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Human Urogenital System

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Presentation on theme: "Human Urogenital System"— Presentation transcript:

1 Human Urogenital System

2 Urogenital System Functions
Filtering of blood, Removal of wastes and metabolites Regulation of blood volume and composition concentration of blood solutes pH of extracellular fluid blood cell synthesis Synthesis of Vitamin D Reproduction and sexual function

3 Urinary System Anatomy

4 Location and External Anatomy of Kidneys
Renal capsule Surrounds each kidney Perirenal fat Engulfs renal capsule and acts as cushioning and source of energy Renal fascia Anchors kidneys to abdominal wall, separates from abdomen Hilum Renal artery and nerves enter and renal vein and ureter exit kidneys Location Lie behind peritoneum on posterior abdominal wall on either side of vertebral column Lumbar vertebrae and rib cage partially protect Right kidney slightly lower than left

5 Internal Anatomy of Kidneys
Cortex: Outer area Renal columns Medulla: Inner area Renal pyramids Calyces Major: Converge to form pelvis Minor: Papillae extend Nephron: Functional unit of kidney Juxtamedullary Cortical

6 The Nephron

7 Histology of the Nephron

8 Internal Anatomy of Kidneys
Renal corpuscle Bowman’s or Renal capsule Parietal layer Visceral layer Glomerulus Network of capillaries goes into another capillary bed called the peritubular Capillaries - Arterioles Afferent Blood to glomerulus Efferent Drains not into veinule but another arteriole Tubules Proximal (convoluted) tubule Loops of Henle Descending limb Ascending limb Distal (convoluted) tubules Collecting ducts

9 Renal Corpuscle

10 Kidney Blood Flow

11 Ureters and Urinary Bladder
Urethra Transports urine from bladder to outside of body Difference in length between males and females Sphincters Internal urinary External urinary Ureters Tubes through which urine flows from kidneys to urinary bladder Urinary bladder Stores urine

12 Ureters and Urinary Bladder

13 Urine Formation

14 Filtration Filtration Filtration pressure Filtration membrane
Renal filtrate Plasma minus blood cells and blood proteins Most (99%) reabsorbed Filtration membrane Fenestrated endothelium, basement membrane and pores formed by podocytes Filtration pressure Responsible for filtrate formation Glomerular capillary pressure (GCP) minus capsule pressure (CP) minus colloid osmotic pressure (COP) Changes caused by glomerular capillary pressure EFP = GCP – CP – COP Where Effective filtration pressure = EFP

15 Filtration Pressure

16 Tubular Reabsorption Reabsorption almost 90% takes place in Proximal tubule via Passive transport Active transport Cotransport Specialization of tubule segments Distal tubule and collecting duct affected by hormones like ADH & Aldosterone Substances transported Active transport moves Na+ across nephron wall Other ions and molecules moved by cotransport Passive transport moves water, urea, lipid-soluble, nonpolar compounds

17 Reabsorption in Proximal Nephron

18 Reabsorption in Loop of Henle

19 Reabsorption in Loop of Henle

20 Tubular Secretion Substances enter proximal or distal tubules and collecting ducts H+, K+ and some substances not produced in body are secreted by countertransport mechanisms

21 Secretion of Hydrogen and Potassium

22 Urine Production In ascending limb of loop of Henle
Na+, Cl-, K+ transported out of filtrate Water remains In distal tubules and collecting ducts Water movement out regulated by ADH If absent, water not reabsorbed and dilute urine produced If ADH present, water moves out, concentrated urine produced In Proximal tubules Na+ and other substances removed Water follows passively Filtrate volume reduced In descending limb of loop of Henle Water exits passively, solute enters Filtrate volume reduced 15%

23 Filtrate and Medullary Concentration Gradient

24 Medullary Concentration and Urea Cycling

25 Urine Concentration Mechanism
When large volume of water consumed Eliminate excess without losing large amounts of electrolytes Response is kidneys produce large volume of dilute urine When drinking water not available Kidneys produce small volume of concentrated urine Removes waste and prevents rapid dehydration

26 Urine Concentrating Mechanism

27 Hormonal Mechanisms ADH Renin Atrial natriuretic hormone Aldosterone
Secreted by posterior pituitary Increases water permeability in distal tubules and collecting ducts Aldosterone Produced in adrenal cortex Affects Na+ and Cl- transport in nephron and collecting ducts Renin Produced by kidneys, causes production of angiotensin II Atrial natriuretic hormone Produced by heart when blood pressure increases Inhibits ADH production Reduces ability of kidney to concentrate urine

28 Effect of ADH on Nephron

29 Aldosterone Effect on Distal Tubule

30 Autoregulation and Sympathetic Stimulation
Involves changes in degree of constriction in afferent arterioles As systemic BP increased, afferent arterioles constrict and prevent increase in renal blood flow Sympathetic stimulation Constricts small arteries and afferent arterioles Decreases renal blood flow

31 Clearance and Tubular Load
Plasma clearance Volume of plasma cleared of a specific substance each minute Used to estimate GFR Used to calculate renal plasma flow Used to determine which drugs or other substances excreted by kidney Tubular load Total amount of substance that passes through filtration membrane into nephrons each minute Normally glucose is almost completed reabsorbed

32 Tubular Maximum Tubular maximum
Maximum rate at which a substance can be actively absorbed Each substance has its own tubular maximum

33 Urine Flow and Micturition Reflex
Hydrostatic pressure forces urine through nephron Peristalsis moves urine through ureters Micturition reflex Stretch of urinary bladder stimulates reflex causing bladder to contract, inhibiting urinary sphincters Higher brain centers can stimulate or inhibit reflex

34 Micturition Reflex

35 Effects of Aging on Kidneys
Gradual decrease in size of kidney Decrease in kidney size leads to decrease in renal blood flow Decrease in number of functional nephrons Decrease in renin secretion and vitamin D synthesis Decline in ability of nephron to secrete and absorb

36 Kidney Dialysis

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