Physiology lecture Flashcards
renal artery–> segmental artery –> ?
interlobar artery
the interloper arteries are connected by:
arcuate arteries
the ______ veins are the collecting vessel of the nephron capillary system
interlobar
- high blood flow
2. 2 capillary beds
renal blood flow
_____% of cardiac output goes to the kidneys
21
high hydrostatic pressure in
glomerular capillary
low hydrostatic pressure in
peritubular capillaries
- filtration
- reabsorption
- secretion
- excretion
4 main processes of renal physiology
- first step in urine formation
- bulk transport of fluid from blood to kidney tubule
- result of hydraulic pressure
- GFR = 180 L/day
Filtration
- process of returning filtered material to bloodstream
- 99% of what is filtered is reabsorbed
- may involve transport proteins
Reabsorption
Is glucose normally totally reabsorbed?
YES
- material added to lumen of kidney tubule from blood
* active transport (usually) of toxins and foreign substances (saccharine, penicillin)
Secretion
*loss of fluid from body in form of urine
Excretion
(Amount filtered + amount secreted) - amount reabsorbed =?
Amount of solute excreted
Occurs as fluids move across the glomerular capillary in response to glomerular hydrostatic pressure
glomerular filtration
- blood enters glomerular capillary
- filters out of renal corpuscle
- large proteins and cells stay behind
- everything else is filtered into nephron
- glomerular filtrate
- plasma like fluid in glomerulus
glomerular filtration
- molecular weight
2. charges of the molecule
factors that determine glomerular filterability
Mechanism: Bulk flow
Direction of movement : From glomerular capillaries to capsule space
Driving force: Pressure gradient (net filtration pressure, NFP)
glomerular filtration
Types of pressure:
Favoring Force: Capillary Blood Pressure (BP) Opposing Force: Blood colloid osmotic pressure(COP) and Capsule Pressure (CP)
Glomerular filtration
Amount of filtrate produced in the kidneys each minute.
**125mL/min = 180L/day
GFR
what does increased renal blood flow do to GFR?
increases GFR
what does increased plasma protein do to GFR?
increase GFR, causes edema
what does hemorrhage to do GFR?
decreases GFR (bc decreased capillary BP)
- Renal Autoregulation
- Neural regulation
- Hormonal regulation
Regulate GFR
*all adjust renal blood pressure and resulting blood flow
Sympathetic nerve fibers innervate afferent and efferent arteriole
Normally sympathetic stimulation is low but can increase during hemorrhage and exercise
Vasoconstriction occurs as a result which conserves blood volume(hemorrhage)and permits greater blood flow to other body parts(exercise)
Neural regulation of GFR
Several hormones contribute to GFR regulation
- Angiotensin II. Produced from Renin, released by JGA cells is a potent vasoconstrictor. Reduces GFR
- ANP(released by atria when stretched) increases GFR by increasing capillary surface area available for filtration
- NO
- Endothelin
- Prostaglandin E2
Hormonal regulation of GFR
If a substance is filtered but neither reabsorbed nor secreted, then the amount present in urine is its…..
plasma clearance
*amount in plasma cleared/min by glomerulus
125ml of plasma is cleared/min in glomerulus, which is about how many L per day?
180L/day
Freely filterable at glomerulus Does not bind to plasma proteins Biologically inert Non-toxic, neither synthesized nor metabolized in kidney Neither absorbed nor secreted Does not alter renal function Can be accurately quantified Low concentrations are enough (10-20 mg/100 ml plasma)
Inulin
*can measure GFR
End product of muscle creatine metabolism
Used in clinical setting to measure GFR but less accurate than inulin method
Small amount secrete from the tubule
Creatinine
Transcellular pathway
Paracellular transport
2 pathways of absorption
- Primary Active Transport
- Secondary Active Transport
- Pinocytosis
- Passive Transport
Mechanisms of transport
Some parts of the tubule, especially the proximal tubule, reabsorb large molecules such as proteins by…
pinocytosis