- The document summarizes calcium and phosphate metabolism and bone physiology. It discusses how parathyroid hormone (PTH), vitamin D, and calcitonin work to regulate calcium and phosphate levels in the body. PTH increases calcium levels by stimulating bone resorption and kidney reabsorption of calcium. Vitamin D increases calcium absorption from the intestine. Calcitonin decreases calcium levels by inhibiting bone resorption. Together these hormones precisely control calcium and phosphate levels in the blood and bones. The document also provides details on bone formation, resorption, and growth through the actions of osteoblasts and osteoclasts.
The adrenal gland is composed of an outer cortex and inner medulla. The cortex develops from intermediate mesoderm and is divided into three concentric layers - the zona glomerulosa, zona fasciculata and zona reticularis. Each layer secretes different hormones - aldosterone from the glomerulosa, cortisol from the fasciculata and sex hormones from the reticularis. The medulla develops from neural crest cells and contains chromaffin cells that secrete epinephrine or norepinephrine into membrane-bound granules. Glucocorticoids stimulate the conversion of norepinephrine to epinephrine in the medulla.
Endocrine functions of the pancreas & regulation ofNkosinathiManana2
The pancreas secretes four polypeptides that regulate carbohydrate metabolism: insulin, glucagon, somatostatin, and pancreatic polypeptide. Insulin is produced by beta cells in the pancreas and lowers blood glucose levels by promoting glucose uptake in tissues. Glucagon is produced by alpha cells and raises blood glucose levels by stimulating glucose production and release from the liver. Somatostatin inhibits the secretion of insulin and glucagon, while pancreatic polypeptide's function is uncertain but may regulate nutrient absorption. Together these hormones maintain blood glucose levels within a narrow range.
The document summarizes the development of the urogenital system from the early embryonic stages through fetal development. It describes how the urinary and genital systems develop from a common ridge in the intermediate mesoderm and initially share a common cavity, the cloaca. It then details the development of the pronephros, mesonephros, and metanephros kidney systems. It discusses the development of the permanent kidney from the metanephric mesoderm and ureteric bud. It also summarizes the development of the bladder, urethra, gonads, genital ducts, and external genitalia in both males and females.
The document summarizes key aspects of renal and urinary system anatomy and physiology. It describes the basic unit of the kidney, the nephron, and its components including the glomerulus and tubules. It explains renal circulation and the mechanisms of glomerular filtration, tubular reabsorption and secretion. Specific topics covered include regulation of sodium, water, glucose, potassium and urea, as well as the roles of diuretics and hormones like vasopressin and erythropoietin. The document concludes with descriptions of urine transport through the ureters and bladder filling and emptying during urination.
This document provides a histological overview of the female reproductive system. It describes the main tissues and structures, including the ovaries, oviducts, uterus, vagina, external genitalia, and mammary glands. It details the layers of the uterus and changes that occur in the endometrium over the menstrual cycle. It also summarizes the types of ovarian follicles from primordial to mature follicles, and the formation and function of the corpus luteum. Following ovulation, the formation of the placenta allows for nutrient exchange between mother and fetus.
The document summarizes key events in implantation and early embryonic development during the first and second weeks. In the first week, the blastocyst undergoes a series of cellular and molecular events to adhere and embed into the endometrium, including degradation of the zona pellucida, adhesion to the epithelium, differentiation of trophoblast layers, erosion of tissues, and establishment of uteroplacental circulation. By the end of the second week, the embryo has undergone rapid proliferation and differentiation, formation of extraembryonic structures like the yolk sac and coelom, emergence of the amniotic cavity and bilaminar disc, and development of the prechordal plate as an organizer of the cranial
The urinary system develops from the intermediate mesoderm and includes three successive kidney structures - the pronephros, mesonephros, and metanephros. The metanephros forms the permanent kidneys. It develops from the ureteric bud penetrating the metanephric mesoderm and inducing nephron formation. The kidneys ascend into the abdominal cavity during development and become fully functional by 12 weeks of gestation. The urinary bladder and urethra also develop from the intermediate mesoderm through partitioning of the cloaca.
The adrenal gland is composed of an outer cortex and inner medulla. The cortex develops from intermediate mesoderm and is divided into three concentric layers - the zona glomerulosa, zona fasciculata and zona reticularis. Each layer secretes different hormones - aldosterone from the glomerulosa, cortisol from the fasciculata and sex hormones from the reticularis. The medulla develops from neural crest cells and contains chromaffin cells that secrete epinephrine or norepinephrine into membrane-bound granules. Glucocorticoids stimulate the conversion of norepinephrine to epinephrine in the medulla.
Endocrine functions of the pancreas & regulation ofNkosinathiManana2
The pancreas secretes four polypeptides that regulate carbohydrate metabolism: insulin, glucagon, somatostatin, and pancreatic polypeptide. Insulin is produced by beta cells in the pancreas and lowers blood glucose levels by promoting glucose uptake in tissues. Glucagon is produced by alpha cells and raises blood glucose levels by stimulating glucose production and release from the liver. Somatostatin inhibits the secretion of insulin and glucagon, while pancreatic polypeptide's function is uncertain but may regulate nutrient absorption. Together these hormones maintain blood glucose levels within a narrow range.
The document summarizes the development of the urogenital system from the early embryonic stages through fetal development. It describes how the urinary and genital systems develop from a common ridge in the intermediate mesoderm and initially share a common cavity, the cloaca. It then details the development of the pronephros, mesonephros, and metanephros kidney systems. It discusses the development of the permanent kidney from the metanephric mesoderm and ureteric bud. It also summarizes the development of the bladder, urethra, gonads, genital ducts, and external genitalia in both males and females.
The document summarizes key aspects of renal and urinary system anatomy and physiology. It describes the basic unit of the kidney, the nephron, and its components including the glomerulus and tubules. It explains renal circulation and the mechanisms of glomerular filtration, tubular reabsorption and secretion. Specific topics covered include regulation of sodium, water, glucose, potassium and urea, as well as the roles of diuretics and hormones like vasopressin and erythropoietin. The document concludes with descriptions of urine transport through the ureters and bladder filling and emptying during urination.
This document provides a histological overview of the female reproductive system. It describes the main tissues and structures, including the ovaries, oviducts, uterus, vagina, external genitalia, and mammary glands. It details the layers of the uterus and changes that occur in the endometrium over the menstrual cycle. It also summarizes the types of ovarian follicles from primordial to mature follicles, and the formation and function of the corpus luteum. Following ovulation, the formation of the placenta allows for nutrient exchange between mother and fetus.
The document summarizes key events in implantation and early embryonic development during the first and second weeks. In the first week, the blastocyst undergoes a series of cellular and molecular events to adhere and embed into the endometrium, including degradation of the zona pellucida, adhesion to the epithelium, differentiation of trophoblast layers, erosion of tissues, and establishment of uteroplacental circulation. By the end of the second week, the embryo has undergone rapid proliferation and differentiation, formation of extraembryonic structures like the yolk sac and coelom, emergence of the amniotic cavity and bilaminar disc, and development of the prechordal plate as an organizer of the cranial
The urinary system develops from the intermediate mesoderm and includes three successive kidney structures - the pronephros, mesonephros, and metanephros. The metanephros forms the permanent kidneys. It develops from the ureteric bud penetrating the metanephric mesoderm and inducing nephron formation. The kidneys ascend into the abdominal cavity during development and become fully functional by 12 weeks of gestation. The urinary bladder and urethra also develop from the intermediate mesoderm through partitioning of the cloaca.
The perineum is the diamond-shaped region between the pelvic outlet and the thighs. It is divided into an anterior urogenital triangle and a posterior anal triangle by an imaginary line between the ischial tuberosities. The anal triangle contains the external anal sphincter and is supplied by the inferior rectal branches of the pudendal nerve. The urogenital triangle contains erectile tissue that forms the clitoris or penis, as well as muscles and glands. The main blood supply is from the internal pudendal artery and its branches, while lymphatic drainage involves the superficial and deep inguinal nodes as well as internal iliac nodes.
Somite differentiation and neural crestVharsha Haran
Neural crest cells arise from the ectoderm layer and give rise to diverse cell lineages including melanocytes, craniofacial cartilage and bone, smooth muscle, and neurons. They have multipotent capability, migrate throughout the embryo, and are precisely regulated. The neural crest can be divided into four main regions that develop into different structures and tissues. Somites form from paraxial mesoderm and later split into dermatomes, myotomes, syndetomes, and sclerotomes which give rise to skin, skeletal muscle, tendons and cartilage, and bone, respectively.
This document discusses the development of the midgut and hindgut in humans. It describes:
1) The midgut extends from the duodenum to the proximal two-thirds of the transverse colon. It rotates 270 degrees during development and forms parts of the small and large intestines.
2) The hindgut forms from the distal hindgut and develops into the distal transverse colon, descending colon, sigmoid colon, rectum and upper anal canal.
3) Potential congenital anomalies that can occur during midgut and hindgut development include errors in rotation, fixation or duplication of intestines, abnormalities of the cecum and colon, Hirschsprung's
The document discusses the anatomy of the perineum region in males and females. It describes the boundaries and contents of the superficial and deep perineal pouches located in the urogenital triangle of the perineum. Key structures discussed include the superficial and deep transverse perineal muscles, sphincter urethrae muscle, bulbourethral glands, internal pudendal artery and related muscles and nerves.
The document summarizes the blood vessels and lymphatics of the thoracic wall. It describes the arteries, veins and lymphatic drainage of the intercostal spaces and chest wall. The posterior intercostal arteries arise from the subclavian artery or descending thoracic aorta and supply the thoracic wall and parietal pleura. The posterior intercostal veins drain into the azygos or hemiazygos veins. Lymph from the chest wall drains to the anterior and posterior axillary nodes or internally to the thoracic nodes along the internal thoracic artery.
The document describes the development of the male and female reproductive systems from the indifferent stage through sexual differentiation. It covers the development of the gonads (testes and ovaries), genital ducts, and external genitalia. Some key points include:
- The gonads initially develop as indifferent gonads before differentiating into testes or ovaries depending on the presence of the SRY gene on the Y chromosome.
- The genital ducts also initially develop in an indifferent stage before the mesonephric ducts develop into male structures like the epididymis and vas deferens, while the paramesonephric ducts develop into female structures like the uterus and fallopian tubes.
- External
During the second week of embryo development:
- The blastocyst is partially or completely embedded in the endometrial lining, with the trophoblast differentiating into layers. The embryoblast also divides into the hypoblast and epiblast.
- A small cavity, the future amniotic cavity, appears in the epiblast. The syncytiotrophoblast penetrates deeper into the endometrial stroma and establishes the first circulatory system between the embryo and mother.
- By the end of the second week, the extraembryonic mesoderm and chorionic cavity have formed, and primary villi with syncytial covering have begun to develop in the chorionic cavity.
The document discusses the pleura, which forms the pleural cavity surrounding the lungs. It describes the two layers of pleura - the visceral pleura adhering to the lungs and the parietal pleura lining the thoracic wall. It then discusses pleural reflections, recesses, nerve supply, and various pleural diseases and conditions like pleurisy, effusions, pneumothorax, and haemothorax. It also shows images related to pleural anatomy, demonstrations of tension pneumothorax, and labels parts on a chest X-ray.
Kidney development - embryology of urinary systemSaachiGupta4
Part of the development of the urinary system
The ascent of the kidney, stages of development of kidney
discussion about pronephros, mesonephros, metanephros.
- Smooth muscle fibers are much smaller in diameter and length compared to skeletal muscle fibers. Smooth muscle lacks striations and is located within organs like the intestines and blood vessels.
- Smooth muscle contraction is initiated by an increase in intracellular calcium ions which can be triggered by nerve stimulation, hormones, stretch of the fiber, or chemical changes. Calcium then binds to calmodulin instead of troponin to drive contraction.
- Smooth muscle exhibits a slow cycling of myosin cross-bridges, requiring less energy for sustained contraction compared to skeletal muscle. Its contraction and relaxation is also slower than skeletal muscle.
During the third week of development, gastrulation occurs where the three germ layers (ectoderm, mesoderm, endoderm) are formed. The notochord also begins developing from epiblast cells that ingress through the primitive streak and primitive node. These cells form the notochordal process which then fuses with endoderm and detaches to form the definitive notochord cord between the ectoderm and endoderm. The mesoderm organizes into three segments - paraxial, intermediate, and lateral plate mesoderm - which will give rise to muscles, skeleton, urinary/genital systems, and other tissues.
The document summarizes the anatomy of the abdominal wall and abdominal viscera. It describes the layers of the abdominal wall from the skin to the peritoneum. It details the five anterolateral muscles - external oblique, internal oblique, transversus abdominis, rectus abdominis, and pyramidalis. It also discusses the innervation, blood supply, and lymphatic drainage of the abdominal wall. Finally, it summarizes the peritoneal folds including the omenta, mesenteries, and ligaments that support the abdominal organs.
During the 4th week of development, the embryo undergoes longitudinal and transverse folding which transforms it from a flat disc into a curved tube. This folding incorporates the yolk sac endoderm to form the gut tube and divides the coelom into the thoracic and abdominal cavities. It also repositions structures like the heart and mouth opening. By the end of the 4th week, the embryo has prominent head and tail folds, limb buds, and many organ systems are established.
The adrenal gland is a retroperitoneal organ located above the kidneys that is composed of an outer cortex and inner medulla. The cortex secretes corticosteroids and androgens, developing from mesoderm, while the medulla secretes catecholamines and develops from neural crest cells. The adrenal gland receives its blood supply from superior, middle, and inferior suprarenal arteries and drains into renal veins. It develops from mesodermal and ectodermal tissues and regulates stress response and metabolism through hormones. Diseases can occur if it over or underproduces hormones, like pheochromocytoma increasing catecholamines or Cushing's syndrome increasing cortisol.
Embryonic development of the urogenital systemAsheer Khan
The urogenital system develops from the intermediate mesenchyme. The urinary system develops from the nephrogenic cord, while the genital system develops from the gonadal ridge. Three sets of kidneys develop in embryos - the pronephroi, mesonephroi, and metanephroi. The metanephroi form the permanent kidneys. The kidneys and ureters develop from the ureteric bud and metanephrogenic blastema. Congenital anomalies that can occur include renal agenesis, malrotated kidneys, ectopic kidneys, horseshoe kidneys, and duplications of the urinary tract. The urinary bladder develops mainly from the vesical
Cleavage, Blastocyte formation and Implantation.pptxFavourUgochukwu
This document summarizes the process of cleavage, blastocyst formation, and implantation in human development. It describes how the zygote undergoes cell division through cleavage to form a morula, which then develops a fluid-filled blastocoel cavity to form the blastocyst. The blastocyst contains an inner cell mass that will become the embryo and outer cells that will become the placenta. Around 3-4 days after fertilization, the blastocyst implants into the uterine wall, where the outer trophoblast cells invade the endometrium and develop into villous structures to establish maternal blood flow and form the placenta over subsequent days.
The document summarizes key aspects of the endocrine pancreas and its hormones. It discusses:
- The islets of Langerhans contain alpha, beta, and delta cells that secrete glucagon, insulin, and somatostatin.
- Insulin regulates blood glucose levels through effects on glucose and lipid metabolism. Insulin secretion is stimulated by high blood glucose.
- Glucagon opposes insulin's effects and raises blood glucose through hepatic glycogenolysis and gluconeogenesis. It is secreted in response to low blood glucose.
- Somatostatin is secreted by delta cells and decreases secretion of insulin and glucagon. It also regulates gastrointestinal functions.
The pineal gland is a small endocrine gland located deep within the brain that produces melatonin, a hormone that regulates sleep-wake cycles and seasonal biological rhythms. It receives blood supply from the posterior medial choroidal artery and drains into the great cerebral vein of Galen. While pineal cysts are common and benign, rare tumors can form. Dysfunction of the pineal gland can impact circadian rhythms and sleep patterns.
The pelvic floor is formed by the pelvic diaphragm and the perineal membrane. The pelvic diaphragm consists of the levator ani and coccygeus muscles, which attach superiorly to the pelvic wall. The levator ani muscles originate from the pelvic wall and join together in the midline, forming a U-shaped defect anteriorly. The coccygeus muscles are triangular shaped and overlie the sacrum and coccyx. The perineal membrane is a thick fascia attached to the pubic arch, with a thin space above it called the deep perineal pouch containing muscles and vessels. The perineal body is a connective
Calcium is the most abundant mineral in the body and is primarily stored in bones and teeth. It performs many important biochemical functions including bone and teeth formation, muscle contraction, blood coagulation, and nerve transmission. Calcium levels are regulated by parathyroid hormone, vitamin D, and calcitonin. These hormones work to maintain calcium homeostasis by impacting absorption in the intestine and kidneys and mobilization from bones.
SOURCES ,BIOCHEMICAL FUNCTION AND CLINICAL SIGNIFICANCES OF CALCIUM AND PH...Aqsa Mushtaq
This document discusses calcium and phosphorus, two important minerals in the human body. It provides information on their sources, functions, and relationship to other minerals and hormones like vitamin D and parathyroid hormone. Specifically, it explains that calcium and phosphorus are required for bone strength, cell functions, muscle contractions, and other metabolic processes. It also outlines how calcium levels in the blood are regulated through homeostasis and what can cause hypocalcemia or low calcium levels in the blood.
The perineum is the diamond-shaped region between the pelvic outlet and the thighs. It is divided into an anterior urogenital triangle and a posterior anal triangle by an imaginary line between the ischial tuberosities. The anal triangle contains the external anal sphincter and is supplied by the inferior rectal branches of the pudendal nerve. The urogenital triangle contains erectile tissue that forms the clitoris or penis, as well as muscles and glands. The main blood supply is from the internal pudendal artery and its branches, while lymphatic drainage involves the superficial and deep inguinal nodes as well as internal iliac nodes.
Somite differentiation and neural crestVharsha Haran
Neural crest cells arise from the ectoderm layer and give rise to diverse cell lineages including melanocytes, craniofacial cartilage and bone, smooth muscle, and neurons. They have multipotent capability, migrate throughout the embryo, and are precisely regulated. The neural crest can be divided into four main regions that develop into different structures and tissues. Somites form from paraxial mesoderm and later split into dermatomes, myotomes, syndetomes, and sclerotomes which give rise to skin, skeletal muscle, tendons and cartilage, and bone, respectively.
This document discusses the development of the midgut and hindgut in humans. It describes:
1) The midgut extends from the duodenum to the proximal two-thirds of the transverse colon. It rotates 270 degrees during development and forms parts of the small and large intestines.
2) The hindgut forms from the distal hindgut and develops into the distal transverse colon, descending colon, sigmoid colon, rectum and upper anal canal.
3) Potential congenital anomalies that can occur during midgut and hindgut development include errors in rotation, fixation or duplication of intestines, abnormalities of the cecum and colon, Hirschsprung's
The document discusses the anatomy of the perineum region in males and females. It describes the boundaries and contents of the superficial and deep perineal pouches located in the urogenital triangle of the perineum. Key structures discussed include the superficial and deep transverse perineal muscles, sphincter urethrae muscle, bulbourethral glands, internal pudendal artery and related muscles and nerves.
The document summarizes the blood vessels and lymphatics of the thoracic wall. It describes the arteries, veins and lymphatic drainage of the intercostal spaces and chest wall. The posterior intercostal arteries arise from the subclavian artery or descending thoracic aorta and supply the thoracic wall and parietal pleura. The posterior intercostal veins drain into the azygos or hemiazygos veins. Lymph from the chest wall drains to the anterior and posterior axillary nodes or internally to the thoracic nodes along the internal thoracic artery.
The document describes the development of the male and female reproductive systems from the indifferent stage through sexual differentiation. It covers the development of the gonads (testes and ovaries), genital ducts, and external genitalia. Some key points include:
- The gonads initially develop as indifferent gonads before differentiating into testes or ovaries depending on the presence of the SRY gene on the Y chromosome.
- The genital ducts also initially develop in an indifferent stage before the mesonephric ducts develop into male structures like the epididymis and vas deferens, while the paramesonephric ducts develop into female structures like the uterus and fallopian tubes.
- External
During the second week of embryo development:
- The blastocyst is partially or completely embedded in the endometrial lining, with the trophoblast differentiating into layers. The embryoblast also divides into the hypoblast and epiblast.
- A small cavity, the future amniotic cavity, appears in the epiblast. The syncytiotrophoblast penetrates deeper into the endometrial stroma and establishes the first circulatory system between the embryo and mother.
- By the end of the second week, the extraembryonic mesoderm and chorionic cavity have formed, and primary villi with syncytial covering have begun to develop in the chorionic cavity.
The document discusses the pleura, which forms the pleural cavity surrounding the lungs. It describes the two layers of pleura - the visceral pleura adhering to the lungs and the parietal pleura lining the thoracic wall. It then discusses pleural reflections, recesses, nerve supply, and various pleural diseases and conditions like pleurisy, effusions, pneumothorax, and haemothorax. It also shows images related to pleural anatomy, demonstrations of tension pneumothorax, and labels parts on a chest X-ray.
Kidney development - embryology of urinary systemSaachiGupta4
Part of the development of the urinary system
The ascent of the kidney, stages of development of kidney
discussion about pronephros, mesonephros, metanephros.
- Smooth muscle fibers are much smaller in diameter and length compared to skeletal muscle fibers. Smooth muscle lacks striations and is located within organs like the intestines and blood vessels.
- Smooth muscle contraction is initiated by an increase in intracellular calcium ions which can be triggered by nerve stimulation, hormones, stretch of the fiber, or chemical changes. Calcium then binds to calmodulin instead of troponin to drive contraction.
- Smooth muscle exhibits a slow cycling of myosin cross-bridges, requiring less energy for sustained contraction compared to skeletal muscle. Its contraction and relaxation is also slower than skeletal muscle.
During the third week of development, gastrulation occurs where the three germ layers (ectoderm, mesoderm, endoderm) are formed. The notochord also begins developing from epiblast cells that ingress through the primitive streak and primitive node. These cells form the notochordal process which then fuses with endoderm and detaches to form the definitive notochord cord between the ectoderm and endoderm. The mesoderm organizes into three segments - paraxial, intermediate, and lateral plate mesoderm - which will give rise to muscles, skeleton, urinary/genital systems, and other tissues.
The document summarizes the anatomy of the abdominal wall and abdominal viscera. It describes the layers of the abdominal wall from the skin to the peritoneum. It details the five anterolateral muscles - external oblique, internal oblique, transversus abdominis, rectus abdominis, and pyramidalis. It also discusses the innervation, blood supply, and lymphatic drainage of the abdominal wall. Finally, it summarizes the peritoneal folds including the omenta, mesenteries, and ligaments that support the abdominal organs.
During the 4th week of development, the embryo undergoes longitudinal and transverse folding which transforms it from a flat disc into a curved tube. This folding incorporates the yolk sac endoderm to form the gut tube and divides the coelom into the thoracic and abdominal cavities. It also repositions structures like the heart and mouth opening. By the end of the 4th week, the embryo has prominent head and tail folds, limb buds, and many organ systems are established.
The adrenal gland is a retroperitoneal organ located above the kidneys that is composed of an outer cortex and inner medulla. The cortex secretes corticosteroids and androgens, developing from mesoderm, while the medulla secretes catecholamines and develops from neural crest cells. The adrenal gland receives its blood supply from superior, middle, and inferior suprarenal arteries and drains into renal veins. It develops from mesodermal and ectodermal tissues and regulates stress response and metabolism through hormones. Diseases can occur if it over or underproduces hormones, like pheochromocytoma increasing catecholamines or Cushing's syndrome increasing cortisol.
Embryonic development of the urogenital systemAsheer Khan
The urogenital system develops from the intermediate mesenchyme. The urinary system develops from the nephrogenic cord, while the genital system develops from the gonadal ridge. Three sets of kidneys develop in embryos - the pronephroi, mesonephroi, and metanephroi. The metanephroi form the permanent kidneys. The kidneys and ureters develop from the ureteric bud and metanephrogenic blastema. Congenital anomalies that can occur include renal agenesis, malrotated kidneys, ectopic kidneys, horseshoe kidneys, and duplications of the urinary tract. The urinary bladder develops mainly from the vesical
Cleavage, Blastocyte formation and Implantation.pptxFavourUgochukwu
This document summarizes the process of cleavage, blastocyst formation, and implantation in human development. It describes how the zygote undergoes cell division through cleavage to form a morula, which then develops a fluid-filled blastocoel cavity to form the blastocyst. The blastocyst contains an inner cell mass that will become the embryo and outer cells that will become the placenta. Around 3-4 days after fertilization, the blastocyst implants into the uterine wall, where the outer trophoblast cells invade the endometrium and develop into villous structures to establish maternal blood flow and form the placenta over subsequent days.
The document summarizes key aspects of the endocrine pancreas and its hormones. It discusses:
- The islets of Langerhans contain alpha, beta, and delta cells that secrete glucagon, insulin, and somatostatin.
- Insulin regulates blood glucose levels through effects on glucose and lipid metabolism. Insulin secretion is stimulated by high blood glucose.
- Glucagon opposes insulin's effects and raises blood glucose through hepatic glycogenolysis and gluconeogenesis. It is secreted in response to low blood glucose.
- Somatostatin is secreted by delta cells and decreases secretion of insulin and glucagon. It also regulates gastrointestinal functions.
The pineal gland is a small endocrine gland located deep within the brain that produces melatonin, a hormone that regulates sleep-wake cycles and seasonal biological rhythms. It receives blood supply from the posterior medial choroidal artery and drains into the great cerebral vein of Galen. While pineal cysts are common and benign, rare tumors can form. Dysfunction of the pineal gland can impact circadian rhythms and sleep patterns.
The pelvic floor is formed by the pelvic diaphragm and the perineal membrane. The pelvic diaphragm consists of the levator ani and coccygeus muscles, which attach superiorly to the pelvic wall. The levator ani muscles originate from the pelvic wall and join together in the midline, forming a U-shaped defect anteriorly. The coccygeus muscles are triangular shaped and overlie the sacrum and coccyx. The perineal membrane is a thick fascia attached to the pubic arch, with a thin space above it called the deep perineal pouch containing muscles and vessels. The perineal body is a connective
Calcium is the most abundant mineral in the body and is primarily stored in bones and teeth. It performs many important biochemical functions including bone and teeth formation, muscle contraction, blood coagulation, and nerve transmission. Calcium levels are regulated by parathyroid hormone, vitamin D, and calcitonin. These hormones work to maintain calcium homeostasis by impacting absorption in the intestine and kidneys and mobilization from bones.
SOURCES ,BIOCHEMICAL FUNCTION AND CLINICAL SIGNIFICANCES OF CALCIUM AND PH...Aqsa Mushtaq
This document discusses calcium and phosphorus, two important minerals in the human body. It provides information on their sources, functions, and relationship to other minerals and hormones like vitamin D and parathyroid hormone. Specifically, it explains that calcium and phosphorus are required for bone strength, cell functions, muscle contractions, and other metabolic processes. It also outlines how calcium levels in the blood are regulated through homeostasis and what can cause hypocalcemia or low calcium levels in the blood.
Ppt file for hematology concepts.
Because such a large amount of calcium is stored in bone, it is the most abundant mineral in the body. Our bodies contain 1200 g of calcium.
About 98% of the calcium in adults is located in the skeleton and teeth, where it is combined with phosphates to form a crystal lattice of mineral salts, hydroxyapatite, Ca10(PO4)6(OH)2.
In addition, calcium helps to stabilize cell membranes and is essential for the release of neurotransmitters from neurons and of hormones from endocrine glands.
Calcium is absorbed through the intestines under the influence of activated vitamin D. A deficiency of vitamin D leads to a decrease in absorbed calcium and, eventually, a depletion of calcium stores from the skeletal system, potentially leading to rickets in children and osteomalacia in adults, contributing to osteoporosis.
Hypocalcemia, bicarbonate, calcium magnesium zinc oxide
The kidneys are the main regulators of blood HCO3− concentration.
The intercalated cells of the renal tubule can either form HCO3− and release it into the blood when the blood level is low or excrete excess HCO3− in the urine when the level in blood is too high.
PTH stimulates resorption of bone extracellular matrix by osteoclasts, which releases both phosphate and calcium ions into the bloodstream.
In the kidneys, however, PTH inhibits reabsorption of phosphate ions while stimulating reabsorption of calcium ions by renal tubular cells.
Thus, PTH increases urinary excretion of phosphate and lowers blood phosphate level.
Procalcitonin Assays and Their Roles in Sepsis and Other Diseases-1 (1).pptDr. majid farooq
Calcium homeostasis is regulated by parathyroid hormone (PTH), calcitonin, and vitamin D3. PTH increases calcium absorption in the intestine and calcium release from bone by stimulating vitamin D conversion to its active form. Vitamin D increases intestinal calcium absorption and bone calcium resorption. Calcium levels directly regulate PTH secretion from the parathyroid glands. Together this hormonal system tightly controls extracellular calcium levels.
This document discusses calcium and phosphate metabolism and bone physiology. It begins by describing the functions and importance of calcium and phosphate in the body. The majority of calcium is stored in the bones, while calcium levels in blood and extracellular fluid are tightly regulated. Several hormones, including PTH, vitamin D, and calcitonin help regulate calcium levels. PTH and vitamin D work to increase calcium levels by promoting bone resorption and intestinal absorption, while calcitonin decreases calcium levels by inhibiting bone resorption. The kidneys also play an important role in calcium regulation through hormone-modulated reabsorption and excretion.
calcium metabolism and trace elements in cariologyMilind Rajan
This document discusses calcium metabolism and regulation. It covers the distribution of calcium in the body, daily requirements, dietary sources, and functions of calcium. The key roles of calcium are in bone and teeth formation, muscle contraction, nerve conduction, blood coagulation, and enzyme activation. Calcium levels are tightly regulated by parathyroid hormone, calcitriol (vitamin D), and calcitonin which act on bone, kidneys, and intestines. Absorption of calcium depends on factors like vitamin D, acidity, proteins and absorption can be decreased by things like phytic acid, oxalates, and high phosphate levels.
This is a PPT of calcium and phosphate metabolism. Clinical correlation are not included. Hope it is useful to you all. Please Like and Share it with your friends
Calcium and phosphate metabolism is tightly regulated in the body. Calcium is mainly stored in bones while phosphate is found intracellularly and extracellularly. Vitamin D, parathyroid hormone, and calcitonin control calcium and phosphate levels by impacting absorption in the gut and kidneys. An imbalance can result in hypercalcemia with symptoms like nausea and fatigue, or hypocalcemia which can cause tetany.
Calcium metabolism is regulated by parathyroid hormone, vitamin D, and calcitonin to maintain normal blood calcium levels. Calcium is important for many bodily functions and is found primarily in bones and blood plasma. Hormonal regulation involves calcium absorption from the gut, resorption from bones, and reabsorption in kidneys. Issues arise if these levels are too high (hyperparathyroidism) or low (hypoparathyroidism, osteoporosis, rickets, osteomalacia).
This document discusses calcium metabolism and homeostasis. It notes that calcium levels are tightly regulated by the intestine, kidneys, bones, and hormones. The parathyroid hormone (PTH) increases calcium absorption from the intestine and bones while decreasing urinary calcium excretion. Vitamin D increases intestinal calcium absorption. Calcitonin decreases bone resorption. Together, these organs and hormones work to maintain calcium levels within a narrow range. Imbalances can lead to hypo- or hypercalcemia with various neurological, cardiac, and musculoskeletal symptoms.
This document discusses the physiologic and biochemical functions of various minerals in the human body. It covers major minerals like calcium, phosphorus, magnesium, sodium, potassium, and chloride. It describes their roles, absorption, transport in the blood, homeostasis, and impact on various diseases when levels are too high or too low. The minerals are essential for many metabolic processes and helping maintain acid-base balance, fluid balance, nerve transmission, muscle contraction and more.
The document summarizes key information about calcium and phosphorus metabolism. It discusses their daily requirements, distribution in the body, dietary sources, functions, factors controlling absorption such as vitamin D, parathyroid hormone, and calcitonin. It also outlines hormonal control of calcium and phosphorus metabolism and clinical importance of hypo- and hypercalcemia and hyperphosphatemia. The objectives are to understand the role of calcium and phosphorus in the body and factors influencing their metabolism.
Introduction to calcium
Sources of calcium
Dietary requirement of calcium
Calcium absorption
Biochemical function of calcium
Calcium in blood
Calcium estimation
Factors regulating calcium level in blood
Disease states of calcium
The document discusses renal handling of calcium, phosphorus, and magnesium. It provides details on:
- Distribution and compartments of calcium, phosphorus, and magnesium in the body
- Mechanisms of renal reabsorption of calcium, phosphorus, and magnesium in different nephron segments including the proximal tubule, thick ascending loop of Henle, and distal convoluted tubule
- Hormonal regulation of calcium and phosphorus by parathyroid hormone and calcitriol
- Clinical conditions associated with abnormalities in calcium, phosphorus, and magnesium levels including hypercalcemia, hypocalcemia, hyperparathyroidism, hypoparathyroidism
Calcium homeostasis involves complex interactions between the bones, kidneys, intestines, and three key hormones:
1) Parathyroid hormone increases calcium levels by stimulating bone resorption and renal reabsorption of calcium while increasing phosphate excretion.
2) Vitamin D facilitates intestinal calcium absorption and renal reabsorption of calcium and phosphate.
3) Calcitonin opposes parathyroid hormone by inhibiting bone resorption, lowering calcium levels.
Together these mechanisms precisely regulate calcium concentrations in the blood and exchange between bones and extracellular fluid.
This document discusses calcium, including its history, functions, absorption, metabolism, and sources. It provides the following key points:
- Calcium is essential for bone formation, muscle and nerve function, and plays a role in many biochemical reactions in the body.
- It is absorbed in the small intestine through both passive and active transport, and its levels are regulated by parathyroid hormone, vitamin D, and calcitonin.
- Good dietary sources include dairy products like milk and cheese, as well as green leafy vegetables. Calcium supplements may be recommended for some groups.
- Disorders can include osteoporosis, rickets, and hypocalcemia or hypercalcemia if levels
The parathyroid glands regulate calcium levels in the blood. They are located behind the thyroid gland and secrete parathyroid hormone (PTH). PTH increases calcium levels in the blood by releasing calcium from bones, reabsorbing calcium in the kidneys, and enhancing calcium absorption in the intestines. PTH also plays a key role in activating vitamin D, which further aids in intestinal calcium absorption. The level of calcium in the blood provides feedback to regulate PTH secretion, with lower calcium triggering more PTH release.
Similar to 6. hormonal control of calcium & phosphate metabolism & (20)
Fetal monitoring aims to assess fetal wellbeing during pregnancy and labor. This document provides guidelines for interpreting cardiotocography (CTG) traces and responding to patterns. CTGs should consider gestational age, fetal growth, movements, and any conditions affecting fetal wellbeing. Antenatally, reduced fetal movements or abnormal fundal height measurements may warrant further assessment. During labor, CTG is recommended for high-risk pregnancies and can identify non-reassuring patterns like late decelerations indicating possible hypoxia. Interpretation requires evaluating baseline rate, variability, decelerations, and accelerations in the context of the clinical situation.
This document provides guidance on antenatal care. It discusses the importance of preconception care, screening and risk assessment during pregnancy, and the essential components of antenatal visits. The goals of antenatal care are to ensure the best outcomes for women and babies by screening for problems, assessing risk, treating issues, providing medications and information. Key aspects covered include taking a medical history, conducting physical exams, estimating gestation, performing essential screening tests, discussing medications and vaccines, creating a management plan, and covering topics for subsequent routine prenatal visits.
This document provides guidelines for preventing mother-to-child transmission of HIV (PMTCT) in antenatal care settings. There are four key elements of PMTCT care: primary HIV prevention, preventing unintended pregnancies among HIV+ women, preventing transmission from mother to child, and treatment/support for HIV+ women and their families. The goals of PMTCT in antenatal care are to identify all HIV+ women, provide same-day ART to optimize health and prevent transmission, and ensure viral suppression through treatment. All pregnant women should be tested for HIV and receive counseling. HIV+ women initiate lifelong ART regardless of CD4 count or clinical stage, while HIV- women receive repeat testing during pregnancy and breastfeeding.
This document provides guidance on performing and managing caesarean deliveries. It discusses:
- The need for caesarean delivery capabilities 24/7 at district hospitals and ability to perform emergency c-sections within 1 hour.
- Testing fetal lung maturity before elective c-sections if gestational age is uncertain.
- Preparation steps like consent, blood availability, and ensuring an experienced surgeon.
- Precautions against hemorrhage like oxytocin administration and careful surgical technique.
- Managing hemorrhage through measures like massaging the uterus, giving uterotonics, exploring for bleeding sources, and considering compression sutures.
- Postoperative orders around analgesia, fluids, thrombosis
Induction of labour is the artificial initiation of labour to achieve a vaginal delivery. Common indications include post-term pregnancy, hypertension disorders, and pre-labour rupture of membranes. The document discusses assessing the need for induction and balancing risks to the mother and baby. It provides guidance on methods for induction including membranes sweeping, prostaglandins, misoprostol, and oxytocin administration. Risks like uterine hyperstimulation are addressed. Special considerations for fetal demise, ruptured membranes, and scarred uteruses are also covered.
This document provides guidance on diagnosing and treating infections during pregnancy and the postpartum period. It discusses abnormal vaginal discharge, sexually transmitted infections like candidiasis, gonorrhea, chlamydia and trichomoniasis. It also addresses genital warts, ulcers, syphilis, urinary tract infections, acute pyelonephritis, and malaria. For each condition, it describes signs and symptoms, recommended testing, and treatment guidelines. It emphasizes treating sexually transmitted infections syndromically and the importance of notifying partners for examination and treatment.
This document provides guidelines for managing medical disorders in pregnancy, including anemia, diabetes mellitus, and cardiac disease. For anemia, it outlines screening, prevention, and treatment protocols. It describes gestational and pregestational diabetes and their management. For cardiac disease, it discusses referral criteria and managing labor and delivery for high-risk patients. The overall aim is to provide optimal care for both mother and baby's health outcomes.
1) Tuberculosis (TB) is a major cause of maternal mortality in South Africa. All pregnant women, especially those with HIV, should be screened for TB at antenatal visits.
2) Symptom screening involves asking about cough, fever, night sweats, and weight loss. A TB test (GeneXpert) is also required for pregnant women with new HIV diagnoses or known HIV.
3) If TB is diagnosed, treatment should begin promptly according to national guidelines. For drug-resistant TB, consultation with infectious disease specialists is recommended due to high mortality risk.
1) Bleeding in early pregnancy, defined as before 22 weeks, can be caused by miscarriage, ectopic pregnancy, molar pregnancy, or other issues. A rapid assessment including vital signs and exam is needed.
2) Miscarriages are categorized as safe, unsafe, threatening, inevitable, incomplete, or septic and management depends on the category and gestational age. Manual vacuum aspiration is preferred for evacuating the uterus under 16 weeks.
3) Post-miscarriage care involves screening for physical and mental health issues, providing counseling and information, and discussing family planning options.
Pregnant and postpartum women with COVID-19 should receive supportive care. While pregnant women are not more likely to get infected, those who do contract COVID-19, especially in the third trimester, are at higher risk of severe outcomes. COVID-19 testing criteria are the same for pregnant women as non-pregnant adults. Preventative measures include vaccination, masks, distancing, and hygiene. COVID-19 vaccination is recommended in pregnancy to protect both mother and baby. Mild cases can be isolated at home but moderate or severe cases require hospital admission. Mode of delivery depends on obstetric needs and maternal stability.
This document provides guidance on the management of antepartum haemorrhage (APH), or bleeding during pregnancy prior to delivery. It discusses causes of APH including placental abnormalities, infections, trauma, and unknown causes. It provides recommendations for emergency management at clinics, community health centers, and hospitals. Specific guidance is given for managing placenta praevia, abruptio placentae, and APH of unknown origin. Recommendations include IV fluids, blood transfusions, ultrasound exams, monitoring vital signs, and determining need for transfer or delivery.
Hypertensive disorders in pregnancy (HDP) are a common cause of maternal and infant health problems and death. HDP include gestational hypertension, preeclampsia, and eclampsia. Risk factors include being young, older than 35, having previous HDP, obesity, diabetes, or kidney disease. Symptoms of severe preeclampsia include headaches, vision issues, low platelets, elevated liver enzymes, pain in the upper right abdomen, HELLP syndrome, or high creatinine. All pregnant people should take calcium and those at higher risk may benefit from low-dose aspirin. HDP requires frequent monitoring, control of blood pressure, delivery by 38 weeks for gestational hypertension or earlier for pre
This document discusses gender-based violence and provides guidance for health workers in responding to GBV. It begins by defining GBV and noting that 1 in 4 women in South Africa experience GBV during pregnancy. It then outlines the negative health impacts of untreated GBV for women and children. The document describes possible signs that a woman is experiencing violence and provides a screening tool for health workers. It provides guidance on first line support, safety planning, and self-care for health workers responding to disclosures of GBV.
The document summarizes various abnormalities that can occur during labour and their management. It discusses prolonged latent phase of labour, poor progress in the active phase, meconium staining of amniotic fluid, prolonged second stage of labour, vacuum extraction, fetal distress, cord prolapse, and shoulder dystocia. For each issue, it provides details on how to assess and manage the situation, including administering drugs, changing positioning, accelerating delivery, or transferring to a hospital if needed. The goal is to safely resolve any problems and deliver a healthy baby.
1. The document discusses fetal maturity and intrauterine growth restriction (IUGR), including definitions, clinical symptoms, signs, biochemical markers, and fetal maturity tests. Fetal maturity tests assess surfactant levels in amniotic fluid to predict risk of respiratory distress syndrome in newborns.
2. IUGR is defined as fetal weight below the 10th percentile and can be symmetric or asymmetric, early or late onset. It increases risks of complications. Management depends on gestational age and Doppler ultrasound results, with delivery generally between 34-37 weeks.
3. There is no worldwide consensus on specific management strategies for IUGR, and guidelines from organizations like RCOG and ACOG have some differences.
The document discusses how the fetus is able to survive as a semi-allograft within the mother's uterus despite having different genetic material. It was first proposed in 1953 that the fetus is able to evade maternal immune detection through lack of fetal antigen expression or maternal lymphocyte suppression. The document then explores various mechanisms by which the fetal-maternal interface avoids rejection, including lack of MHC class I expression on trophoblast cells, shifts in maternal immune cell profiles toward anti-inflammatory responses, and expression of inhibitory ligands on trophoblasts. Immune cells in both the peripheral maternal system and local decidua are adapted to tolerate the semi-allogeneic fetus through these various mechanisms.
Teratology is the study of birth defects and their causes. Some key points:
- Around 5% of newborns have a detectable birth defect, though the cause is unknown for 70% of cases. Less than 1% are due to medications.
- Teratogens are agents that cause permanent changes to embryonic or fetal development, and can cause malformations (teratogen), altered growth (trophogen), or interference with organ maturation (hadegen).
- Studying teratogenicity in humans is difficult due to ethical concerns, so animal studies are also used but not definitive. Counseling women exposed to potential teratogens is important to avoid anxiety.
- Amniotic fluid serves several important roles in fetal development including allowing movement, swallowing, breathing and protecting the fetus.
- The normal volume of amniotic fluid increases throughout pregnancy reaching around 800mL by the mid-third trimester. Abnormally low (oligohydramnios) or high (hydramnios) volumes can occur.
- Hydramnios, which complicates 1-2% of pregnancies, has many potential causes including fetal anomalies, diabetes or infections. It can lead to pregnancy complications like cesarean delivery. Oligohydramnios also has various causes like renal abnormalities and medications and is associated with adverse outcomes such as pulmonary hypoplasia
This document discusses various fetal disorders, focusing on fetal anemia, hydrops fetalis, and thrombocytopenia. It describes the main causes of fetal anemia as red blood cell alloimmunization and various infections. Doppler evaluation and fetal blood sampling are used to identify and monitor anemia. Left untreated, anemia can lead to heart failure, hydrops, and death. However, intrauterine transfusions have dramatically improved survival rates. Hydrops fetalis refers to fluid accumulation and can result from immune or nonimmune causes. For immune hydrops, the main cause is red blood cell alloimmunization, while aneuploidy and infections are common nonimmune causes. Thrombocytopenia can
Genetics is the study of genes, heredity, and inherited traits. Medical genetics deals with genetic causes of human diseases. The document discusses several types of chromosomal abnormalities including trisomies like Down syndrome, Edwards syndrome, and Patau syndrome. It also discusses sex chromosome abnormalities such as Turner syndrome, Klinefelter syndrome, and other conditions. Structural abnormalities of chromosomes including deletions, duplications, translocations, and microdeletions are also summarized. Chromosomal abnormalities are a major cause of genetic diseases and pregnancy complications.
Basavarajeeyam is a Sreshta Sangraha grantha (Compiled book ), written by Neelkanta kotturu Basavaraja Virachita. It contains 25 Prakaranas, First 24 Chapters related to Rogas& 25th to Rasadravyas.
share - Lions, tigers, AI and health misinformation, oh my!.pptxTina Purnat
• Pitfalls and pivots needed to use AI effectively in public health
• Evidence-based strategies to address health misinformation effectively
• Building trust with communities online and offline
• Equipping health professionals to address questions, concerns and health misinformation
• Assessing risk and mitigating harm from adverse health narratives in communities, health workforce and health system
micro teaching on communication m.sc nursing.pdfAnurag Sharma
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Knee anatomy and clinical tests 2024.pdfvimalpl1234
This includes all relevant anatomy and clinical tests compiled from standard textbooks, Campbell,netter etc..It is comprehensive and best suited for orthopaedicians and orthopaedic residents.
Muktapishti is a traditional Ayurvedic preparation made from Shoditha Mukta (Purified Pearl), is believed to help regulate thyroid function and reduce symptoms of hyperthyroidism due to its cooling and balancing properties. Clinical evidence on its efficacy remains limited, necessitating further research to validate its therapeutic benefits.
- 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
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
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Basavarajeeyam is an important text for ayurvedic physician belonging to andhra pradehs. It is a popular compendium in various parts of our country as well as in andhra pradesh. The content of the text was presented in sanskrit and telugu language (Bilingual). One of the most famous book in ayurvedic pharmaceutics and therapeutics. This book contains 25 chapters called as prakaranas. Many rasaoushadis were explained, pioneer of dhatu druti, nadi pareeksha, mutra pareeksha etc. Belongs to the period of 15-16 century. New diseases like upadamsha, phiranga rogas are explained.
ABDOMINAL TRAUMA in pediatrics part one.drhasanrajab
Abdominal trauma in pediatrics refers to injuries or damage to the abdominal organs in children. It can occur due to various causes such as falls, motor vehicle accidents, sports-related injuries, and physical abuse. Children are more vulnerable to abdominal trauma due to their unique anatomical and physiological characteristics. Signs and symptoms include abdominal pain, tenderness, distension, vomiting, and signs of shock. Diagnosis involves physical examination, imaging studies, and laboratory tests. Management depends on the severity and may involve conservative treatment or surgical intervention. Prevention is crucial in reducing the incidence of abdominal trauma in children.
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6. hormonal control of calcium & phosphate metabolism &
1. Hormonal Control of Calcium &
Phosphate Metabolism & the
Physiology of Bone
Themba Hospital FCOG(SA) Part 1 Tutorials
By Dr N.E Manana
2. INTRODUCTION
• Calcium is an essential intracellular signalling molecule and also plays a
variety of extracellular functions, thus the control of body calcium
concentrations is vitally important
• The components of the system that maintains calcium homeostasis include
cell types that sense changes in extracellular calcium
• and release calcium-regulating hormones, and the targets of these
hormones, including the kidneys, bones, and intestine
• Three hormones are primarily concerned with the regulation of calcium
homeostasis.
• Parathyroid hormone (PTH), 1,25-Dihydroxycholecalciferol and Calcitonin
3. CALCIUM
• The body of a young adult human contains about 1100 g (27.5 moles)
of calcium
• Ninety-nine per cent of the calcium is in the skeleton.
• Plasma calcium, normally at a concentration of around 10 mg/dL (5
mEq/L, 2.5 mmol/L), is partly bound to protein and partly diffusible
• It is the free, ionized calcium (Ca 2+ ) in the body fluids that is a vital
second messenger and is necessary for blood coagulation, muscle
contraction, and nerve function
• Because the extent of Ca 2+ binding by plasma proteins is
proportional to the plasma protein level, it is important to know the
plasma protein level when evaluating the total plasma calcium
4. CALCIUM
• As Ca2+ uptake rises, moreover, 1,25-dihydroxycholecalciferol levels
fall in response to increased plasma Ca 2+
• Plasma Ca2+ is filtered in the kidneys, but 98–99% of the filtered Ca2+
is reabsorbed
• About 60% of the reabsorption occurs in the proximal tubules and the
remainder in the ascending limb of the loop of Henle and the distal
tubule
6. PHOSPHORUS
• Phosphate is found in ATP, cyclic adenosine monophosphate (cAMP),
2,3-diphosphoglycerate, many proteins, and other vital compounds in
the body
• Phosphorylation and dephosphorylation of proteins are involved in
the regulation of cell function
• Therefore, it is not surprising that, like calcium, phosphate
metabolism is closely regulated
• Total body phosphorus is 500–800 g (16.1–25.8 moles), 85–90% of
which is in the skeleton.
• Total plasma phosphorus is about 12 mg/dL,
7. VITAMIN D
• The active transport of Ca 2+ and PO4 3– from the intestine is
increased by a metabolite of vitamin D
• The term “vitamin D” is used to refer to a group of closely related
sterols produced by the action of ultraviolet light on certain
provitamins
• Vitamin D3 , which is also called cholecalciferol, is produced in the
skin of mammals from 7-dehydrocholesterol by the action of sunlight.
• Vitamin D3 and its hydroxylated derivatives are transported in the
plasma bound to a globulin vitamin D-binding protein (DBP).
• Vitamin D3 is also ingested in the diet
8. VITAMIN D ACTION
• 1,25 Dihydroxycholecalciferol stimulates the expression of a number of
gene products involved in Ca2+ transport and handling via its receptor
• Ca2+ -binding proteins that also includes calmodulin
• Calbindin-Ds are found in human intestine, brain, and kidneys
• 1,25-Dihydroxycholecalciferol also increases the number of Ca2+ –ATPase
in the intestinal cells, and thus, the overall capacity for absorption of
dietary calcium
• In addition to increasing Ca2+ absorption from the intestine, it facilitates
Ca2+ reabsorption in the kidneys, increases the synthetic activity of
osteoblasts
11. SYNTHESIS & METABOLISM OF PTH
• Human PTH is a linear polypeptide that contains 84 amino acid
residues
• It is synthesized as part of a larger molecule containing 115 amino
acid residues ( preproPTH ).
• PTH is packaged in secretory granules and released as the main
secretory product of the chief cells.
• The normal plasma level of intact PTH is 10–55 pg/mL. The half-life of
PTH is approximately 10min
12. PTH ACTIONS
• PTH acts directly on bone to increase bone resorption and mobilize
Ca2+
• In addition to increasing plasma Ca2+ , PTH increases phosphate
excretion in the urine and thereby depresses plasma phosphate levels
• PTH also increases reabsorption of Ca2+ in the distal tubules,
although Ca2+ excretion in the urine is often increased in
hyperparathyroidism because the increase in the load of filtered
calcium overwhelms the effect on reabsorption
• PTH also increases the formation of 1,25-dihydroxycholecalciferol,
and this increases Ca2+ absorption from the intestine
13. REGULATION OF SECRETION
• Ca2+ acts directly on the parathyroid glands in a negative feedback
fashion to regulate the secretion of PTH.
• When the plasma Ca2+ level is high, PTH secretion is inhibited and
Ca2+ is deposited in the bones.
• When it is low, secretion is increased and Ca2+ is mobilized from the
bones. 1,25-Dihydroxycholecalciferol acts directly on the parathyroid
glands to decrease preproPTH mRNA.
• Plasma phosphate stimulates PTH secretion by lowering plasma levels
of free Ca2+ and inhibiting the formation of 1,25-
dihydroxycholecalciferol.
14. CALCITONIN
• The Ca2+ - lowering hormone has been named calcitonin.
• Calcitonin is produced by the parafollicular cells of the thyroid gland,
which are also known as the clear or C cells.
• Human calcitonin contains 32 amino acid residues.
• Its secretion is increased when the thyroid gland is exposed to a
plasma calcium level of approximately 9.5 mg/dL
• β-Adrenergic agonists, dopamine, and estrogens also stimulate
calcitonin secretion.
• Gastrin, cholecystokinin (CCK), glucagon, and secretin have also been
reported to stimulate calcitonin secretion
15. CALCITONIN ACTIONS
• Receptors for calcitonin are found in bones and the kidneys.
• Calcitonin lowers circulating calcium and phosphate levels.
• It exerts its calcium-lowering effect by inhibiting bone resorption.
• This action is direct, and calcitonin inhibits the activity of osteoclasts
in vitro. It also increases Ca2+ excretion in the urine.
16. EFFECTS OF OTHER HORMONES
• Glucocorticoids lower plasma Ca2+ levels by inhibiting osteoclast formation
and activity, but over long periods they cause osteoporosis by decreasing
bone formation and increasing bone resorption.
• Growth hormone increases Ca2+ excretion in the urine, but it also
increases intestinal absorption of Ca2+ , with a resultant positive calcium
balance
• Thyroid hormones may cause hypercalcemia, hypercalciuria, and, in some
instances, osteoporosis.
• Estrogens prevent osteoporosis by inhibiting the stimulatory effects of
certain cytokines on osteoclasts
• Insulin increases bone formation, and there is significant bone loss in
untreated diabetes
17. BONE PHYSIOLOGY
• Bone is a special form of connective tissue with a collagen framework
impregnated with Ca2+ and PO4 3– salts
• Bone is also involved in overall Ca2+ and PO4 3– homeostasis
• It protects vital organs, and the rigidity it provides permits locomotion
and the support of loads against gravity.
• Old bone is constantly being resorbed and new bone formed,
permitting remodelling that allows it to respond to the stresses and
strains that are put upon it
• It is a living tissue that is well vascularized and has a total blood flow
of 200–400 mL/min in adult humans.
19. BONE GROWTH
• During fetal development, most bones are modelled in cartilage and
then transformed into bone by ossification (enchondral bone
formation )
• The exceptions are the clavicles, the mandibles, and certain bones of
the skull in which mesenchymal cells form bone directly
(intramembranous bone formation )
• During growth, specialized areas at the ends of each long bone
(epiphyses) are separated from the shaft of the bone by a plate of
actively proliferating cartilage, the epiphysial plate
• The bone increases in length as this plate lays down new bone on the
end of the shaft
21. BONE FORMATION & RESORPTION
• The cells responsible for bone formation are osteoblasts and the cells
responsible for bone resorption are osteoclasts.
• Osteoblasts are modified fibroblasts.
• Their early development from the mesenchyme is the same as that of
fibroblasts, with extensive growth factor regulation
• Osteoclasts are members of the monocyte family
• Osteoclasts erode and absorb previously formed bone
Although the role of calcitonin seems to be relatively minor, all three hormones probably operate in concert to maintain the constancy of the calcium level in the body fl uids. Phosphate homeostasis is likewise critical to normal body function, particularly given its inclusion in adenosine triphosphate (ATP), its role as a biological buff er, and its role as a modifi er of proteins, thereby altering their functions.
Thus, for example, symptoms of tetany appear at higher total calcium levels if the patient hyperventilates, thereby increasing plasma pH.
Plasma proteins are more ionized when the pH is high, providing more protein anions to bind with Ca 2+
Two independent but interacting homeostatic systems affect the calcium in bone. One is the system that regulates plasma Ca 2+ , providing for the movement of about 500 mmol of Ca 2+ per day into and out of the readily exchangeable pool in the bone ( Figure 21–1 ).
The other system involves bone remodeling by the constant interplay of bone resorption and deposition
Ca 2+ is transported across the brush border of intestinal epithelial cells via channels known as transient receptor potential vanilloid type 6 (TRPV6) and binds to an intracellular protein known as calbindin-D 9k . Calbindin-D 9k sequesters the absorbed calcium so that it does not disturb epithelial signaling processes that involve calcium. The absorbed Ca 2+ is thereby delivered to the basolateral membrane of the epithelial cell, from where it can be transported into the bloodstream by either a Na + /Ca 2+ exchanger (NCX1) or a Ca2+-dependent ATPase
Distal tubular reabsorption depends on the TRPV5 channel, which is related to TRPV6 discussed previously, and whose expression is regulated by PTH
Pi in the plasma is filtered in the glomeruli, and 85–90% of the filtered Pi is reabsorbed.
Active transport in the proximal tubule accounts for most of the reabsorption and involves two related sodium-dependent P i cotransporters, NaPi -IIa and NaPi -IIc. NaPi -IIa is powerfully inhibited by PTH, which causes its internalization and degradation and thus a reduction in renal Pi reabsorption
Pi is absorbed in the duodenum and small intestine.
Uptake occurs by a transporter related to those in the kidney, NaPi -IIb, that takes advantage of the low intracellular Na + concentration established by the Na, K ATPase on the basolateral membrane of intestinal epithelial cells to load P i against its concentration gradient.
The reaction involves the rapid formation of previtamin D3 , which is then converted more slowly to vitamin D3
Vitamin D3 is metabolized by enzymes that are members of the cytochrome P450 (CYP) superfamily
In the liver, vitamin D 3 is converted to 25-hydroxycholecalciferol (calcidiol, 25-OHD 3 ).
The 25-hydroxycholecalciferol is converted in the cells of the proximal tubules of the kidneys to the more activemetabolite 1,25-dihydroxycholecalciferol , which is also called calcitriol or 1,25-(OH) 2 D 3 . 1,25-Dihydroxycholecalciferol is also made in the placenta, in keratinocytes in the skin, and in macrophages
via increased TRPV5 expression in the proximal tubules
In the intestinal epithelium and many other tissues, two calbindins are induced: calbindinD 9K and calbindinD 28K , with molecular weights of 9000 and 28,000, respectively.
ANATOMY
Humans usually have four parathyroid glands: two embedded in the superior poles of the thyroid and two in its inferior poles
Each parathyroid gland is a richly vascularized disk, about 3 × 6 × 2 mm, containing two distinct types of cells
The abundant chief cells , which contain a prominent Golgi apparatus plus endoplasmic reticulum and secretory granules, synthesize and secrete PTH .
The less abundant and larger oxyphil cells contain oxyphil granules and large numbers of mitochondria in their cytoplasm. In humans, few oxyphil cells are seen before puberty, and thereafter they increase in number with age. Their function is unknown.
Amino acid residues are removed from the amino terminal of proPTH in the Golgi apparatus, and the 84-amino-acid polypeptide
On entry of preproPTH into the endoplasmic reticulum, a leader sequence is removed from the amino terminal to form the 90-amino-acid polypeptide proPTH
the secreted polypeptide is rapidly cleaved by the Kupffer cells in the liver into fragments that are probably biologically inactive.
PTH and these fragments are then cleared by the kidneys
This phosphaturic action is due to a decrease in reabsorption of phosphate via effects on NaPi -IIa in the proximal tubules, as discussed previously
On a longer time scale, PTH stimulates both osteoblasts and osteoclasts.
It now appears that there are at least three different PTH receptors.
One also binds parathyroid hormone-related protein (PTHrP; see below) and is known as the hPTH/PTHrP receptor.
A second receptor, PTH2 (hPTH2-R), does not bind PTHrP and is found in the brain, placenta, and pancreas
In the disease called pseudohypoparathyroidism , the signs and symptoms of hypoparathyroidism develop but the circulating level of PTH is normal or even elevated. Because tissues fail to respond to the hormone, this is a receptor disease
The key to this regulation is a cell membrane Ca 2+ receptor, CaR
Magnesium is required to maintain normal parathyroid secretory responses. Impaired PTH release along with diminished target organ responses to PTH account for the hypocalcemia that occasionally occurs in magnesium defi ciency
Above this level, plasma calcitonin is directly proportional to plasma calcium.
However, the dose of gastrin needed to stimulate calcitonin secretion is supraphysiological and not seen after eating in normal individuals, so dietary calcium in the intestine probably does not induce secretion of a calcium-lowering hormone prior to the calcium being absorbed.
In any event, the actions of calcitonin are short-lived because it has a half-life of less than 10 min in humans.
gastrin being the most potent stimulus
The calcitonin content of the human thyroid is low, and after thyroidectomy, bone density and plasma Ca 2+ level are normal as long as the parathyroid glands are intact
This may be explained in part by secretion of calcitonin from tissues other than the thyroid.
However, there is general agreement that the hormone has little long-term effect on the plasma Ca 2+ level in adult animals and humans. Further, unlike PTH and 1,25-dihydroxycholecalciferol, calcitonin does not appear to be involved in phosphate homeostasis
They decrease bone formation by inhibiting protein synthesis in osteoblasts.
They also decrease the absorption of Ca 2+ and PO 4 3– from the intestine and increase the renal excretion of these ions.
The decrease in plasma Ca 2+ concentration also increases the secretion of PTH, and bone resorption is facilitated
Bone in children and adults is of two types: compact or cortical bone , which makes up the outer layer of most bones ( Figure 21–8 ) and accounts for 80% of the bone in the body; and trabecular or spongy bone inside the cortical bone, which makes up the remaining 20% of bone in the body
In compact bone, the surface-to-volume ratio is low, and bone cells lie in lacunae.
They receive nutrients by way of canaliculi that ramify throughout the compact bone ( Figure 21–8 ).
Trabecular bone is made up of spicules or plates, with a high surface to volume ratio and many cells sitting on the surface of the plates.
Nutrients diff use from bone extracellular fluid (ECF) into the trabeculae, but in compact bone, nutrients are provided via haversian canals
The protein in bone matrix is over 90% type I collagen, which is also the major structural protein in tendons and skin.
This collagen, which weight for weight is as strong as steel, is made up of a triple helix of three polypeptides bound tightly together
The width of the epiphysial plate is proportional to the rate of growth. Th e width is affected by a number of hormones, but most markedly by the pituitary growth hormone and IGF-I
Linear bone growth can occur as long as the epiphyses are separated from the shaft of the bone, but such growth ceases after the epiphyses unite with the shaft (epiphysial closure)
The epiphyses of the various bones close in an orderly temporal sequence, the last epiphyses closing after puberty.
The normal age at which each of the epiphyses closes is known, and the “bone age” of a young individual can be determined by X-raying the skeleton and noting which epiphyses are open and which are closed
The periosteum is a dense fibrous, vascular, and innervated membrane that covers the surface of bones.
This layer consists of an outer layer of collagenous tissue and an inner layer of fine elastic fibers that can include cells that have the potential to contribute to bone growth
As one ages, the periosteum becomes thinner and loses some of its vasculature.
This renders bones more susceptible to injury and disease
The renewal rate for bone is about 4% per year for compact bone and 20% per year for trabecular bone.
The remodelling is related in part to the stresses and strains imposed on the skeleton by gravity.
At the cellular level, there is some regulation of osteoclast formation by osteoblasts via the RANKL–RANK and the M-CSF–OPG mechanism; however, specific feedback mechanisms of osteoclasts on osteoblasts are not well defined. In a broader sense, the bone remodeling process is primarily under endocrine control.
PTH accelerates bone resorption, and estrogens slow bone resorption by inhibiting the production of bone-eroding cytokines.
leptin decreases bone formation.
This finding is consistent with the observations that obesity protects against bone loss and that most obese humans are resistant to the effects of leptin on appetite.
Thus, there may be neuroendocrine regulation of bone mass via leptin.
ossification specific transcription factors, such as Cbfa1/Runx2, contribute to their differentiation.
The importance of this transcription factor in bone development is underscored in knockout mice deficient for the Cbfa1/Runx gene.
These mice develop to term with their skeletons made exclusively of cartilage; no ossification occurs.
Normal osteoblasts are able to lay down type 1 collagen and form new bone.
When these cells come in contact with appropriate monocytes expressing RANK (ie, the RANKL receptor) two distinct signaling pathways are initiated:
there is a RANKL/RANK interaction between the cell pairs,
(2) mononuclear phagocyte colony stimulating factor (M-CSF) is secreted by the nonmonocytic cells and it binds to its corresponding receptor on the monocytes (c-fi n).
The combination of these two signaling events leads to differentiation of the monocytes into osteoclasts
Throughout life, bone is being constantly resorbed and new bone is being formed.
The calcium in bone turns over at a rate of 100% per year in infants and 18% per year in adults
Bone remodeling is mainly a local process carried out in small areas by populations of cells called bone-remodeling units.
First, osteoclasts resorb bone, and then osteoblasts lay down new bone in the same general area
Modeling drift s also occur in which the shapes of bones change as bone is resorbed in one location and added in another.
Osteoclasts tunnel into cortical bone followed by osteoblasts, whereas trabecular bone remodeling occurs on the surface of the trabeculae
About 5% of the bone mass is being remodeled by about 2 million bone remodeling units in the human skeleton at any one time