Glomerular Filtration and Renal Clearance - Ch 16 Flashcards
(31 cards)
What hormones does the kidney produce / convert?
Erythropoietin
Renin
1,25-dihydroxyvitamin D (convert to active form)
What can the kidney produce during starvation and how?
Glucose (via gluconeogenesis)
What percent of the cardiac output enters the kidney? What volume of blood is this?
20% (1 L / min)
What is the ratio of cortical (superficial) to juxtamedullary (deep) nephrons?
85% Cortical - 15% Juxtamedullary
What do the efferent arterioles associated with the cortical and juxtaglomerular nephrons lead to, respectively?
Cortical - peritubular capillaries (collect material reabsorbed from nephrons)
Juxtaglomerular - vasa recta (collect material reabsorbed from medullary tubules)
What is the juxtaglomerular apparatus?
Specialized site where the macula densa is in contact with the distal convoluted tube and afferent arteriole
What do the macula densa cells regulate?
Glomerular filtration rate (GFR)
Renin release
What are the consequences of damage to the glomerular basement membrane?
Reduce the negative charge and allow large proteins (ie albumin) to be filtered
What is the consequence of mesangial matrix deposition?
Decrease area of filtration and reduced renal function
What are the symptoms of acute glomerulonephritis?
Edema Low urine volume Headaches Nausea Joint pain
How do you calculate renal plasma flow?
RPF = RBF x (1 - HCT)
What is used to determine effective renal plasma flow (ERPF)
Para-aminohippurate (PAH)
What is the effective pore size of the glomerulus?
30 A
How do you calculate net filtration pressure?
(HP gc - HP bs) - pi gc
What is a normal GFR?
100-125 mL/min
130 ml/min (Rao)
What is the filtration fraction and how do you calculate it?
The proportion of the RPF that becomes glomerular filtrate
FF = GFR / RPF
What is filtered load and how do you calculate it?
Amount of a specific substance filtered per unit time
FLx = Px x GFR
What is urinary excretion and how do you calculate it?
The urine concentration of the substance times the volume of urine produced per unit time
Ex = Ux x V
How do you calculate reabsorption rate?
Rx = FLx - Ex
How do you calculate secretion rate?
Sx = Ex - FLx
What is renal clearance and how do you calculate it?
Volume of plasma cleared of a substance per unit time
Cx = (Ux x V) / Px
When does clearance equal GFR?
When a substance is freely filtered, but not reabsorbed or secreted
What is the relationship between plasma creatinine and GFR?
Proportional to 1 / mg% Pcr
ie 1 = 100%, 2 = 50%, etc
What is the mechanism by which arteries and arterioles respond directly to increases in systemic blood pressure?
Mycogenic mechanism
