RS. Kidney 1 Flashcards
what is the function of the kidneys?
maintain internal homeostasis of fluid
what is the function of kidneys thats produces a by product ?
process blood and rid the body of waste products of metabolism via urine
what are the 4 stages of the urinary system?
kidneys - produce urine
ureters - convey urine
bladder - stores urine
urethra. - void urine
what happens at the renal hilum?
vessels, nerves and ureter pass
where are the kidneys positioned?
retroperitoneal
what are the 3 parts of the kidney?
cortex - outer
medulla
pelvis - inner
what is contained in the cortex of the kidney?
85% of all kidney tubules (nephrons)
what part of the kidney prevents excess water loss and is the site where urine is concentrated?
medulla
what happens in the pelvis of the kidney?
collection area for urine which is funnelled into the ureter
what is the kidney encased in?
fibrous capsule of dense irregular tissue
why is the kidney highly vascular?
helps it to filter blood
what delivers blood straight from the abdominal aorta to the kidneys?
renal artery
once blood is filtered in the kidney it is returned to the cardiovascular system via what vein and where does it go?
renal vein to vena cava
how much of our cardiac output is in received by the kidneys?
1/5
how much blood is processed by the kidneys every minute?
1.2 litres
how is the vascular anatomy of the kidneys unique?
they have a capillary between 2 arterioles
which capillary lies between the afferent and efferent arterioles the kidney?
glomerular capillary (glomerulus)
what happens in the glomerular capillaries?
blood filtrations
what happens in the peritubular capillaries of the kidney?
delivery of O2 and nutrients to rest of kidney
facilitates water reabsorption/ conc of urine
what is the basic functional unit of the kidney?
nephron
after blood has been filtered in the glomerular capillary where does the fluid leave the blood and go?
nephron
what are the 2 different types of nephrons?
cortical
juxtamedullary
describe a cortical nephron?
short loop of henle which only just extends to medulla so most of nephron is in cortex
describe the juxtamedullary nephron?
long loop of henle to concentrate urine and conserve water in body
- loop of henle descends deep into medulla
what is the function of the renal corpuscle part of a nephron?
filtration
what is the function of the renal tubule part of a nephron?
conservation/ fine tuning of what the body wants to get rid of vs what it wants to keep
what is the glomerulus?
a single layer of endothelial cells resting on a basement membrane
fine capillaries branching from afferent to efferent arterioles
what does fenestrated mean?
tiny pores penetrating surface which makes them leak
what does fenestration allow for in a glomerulus?
rapid filtration of blood plasma
what surrounds the glomerulus?
Bowmans capsule
what are the outer and inner layers of Bowmans capsule?
outer = parietal
inner = visceral
describe the epithelium on the outer layer of Bowmans capsule?
simple squamous epithelium
describe the epithelium on the inner layer of Bowmans capsule?
specialised epithelium - podocytes
what are podocytes?
epithelial cells with long foot like processes that wrap around glomerular capillaries
what form the renal corpuscle?
glomerulus and Bowmans capsule
what forms the filtration barrier?
glomerular endothelium, basement membrane and pedicels
what is the filtration barrier freely permeable to?
small molecules and water
what are the 3 steps in glomerular filtration?
- unfiltered blood arrives at glomerulus via afferent arteriole
- blood components filtered through filtration barrier
- filtered blood exits the glomerulus via the efferent arteriole
what is the first step in blood processing?
glomerular filtration
what facilitates glomerular filtration?
hydrostatic pressure gradient
does afferent or efferent arteriole have a bigger diameter? what is this helpful for?
afferent so blood can arrive faster than it leaves which helps to push fluid and solutes through filtration barrier to Bowmans space
what are the waste products that come from filtration through the filtration barrier to a nephron?
urea
creatinine
what can’t be passed through the filtration barrier?
negatively charged proteins - albumin
cells/large proteins - haemoglobin
what is the glomerular filtration rate?
rate at which blood is filtered through the glomerulus into the Bowmans capsule
what drive the glomerular filtration rate?
glomerular hydrostatic pressure
what is the glomerular filtration rate counteracted by?
- hydrostatic pressure in the Bowmans capsule
- glomerular osmotic pressure
what is glomerular hydrostatic pressure?
the pressure generated in glomerular capillaries that pushes solutes and fluid from capillaries into bowmans space
what is a normal healthy glomerular filtration rate?
125 ml/min
180 l/day
what effect does kidney damage have on the glomerular filtration rate?
reduces
what happens when the glomerular filtration rate is reduced?
inefficient blood clearance and waste removal
what can be used to estimate the glomerular filtration rate?
serum creatinine (and urea)
if 180 l/day fluid is filtered in the renal corpuscle why do we not pass that much liquid?
99% reabsorbed
