Slide 1 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Chapter 17 The Urinary System

Slide 2 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. 2 “Down the Flush”

Slide 3 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. KIDNEYS Location—under back muscles, behind parietal peritoneum, just above waistline; right kidney usually a little lower than left (Figure 17-1) Location—under back muscles, behind parietal peritoneum, just above waistline; right kidney usually a little lower than left (Figure 17-1) Internal structure (Figure 17-2) Internal structure (Figure 17-2) Cortex—outer layer of kidney substance Cortex—outer layer of kidney substance Medulla—inner portion of kidney Medulla—inner portion of kidney Pyramids—triangular divisions of medulla Pyramids—triangular divisions of medulla Papilla—narrow, innermost end of pyramid Papilla—narrow, innermost end of pyramid Pelvis—expansion of upper end of ureter; lies inside kidney Pelvis—expansion of upper end of ureter; lies inside kidney Calyces—divisions of renal pelvis Calyces—divisions of renal pelvis

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Slide 7 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. KIDNEYS (cont.) Microscopic structure—nephrons are microscopic units of kidneys; consist of (Figure 17-3): Microscopic structure—nephrons are microscopic units of kidneys; consist of (Figure 17-3): Renal corpuscle Renal corpuscle Bowman’s capsule—the cup-shaped top Bowman’s capsule—the cup-shaped top Glomerulus—network of blood capillaries surrounded by Bowman’s capsule Glomerulus—network of blood capillaries surrounded by Bowman’s capsule Renal tubule Renal tubule Proximal convoluted tubule—first segment Proximal convoluted tubule—first segment Loop of Henle—extension of proximal tubule; consists of descending limb, loop, and ascending limb Loop of Henle—extension of proximal tubule; consists of descending limb, loop, and ascending limb Distal convoluted tubule—extension of ascending limb of loop of Henle Distal convoluted tubule—extension of ascending limb of loop of Henle Collecting tubule—straight extension of distal tubule Collecting tubule—straight extension of distal tubule

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Slide 10 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. KIDNEYS (cont.) Functions Functions Excretes toxins and nitrogenous wastes Excretes toxins and nitrogenous wastes Regulates levels of many chemicals in blood Regulates levels of many chemicals in blood Maintains water balance Maintains water balance Helps regulate blood pressure via secretion of renin Helps regulate blood pressure via secretion of renin

Slide 11 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. FORMATION OF URINE (Figure 17-5) Occurs by a series of three processes that take place in successive parts of nephron Occurs by a series of three processes that take place in successive parts of nephron Filtration—goes on continually in renal corpuscles; glomerular blood pressure causes water and dissolved substances to filter out of glomeruli into Bowman’s capsule; normal glomerular filtration rate 125 mL per minute Filtration—goes on continually in renal corpuscles; glomerular blood pressure causes water and dissolved substances to filter out of glomeruli into Bowman’s capsule; normal glomerular filtration rate 125 mL per minute Reabsorption—movement of substances out of renal tubules into blood in peritubular capillaries; water, nutrients, and ions are reabsorbed; water is reabsorbed by osmosis from proximal tubules Reabsorption—movement of substances out of renal tubules into blood in peritubular capillaries; water, nutrients, and ions are reabsorbed; water is reabsorbed by osmosis from proximal tubules Secretion—movement of substances into urine in the distal and collecting tubules from blood in peritubular capillaries; hydrogen ions, potassium ions, and certain drugs are secreted by active transport; ammonia is secreted by diffusion Secretion—movement of substances into urine in the distal and collecting tubules from blood in peritubular capillaries; hydrogen ions, potassium ions, and certain drugs are secreted by active transport; ammonia is secreted by diffusion Control of urine volume—mainly by posterior pituitary hormone’s ADH, which decreases it Control of urine volume—mainly by posterior pituitary hormone’s ADH, which decreases it

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Slide 13 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. URETERS Structure (Figure 17-6)—narrow, long tubes with expanded upper end (renal pelvis) located inside kidney and lined with mucous membrane Structure (Figure 17-6)—narrow, long tubes with expanded upper end (renal pelvis) located inside kidney and lined with mucous membrane Function—drain urine from renal pelvis to urinary bladder Function—drain urine from renal pelvis to urinary bladder

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Slide 15 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. URINARY BLADDER Structure (Figure 17-7) Structure (Figure 17-7) Elastic muscular organ, capable of great expansion Elastic muscular organ, capable of great expansion Lined with mucous membrane arranged in rugae, as is stomach mucosa Lined with mucous membrane arranged in rugae, as is stomach mucosa Functions Functions Storage of urine before voiding Storage of urine before voiding Voiding Voiding

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Slide 17 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. URETHRA Structure Structure Narrow tube from urinary bladder to exterior Narrow tube from urinary bladder to exterior Lined with mucous membrane Lined with mucous membrane Opening of urethra to the exterior called urinary meatus Opening of urethra to the exterior called urinary meatus Functions Functions Passage of urine from bladder to exterior of the body Passage of urine from bladder to exterior of the body Passage of male reproductive fluid (semen) from the body Passage of male reproductive fluid (semen) from the body

Slide 18 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. MICTURITION Passage of urine from body (also called urination or voiding) Passage of urine from body (also called urination or voiding) Regulatory sphincters Regulatory sphincters Internal urethral sphincter (involuntary) Internal urethral sphincter (involuntary) External urethral sphincter (voluntary) External urethral sphincter (voluntary) Bladder wall permits storage of urine with little increase in pressure Bladder wall permits storage of urine with little increase in pressure Emptying reflex Emptying reflex Initiated by stretch reflex in bladder wall Initiated by stretch reflex in bladder wall Bladder wall contracts Bladder wall contracts Internal sphincter relaxes Internal sphincter relaxes External sphincter relaxes, and urination occurs External sphincter relaxes, and urination occurs

Slide 19 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. MICTURITION (cont.) Urinary retention—urine produced but not voided Urinary retention—urine produced but not voided Urinary suppression—no urine produced but bladder is normal Urinary suppression—no urine produced but bladder is normal Urinary incontinence—urine is voided involuntarily; a common bladder control problem in elderly people Urinary incontinence—urine is voided involuntarily; a common bladder control problem in elderly people May be caused by spinal injury or stroke May be caused by spinal injury or stroke Retention of urine may cause cystitis Retention of urine may cause cystitis Cystitis—bladder infection Cystitis—bladder infection Overactive bladder—need for frequent urination Overactive bladder—need for frequent urination Called interstitial cystitis Called interstitial cystitis Amounts voided are small Amounts voided are small Extreme urgency and pain are common Extreme urgency and pain are common