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Urinary System Chapter 17. Functions Filtration of blood Body fluid regulation – Water/salt balance – pH balance Waste removal.

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Presentation on theme: "Urinary System Chapter 17. Functions Filtration of blood Body fluid regulation – Water/salt balance – pH balance Waste removal."— Presentation transcript:

1 Urinary System Chapter 17

2 Functions Filtration of blood Body fluid regulation – Water/salt balance – pH balance Waste removal

3 Key Structures Kidneys Renal Veins Renal Arteries Ureters Urinary Bladder Urethra

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5 Path of Urine Blood to kidney Urine Out – Ureter – Bladder – Urethra – Out

6 Kidneys Red/Brown color, bean shaped 12 cm long Enclosed by a capsule

7 Functions of Kidneys Filter blood – Keep what is needed; excrete what is not Maintain content, volume, pH of body fluid Other functions – Maintain RBC production – Regulate blood volume and pressure

8 Kidney Structures Renal Medulla Renal Cortex – Nephrons Major Calyx Minor Calyx

9 Blood Flow to Kidneys Blood from abdominal aorta to renal arteries – Blood filtered 1 st – Gas exchange 2 nd Renal veins take deoxygenated blood from kidneys Veins lead to inferior vena cava

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11 Nephrons A kidney has 1 million of these Smallest unit of filtration Blood supply to nephron – Blood taken to nephron by afferent arteriole – Efferent arteriole takes filtered (but not deoxygenated blood) to peritubular capillaries (surround tubes of nephron)

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13 Fig17.02 Renal pelvis Minor calyx Major calyx Renal papilla Renal pyramid Collecting duct Nephrons Renal sinus Renal medulla Renal capsule Renal cortex Ureter (a) (b)(c) Renal corpuscle Renal tubule Papilla Minor calyx Renal medulla Renal cortex Fat in renal sinus Renal column Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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15 Fig17.03 Cortex Medulla Renal artery Renal pelvis Renal vein Ureter Cortical radiate artery and vein Interlobar vein and artery Arcuate vein and artery Proximal convoluted tubule Cortical radiate artery and vein Efferent arteriole Afferent arteriole Distal convoluted tubule Peritubular capillary Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

16 Blood Supply cont. Glomerulus: cluster of blood capillaries Bowman’s capsule: cup like structure that surrounds blood capillaries

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19 Parts of Nephron Bowman’s Capsule Proximal (Convoluted) Tubule Loop of Henle (Desecending/Ascending) Distal (Convoluted) Tubule Collecting Duct

20 Fig17.03 Cortex Medulla Renal artery Renal pelvis Renal vein Ureter Cortical radiate artery and vein Interlobar vein and artery Arcuate vein and artery Proximal convoluted tubule Cortical radiate artery and vein Efferent arteriole Afferent arteriole Distal convoluted tubule Peritubular capillary Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

21 Fig17.06 Proximal convoluted tubule Cortical radiate artery Glomerulus Glomerular capsule Efferent arteriole Afferent arteriole Distal convoluted tubule From renal artery To renal vein Peritubular capillary Descending limb Nephron loop Collecting duct Cortical radiate vein Ascending limb Renal cortex Renal medulla Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 21

22 22 Fig17.07 Glomerular capsule Glomerulus Afferent arteriole Efferent arteriole Juxtaglomerular apparatus Distal convoluted tubule Proximal convoluted tubule Nephron loop Glomerulus Afferent arteriole Glomerular capsule Efferent arteriole Ascending limb of nephron loop Juxtaglomerular cells Podocyte Macula densa (a) (b) Juxtaglomerular apparatus Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

23 Urine Formation Three Stages 1. Filtration Glomerulus/Bowman’s Capsule 2. Secretion 3. Reabsorption 2 & 3 happen in rest of the nephron

24 Filtration Glomerulus is leaky; so portion of the blood is filtered out of it and into the Bowman’s capsule Filtration depends on pressure

25 Pressure High Pressure – Forces small things from glomerulus to Bowman’s capsule – Anything that leaves blood and enters capsule is called filtrate

26 Pressures to Know Hydrostatic pressure: pressure due to presence of water Osmotic pressure: pressure due to high concentration of dissolved solutes – “Pulling pressure” – Water is pulled toward solutes

27 27 Fig17.10 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Blood flow Plasma colloid osmotic pressure Blood flow Glomerular hydrostatic pressure Capsular hydrostatic pressure Net filtration pressure Net Outward Pressure Outward force, glomerular hydrostatic pressure = +60 mm Inward force of plasma colloid osmotic pressure = –32 mm Inward force of capsular hydrostatic pressure = –18 mm Net filtration pressure = +10 mm

28 Overall Net filtration pressure forces substances out of glomerulus and into capsule

29 Factors Affecting Filtration Change in diameter of arterioles – Smaller afferent arteriole = less filtration – Smaller efferent arteriole = more filtration Less proteins in blood = less glomerular osmotic pressure = more filtration More pressure in capsule = less filtration

30 Reabsorption Mostly in proximal tubule – Microvilli Glucose, amino acids, water, protein There is a limit to reabsorption, so these are still excreted in urine as well

31 Fig17.06 Proximal convoluted tubule Cortical radiate artery Glomerulus Glomerular capsule Efferent arteriole Afferent arteriole Distal convoluted tubule From renal artery To renal vein Peritubular capillary Descending limb Nephron loop Collecting duct Cortical radiate vein Ascending limb Renal cortex Renal medulla Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 31

32 Secretion Opposite of reabsorption Excess H ions and organic compounds

33 Urine Composition Varies from time to time; reflects the amounts of water/solutes that the kidneys eliminate to maintain homeostasis 95% water, and also contains urea, uric acid, a trace of amino acids, and electrolytes

34 Urine Elimination Pathway of urine after forming in nephron: – Collecting Duct – Minor calyces – Major calyces – Renal Pelvis – Ureter – Bladder – Urethra – OUT!

35 Fig17.03 Cortex Medulla Renal artery Renal pelvis Renal vein Ureter Cortical radiate artery and vein Interlobar vein and artery Arcuate vein and artery Proximal convoluted tubule Cortical radiate artery and vein Efferent arteriole Afferent arteriole Distal convoluted tubule Peritubular capillary Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

36 Ureters 1 per kidney Peristalsis forces urine down Valve at end allows urine into bladder

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38 Bladder Muscular, hollow, sphere, highly folded Stores urine, forces it into urethra

39 Micturition Reflex Process by which urine leaves bladder Stretching of bladder detected by micturition reflex center of spinal cord Causes: – Bladder muscle contraction – Urge to urinate – Internal urethral sphincter relaxes – External urethral sphincter relaxes (voluntary control)

40 Urethra Opening from bladder to external environment

41 Diuretics

42 Kidney Stones


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