a&p urinary system instructor terry wiseth. 2 urinary anatomy kidney ureter bladder urethra

A&P

URINARYSYSTEM

Instructor Terry Wiseth

2

Urinary Anatomy

Kidney

Ureter

Bladder

Urethra

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Functions of Urinary System

Clears blood of waste products of metabolismUremia

accumulation of toxic levels of wastes in blood

maintain normal

H2O and electrolyte balance

fluid volumesblood pressurebody pH

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Kidneys

Excretory OrganIntestine, Skin, Lungs

Excretes

N2 wastes

Toxins

H20

Electrolytes

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Microscopic Structure

Nephronunit of function1.25 million /

kidneyHighly

vascular20% of blood

pumped / min

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Functions

1) maintain fluid balance2) maintain electrolyte

balance3) maintain acid-base balance

4) remove N2 wastes

urea5) synthesize prostaglandin's6) influence rate of secretion

of hormonesADH / Aldosterone

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Kidney Failure

blood constituents cannot be held in normal concentrations

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Nephron Anatomy

1) Glomerulus1) GlomerulusArteriolesBowman’s Capsule

2) Tubule2) TubuleProximalLoop of Henle

AscendingDescending

DistalCollecting

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Urine Formation

Actions in forming urine1) filtration2) reabsorption3) secretion

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Glomerular Filtration

blood flows through glomerular capillaries

H2O and solutes filter out into Bowman’s Capsule

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blood flows through glomerular capillaries

H2O and solutes filter out into Bowman’s Capsule

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pressure gradient causes filtrationsome kidney diseases

permeability of glomerulus increasesallows blood proteins to filter out into

the capsule

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High blood pressure in the glomerulus forces small molecules from blood into the Bowman’s capsule

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TEM of filtration slits from capillaries in Bowman’s Capsule

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Stress can lead to constriction of afferent arteriolescauses filtration rate to lower and renal suppression “kidney

shutdown”

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glomerular filtration ratedirectly related to systemicblood pressure

↓ BP = ↓ glomerular filtration

↑ BP = ↑ glomerular filtration (slight)

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Tubular Reabsorption

movement of substances from tubular fluid out to bloodreabsorption from proximal

convoluted tubules to blood

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movement of substances from tubular fluid out to bloodreabsorption from proximal

convoluted tubules to blood

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Glucose, amino acids, ions and other useful substances are actively transported from the tubule into blood

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Proximal Tubules

Water follows passively by osmosis

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Glucose Reabsorption

if blood glucose levels exceed threshold amount (150mg/100ml)not all glucose is reabsorbed

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Renal Diabetes

congenitalsometimes maximum transfer capacity

is reduced and excess glucose appears in urine even though blood glucose level is normal

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Reabsorption from Loop of Henle

Descending LoopWater diffuses out of the tubule by

osmosis

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Ascending LoopSalts are actively transported out of

the tubule, but water cannot follow because the walls of the tubule are impermeable to water

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NaCl is trapped in interstitial fluid of kidney medulla

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Reabsorption from Distal Tubules

proximal tubules reabsorb 2/3 of Na+

distal tubules reabsorb 1/10 of Na+

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Reabsorption from Distal Tubules

distal tubules reabsorb H2O if antidiuretic hormone (ADH) is present

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Distal Tubule

K+, H+ and other ions, and certain large molecules are actively transported from the blood into the tubule, regulating the pH and ionic concentration of the blood

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Collecting Duct

As the urine passes down the duct, water moves by osmosis from the duct into the blood

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Collecting Duct

As the urine passes down the duct, water moves by osmosis from the duct into the blood

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ADH

cause distal tubules to become permeable to H2O

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ADH

small concentrated volume of urine is excreted

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ADH

if no ADH in blood, then large volumes of urine produced (dilute concentration)

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Regulation of Urine Volume

1) ADH2) Aldosterone3) Extracellular fluid volume4) Urine solute concentration

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1) ADHPresence

decrease Urine VolumeAbsence

increase Urine Volume

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2) Aldosteroneincreases Na+ reabsorption in distal

tubule with H2O following

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3) urine volume relates directly to extracellular fluid volume (ECF)

ECF ↓ urine volume ↓ECF ↑ urine volume ↑rapid ingestion of large

amount of fluid and resultingincreased ECF leads toincreased urinary output

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4) high solute concentration in urine increases urine volume by osmotic pressureuntreated diabetes

void large amounts of urine because excess glucose in blood “spilling over”

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Influence of Kidney on Blood Pressure

Renal Hypertensiondecreased blood

flow to kidneyconstriction of

arteriolesincreased BP

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Ureters

Tubes leading from kidney to bladderUrine moves by

peristaltic movement

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Ureters

Renal Calculistones develop in kidney, washed out

by urine into ureterdistend ureter walls

pain

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Bladder

collapsible, elastic bagUreters

2BladderUrethra

1

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Functions of Bladder

1) reservoir for urine2) expels urinedistended causes sensation and desire

to void

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Urethra

passageway for eliminating urine

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Urethra

passageway for eliminating urine

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Urine

H2O

95%

N2 wastes

ElectrolytesToxinsPigmentsHormones

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Artificial Kidney

Dialysis

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Artificial Kidney

Dialysis

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Artificial Kidney

continuous ambulatory peritoneal dialysis (CAPD)dialysis fluid administered to

peritoneal cavity

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Kidney Transplant

ENDURINARY SYSTEM

a&p urinary system instructor terry wiseth. 2 urinary anatomy kidney ureter bladder urethra

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