Transcript a&p 2 urinary system

A&P
URINARY
SYSTEM
Instructor Terry Wiseth
Urinary Anatomy
Kidney
Ureter
Bladder
Urethra
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Functions of Urinary System
Clears blood of waste products of
metabolism
Uremia
accumulation of toxic levels of
wastes in blood
maintain normal
H2O and electrolyte balance
fluid volumes
blood pressure
body pH
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Kidneys
Excretory Organ
Intestine, Skin, Lungs
Excretes
N2 wastes
Toxins
H20
Electrolytes
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Microscopic Structure
Nephron
unit of function
1.25 million /
kidney
Highly vascular
20% of blood
pumped / min
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Functions
1) maintain fluid balance
2) maintain electrolyte
balance
3) maintain acid-base balance
4) remove N2 wastes
urea
5) synthesize prostaglandin's
6) influence rate of secretion
of hormones
ADH / Aldosterone
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Kidney Failure
blood constituents cannot be held in
normal concentrations
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Nephron Anatomy
1) Glomerulus
Arterioles
Bowman’s Capsule
2) Tubule
Proximal
Loop of Henle
Ascending
Descending
Distal
Collecting
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Urine Formation
Actions in forming urine
1) filtration
2) reabsorption
3) 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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Glomerular Filtration
blood flows through
glomerular capillaries
H2O and solutes filter out
into Bowman’s Capsule
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Glomerular Filtration
pressure gradient causes filtration
some kidney diseases
permeability of glomerulus increases
allows blood proteins to filter out into
the capsule
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Glomerular Filtration
High blood pressure in the glomerulus
forces small molecules from blood into
the Bowman’s capsule
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Glomerular Filtration
TEM of filtration slits from capillaries in
Bowman’s Capsule
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Glomerular Filtration
Stress can lead to constriction of afferent
arterioles
causes filtration rate to lower
and renal suppression “kidney
shutdown”
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Glomerular Filtration
glomerular filtration rate
directly related to systemic
blood pressure
↓ BP = ↓ glomerular filtration
↑ BP = ↑ glomerular filtration (slight)
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Tubular Reabsorption
movement of substances from tubular
fluid out to blood
reabsorption from proximal convoluted
tubules to blood
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Tubular Reabsorption
movement of substances from tubular
fluid out to blood
reabsorption from proximal convoluted
tubules to blood
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Tubular Reabsorption
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
congenital
sometimes 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 Loop
Water diffuses out of the tubule by
osmosis
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Reabsorption from Loop of Henle
Ascending Loop
Salts 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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Reabsorption from Loop of Henle
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) ADH
2) Aldosterone
3) Extracellular fluid volume
4) Urine solute concentration
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Regulation of Urine Volume
1) ADH
Presence
decrease Urine Volume
Absence
increase Urine Volume
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Regulation of Urine Volume
2) Aldosterone
increases Na+ reabsorption in distal
tubule with H2O following
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Regulation of Urine Volume
3) urine volume relates directly to
extracellular fluid volume (ECF)
ECF ↓
urine volume ↓
ECF ↑
urine volume ↑
rapid ingestion of large
amount of fluid and resulting
increased ECF leads to
increased urinary output
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Regulation of Urine Volume
4) high solute concentration in urine
increases urine volume by osmotic
pressure
untreated diabetes
void large amounts of urine because
excess glucose in blood “spilling over”
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Influence of Kidney on Blood Pressure
Renal Hypertension
decreased blood flow
to kidney
constriction of
arterioles
increased BP
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Ureters
Tubes leading from
kidney to bladder
Urine moves by
peristaltic
movement
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Ureters
Renal Calculi
stones develop in kidney, washed out
by urine into ureter
distend ureter walls
pain
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Bladder
collapsible, elastic bag
Ureters
2
Bladder
Urethra
1
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Functions of Bladder
1) reservoir for urine
2) expels urine
distended 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
Electrolytes
Toxins
Pigments
Hormones
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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
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END
URINARY SYSTEM