Renal System Flashcards
organization of renal system
- right and left kidneys
- ureters leave kidneys and enter urinary bladder
- urethra is the tube connecting urinary bladder to external environment
functions of kidney
- regulates extracellular fluid volume and blood pressure
- regulation of osmolarity
- maintenance of ion balance
- regulation of pH
- excretion of wastes
- production of hormones
nephrons
~ how many /kidney
- functional units of the kidney
- approx 1 million per kidney
- found in the medulla (pink triangles) and cortex (outermost region) of the kidney
anatomy of nephron
look at slides pg 9 and 10 of slides
microvilli
increases surface area of epithelial cells of the nephron, important for absorption
glomerular filtration
amount of solute excreted = amount filtered from blood to urine - amount reabsorbed + amount seccreted
loss of plasma
20% of volume gets filtered, and 19% is reabsorbed
–> 99% of plasma entering kidney returns to systemic circulation
filtration barriers
- glomerular capillary endothelium
- basal lamina
- epithelium of Bowman’s capsule
main components of filtrate
- urea
- glucose
- ions
- creatinine
- H20
what is GFR and what is it influenced by
- glomerular filtration rate
- volume of fluid that filters into Bowman’s capsule/time
- approx 180 L/day
- is influenced by pressure: hydrostatic, colloid osmotic
resistance changes in renal arterioles
- increased resistance in efferent (above, e comes later than a) arteriole –> increases GFR
- increased resistance in afferent (below, a comes first) arteriole –> decreases GFR
regulation of GFR
autoregulation
- myogenic response to bp changes: stretch due to increased pressure causes vasoconstriction of afferent arterioles
- tubuloglomerular feedback:
extrinsic regulation
- hormones
- sympathetic neurons
juxtaglomerular apparatus
macula densa cells on the ascending loop of Henle are in contact with the arterioles, and send paracrine signals that affect afferent arteriole diameter
tubuloglomerular feedback
- GFR increases
- flow through loop of henle increases
- flow pas macula densa increases
- paracrine signal from macula densa to afferent arteriole
- afferent arteriole constricts –> pressure changes lead to GFR decrease!!
reabsorption
- most reabsorption happens in the proximal tubule
- transepithelial transport: substances cross apical membrane and basolateral membrane
- paracellular pathway: substances pass through tight junctions