Physiology 2 Flashcards
What are the functions of the kidneys
water balance salt balance maintenance of plasma volume maintenance of plasma osmolarity acid-base balance excretion of metabolic waste products excretion of exogenous waste products excretion of exogenous foreign compounds secretion of renin secretion of erythropoietin conversion of vitamin D into active form (calcitriol)
what is secreted by the kidneys
renin (to control arterial BP)
erythropoietin (RBC production)
what is the PRIMARY function of the kidneys
to regulate the volume, composition and osmolarity of the body fluids via the controlled excretion of electrolytes and other substances
what are the 2 main parts of the kidney
cortex
medulla
what is the nephron
functional unit of the kidney (smallest structural compartment that can perform all the primary functions)
what are the functions of the nephron
filtration
reabsorption
secretion
what is the firs place the blood is filtered in the nephron
bowman’s capsule
how does blood enter the bowman’s capsule
it goes through an afferent arterial which drains into a glomerular capillary
where does the blood drain after the glomerulus
the blood that did not go through the filter continues through the efferent tubule into the PERITUBULAR CAPILLARIES
how thick are the renal tubules
1 cell thick - single layer of epithelial cells
where do the peritubular capillaries drain into
a venule and then a vein
what is the function of the peritubular capillaries
supply tubular cells with nutrients as well as receive any substances reabsorbed from the tubular fluid
what are the 4 different segments of the nephron
Bowman’s capsule
Proximal tubule
Loop of Henle
Distal tubule
where does the distal tubule empty into
into collecting ducts
originates in cortex but travels down into the medulla where it empties into the renal pelvis
what do you call the fluid in the renal tubules
tubular fluid
what do you call the fluid in the collecting duct
urine
what are the 2 types of nephron
cortical
juxtamedullary
how does the juxtamedullary nephron differ from the cortical nephron
Much longer loop of Henle
Has a single capillary instead of a network following the tubule
produces more concentrated urine
what is the tubular capillary in the juxtamedullary nephron called
vasa recta
how are nephrons arranges in the kidney
in a radial fashion with the loops of Henle pointing down into the medulla giving its striated appearance
the diameter of the efferent arterial is wider than that of the afferent true/false
false
the afferent arteriole is wider than the efferent - this is so more blood can come in and be held in the glomerulus to create
if there is contraction of the afferent arteriole there is a change in blood volume in the glomerulus
relaxation of the afferent arteriole increases blood flow into the glomerulus
what 3 layers does blood have to pass through to get from the glomerular capillary into the tubular fluid
Capillary endothelial cells
Basement membrane
Podocyte cells
what are the 3 layers collectively called (in the bowman’s capsule)
the glomerular membrane
what does the glomerular membrane do
works as a molecular sieve letting small molecules through and preventing large ones going through (RBCs and proteins)
what is the juxtaglomerular apparatus
specialised cells in the part of the distal tubule where it passes between the afferent and efferent arterioles
what specialised cells are found in the juxtaglomerular apparatus and what do they do
granular cells - produce and secrete renin to initiate RAS
Macula dena cells - monitor the amount of salt in tubular fluid as it passes this region
what is urine
notified filtrate of blood
what are the 3 main processes done to the blood by the kidney to make urine
glomerular filtration
tubular reabsorption
tubular secretion
what is tubular secretion
substances being secreted from the peritubular capillaries into the tubule
what is reabsorption
molecules going back into the peritubular capillaries from the tubular fluid
how do you calculate the rate of excretion
rate of excretion = rate of filtration + rate of secretion - rate of reabsorption
what is GFR
glomerular filtration rate
how do you calculate the rate of filtration of a substance
rate of filtration = plasma concentration of substance x GFR
how do you calculate the rate of excretion of a substance
rate of excretion = concentration of substance in urine x urine production
how do you calculate the rate of reabsorption of a substance
reabsorption = rate of filtration - rate of excretion
what does it mean if rate of filtration > rate of excretion
a net reabsorption of the substance has occurred
what does it mean is the rate of filtration < rate of excretion
a net secretion of a substance has occurred
how do you calculate the rate of secretion of a substance
secretion = rate of excretion - rate of filtration
what is a normal GFR
125 mms/m
