kidneys Flashcards
ureter
carry urine from kidney to bladder
what does it mean for kidneys to be retroperitoneal
memobronous sac
loated posterior
not in abdominal cavity
behind peritoneal membrane that holds abdominal organs
urethra
tube connecting urinary bladder to external environment
main functions of the kidney
filtration
regulation of extracellular fluid volume and blood pressure
regulation of osmolarity
maintenance of ion balance -
homeostatic regulation of pH - excretion/making of H+ and bicarbonate
excretion of metabolic wastes - creatinine, urea, hormones, uribilinogen
production of hormones
renin
hormone but functions as an enzyme, important regulator of blood pressure
how many nephrons per kidney
about one million
cortical nephron
includes bowman’s capsules, proximal and distal tubules
short
juxtamedullary nephron
long
includes loops of henle (acending and decending and collecting ducts
what does the collecting duct drain into
renal pelvis
where do renal arteries take blood
to the cortex
what delivers blood to the nephron
afferent arteriole
vasa recta
part of the capillaries that surrounds nephron
re-entry point into circulation
what makes up the renal corpuscle
bowman’s capsule and glomerulus
proximal tubule
glucose and sodium reabsorption
distal tubule
secretes h2o to dilute urine
what kind of cells is the nephron made out of
epithelial
what are the four processes of the nephron
filtration - movement from blood to lumen
reabsorption - from lumen to blood
secretion - from blood to lumen
excretion - from lumen to outside of body
how much water is filtered daily
180 L
how much water is at the end of the collecting duct a day
1.5L
filtration
the percent of total plasma volume that filters into the tubule
1. plasma volume entering afferent arteriole 180L/day
2. 20% of volume filters
3. 99% of filtrate is reabsorbed
4. 99% of plasma entering kidney returns to systemic circulation
5. less than 1% (1.5 L/day) volume is excreted to external environment
go through: glomerular capillary endothelium, basal lamina, epithelium of bowmans capule ( podocyte)
podocyte
epithelium of bowmans capsule
have feet that have windows that will slip through the holes of bowman’s space
what is made and secreted out at the renal corpuscle
potassium, H+, urea
what is made and reabsorbed at the renal corpuscle
sodium and glucose
what are the pressures that influence glomerular filtration rate
hydrostatic pressure, colloid osmotic pressure gradient, fluid pressure within Bowman’s capsule
Glomerular filtration rate
the volume of fluid that filters into bowmans capsule per unit time
180L/day
100 mL/min
osmolarity
number of osmotically active particles per liter of solution
osmotic pressure
the driving force of osmotic, force that has to be applied to prevent osmosis
colloid osmotic pressure gradient
due to the presence of proteins in the plasma, but not the filtrate
why does someone with cirrhosis have lower than normal levels of plasma proteins, and a higher than normal GFR
colloid osmotic pressure is lower
Net filtration pressure equation
PH- pi -Pfluid
55-30-15 = 10 mm Hg
how is GFR maintained
regulating renal blood flow
maintains a constant GFR when mean arterial blood is between 80-180 mm Hg which is the normal mean blood pressure
what happens when the afferent arteriole vasoconsticts
increase resistance
decrease flow
decrease hydrostatic pressure
decrease GFR
what happens where the efferent arteriole vasoconstricts
increased resistance
blood pooling in glomerulus
increase hydrostatic pressure (PH)
increase GFR
what is the myogenic response to changes in blood pressure
intrinsic ability of vascular smooth muscle
stretch due to increased pressure causes vasoconstriction of afferent arterioles
- stretch- activated cation channels on vascular smooth muscle
-depolarization leads to smooth muscle contraction
Tubuloglomerular feedback
paracrine signaling
happens at juxtaglomerular apparatus
macula densa senses increased flow due to high GFR which will release paracrines that act of afferent arteriole to vasoconstrict
negative feedback
1. GFR increases ie/ at the gym
2. flow through tubule increases
3. flow (NaCl) past macula densa increases
4. paracrine from macula densa to afferent arteriole
5. afferent arteriole vasoconstricts
6. resistance in afferent arteriole increases
7. Hydrostatic pressure in glomerulus decreases
8. GFR decreases
juxtaglomerular apparatus
region where ascending limb of oop of henle passes afferent and efferent arterioles
where blood flow is checked
macula densa
specialized cells of the ascending tubule. In the juxtaglomerular apparatus
has flow sensors, if low paracrine signal will be released to act of arteriole
granular cells
secrete renin
reabsorption
movement from tubule lumen into blood
majority occurs in proximal tubule of nephron
Transepithelial transport
paracellular pathway
Na+ and glucose (active transport, sodium potassium pump)
1. sodium is reabsorbed by active transport
2. electrochemical gradient drivers anion reabsorption
3. water moves by osmosis, following solute reabsorption. Concentrations of other solutes increase as fluid volume in lumen decreases
4. permeable solutes are reabsorbed by diffusion through membrane transporters or by the paracellular pathway
transepithelial transport
substance cross both apical and basolateral membranes of transporting epithelium
channels and transporters for Na+ and glucose
paracellular pathway
substances pass through tight junction of adjacent cells
CL-
secretion
important in homeostatic regulation (K+ and H+)
removes organic compounds from body (metabolites and foreign substances)
increasing secretion enhances nephron excretion
excretion
at the end of the collecting duct where the filtrate can no longer be modified
Urine is the output - variable concentration of organic wastes ions and water
should not contain and glucose, a.as or metabolites or useful metabolites as they have been reabsorbed
