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39 terms

physiology

lecture 6
STUDY
PLAY
functions of the kidneys
1.regulation of extracellular fluid volume & BP
2.regulation of osmolarity
3.maintain of ion balance (na+ K+ Ca2+)
4.homeostatic regulation pH
(removal of conservation of H+ or HCO3-)
5.excretion of wastes
6.production of hormones
Production of hormones...
-synthesize erythropoietin (regulates RBS synthesis)
-synthesize renin (regulates hormones involved in Na+ balance and BP homeostasis)
adrenal glands are located
on top of kidneys
nephron
functional unit (cell that does the work)
portal system caries
capilaries to capilaries
80% of nephrons are in the
cortex
20% of nephrons are in the
medulla
Renal portal system
-filter fluid out of the blood and into the lumen of the nephron at the glomerular capillaries.
-to reabsorb fluid from the tubule back into the blood at the at the peritubular capillaries
glomerous+
Bowman's Capsule
Renal
Corpuscle
proximal tubule of the nephron..
reabsorption and secretion
descending limb of nephron
reabsorbs water
ascending limb of nephron
reabsorbs ions
secretion
is more selective than Filtration and uses membrane proteins to move molecules
across the tubule
epithelium
filtration
only takes place in the Renal Corpuscle
filtration
blood to lumen
reabsorption
lumen to blood
secretion
blood to lumen
excretion
lumen to external environment
70% of filtrate is reabsorbed in
the proximal tube
90% of the volume is filtered into Bowman's capsule has been
reabsorbed into
peritubular
capillaries
how do you find out the amount of solute secreted?
amount filtered - the amount reabsorbed + the amount secreted
podocytes used for filtering
Capsule epithelium that surrounds each glomerular
capillary are specialized cells
Glomerularcapillary endothelium
Has negatively charged pores for
secretion; repels negative proteins
and RBCs
Basal lamina
Excludes most plasma proteins
Epithelium of Bowman's Capsule
Podocyteshave foot processes that
wrap around glomerularcapillaries
leaving narrow filtration slits
Substances pass through 3 barriers
before entering the tubule lumen:
Glomerularcapillary endothelium
Basal lamina
Epithelium of Bowman's Capsule
podocyte foot processes......
surround each capillary, leaving slits where filtration takes place
Filtration Fraction
The percentage of total plasma
volume that filters into the tubule
#1 filtration
plasma volume afferent arteriole= 100%
#2 filtration
20% of volume filters (efferent?)
#3 filtration
19% of fluid is reabsorbed
#4 filtration
99% of plasma entereing kidney returns to systemic circulation
#5 filtration
1% of volume is excreted to external environment
Filtration pressure in the renal corpuscle depends on
hydrostatic pressure, colloid osmotic pressure, and fluid
pressure
Hydrostatic pressure
Capillary blood pressure
Capillary colloid osmotic pressure
Glomerularcapillaries higher than Bowman's capsule,
moves fluid back into the capillaries
Capsule fluid pressure
Created by fluid in Bowman's capsule opposes filtration
net filtration measure
10 mm Hg
Autoregulation
maintains a constant glomerularfiltration rate (180 L/day) over a wide range of blood pressures (which provides the hydrostatic pressure that drives glomerularfiltration)