basic kidneys
what are the 2 main functions of the kidneys:
removal of....
retention of....
removal of toxins, metabolic wastes, and excess ions from blood that leave in urine
retention of needed substances that return to blood
what are the two main parts of the nephron
1. renal corpuscle
2. renal tubule
what are the two cells of the collecting ducts?
1. principal cells
2. intercalated cells
distal ascending limb of nephron loop lies against the afferent arteriole
what are the three processes of urine formation
1. glomerular filtration
2. tubular reabsorption
3. tubular secretion
what are the three outer supportive layers of the kidney?
renal fascia - dense fibrous
perirenal fat capsule - adipose, protects kidney
fibrous capsule - outer surface of kidney, barrier to infections
what are the parts of the renal corpuscle (structure & function)?
1. glomerulus - capillaries, fenestrated endothelium, allows filtrate formation
2. glomerular capsule (Bowman's capsule) - surrounds glomerulus, 2 layers
what are the function of the cells of the collecting ducts?
principal - maintain water & Na balance
intercalated - help maintain acid-base balance
what is the function of the JGC
regulation of rate of filtrate formation & blood pressure
describe glomerular filtration.
blood hydrostatic pressure forces fluids & solutes through membrane
effective filter bc very permeable & large surface area, & high blood pressure
name me 2 of the internal structures of the kidney?
renal cortex - vascular supply
renal medulla - releases urine to minor
minor calyces - collect urine
major calyces - empty urine into pelvis
renal pelvis - continuous with ureter
what are the two layers of the glomerular capsule?
1. parietal layer - simple squamous epithelium
2. visceral layer - contains podocytes; filtration slits that allow filtrate to pass into capsular space
what are our classes of nephrons
1. cortical nephrons - 85%, entirely in cortex
2. juxtamedullary nephron - long nephron loops; important in production of concentrated urine
what are the three cells that are found in the JGC
macula densa
granular cells
extraglomerular mesangial cells
what makes up the filtration membrane of the kidney
1. fenestration - prevent filtration of blood cells
2. basement membrane - negatively charged repels anions, blocks plasma proteins
3. filtration slits - prevent macromolecules from going farther
is the kidney dual innervated?
what is the function of the renal tubule & the parts?
processes filtrate to form urine
1. proximal CT
2. nephron loop
3. distal CT
what are the capillary beds associated with the cortical nephrons & the ones associated with the juxtamedullary nephrons?
cortical - glomerulus & peritubular capillaries
juxtamedullary - glomerulus & vasa recta
describe the macula densa & granular cells
macula - in ascending limb of nephron loop, contains chemoreceptors that monitor NaCl content of filtrate
granular - in afferent arteriole, contain renin, mechanoreceptors that sense blood pressure in afferent arteriole
what are the inward & outward pressure that affect filtrations
outward: hydrostatic pressure in glomerular capillaries (HPgc) glomerular BP
inward: hydrostatic pressure in capsular space (HPcs) filtrate in capsule
colloid osmotic pressure in capillaries (OPgc) due to plasma proteins in blood
what does the sympathetic nervous system do for kidney filtration & absorption?
vasomotor fibers that regulate renal blood flow by adjusting diameter of arterioles
what is some characteristics and the function of the parts of the renal tubule
PCT - dense microvilli & large mitochondria, reabsorption
nephron loop - in medulla
DCT - few microvilli; decreases reabsorption
explain the three different types of capillaries we have (glomerulus, peritubular, vasa recta)
glomerulus - filtration, fed & drained by arterioles (afferent arterioles > glomerulus > efferent arteriole) high pressure
peritubular - from efferent arterioles of cortical nephrons, reabsorption, low pressure, water & solutes
vasa recta - from efferent arterioles of juxtamedullary nephrons, concentrated urine
describe the extraglomerular mesangial cells
lie between arteriole & tubule cells, pass signals between macular densa & granular cells
what is glomerular filtration rate (GFR)? what changes the rate of GFR?
volume of filtrate formed per minute by both kidneys
NFP, total surface area available for filtration, filtration membrane permeability