kidney structure & function Flashcards
what is the function of the kidneys?
excretory organs
process blood and rid the body of the waste products of metabolism via urine
what do the kidneys maintain the internal homeostasis of?
fluid & electrolytes-bp
acid/base
calcium/vit. D metabolism
erythropoietin
what is the basic anatomy of the urinary system?
2 kidneys-produce urine
ureters-convey urine
bladder-store
urethra-void urine
what is the cortex?
contains 85% of all kidney tubules-nephrons
what are the 3 distinct parts of the kidney (macroscopic)
cortex, medulla, pelvis
what is the medulla?
site urine is concentrated
prevents excess water loss
what is the pelvis?
collection area for urine which is funnelled into the ureter
describe the bv of the kidney
highly vascular
renal artery delivers blood from abdominal aorta
process 1.2L per min
what are the bv of the kidney?
interlobular arteries afferent arterioles glomerular capillaries -glomerulus efferent arterioles peritubular capillaries -vasa recta interlobular veins
what is the nephron?
basic functional unit filters blood plasma excrete waste prod. of metabolism in urine -cortical nephrons -juxtamedullary nephrons
what are the components of a nephron?
glomerulus bowman's capsule proximal convoluted tubule loop of henle distal convoluted tubule collecting duct
what is the renal corpuscle?
filtration
glomerulus & bowman’s capsule
what is the renal tubule?
reabsorption and secretion proximal convoluted tubule loop of henle distal convoluted tubule collecting duct
what is the glomerulus?
network of fine capillaries single layer endothelial cells resting on basement membrane fenestrated enables rapid filtration of blood plasma surrounded by bowman's capsule
what is bowman’s capsule?
cuplike structure surrounding glomerulus
bowman’s space-in between layers
parietal-outer-layer
visceral-inner-layer comprised of specialised epithelium - podocytes
how is the filtration barrier formed?
long branched processes (pedicels) of podocytes wrap around glomerular capillaries
glomerular endothelium, basement membrane and pedicels form filtration barrier
what can move through the filtration barrier?
water and small molecules
not large proteins or cells
what determines which molecules are filtered through the filtration barrier?
size and charge of filtration
what are the 3 steps of glomerular filtration?
- unfiltered blood arrives at glomerulus via afferent arteriole
- blood components filtered though filtration barried
- filtered blood exits glomerulus via efferent arteriole
what is hydrostatic pressure?
filtration facilitated by pressure gradient
afferent has wider diameter- so blood arrives faster than can leave
what is filtered?
water, glucose, amino acids, urea, creatinine, sodium, chloride, calcium, phosphate, potassium, bicarbonate
what is not filtered?
cells, large proteins eg. haemoglobin, negatively charged proteins eg. albumin
what is glomerular filtration rate? (GFR)
the rate at which blood is filtered through the glomerulus into the bowman’s capsule
healthy =125ml/min
how is GFR mediated?
driven by glomerular hydrostatic pressure
counteracted by hydrostatic pressure in the bowman’s capsule & glomerular osmotic pressure
