Glomerular Flitration Flashcards
Why is collagen used in the basement membrane?
Provide support
Are podocytes negatively charged?
Yes
What does the mesangial cells surround and what 4 things do they provide?
Glomerular capillaries
Structural support of the capillaries, possess phagocytic activity, secrete extracellular matrix and prostaglandin
What is the maximum mw which can pass through the glomerular and give examples of substances which can pass through?
70kDa
Glucose, amino acids, Na+, urea and K+
Apart from mw what else is filtration dependent on?
Electrical charge of the molecule
Define glomerular filtration rate (GFR)
Amount of filtrate produced from blood flowing through glomerulus per unit time
GFR = Kf X net filtration pressure
What is the equation of the filtration coefficient Kf and it is effected under physiological conditions?
Kf = glomerular SA X glomerular capillary permeability
Stays relatively constant
What is net filtration pressure determined by and what are they?
Starling forces:
Glomerular capillary hydrostatic pressure Pg
Plasma colloid osmotic pressure piG
Bowman’s capsule hydrostatic pressure Pb
Bowman’s capsule colloid pressure piB
What is auto regulation of renal blood flow and GFR and what two factors effect it?
Maintain constant renal blood flow and GFR over physiological range of MAP, kidney can autoregulate quite rapidly to change in BP by adjustment of afferent arteriole diameter
Factors: myogenic and tubuloglomerular feedback
Why do we estimate GFR?
Can provide an estimate of how efficient kidney filters waste from blood
Severity and course of kidney disease
How much of a drug you can prescribe
What are the 3 methods used clinically to estimate GFR?
Creatinine clearance
Cockcroft and Gault formula
Modification of diet in renal disease MDRD formula
Do the pores between the endothelial cells of the glomerular capillary contain negatively charged glycoproteins?
Yes
