51 Renal blood flow and glomerular filtration Flashcards
T/F. The kidneys are responsible for regulation of arterial blood pressure
True
T/F. The kidneys are responsible for regulation of acid-base balance
True
T/F. The kidneys are responsible for synthesis of vitamin D
False. The kidneys are responsible for synthesis of the active form of vitamin D
T/F. The kidneys are responsible for synthesis of erythropoietin, prostaglandins, and bradykinin
True
What is the function of bradykinin?
It is a vasodilator
A vasodilator. Vasodilates the afferent more than the efferent arterioles
Prostaglandins
T/F. The kidneys are capable of gluconeogensis
True
Filtration, reabsorption, secretion, and metabolism
Four main processes of the nephron
The volume that a given substance occupies in the plasma appearing in the urine in a period of time. C=(excretion rate)/(concentration in plasma)=V/P. Units are ml/min
Clearance
Secretion and reabsorption occur b/t the ___ capillaries and the convoluted tubule
Peritubular capillaries
T/F. Filtration is the non-selective process by which about 40% of the renal plasma flow is filtered
False. Filtration is the non-selective process by which about 20% of the renal plasma flow is filtered
delP/R = ? delP = P renal artery - P renal vein R = total renal vascular resistance
Renal blood flow
(1-Hct)*RBF = ?
Renal plasma flow
Three layered components –the fenestrated capillary endothelium, the glomerular basement membrane (GBM), and filtration slit diaphragms b/t pedicels.
Glomerular filtration barrier
T/F. • The Glomerular filtration barrier is responsible for determining what is filtered from plasma according to size only
False. • The Glomerular filtration barrier is responsible for determining what is filtered from plasma according to size and net charge:
Component of glomerular filtration barrier that excludes large blood components (mainly lipoproteins and RBCs)
Capillary endothelium
Component of glomerular filtration barrier that is composed of glycosaminoglycans (GAGs), which are negatively charged. Functions to repel molecules w/ large negative charges (primarily proteins)
Basement membrane
Component of the glomerular filtration barrier that forms filtration slit pores. These mainly exclude remaining large blood components
Podocytes
T/F. Cells, proteins, and lipids (b/c they are bound to proteins) are not filtered
True
The glomerular filtration barrier loses is lost (any of the three components of the basement membrane). Symptoms: Hypoproteinemia, albuminuria, generalized edema, and hyperlipidemia
Nephrotic syndrome
T/F. TF/P = 0 for a substance that is freely filtered
False. If TF/P= 1 (in bowman’s space): the substance is freely filtered
T/F. Major electrolytes (including bicarbonate), waste products (urea, creatinine), AAs, ketone bodies, non-natural substances (inulin, PAH), and low MW proteins and peptides (insulin & myoglobin) are all freely filtered
True
T/F. TF/P > 1 in bowman’s space for a substance that is not freely filtered
False. TF/P s space for a substance that is not freely filtered
T/F. Plasma proteins (e.g. albumin) and lipid soluble substances bound to proteins (e.g. TAG, cholesterol, FS-vitamins, hormones) are not freely filtered
True
T/F. Filtration is an active process
False. Filtration is a passive process
T/F. Nephrons are connected in series
False, nephrons are connected in parallel
This is the most important factor affecting glomerular filtration rate (GFR)
Glomerular hydrostatic pressure
T/F. Increasing afferent arteriolar resistance: decreases renal blood flow and decreases GFR
True
T/F. Increasing efferent arteriolar resistance: decreases renal blood flow and decreases GFR.
False. o Increasing efferent arteriolar resistance: decreases renal blood flow and increases GFR.
(strong activation) via catecholamines [alpha-1 receptors]: serves as a vasoconstrictor of the arterioles of the kidney. E.g. severe hemorrhage.
Afferent arterioles are constricted more than efferent arterioles (however, resistance is increased in both)
Sympathetic NS
Low doses preferentially constrict the efferent arteriole. However, high doses lead to constriction of the afferent arteriole, which results in no change in the GFR. Release during: low sodium diet, blood volume depletion, renal artery stenosis
Angiotensin II
A vasodilator that protects against excessive vasoconstriction. Patients w/ endothelial dysfunction (e.g. atherosclerosis) may have greater risk for excessive decrease in GFR in response to stimuli such as volume depletion
Nitric oxide (endothelium-derived)
This parameter can be used to measure: Renal function (decreased GFR is a marker for progression of disease), Evaluation of risk of kidney failure, Evaluation for kidney donation, Dose and monitoring for medications cleared by the kidney, Determine safety of diagnostic tests or procedures, Renal insufficiency (25-30% of normal ___), Renal failure (10-25% of normal ___)
GFR
GFR/RPF = ?
Filtration fraction (FF)
Clearance of ___ is clinically used to measure GFR
Creatinine. However, Creatinine is excreted in higher amounts than inulin b/c it is secreted as well as filtered (inulin is only filtered). Therefore, Creatinine clearance is higher, and therefore overestimates the GFR
What increases from afferent to efferend ends of the glomerulus? What decreases?
colloid osmotic pressure increases from the afferent to the efferent ends. GFR therefore decreases from afferent to efferent ends
