Renal Flashcards
three main functions of the kidney
- excretion
- regulation
- absorption
six major functions of the kidney
- stabilizing electrolytes
- water balance/proper osmolarity
- excretion of nitrogenous waste
- acid/base regulation
- maintaining the blood concentration and ridding of hormones, drugs, pesticides, food additives, and nonnutritive materials
- production of 2 VIP hormones
what two VIP hormones do kidneys produce?
erythropoietin and renin
what is the smallest functional unit of the kidney?
nephron
two types of nephrons
juxtamedullary and cortical
cortical nephron
glomeruli in the outer cortex, smaller loops of Henle, ~80% of nephrons
juxtamedullary nephron
glomeruli next to medulla, long loops of Henle penetrating into medulla, ~20% of nephrons
five major regions
- Bowman’s capsule/glomerulus
- proximal convoluted tubule
- loop of Henle
- distal convoluted tubule
- juxtaglomerular apparatus
region 1
glomerulus and Bowman’s capsule
Bowman’s capsule and glomerulus primary function
filtration
ultrafiltration
pressure inside the capillaries is greater than outside, driving fluids through pores
fenestrae
pores in Bowman’s capsule
what size substrates fit in the fenestrae
less than 6 nm or 68 kDa
four types of filtrate entering the proximal convoluted tubule
- carbohydrates
- electrolytes
- H2O and small particles
- plasma and free cellular material
to be filtered a substance must pass through…
- the pores between endothelial cells of the glomerular capillaries
- an acellular basement membrane
- the filtration slits between the foot processes of the podocyte
podocyte
- contraction causes foot processes to flatten, decreasing pore diameter
- contraction under sympathetic stimulation, acts upon actin-like filaments
- can also decrease the number of slits, decreasing glomerular filtration rate
glomerular filtration rate
how many pore of the glomerulus are available for permeation
(Kf)(NFP)
Kf in glomerular filtration rate
filtration coefficient
NFP in glomerular filtration rate
net filtration pressure based on 3 pressures
what three pressures are NFP based on?
- glomerular-capillary bp
- plasma-colloid osmotic psi
- Bowman’s hydrostatic psi
glomerular-capillary bp
systemic bp, favors filtration
plasma-colloid osmotic psi
blood osmolarity, opposes filtration
Bowman’s hydrostatic psi
the psi pushing against the glomerular capillaries, opposes filtration
greatest factor in changing GFR is…
systemic bp
how does exercise affect systemic bp?
increases blood pressure
how does hemorrhage affect systemic bp?
decreases blood pressure
how does excess fluids affect systemic bp?
decreases blood pressure
what does diarrhea do?
increases/decreases plasma osmolarity
what do burns and trauma do?
decreases NFP
what do kidney stones do?
increase Bowman’s hydrostatic psi
vasa recta
straight (vertical) vessels
peritubular capillaries
convoluted
region 2
proximal convoluted tubule
main function of the proximal convoluted tubule
glucose uptake
what particles does the PCT take up?
small mw amino acids and proteins, 100% of glucose, polypeptides, organics, salts, and water
hyperglycemia
high concentrations of glucose in the blood
glucosuria
glucose in urine
glucose has a _____ _____ because of limited supply of glucose transporters
renal threshold
renal threshold
the amount of glucose the renal system can filter at any given point, 300mg/100mL
tubular maximum
375mg/min
how is glucose reabsorbed via the PCT?
secondary active transport via Na+ support
how is sodium reabsorbed via the PCT? (4 steps)
- luminal membrane
- basal lateral membrane *
- interstitial fluid
- endothelial membrane
*requires Na/K pump, making the whole process active
what does alcohol block?
secondary active transport
uremia
renal failure
water moves through the tight junction attracted by the _____ _____ of sodium
osmotic force
water is osmotically attracted to _____ _____ in the blood
plasma proteins
plasma proteins can/cannot pass through podocytes?
cannot
region 3
loop of henle
counter-current multiplication
descending loop of Henle is very permeable, ascending loop is not permeable
as you enter the medulla, there will be…
a steep salt gradient
salts act as an attractant to _____
water
descending loop of Henle does what
releases lots of water, leaving salts behind
ascending loop of Henle does what
releases a lot of salt, so the water can be reabsorbed
region 4
distal convoluted tubule
distal convoluted tubule primary function
hormone regulation
hormones produced by the distal convoluted tubule
ADH and aldosterone
aldosterone
increases Na+ and K+ secretion
aldosterone is what type of hormone?
steroid hormone
how does aldosterone work?
turns on gene transcription in the nucleus to produce new Na/K pumps and Na channels
ADH - vasopressin
increases H2O absorption, lowers blood pressure and volume
what type of hormone is ADH?
protein hormone
how does ADH work?
activates cAMP, triggering the insertion of aquaporins into the DCT membrane
where is ADH released from?
posterior pituitary
what molecule inhibits aldosterone when blood volume is too high?
ANP
what does a high concentration of K+ cause?
more production of aldosterone via the adrenal cortex
what does low sodium/blood pressure trigger?
renin-angiotensin-aldosterone pathway
what does high K+ cause?
a decrease in resting membrane potential, lowering AP threshold, causing hyperexcitability of the heart (arrhythmias)
what does lower K+ cause?
increase in resting membrane potential. leading to hyperpolarization, skeletal muscle weakness, abnormal heart conduction etc.
region 5
juxtaglomerular apparatus
what does an increased flow rate cause the macula densa cells to do?
secrete a vasoactive chemical to contract smooth muscle
macula densa cells
detect blood flow rate; release a chemical that helps restrict the afferent arteriole if GFR is too high
vasoconstriction
decreases blood flow to the glomerulus
vasodilation
increases blood flow to the glomerulus
granular cells
detect low bp, and [Na+] to release return
hypertension
bp is greater or equal to 140-180
abnormally high increase in the renin-angiotensin-aldosterone activity
glomerulonephritis
thickening of podocytes, fall of GFR, too much water leading to hypertension
congestive heart failure
blood volume is elevated (15%-20% more)
excess ECF
albuminuria
protein in urine
pseudonephritis
after extreme exercise, protein in urine
edema
fluid retention
inappropriate triggers to heart failure (1/2)
activates autoregulation, sympathetic control to try and get GFR back up
inappropriate triggers to heart failure (2/2)
stimulates renin to increase H2O reabsorption and increase Na/K pumps to stabilize
patient treatments
low salt diet
diuretic drug therapy
ACE inhibitors
ANP treatment
ACE does what?
converts angiotensin I to angiotensin II
ANP (atrial natriuretic peptide)
acts to decrease bp, increase urine output, and increase Na+ loss
acute renal failure
rapid reduction in urine, only 500 or less in a day
reversible
chronic renal failure
slow, progressive loss of nephron function
undetectable
up to 75% of nephrons are not functioning
end stage renal failure
90% or more nephrons are not working
every organ is affected
irreversible loss
fatal
two treatments for end stage renal failure
transplant
dialysis
CAPD
continuous ambulatory peritoneal dialysis
advantages of dialysis
- 4x faster than normal
- increase life from 15-20 years
- feed individuals
disadvantages of dialysis
- not great quality of life
- 4-6 hours three times a week
- still affects organs
- take anticoagulants
