EXAM 4 - Renal and Reproductive Systems Flashcards
SGLT1
glucose absorption
SI, renal tubules
secondary active
GLUT2
B cell glucose sensor, transports glucose out of epithelia
liver, epithelia of intestine, kidneys
GLUT4
insulin stimulated glucose uptake
muscle, adipose
absence of insulin
no glucose uptake
presence of insulin
lipogenesis (stimulated by G3P)
hormone sensitive lipase inhibited
insulin affects
GLUT2
glucagon promotes
glycogenolysis (not in muscle)
gluconeogenesis
ketogenesis
lipolysis
renal function
excretes metabolic end products, drugs, xenobiotics
regulates essential ions, osmolarity, pH, arterial bp
secretes renin, erythropoietin, activates vitamin D
cortical nephrons
reabsorption, peritubular capillaries
juxtamedulliary nephrons
concentrates urine, vasa recta, and peritubular capillaries
excretion = filtration - reabsorption + secretion
know it
macula densa cells
modified epithelial cells with osmoreceptors in distal tubule
granular cells
afferent arterial; modifies smooth muscle, secretes renin
mesangial cells
contractile, regulate glomerular filtration
average GFR
125 mL/min or 180 L/day
factors that change GFR: favor filtration
glomerular capillary hydrostatic pressure (Ph)
factors that change GFR: oppose filtration
bowman’s hydrostatic pressure (Pfluid)
colloid osmotic force (pi)
glomerular filtration rate (GFR)
amount of plasma filtered from glomeruli into bowman’s space per unit time
glomerular net filtration
Ph - pi - Pfluid
variables for glomerular capillary hydrostatic pressure (Ph)
arterial pressure (buffered by autoregulation)
afferent arteriolar resistance
efferent arteriolar resistance
increase resistance of afferent arteriole
decreases renal blood flow, decreases Ph, decreases GFR
decrease resistance of afferent arteriole
increases RBF, increases Ph, increases GFR
myogenic response of GFR
increasing renal blood pressure leads to constriction of afferent arteriole
tubuloglomerular feedback
paracrine control
adenosine
when GFR increases, adenosine constricts
renin-angiotensin system
activated by drop in systemic BP or heart attack or severe stress or circulatory shock –> leads to decreased Ph and decreased GFR
renin is released when
bp decreases, sympathetic innervation, osmolarity of tubular fluid is too low (sensed by macula densa)
angiotensin
restores BP
arteriole vasoconstriction aldosterone secretion CNS stimulation (for thirst and ADH release) salt and water retention
atrial natriuretic peptide (ANP)
dilates afferent arteriole, constricts efferent arteriole to decrease GFR
inhibits salt reabsorption leading to increased urine production and decreased BV and BP
inhibits renin secretion and angiotensin
produced by the heart
renal clearance
calculated value representing volume of plasma from which “S” is completely cleared per unit of time
renal clearance equation
clearance of S = urine excretion rate of S / plasma concentration of S
Cs = (Us * V)
————
Ps
clearance of S = the glomerular filtration rate when
- S is not freely filterable at glomerulus
- S is not reabsorbed
- not secreted
- not synthesized
- not broken down
how can creatinine clearance estimate GFR?
is endogenous that fits criteria
small protein secreted by proximal tubules
excretion rate exceeds filtration by 5 to 10%
renal disease
decreased GFR (elevated creatinine or decreased creatinine clearance)
Estimating renal blood flow
substance’s clearance can be used to calculate renal blood flow if it is freely filtered and completely secreted
Renal plasma flow =
RPF = (Urine(PAH) * Urine flow rate) / plasma(PAH)
Renal blood flow =
RPF/ (1-Hct)
PCT absorption
water, organic nutrients, glucose, Na+, K+, Cl-, amino acids, vitamins
DCT reabsorption
selective Na+, cl-, water, active secretion of ions
LH reabsorption
descending: water
ascending: Na+, K+, Cl-, Ca2+, HCO3-
renal threshold
the plasma concentration at which a specific compound or ion will begin appearing in urine (saturation of mediated transport)
calculating renal threshold
Tm / GFR
glucose clearance
excretion rate / plasma concentration
aka
plasma concentration * GFR - tubular maximum
/
plasma concentration
proximal tubule reabsorption: sodium
apical = variety of transporters basolateral = active transport
proximal tubule reabsorption: HCO3- and Na-organic solutes
cotransporter with glucose, amino acids, organic solutes
counter transport with H+ ions
active reabsorption
proximal tubule reabsorption: Urea
no active transport
passive reabsorption due to concentration gradient
transcellular and paracellular pathways
proximal tubule reabsorption: protein
small proteins and peptides can pass through filtration barrier
most removed from filtrate
receptor mediated endocytosis
renal digestion terminates peptide signal
transcytosis**
loss of PT
increased bicarbonate, amino acids, glucose, proteins in urine
collecting duct reabsorption: principal cells
water reabsorption
sodium reabsorption
principal cells: water reabsorption
ADH sensitive
principal cells: sodium reabsorption
aldosterone sensitive
collecting duct reabsorption: intercalated cells
H+ and HCO3- transport (pH dependent)
PT secretion
secondary and tertiary active transport for organic compounds
organic anions and cations
organic anions
bile salts, urate, PAH, penicillin, toxic chemicals
organic cations
creatinine, dopamine, epinephrine, atropine, morphine, isoproterenol, prolineamide
DT and CD secretion
K+, H+, NH4+, organic ions, cretinine, penicillin
concentration dependent
K+ exchanges for Na+
H+ exchanges for K+
Excretion:
detrussor
internal urethral sphincter
external urethral sphincter
detrussor
smooth muscle; parasympathetic activation for contraction
filling: inhibited
micturition: stimulated
internal urethral sphincter
smooth muscle; sympathetic activation for contraction
filling: stimulated
micturition: inhibited
external urethral sphincter
skeletal muscle; sympathetic activation for contraction
filling: stimulated
micturition: inhibited
bladder: micturition
stretch receptors in bladder send sensory info to CNS
parasympathetic neurons activate, motor neurons to external sphinc. inactivate
smooth muscle contracts, internal sphincter passively opens, external relaxes
bladder: filling
CNS sends tonic discharge
Motor neuron fires
internal sphincter passively contracts
external sphincter stays contracted
3 stimuli that contribute to water balance (vasopressin)
increased plasma osmolarity
decreased blood volume
decreased BP
ADH (vasopressin)
insertion of water pores in apical membrane to increase water reabsorption
aldosterone
released when BP decreases (via renin-angiotensin II) and increased K+ extracellular concentration
aldosterone + K+
increased extracellular K+ stimulates aldosterone secretion to prevent hyperkalemia which leads to cardiac arrhythmias
increased plasma K+ –> increased aldosterone –> increased tubular K+ secretion in exchange for Na+
