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Survey of Anatomy & Physiology Chapter 16
 

Survey of Anatomy & Physiology Chapter 16

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    Survey of Anatomy & Physiology Chapter 16 Survey of Anatomy & Physiology Chapter 16 Presentation Transcript

    • 16 Part One: The Urinary System: Filtration and Fluid Balance
    • Introduction  Urinary system acts as purification plant, cleaning blood of waste materials  Liver does some purification, but urinary system controls electrolyte and fluid balances for body
    • Introduction  Kidneys filter blood, reabsorb and secrete ions, and produce urine  Without this important function you would die in a few days
    • System Overview  Urinary system consists of two kidneys, beanshaped organs located in superior dorsal abdominal cavity that filter blood and make urine, as well as accessory structures
    • System Overview  Ureter is tube that carries urine from each kidney to single urinary bladder, located in inferior ventral pelvic cavity  Urinary bladder is basically expandable sac that holds urine
    • System Overview  Job of urinary system is to make urine, thus controlling body's fluid and electrolyte balance and eliminating waste products
    • http://www.youtube.com/watch?v=lfGYd1wrTgE
    • 3 Processes to Make Urine
    • Function of the Urinary System  Filtration involves passing substances in blood through walls of glomerular capillaries that are dotted with pores to create filtrate; contains various substances that can either be
    • Function of the Urinary System  Reabsorbed from tubules to capillaries or  Secreted from capillaries to tubules and removed in the urine  Part of filtrate is reabsorbed and sent back into bloodstream, some is secreted into tubules and eliminated from body
    • Figure 16-1 Anatomy of the urinary system.
    • Anatomy of the urinary system  Kidney covered by fibrous layer of connective tissue called renal capsule  Indentation that gives kidney bean-shaped called renal hilum External Anatomy of the Kidney
    • Anatomy of the urinary system  At hilum, renal arteries bring blood to kidneys to be filtered; blood leaves kidney via renal vein  Ureter also attached to transport urine from kidney to bladder External Anatomy of the Kidney
    • Anatomy of the urinary system  Renal cortex: outer layer, grainy in appearance; little obvious structure to naked eye; where blood filtration occurs Internal Anatomy of the Kidney
    • Anatomy of the urinary system ◦ Renal medulla: Contains number of triangleshaped, striped areas called renal pyramids Internal Anatomy of the Kidney
    • Anatomy of the urinary system ◦ Renal medulla: ◦ Renal pyramids composed of collecting tubules for urine formed in kidney Internal Anatomy of the Kidney
    • Anatomy of the urinary system  Renal pelvis  Funnel, divided into two or three large collecting tubes called major calyces Internal Anatomy of the Kidney
    • Anatomy of the urinary system  Renal pelvis  Each calyx divided into several minor calyces, forming cup-shaped areas around tips of pyramids to collect urine that continually drains through pyramids Internal Anatomy of the Kidney
    • Filtration and Collection System
    • Figure 16-2 The internal and external anatomy of the kidney
    • Figure 16-3 Renal blood vessels and the pathway of blood through the renal system.
    • The NephronFunctional Unit of Kidney  Consisting of millions of microscopic funnels and tubules  Divided into two distinct parts:  Renal corpuscle  Renal tubule
    • The NephronFunctional Unit of Kidney  Blood flows through afferent arteriole and into the glomerulus, a capillary ball  Walls of glomerular capillaries dotted with pores
    • The NephronFunctional Unit of Kidney  Surrounding glomerulus is a double-layered membrane called glomerular capsule (Bowman's capsule)
    • The NephronFunctional Unit of Kidney  Blood flows into glomerulus and blood cells and few large molecules, mainly plasma protein, remain in blood.  Water and small solutes allowed to pass through pores in capillaries across filter and into glomerular capsule The NephronFiltration
    • http://www.youtube.com/watch?v=Hlg7oh2OcOc
    • The NephronFunctional Unit of Kidney  Blood then exits the glomerulus through the efferent arteriole and the small blood vessels become part of the peritubular capillaries that surround the renal tubules
    • The NephronFunctional Unit of Kidney  Material filtered from blood into glomerular capsule is called the glomerular filtrate  If blood or protein leaks into urine, this can indicate kidney filtration problem The NephronFiltration
    • The NephronFunctional Unit of Kidney  The rest of nephron is series of tubes known as renal tubules  Glomerular filtrate travels from glomerular capsule into first part of renal tubule called the proximal tubule  Wall of proximal tubule made cells with microvilli The Nephron
    • The NephronFunctional Unit of Kidney  From proximal tubule, glomerular filtrate flows into nephron loop (Loop of Henle)  Nephron loop consists of:  Descending loop (similar in structure to proximal tubule) and Ascending loop The Nephron
    • http://www.youtube.com/watch?v=_CnhwhHsWLI&list=PL315
    • The NephronFunctional Unit of Kidney  Glomerular filtrate then flows into distal tubule  From distal tubule, glomerular filtrate flows into one of several collecting ducts,
    • Flow of Urine to External Kidney  Collecting ducts lead to  1) minor calyces, then to  2)major calyces,  3)renal pelvis,  4) ureter At this point, glomerular filtrate is urine
    • Figure 16-5 A functional renal unit.
    • Urine Formation-3 Processes  Kidney controls fluid and electrolyte balance by controlling urine volume and composition  In order to form urine, nephron must perform three processes:
    • Urine Formation at Level of the Nephron the
    • Urine Formation at the Level of the Nephron Urine Formation
    • Urine Formation at the Level of the Nephron  Filtration moves fluid and chemicals into nephron from blood  Reabsorption and secretion control concentration of chemicals and volume of urine Urine FormationSummary
    • Urine Formation at the Level of the Nephron  Due to the action of reabsorption and secretion, the urine is chemically very different that the original glomerular filtrate.  In other words, what starts out looking very similar to blood, changes after passing through the tubules Urine FormationSummary
    • Figure 16-7 The processes involved in urine formation
    • Figure 16-8 Filter selectivity Only when filter is damaged, do blood and Only when filter is damaged, do blood and protein pass through protein pass through  Control of filtration (amount and composition of fluid filtered) is determined by size of pores in the walls of the renal corpuscle  Like a coffee filter, it is selective as to what it let’s pass through
    •  If GFR controls rate of urine formation then….  Tubular reabsorption and secretion control chemistry and volume of urine Control of Tubular Reabsorption and Secretion
    •  REMEMBER:  Substances that are reabsorbed move from tubule back to bloodstream via peritubular capillaries and stay in body  Substances that are secreted stay in tubule and eventually leave body via urine Control of Tubular Reabsorption and Secretion
    • Control of Tubular Reabsorption and Secretion  IMPORTANT:  Anything that affects reabsorption and secretion affects urine chemistry and/or composition and volume
    •  First thing that affects tubular reabsorption and secretion is tubule permeability  Each portion of tubule can reabsorb and secrete different substances Control of Tubular Reabsorption and Secretion
    • Control of Tubular Reabsorption and Secretion  Molecules move across membranes through several different methods (diffusion, osmosis, active or passive transport)
    • Control of Tubular Reabsorption and Secretion  Differences in tubular permeability result in dramatic differences in which molecules are reabsorbed or secreted in each part of tubule
    • Table 16-2 Individual Tubule Functions Most of important substances reabsorbed or secreted Most of important substances reabsorbed or secreted in PROXIMAL TUBULE in PROXIMAL TUBULE 90% of water reabsorbed in descending loop 90% of water reabsorbed in descending loop
    • Balancing H20 & IONS  Filtrate flows into descending loop, reabsorbing water and increasing concentration of ions
    • Balancing H20 & IONS  As filtrate enters ascending loop, fluid is concentrated because of water loss, membrane is permeable to only ions, so ions are reabsorbed from ascending loop
    • Figure 16-11 Sites of tubular reabsorption and secretion
    • Figure 16-11 Sites of tubular reabsorption and secretion Use handout and Use handout and follow along follow along
    • Complete worksheets using your notes from Power Complete worksheets using your notes from Power Point Presentation notes and textbook on Point Presentation notes and textbook on ••TheNephron (page 457 and slides 22-30) The Nephron (page 457 and slides 22-30) ••GlomerularFiltration (page 458 and PPP) Glomerular Filtration (page 458 and PPP)
    • 16 Part Two:The Urinary System: Filtration and Fluid Balance
    • Pressure Affects Glomerular Filtration  Higher pressure in glomerulus increases filtration, while lower pressure decreases filtration  Glomerulus protected from minor changes in blood pressure by mechanism called autoregulation Filtration RateAmount of Filtered Fluid
    • BP and Formation of Urine-GFR*  As systemic BP increases, afferent arterioles leading into glomerulus constrict, thereby decreasing amount of blood getting into glomerulus *glomerular filtration rate Autoregulation of GFR*
    • BP and Formation of UrineGlomerular Filtration  Autoregulation can be overridden when BP must be regulated.  Kidney controls fluid volume, so when BP or blood volume drops, (extreme blood loss) GFR decreases to conserve fluid volume Autoregulation of GFR
    • BP and Formation of UrineGlomerular Filtration  Glomerular filtration rate can decrease to conserve fluid when blood pressure falls, or increase filtration if blood pressure rises Autoregulation of GFR
    • ADH-Hormone that controls Reabsorption and Secretion  ADH is a hormone that regulates blood pressure  Made by hypothalamus and secreted from posterior pituitary when BP decreases or ionic concentration increases
    • ADH-Hormone that controls Reabsorption and Secretion  Increases permeability of distal tubule and collecting duct; more water reabsorbed, increasing blood volume and blood pressure, and diluting ionic concentration
    • ADH-Hormone that controls Reabsorption and Secretion  Less urine is produced  Alcohol inhibits ADH production, increasing urine production
    • The Urinary Bladder – Next Stop for the Urine
    • The Urinary Bladder and Urination Reflex  Urinary bladder: small, hollow organ  Lined with transitional epithelium, which is the only epithelium stretchy enough to expand as bladder fills
    • The Urinary Bladder and Urination Reflex  Ability to stretch enhanced by series of pleats called rugae  Has muscular wall consisting of circular and longitudinal smooth muscle  Muscle layer known as detrusor muscle
    • Figure 16-14 The urinary bladder.
    • Figure 16-15 Control of urination As urine accumulates, bladder fills and stretches Stretch triggers urinary reflex and need to void to empty bladder
    • Figure 16-15 Control of urination Urination had been thought to be Urination had been thought to be spinal reflex; new research spinal reflex; new research indicates controlled by brain indicates controlled by brain When bladder is full, signals sent from bladder to spinal cord to pons, then Pons sends parasympathetic signals down spinal cord, causing contraction of muscular walls of bladder, and bladder empties
    • Figure 16-15 Control of urination Urine leaves bladder via urethra, thin muscular tube lined with several different types of epithelium along its length
    • Figure 16-15 Control of urination Parts of brain can inhibit urination by controlling internal urethral sphincter, valve at junction of bladder and urethra, and external urethral sphincter, valve that is part of muscles of pelvic floor
    • Figure 16-15 Control of urination Sympathetic stimulation of these sphincters prevents urine from leaving body Although you have little control over contractions of bladder wall, you have very good voluntary control over sphincters