Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Location—under back muscles, behind parietal peritoneum,

Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

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) Cortex—outer layer of kidney substance Medulla—inner portion of kidney Pyramids—triangular divisions of medulla Papilla—narrow, innermost end of pyramid Pelvis—expansion of upper end of ureter; lies

inside kidney Calyces—divisions of renal pelvis

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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 3





Microscopic structure—nephrons are microscopic units of kidneys; consist of (Figure 17-3): Renal corpuscle

▪ Bowman’s capsule—the cup-shaped top▪ Glomerulus—network of blood capillaries surrounded

by Bowman’s capsule Renal tubule

▪ Proximal convoluted tubule—first segment▪ 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▪ Collecting tubule—straight extension of distal tubule

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Functions Excretes toxins and nitrogenous

wastes Regulates levels of many chemicals

in blood Maintains water balance Helps regulate blood pressure via

secretion of renin

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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

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

Control of urine volume—mainly by posterior pituitary hormone’s ADH, which decreases it

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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

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Structure (Figure 17-7) Elastic muscular organ, capable of

great expansion Lined with mucous membrane

arranged in rugae, as is stomach mucosa

Functions Storage of urine before voiding Voiding

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Structure Narrow tube from urinary bladder to

exterior Lined with mucous membrane Opening of urethra to the exterior called

urinary meatus Functions

Passage of urine from bladder to exterior of the body

Passage of male reproductive fluid (semen) from the body

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Passage of urine from body (also called urination or voiding)

Regulatory sphincters Internal urethral sphincter (involuntary) External urethral sphincter (voluntary)

Bladder wall permits storage of urine with little increase in pressure

Emptying reflex Initiated by stretch reflex in bladder wall Bladder wall contracts Internal sphincter relaxes External sphincter relaxes, and urination occurs

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Urinary retention—urine produced but not voided

Urinary suppression—no urine produced but bladder is normal

Incontinence—urine is voided involuntarily May be caused by spinal injury or stroke Retention of urine may cause cystitis

Cystitis—bladder infection Overactive bladder—need for frequent

urination Called interstitial cystitis Amounts voided are small Extreme urgency and pain are common

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Documents

Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Location—under back muscles, behind parietal peritoneum,