renal 1 Flashcards
What are the functions of the kidney
- regulation of water/electrolyte balance/extracellular fluid
- regulation of arterial blood pressure (renin-angiotensin)
- excretion of metabolic waste (protein, creatinine, uric acid, urobilins)
- excrete foreign substances (drugs and hormones)
- blood cell production (main source of erythropoietin)
- last step in vit D production (1, 25-Dihydroxyvitamin D3)
- gluconeogenesis
what are the two types of nephrons
- Juxtamedullary - extend into the inner zone
- corticol = found in cortical zone and only extend into outer zone
what does the afferent arteriole feed
juxtaglomerular cells
What is the glomerulus
capillary bed between the afferent and efferent arterioles
what is the function of peritubular capillaries
reabsorb a lot of the fluid and electrolytes that are filtered
What nephrons are the vasa recta found in.
Juxtamedullary nephrons
describe the blood supply of an individual nephron
Afferent arteriole –> glomeruli –> efferent arteriole –> peritubular capillaries
Describe the order of juxtamedullary nephron filtration
Bowman’s capsule –> prox convoluted tubule –> thin descending loop –> thin ascending –> thick ascending
describe glomerular filtration
1) glomerular hydrostatic pressure builds in the capsule and forces out
2) glomerular colloid pressure is in the glomerular capillaries and wants to pull in
3) bowman’s capsule has a pressure wanting to push filtrate back into the glomeruli (NO Colloid pressure in bowman’s b/c no proteins
describe the overall affect of glomerular filtration
- biggest of the 3 is glomerular hydrostatic so the FILTRATE LEAVES the capillaries
what is the difference in the filtrate between the plasma and what is in the bowman’s
no proteins in bowman’s; all other things are the same
where does reabsorption occur
- peritubular capillaries and vasa recta
- THESE DO NOT FILTER
- Peritubular have MUCH more proteins than afferent arterioles so way more colloid pressure wanting the fluid to reabsorb
Define Isoosmotic area
proximal tubules because water and solute moves together
what part is the diluting segment
thick ascending loop of henle because impermeable to H20
Which part reabsorbs the most water, glucose, electrolytes
PROXIMAL TUBULE
Describe the scheme of Na+ reabsorption in the 1st half of proximal tubule
- first half of proximal tubule = uses bicarbonate (HCO3-) and glucose; Na+ symport of glucose and Na+/H+ antiporters for bicarb reabsorption
- -> raise level of glucose in tubule cells which allows passive transport of glucose across BASOLATERAL SIDE INTO BLOOD
- -> the rise in osmolatlity on basolateral side allows for water re-ABSORPTION via aquaporins passively into blood; in addition, Na is pumped across basolateral (Na-K pump)
describe the scheme of Na+ reabsorption in the 2nd half of proximal tubule
- second half of proximal tubule sees Na+ and Cl- reabsorbed together across trans and pericelular: Na-H and Cl-anion antiporters put Na and Cl into the cell –> Na can be pumped out via Na/K pump and Cl can be transported down grad with K through K-Cl transporter (down grad for both)
What substance is not coupled to Na+ for reabsorption
Protein
how is protein reabsorbed
Overall it is endocytosis –> enzymes digest the proteins –> a.a. leave tubule across basolateral membrane
Where does secretion occur
- Proximal tubule –> many organic compounds bound to plasma proteins are excreted, drugs, and organic anions and cations are excreted here
what is the loop of henle responsible for
counter current multiplication (conc and dil. of urine)
What is the macula densa a part of?
Distal convoluted tubule
What occurs in the distal convoluted tubule
some Na+ reabsorption
What part of the collecting duct responsive to ADH
Entire
What part of the collecting duct responsive to aldosterone
Corticol
How can urine conc be changed
sensing composition of plasma (osmoreceptors in hypothalmus)
What parts of the nephron does ADH increase Perm on
distal tubules and collecting ducts
What are the effects of ingesting too much NaCl
Na/K pump keeps the Na+ in the ECF –> water leaves to go to ECF –> raises Blood pressure –> decreases renal sympathetics and decrease renin secretion –> decrease prox tubule Na reabsorption –> dilation of affereant arteriole –> Increase GFR (glomularus filtration rate?)
What is the effect of decreasing renin when you ingest too much salt
- less angiotension I so less angiotension II so less aldosterone, less vasoconstriction, and less sodium reabsorption (in prox and collecting tubules)
What happens when we ingest a lot of sodium in regards to ANP
More sodium more ANP released due to stretch receptors activated –> ANP relaxes afferent arteriole and increases GFR and also INHIBITS renin release and angiotension II action, therefore inhibiting sodium reabsorption.
What are the effects of NaCl on ADH and thirst
ECF osmolality increases causeing thirst –> ADH released –> H20 reabsorbed –> increases water ingestion and urine concentration, increased BP so get decreased ADH –> all this leads to temporary expansion of ECF
function of macula densa
- feedback to juxtaglomerular apparatus
- vasodilates/constricts afferant arteriole to maintain constant GFR and renal blood flow despite changes in systemic arteriole blood pressure
function of proximal confoluted tubule
- 67% of H20, Na, K, Cl and nearly all glucose and AAs REABSORBED
function of cortical collecting duct
- principle cells, reabsorbs Na and secretes K
- intercalating cell reabsorbs K and secretes (something H?)
