Flashcards in Flow, GFR And Pharmacology Deck (45)
What is the average renal blood flow?
What is the renal plasma flow?
Renal blood flow minus the haematocrit (erythrocyte volume fraction - usually 45%)
RPF = 0.55 x RBF
Generally, how many segmental arteries are there per kidney?
What are the 2 types of nephron?
Give some features of cortical nephrons
Afferent arteriole has large diameter than efferent
High concentration of renin
Give some features of the juxtamedullary nephrons
Diameter of afferent close to diameter of efferent
Almost no concentration of renin
How much of the blood from a renal artery is filtered at any one time?
What are the 3 layers of the glomerular filter?
Which molecule do we think is the biggest molecule that can pass through glomerular filtration?
Which charge is repelled more at the glomerulus?
What are the 3 forces acting at the filter?
Hydrostatic pressure in capillary
Hydrostatic pressure in Bowman's capsule
Oncotic pressure in capillary
What is the myogenic response?
The control over GFR by changing the tone of the arteriole walls
Controls GFR through day-to-day BP changes
Describe the effect on the GFR of an increase in tone in the afferent arteriole
Increased resistance leads to reduced blood flow
Decreased hydrostatic pressure
Why doesn't the flow rate change?
Because change is resistance is proportional to change in pressure
Which organs have the best autoregulation?
What is the role of autoregulation?
To keep GFR within the normal ranges
Describe tubular-glomerular feedback
Changes in tubular flow rate occur as a result of changes in GFR
This changes the amount of NaCl that reaches the DCT
Cl- ions detected in the macula densa
Stimulates juxtaglomerular apparatus to release appropriate chemicals
What chemicals can be released by the JGA and what are their effects?
Adenosine - vasodilator of the efferent arteriole - reduces GFR
Prostaglandins - vasodilator of afferent arteriole - increases GFR
Describe glucose cotransport in the PCT
2 Na+ ions plus 1 glucose molecule
Secondary active transport
What substances do we secrete into the kidney tubules?
Organic anions and cations (a lot of the drugs that we prescribe)
Give examples of endogenous cations
Give examples of drugs that are cations
Give examples of endogenous anions
Give examples of drugs that are anions
What is the normal GFR range for males and females?
Males = 115 - 125 ml/min
Females = 90 - 100
What is the formula for renal clearance?
RC = UV/P
U = urinary conc of substance
V = flow rate of urine formation
P = plasma conc of same substance
What factors does the complicated eGFR equation take into account?
What does xenobiotic mean?
Not belonging in the body
What processes contribute to pharmacokinetics?