Renal physiology Flashcards
what is the role of the kidneys?
- regulate water balance
- contribute to long term regulation of acid-base balance
how do the kidneys help with acid-base balance regulation?
excrete H+ when there is excess acid or HCO3- when there is an excess of base
what is the functional unit of a kidney?
the nephron
what is the entry point to the nephron from the blood?
Bowman’s capsule, it wraps around the vasculature
how does Diabete’s affect the exchange that occurs at the Bowman’s capsule?
it changes the structures of the basement membrane of epithelial cells in Bowman’s capsule
thickens/hardens them which makes it harder to move materials from vasculature to Bowman’s capsule
name some patient populations that can have issues with kidney function at Bowman’s capsule
- Diabetic
- hypertensive
what is the role of the Bowman’s capsule?
to act a barrier and alllow passage of some materials into the nephron and not others.
Filtration
what is filtrate?
the fluid that will eventually become urine
where do materials go once inside the Bowman’s capsule?
proximal convoluted tubule
where is most of the work done in the kidney?
the area between the glomerulus and the proximal convoluted tubule
what processes occur in the tubule and loops of the nephron?
reabsorption and secretion
what is reabsorption in the kidney?
a process that removes materials from the filtrate and brings it to the interstitial space where it will be reintegrated back into circulation
what is secretion in the kidney?
process by which materials move into the nephron for excretion
define Glomerular filtration rate (GFR)
an estimate of how much fluid is filtered from the glomerular capillareis into Bowman’s capsules per unit time
what would a GFR of 60 indicate?
what about 15?
60 = kidney disease
below 15 = stage 4 kidney disease
T/F: the kidney recieves a large amount of CO
TRUE, 20% of CO is delivered ot the kidneys in order to help maintain a constant GFR
how is blood flow regulated at the kidneys?
renal capillaries have intrinsic and extrinsic factors that affect blood flow regulations
what are some extrinisic factors that affect renal blood flow?
SNS input
decreased SNS = vasodilation and greater blood flow
increased SNS = vasoconstriction
what are some intrinsic factors that affect renal blood flow?
- autoregulation
- arteriolar myogenic mechanism
- tubuloglomerular feedback mechanism
what is the arteriolar myogenic mechanism?
Stretching smooth muscle causes it to contracts
remove the stretch and smooth muscle relaxes, restoring its resting length
what is tubuloglomerular feedback mechanism?
tubular monitoring of filtrate flow rate and Na+ concentration
Increased osmolarity of the filtrate causes the afferent arterioles to constrict, slowing blood flow and vice versa
how does the glomerulus regulate what it filters?
the epithelial walls of the capillareis in this area are fenestrated = increased permeability
what is rhabdomyolysis?
severe muscle damage leading to kidney disease.
muscle breaks down and peices of muscle get into blood stream and then to the kidney but can’t pass into the Bowman’s capsule.
thus they clog pores and movement of fluid becomes compromised
what are antigen-antibody complexes (Ag - Ab)?
obstruct openings in epithelial linings and prevent movement of fluid and solutes into tubules.
Ag-Ab complexes are larger than the pores
how does tubular reabsorption occur?
water moves down it’s concentration gradient to be reabsorbed into the blood.
Ions move down their concentration gradients and can also be reabsorbed.
how does Na+ move from the tubule into the interstitial space?
mediated transport mechanism and channels help over come the gradient from the cell to the interstitial fluid
what gets secreted in tubular secretion?
molecules like H+, K+ ,creatinine, HCO3 get secreted by diffusion or mediated transport
water follows _______
Na+
where is Na+ reabsorbed?
in the proximal convoluted tubule (PCT)
what is reabsorbed at the PCT?
Na and most of the water
the descending loop of Henle is permeable to ________
water
the ascending loop of Henle is permeable to _________
Na and Cl
but NOT water
where is the last bit of water reabsorped at?
the distal convoluted tubule and collecting ducts
how is does water move out of the distal convoluted tubule?
via aquaporin channels which are requried by ADH and inserted into the walls of the distal tubule and collecting ducts as needed
how would you expect the urine concentration to differ between water dwelling and desert dwelling animals?
water dwelling = more dilute
desert dwelling = more concentrated
what is the harm in drinking salt water?
too much Na+ in salt water
getting rid of that ingested Na+ would cause a loss of water
end result is amplified dehydration
where is renin produced?
Kidney cells
what prompts the kidney to release renin?
decreased BP,
decreased NaCl
increased sympathetic outflow in kidney
what does Aldosterone do?
favors reabsorption of water and Na+
helps create osmotic gradient needed for movement
T/F: reabsorption of glucose occurs in the kidneys?
TRUE
where is glucose reabsorbed in the kidney?
proximal convoluted tubule
at SGLT2 transport molecules
effect of renin angiotensin system on BP?
Increase BP
how would eating salty food affect the kidney?
kidney wants to conserve water and get ride of excess Na+
renin angiotensin system is slowed down to get rid of Na
Water has to be lost to get rid of Na+
effect of CHG on kidney function
heart is weak due to reduced cardiac contractility
body thinks there is a reduced blood volume
body trys to increase water retention to increase blood volume
kidney increases water retention = not good for these patients
