Exam - Kidney Structure/Function Flashcards
what is the urinary system the primary regulator of
fluid volume and ion concentration
what must remain constant
composition and volume of body fluids
why must body fluids remain constant
stabilize osmolality
secrete excesses/Retain (reabsorb) when source is scarce
what is selective excretion
important products are retained and waste is removed
what are important products that are retained during selective excretion
glucose
amino acids
proteins
what does selective excretion excrete
foreign susbtances
body organic wastes:
- urea, bile
what is urea from
metabolism of protein
what is bile from
degradation of hemoglobin
what do the kidneys contribute to
the acid balance by removing H+ and bicarbonate
what do the kidneys produce
glucose by gluconeogenesis
erythropoietin
calcitriol
renin
what does erythropoietin do
stimulates the formation of erythrocytes
what is calcitriol
active form of Vit D
what is renin
an enzyme that regulates the formation of angiotensin II - regulates bp and aldosterone
where are kidneys located
upper abdominal wall
where do arteries, veins and ureters enter the kidney
through the renal hilus
what is the kidney composed of
outer cortex
inner medulla
what are the basic urine forming units
nephrons
what does the glomerulus do
filters blood
what does the tubular system do
reabsorption of filtered substances
secretion of others
what is the nephron blood supply composed of
3 capillary beds
what are the 3 capillary beds
glomerular capillaries
peritubular capillaries
vasa recta (capillaries of the medulla)
where is the glomerulus confined
in cortex
what is the glomerulus enclosed in
the Bowmans capsule
what makes the proximal tubules in the glomerulus
protein free fluid is filtered and accumulated in the Bow,ans space and then enters the first part of the tubule
what is the glomerulus composed of
many parallel capillaries
where does the blood enter the glomerulus
afferent arteriole
do the capillaries of the glomerulus connect with venues
no
what do the glomerulus capillaries connect with
efferent arteriole that will feed the peritubular capillaries
what are the walls of the tubular system made of
single layer of epithelial cells
what do the structure function of the epithelial cells of tubular system define
the 4 major components of the tubular system
what are the 4 majors components of the tubular system
proximal tubule
loop of henle
distal tubule
collecting duct
proximal tubule
highly convoluted in the cortex
loop of Henle
hairpin structure in the medulla composed of the descending thin limb, the ascending thin limb, and the thick ascending limb
distal tubule
highly convoluted in the cortex
collecting ducts
receive distal tubules from multiple nephrons, small ducts merge into large ducts and bring urine to the renal pelvis
how does the initial part of the distal tubule pass between afferent and efferent arteriole of its own glomerulus
using epithelial cells called macula densa
what is the juxtaglomerular
adjacent smooth muscle cells that produce and secrete renin
the 3 basic renal processes
glomerular filration
tubular reabsorption
tubular secretion
glomerular filtration
filtration of plasma from glomerular capillaries into Bowman’s space
tubular reabsorption
movement of substance from tubular lumen to peritubular capillaries
tubular secretion
movement of substance from peritubular plasma to tubular lumen
what is the glomerulus’s complex network of capillaries and specialized structure designed to do
retain cells and medium- and high-molecular weight proteins
what is an important index of renal function
glomerular filtration rate (GRF)
what are the 3 layers of the gl0merular membrane
capillary endothelium
basal lamina
inner epithelial layer of Bowmans capsule
what is the capillary endothelum
fenestrated on about 10% of their surface–> blocks cells, not blood constituents
what is the basal lamina
ash of protein fibers –> blocks most of the plasma proteinsw
what is the inner epithelial layer of Bowmans capsule
composed of podocytes –> last level of filtration between the fingers
what do the 3 layers of the glomerular membrane function as
collectively as a fine sieve
what is the best size selection against proteins
basal lamina… it is negatively charged therefore repulses proteins
what governs filtration pressure
forces across glomerular capillary wall - same as in capillaries
GRF
differences in hydrostatic and oncotic pressures
what is filtration facilitated by
higher hydrostatic pressure of blood in capillaries - remains fairly constant
what is filtration reduced by
hydrostatic pressure in Bowmans space (usually low)
plasma oncotic pressure within glomerular capillary
what is hydrostatic pressrue
fairly constant
where is the rate of filtration higher
int he first part of the capillary where osmotic pressure is lower
what happens to the rate further along
it decreases while the osmotic pressure increases due to proteins stuck in the blood compartment
what are other primary determinants of GFR
permeability of the filtration barrier and the surface area available for filtration
what maintains a tight control over GFR
kidneys
what cannot be regulated
hydrostatic pressure in glomerular space and oncotic pressure
what is the only regulated blood flow
blood flow in the glomerular capillaries (hydrostatic pressure)
what does the blood flow in the glomerular capillaries depend on
2 arterioles:
afferent - enters the glomerulus
efferent = exists the glomerulus
what will determine the local hystorstatic pressure in these capillaries
affecting the constriction levels of these arteriole
what are the 2 levels of control that Will affect the blood hydrostatic pressure
renal modulation of systemic blood pressure and volume (EXTRINSIC)
control of renal blood flow, glomerular capillary pressure, and ultra-filtration coefficient (INTRINSIC)
what is renin-angiotensin-aldosterone involved in
long standing falls in bp, or when decreased bp is accompanied by decreased extracellular fluid volume
how does renin-angiotensin-aldosterone release renin from juxtaglomerular cells
reduced stretch of the renin cells in the renal afferent arterioles (baroreceptors)
sympathetic nerve impulses
what do the sympathetic nerve impulses do
arteriole bararecptors respond to fall in BP by “unbarring” sympathetic nerve activity in kidney
what is the effect of renin secretion
increase in angiotensin II, locally and in plasma
what is angiotensin II
a potent vasoconstrictor
what does angiotensin II act to do
increase systemic BP and renal perfusion pressure
stimulates release of aldosterone and vasopressin
what does aldosterone do
enhance sodium/water reabsorption
what does vasopressin do
enhances urea and water reabsorpotion
how does renin release get turned off
augmented fluid uptake increases intravascular volume —> improves renal perfusion –> turns off renin release
what level does intrinsic auto regulation act at
the level of the kidney
what does intrinsic auto regulation prevent
short term changes in arterial blood pressure to affect the GFR
how does intrinsic auto regulation act
through feedback mechanisms that allow the kidney to vary the resistance of the afferent arterioles
how do smooth muscle cells react to the stretch in intrinsic autoregulation
by contracting
what do cells in the macula dense (distal tubule) do during intrinsic autoregulation
secrete unidentified facto that stimulates smooth muscle contraction
what does auto regulation affect
varying effects in local arterial blood pressure on:
perfusion of kidney
GFR
Urine formation
between 80mmHg and 200mmHG -
small effect on perfusion and GFR… small changes have great effect on urine volume
