Renal Physiology Flashcards
Innervation
T10-L2 SNS
Hypo gastric Ganglion/Nerve–bladder relaxation, internal sphincter contraction
PNS (S2-S4)
Pelvic nerve
—bladder contraction
–internal sphincter relaxation
Voluntary–
Pudendal nerve
–external sphincter
Process of micturation
Bladder pressure stimulates afferent sensory nerves
Urethral sphincter relaxes
Pudendal nerve contraction to override parasympathetic micturation reflex
Filling of the bladder
Contraction of striated sphincter (somatic)
Contraction of smooth muscle (sympathetic)
Inhibition of destructor muscle (sympathetic
Emptying the bladder
Relaxation of striated spin her (somatic)
Relaxation of smooth muscle sphincter and opening of the bladder neck (sympathetic)
Detrusor muscle contraction (para)
Pressure
Stretch receptors–>SNS efferent–>pons–>SNS afferent–>NE–> B3
–>destrusor relaxation (inhibition of contraction)
NE–>alpha1–>contraction of internal urethral sphincter
SNS efferent and afferent so=hypo gastric
Pudendal–>ACh–>contract external urethral spinner
Pressure>10cmH20 (emptying phase)
> 10cmH2O–>pelvic PNS afferents–>pons–>pelvic PNS efferents–>ACh–>M3 receptors–>destrusor contraction
NO–>internal urethral sphincter relaxes
Pons–>pudendal–>ACh–>nicotinic–>contraction of external urethral sphincter until it is ready
Major functions of the Kidneys
Regulate body fluid osmolality and volumes, electrolyte balance, acid-base balance, excretion of metabolites and substances, production and secretion of hormones
Kidney Blood Flow
Renal artery, interlobar artery, arcuate artery, interlobular artery (comes second, longer name), afferent arteriole, glomerular capillaries, efferent arterioles, peritubular capillaries, interlobular vein, arcuate vein, interlobar vein, renal vein
Artery that enters the nephron
Afferent arteriole
Portion of the peritubular capillary that dives into the renal medulla
Vasa recta then back into an interlobular vein
Glomerulus vs peritubular capillary system
Glomerulus–high pressure, fluid out of capillaries
Peritubular–low pressure, filter fluid into capillaries
Two major divisions of peritublar capillary system
Cortical capillaries and deep medullary capillaries
3 layers of the barrier that any solute must pass from the glomerular capillary blood into bowman’s space
Capillary epithelium (Fenestrations) Combined basement membrane(most restrictive) Podocytes (filtration slits,structural integrity)
What does the nephron clear from blood plasma
Unwanted substances:
Urea, creatinine, Uris acid, unrated, Na+, K+, Cl-, H+, Drugs, organics
Blood supply to glomerular capillaries
Afferent arteriole
Blood supply to peritubular capillaries
Efferent arteriole
GFR values
100-140 ml/min (120 ml/min)
180 L/day
99% reabsorbed, 179 liters/day
Always permeable to H20
Proximal convoluted
Thick descending limb
Thin descending limb
Half of loop
Never permeable to H2O
Half of loop
Thin ascending limb
Thick ascending limb (distal straight tubule)
Distal convoluted tubule (early)
ADH permeable to H2O
Late distal convoluted tubule, cortical and medullary collecting tubule
GFR
Glomerular capillary permeability/surface area product (Kf)
Times the net hydrostatic pressure (glomerular capillary minus bowman’s) minus the PCOP (colloid pressure of glomerular capillary blood)
Kf
Permeability times surface area
Permeability: Fenestrations, basement membrane, filtration slits
Surface area:capillary size and number
Major Determinants of GFR
1) hydrostatic or blood pressure
2) permeability/cell-cell junctions
3) plasma components
Pt normal value
Normally 0 due to the drainage by the PCT
Blocking of a structure beyond the glomerulus will cause problems