and to the afferent and efferent arterioles. Within
the JGA is a group of cells lining the distal tubule called the macula densa
cells. These cells monitor the rate of filtrate flow in the distal tubule, which is
directly related to the glomerular filtration rate (GFR) and the glomerular
pressure.
42. 42
Functions of the JGA Cells:
Macula densa cells sense the glomerular filtration rate via
the salt (Na+) concentration in the distal tubule.
Juxtaglomerular cells secrete renin into the blood
of the arterioles. They are modified smooth muscle
cells which can also vasoconstrict or vasodilate.
Macula densa cells basically sense the salt (Na+
) levels in the DCT.
Increased salt levels can mean the body is losing excess sodium. They can
also reflect reduced glomerular filtration rate.
43. 43
Response to GFR and
glomerular pressure
Juxtaglomerular
cells
Renin
angiotensin II angiotensin I angiotensinogen
ACE
Macula
densa cells
Vasodilation of
afferent arteriole
Vasoconstriction in
efferent arteriole
Neg. feedback
filtration rate
and/or Na+ in
DCT
glomerular pressure
Adrenal cortex aldosterone Na+ reabsorption
in DCT
1) The macula densa causes the juxtaglomerular cells lining the arterioles
to secrete renin. Renin acts as an enzyme to cause a substance already in
the blood, angiotensinogen, to undergo a structural change to become
angiotensin I, which is then converted to angiotensin II by angiotensin
converting enzyme. See [Angiotensin Converting Enzyme, ACE].
Angiotensin II acts as a vasoconstrictor, first causing vasoconstriction in the
efferent arteriole. Since the efferent arteriole is the outflow from the
glomerulus, constricting it rapidly raises glomerular pressure. Angiotensin II
also causes the adrenal cortex to release aldosterone. Aldosterone acts
on the distal convoluted tubule to increase Na+ reabsorption. More sodium
reabsorption means more water reabsorption, and more water reabsorption
means and increase in blood pressure.
2) The macula densa also acts directly on the afferent arteriole and cause it
to vasodilate. So at the same time the efferent arteriole is constricting, the
afferent arteriole is dilating bringing in more blood and the combination
dramatically raises glomerular pressure and GFR.
ACE = angiotensin converting enzyme. Some antihypertensive drugs use
ACE inhibitors to block production of
angiotensin II. Angiotensin II causes general peripheral vasoconstriction,
increasing overall blood pressure.
Reabsorption counteracts the original stimulus and increases overall blood
pressure due to water
reabsorption.
44. 44
Response to Glomerular Pressure
Myogenic response: high glomerular pressure in
the afferent arteriole causes the juxtaglomerular
cells, which are modified smooth muscle cells, to
constrict, reducing blood flow into the
glomerulus.
General vasoconstriction raises peripheral
blood pressure, but local vasoconstriction
reduces blood flow and pressure to the tissue.
General vasoconstriction raises peripheral
blood pressure, but local vasoconstriction
reduces blood flow and pressure to the tissue.
The only mechanism responsive to high blood pressure is the direct
myogenic autoregulation of the afferent arteriole. This vessel, like others in
the body, responds to high pressure with vasoconstriction. This reduces
blood flow into the glomerulus and brings GFR back down to normal levels.
This mechanism works only for transitory pressure increases and is not
effective against sustained hypertension.
45. 45
Effect of Sympathetic N.S.
on the Kidney
Sympathetic stimulation causes vasoconstriction in
arteries leading into the kidneys and in afferent
arterioles, reducing glomerular pressure and reducing
kidney function.
The sympathetic nervous system reduces blood flow to the kidney and GI
tract during exercise. This significantly shuts down blood flow, and over time
can result in significant build up of wastes in the plasma.
46. 46
Renal Connection to the Heart and Circulation
Rt. Atrium and other stretch receptors:
stretch acts to inhibit ADH secretion and release
ANF (atrial natriuretic factor) which dilates the
afferent arteriole and reduces Na+ reabsorption.
These actions effectively release fluid into the urine
thus reducing the blood volume.
Absence of stretch due to excessively low blood
volume acts to release significant amounts of ADH
(vasopressin) which acts to generally vasoconstrict
arterioles throughout the body. These actions
increase blood pressure and blood volume.
We discussed the importance of pressoreceptors in the right atrium in
cardiac control. But these receptors also respond to excessive high or low
pressure and act through the kidneys to help regulate it.
47. 47
Normal Constituents of Urine
Water (sp. Gravity 1.001 to 1.035),
urea,
uric acid,
creatinine,
Na+, K+, PO4
-3, SO4
-2, Ca+2, Mg+2
Nitrogenous waste from deamination.Nitrogenous waste from deamination.
Waste from purine metabolismWaste from purine metabolism
Released during anaerobic muscle activity.Released during anaerobic muscle activity.
Urine has a specific gravity slightly higher than pure water due to the solutes.
Urea and uric acid are nitrogenous wastes which have been put into the
blood by the liver. Creatinine is a combination of two creatine molecules,
released from skeletal muscle during exercise. The other electrolytes are
normal and vary in amount.
48. 48
Abnormal Constituents of Urine (Table 26.2)
Glucose - Recent intake of sugary foods, diabetes m.
Protein - Physical exertion, high protein;
hypertension, glomerulonephritis.
Ketone bodies - Starvation, untreated diabetes mellitus
Hemoglobin - Hemolytic anemia, severe burns
Bile pigments - Hepatitis, cirrhosis, bile obstruction
Erythrocytes - Bleeding due to trauma, kidney stones,
infection, cancer.
Leucocytes - Urinary tract infection
49. 49
The
Urinary
Bladder
ureters
rugae
Ureter
openings
3-layered detrusor
muscle
Trigone
Internal urethral
sphincter
External urethral
sphincter
Urethra
Prostate
gland
Bulbourethral
gland
Urethra
The bladder and the ureters are lined by transitional epithelium in order
to stretch. The bladder stretches to accommodate an increase in volume, the
ureters stretch of absorb any back pressure created when the detrusor
muscle contracts. The detrusor muscle is a 3-layered muscle, whose layers
are in reverse order to those of the stomach. This muscle contracts to
produce bladder compression during micturition.
Two urethral sphincters regulate urine flow into the urethra: the internal
urethral sphincter is involuntary, and relaxes when fullness is
experienced. The external urethral sphincter is voluntary, and relaxes
with voluntary stimuli from the cerebral cortex.
The trigone funnels urine out through the urethra, and partially closes the
ureteral openings into the bladder.
50. 50
The Ureters
Two layers of smooth
muscle (three near the
bladder) move urine by
peristalsis.
Mucosa of transitional
epithelium allows
expansion and damping
of pressure.
Low power
High power
The Ureters
Transitional epithelial lining allows both the bladder and ureter to stretch.
There is no
audio file for
this slide.
51. 51
Micturition Reflex
When pressure in bladder
sensory stimuli cause reflexive
inhibition of internal sphincter
and mild contractions of detrusor
muscle. Parasympathetic stimuli
inhibit sphincters and stimulate
detrusor muscle.
When not urinating, sympathetic stimuli
inhibit detrusor muscle and contract
sphincters.
Pons
When urine pressure stimulates presso-receptors in the bladder wall it triggers a
parasympathetic reflex which stimulates mild detrusor contractions and relaxation
of the internal urethral sphincter. Pathways to the brain stimulate the sense of a need
to urinate. Then, when conditions are appropriate, additional parasympathetic
stimuli result in micturition and voluntary stimuli relax the external sphincter.