Exam 5: Chapter 19 Flashcards
how do the kidneys regulate plasma and BP?
through water absorption and excretion
what happens to BP when the ECF decreases?
BP decreases
which part of the brain regulates osmolarity?
hypothalamus
-thirst drive
which three hormones does the kidney produce?
EPO
Renin
active form of vitamin D3
where are the kidneys in the body?
retroperitoneal
what is the cortex of the kidney? what is the medulla?
Cortex = outer later
Medulla = inner layer
what do the ureters do?
carry urine from the kidney to the bladder
what does the bladder do?
store urine
what does the urethra do?
takes the fluid from the bladder to the environment
what is the portal system of the kidneys?
afferent arteriole
glomerulus
efferent arteriole
peritubular capillaries (vasa recta)
what do the afferent arterioles do?
deliver blood to the nephron from the aorta
what does the glomerulus do?
surround by bowman’s capsule
-takes blood from the afferent art.
-1st capillary bed
what does the efferent arteriole do?
takes blood from the glomerulus to the peritubular capillaries
what does the peritubular capillaries do?
sends blood to the veins (inferior vena cave)
-surround the nephron
what does the vasa recta do?
type of peritubular capillaries found in the juxtamedullary nephron
-MEDULLA
what does the nephron do?
where urine is formed
-functional unit of the kidney
where is the nephron found in the kidney?
mainly in the cortex
-some are found in the medullar (juxtamedullary nephron)
what does Bowman’s capsule do?
get blood from the glomerulus to pushes it into the nephron
what is the renal corpuscle?
bowman’s capsule and glomerulus
-FILTRATION
what does the proximal tubule do?
receive fluid from Bowman’s Capsule
-Reabsorption and Secretion!
what does the loop of henle do?
receive fluid from the proximal tubule
-descending LOH
-ascending LOH
-REABSORPTION
what is the difference in structure of the descending and ascending LOH?
descending: THIN
ascending: THIN -> THICK
what does the distal tubule do?
receives fluid from the LOH
-Reabsorption and Secretion!
what does the collecting duct do?
Reabsorption and Secretion!
what is the process of fluid once it leaves the collecting duct?
- collecting duct
- cortex
- medulla
- renal pelvis
- ureter
- bladder
- urethra
- environment
what is the juxtaglomerulus apparatus?
part of the nephron that folds back on itself
-end part of the ascending LOH passes b/w the afferent and efferent arterioles
-allows for paracrine communication and regulation b/w blood and the nephron
what structures in the nephron does filtration?
renal corpuscle (Bowman’s Capsule, Glomerulus)
what is the filtration fraction?
% of renal plasma flow that is filtered
-only about 20% normally
what are three filtration barriers?
glomerular capillary endothelium
bassement MB
Bowman’s Capsule epithelium
how does the glomerular capillary endothelium filter?
contains fenestrated capillaries
-large pores
-NO plasma proteins or cells pass through
how does the basement MB filter?
negatively charged proteins repel plasma proteins
how does Bowman’s Capsule epithelium filter?
contains podcytes that act like a screen to filter
-wrap around the glomerulus
-has filtration slits
what are filtration slits?
where the filtrate comes through
what does hydrostatic pressure do to filtration? (P(H))
increases filtration
what does colloid osmotic pressure do to filtration? (pie)
decreases filtration
what is filtration pressure? (P(fluid)) what does it do to filtration overall?
displaces previous fluid for the new fluid
-decreases filtration
what is the equation for net filtration? what does a positive and negative value mean?
P(H) - (pie) - P(fluid)
(+) = yes filtration
(-) = no filtration
what is the glomerular filtration rate? (GFR)
volume of fluid filtered per unit of time (mL/min)
what two factors impact GFR? how does it impact GFR?
net filtration pressure: increase NFP = increase GFR
filtration coefficient: increase FC = increase GFR
what does the filtration coefficient depend on?
surface area of the glomerulus (stable)
permeability of filtration slits
does the GFR drastically change?
no, stays relatively stable as long MAP is stable (80-180)
what happens to GFR when the afferent arteriole increases in resistance?
increase R (afferent)=
constriction =
decrease P(H): less blood =
decrease NFP =
decrease GFR
what happens to the GFR when the efferent arteriole increases in resistance?
increase R (efferent) =
constriction =
increase P(H): blood builds up =
increase NFP =
increase GFR
rarely occurs
what does the myogenic response do to GFR?
- increase BP
- stretches
- mechanoreceptors detect
- depolarization
- Ca2+ entry
- constriction
- increase R in afferent arteriole
- decrease P(H)
- decrease NFR
- decrease GFR
no CNS input
where in the renal system does tubuloglomerular feedback?
juxtaglomerular apparatus
no CNS input
what are the steps of tubuloglomerular feedback?
- increase fluid flow in ascending LOH
- macula densa releases a paracrine to the afferent arteriole
- granular cells secrete renin
- afferent arteriole constricts
- increase R = decrease P(H) = decrease NFR = decrease GFR
what is the macula densa?
modified region in the ascending LOH
-releases paracrine
what are granular cells?
smooth muscle cell in afferent arteriole
-secretes renin (constrictor)
what does the sympathetic NS do the GFR?
binds to alpha receptors in the afferent arteriole
-increase resistance through constriction
-overall decreases GFR
what does angiotensin 2 do to GFR?
constricts!
-decrease GFR
what do prostaglandins do to GFR?
dilates!
-increase GFR
what happens to blood volume and MAP when GFR increases?
GFR increases = decrease blood volume = decreases MAP
what does reabsorption do?
moves filtrate from the nephron to the blood (peritubular capillaries)
what is transepithelial transport?
moving through the apical MB of epithelial cell to the basolateral MB
where is the basolateral MB? apical MB?
basolateral MB: closer to blood supply
apical MB: closer to nephron
what is paracellular transport?
moving b/w cell junctions
where does Na+ active transport take place in the nephron?
proximal tubule
what is the Na+ primary active transport in the nephron?
Apical MB: Na+/H+ exchanger (Na+ IN nephron, H+ OUT)
Basolateral MB: Na+/K+ ATPase (Na+ OUT nephron, K+ IN)
what is the purpose of Na+ primary active transport?
to create an electrochemical gradient
-Na+ LOW in nephron, HIGH in ECF
-water follows Na+!!!!
what is Na+ secondary active transport in the nephron?
APICAL SIDE
-SGLT co-transporter moves Na+ and glucose into the cell
-Na+ moves with concentration gradient, glucose moves against concentration gradient
BASOLATERAL SIDE
-glucose diffuses out (GLUT)
-Na+/K+ ATPase pumps Na+ out into fluid to be reabsorbed
what is passive urea transport?
urea concentration created by active transport of Na+
-higher urea in cell compared to ECF (more concentrated)
-urea passively diffuses through epithelial junctions to balance it out
how are plasma proteins transported?
ENDOCYTOSIS (active transport)
-vesicular transport
-too big for transport proteins or diffusion
-does not use gradients!!
does reabsorption have saturation, specificity, and competition?
YES!!! (filtration does not)
what is saturation?
maximum transportation when all carriers are full
-expressed as a concentration (mg/mL)
what is renal threshold?
concentration when saturation occurs (all carriers full)
what is the renal threshold of glucose?
when glucose goes above renal threshold, saturation is reached
-glucose over the limit is excreted
is glucose normally secreted?
NO!!
-only reabsorbed
how does the peritubular capillaries work with pressure to reabsorb molecules?
site where reabsorbed molecules go!
-colloid pressure is greater than hydrostatic, therefore they want to stay inside to be reabsorbed
what is the process of secretion?
peritubular capillaries going to the nephron
what is the process of secretion? what type of active transport does it use?
Tertiary active transport
BASOLATERAL MB (towards blood)
1. generates a Na+ gradient
2. Na+/K+ pump (Na+ OUT, K+ IN) (Na+ low in cell)
3. Na+ gradient mores a dicarbonate IN (symporter, Na+ high in cell)
4. dicarboxylate gradient moves organic anion IN (antiporter) using OAT(1-3) transporter
APICAL MB (towards nephron)
5. organic anion enters the lumen using OAT4 transporter
does secretion have saturation, specificity, and competition?
YES!!
explain competition with Penicillin
penicillin is easily secreted
-Probenecid competes with penicillin and binds OAT transporter
-allows penicillin to stay in the body longer
what is the equation for excretion?
filtration - reabsorption + secretion
what promotes excretion?
filtration and secretion
what inhibits excretion?
reabsorption
what is renal handling?
tubular transport mechanisms for a substance
-how it is excreted
what is reabsorbed in the proximal tubule?
Na+
Cl-
K+
Ca2+
glucose!!
urea!!
what is reabsorbed in the ascending LOH?
Na+
Cl-
K+
Ca2+
what is secreted in the ascending LOH?
urea
what is reabsorbed in the distal tubule and collecting ducts?
Na+
Cl-
Ca2+
urea!!
K+ can sometimes be reabsorbed or secreted
what is clearance?
rate at which the solute disappears from the body
-excretion or metabolism
what is special about inulin and creatine when it comes to clearance?
only FILTERED
-not reabsorbed or secreted
-clearance = GFR
what is the equation for clearance rate?
excretion rate / amount in plasma
what is the equation for excretion rate?
urine volume * urine creatine
what happens when clearance is less than GFR?
reabsorption
what happens when clearance is more than GFR?
secretion
what happens when clearance equals GFR?
filtration
what is micturation?
the process of urination
-ureter -> bladder -> urethra
what is the internal sphincter?
smooth muscle
-open by pressure of bladder contraction
what is the external sphincter?
skeletal muscle
-tonic activity
-keeps bladder closed through contraction
what is the process of urination?
- stretch receptors activate and sends signal to spinal cord
- activate PARASYMP sensory interneuron
- bladder contracts and pulls internal sphincter opens
- inhibitory motor interneuron blocks signal
- external sphincter relaxes (opens) , bladder contracts
- urination
what is the process if you are holding your pee?
- higher input from the brain inhibits both sensory and motor interneurons
- inhibition of parasym sensory interneuron
- bladder relaxes, internal sphincter stays closed
- inhibition of inhibitory motor interneuron
- external sphincter contracts (closes)
- no urination
