Renal Phys. Functional Overview Flashcards
What is the primary fxn of the kidneys?
Regulates the composition of the ECF.
What are 6 regulatory fxns the kidneys maintain?
- Blood Volume
- ECF volume
- Systemic arterial BP
- Hematocrit
- Acid-base balance
- Plasma conc. of electrolytes, minerals, metabolic waste, water.
Define azotemia.
Inc. nitrogenous waste in blood
Most energy use by the kidneys is for……?
Reabsorbing Na
Where does filtration occur in the kidneys?
Glomerulus
Where does re-absorption and secretion occur in the kidneys?
Tubules
Explain the steps of reabsorption.
- Remove substances from tubular lumen across the epithelial layer to the interstitium
- Movement into blood from interstitium
Why are there 2 capillary beds in the kidneys?
- Produces filtrate
2. For reabsorption
What drives Glomerular Filtration?
Hydrostatic Pressure
Define filtration fraction.
“the fraction of plasma flowing through the glomerulus that is diverted into Bowmans space by filtration”
Which is correct?
A. As filtration fraction inc., the Starling forces promoting re-absorption of fluid into the peritubuar capillaries inc.
B. As the filtration fraction dec., the Starling forces promoting re-absorption of fluid into the peritubular capillaries inc.
A. Starling forces promoting re-absorption increase.
Define specific gravity.
the density of a urine sample compared to the density of water
water =1 as you go above 1 more dense urine
What do the following USG values mean?
A. -1.001
B -1.050
A. more water than solute
B. more solute than water
List some key factors needed to develop the concentration gradient.
- slow blood flow through medulla of filtrate and blood
- differential permeabilities of tubular segments in Henles loop (water, salt)
- smaller amts of filtrate to modify
- water movement through collecting ducts.
Matching:
permeable, impermeable, variable (to water)
proximal, distal, collecting
Proximal=Permeable
Distal=impermeable
Collecting=variable
What hormone is produced by the kidney in response to low tissue oxygenation?
Erythropoietin (glycoprotein) produced in renal peritubular fibroblast-like type 1 interstitial cells
What does erythropoietin stimulate?
RBC production in bone marrow
What is the function of calcitriol?
facilitates release of Ca and P from bone, and absorption from GI tract
cell growth
Where is calcitriol produced?
Precursor in the liver (25-hydroxycholecalciferol) then formed in proximal tubules by 1-alpha hydroxylation.
What enzyme is released by the kidneys to inc. retention of NaCl?
Renin
What does renin regulate?
Extracellular volume
Arterial BP
Where is renin produced?
Granular cells of the juxtaglomerular apparatus
What is the RAAS cascade?
Renin release from kidney–> Angiotensin I –> ACE and other enyzmes–> Angiotension II–> AT 1/2 Receptor (1 stimulates Aldosterone release)
Aldosterone:where is it produced? its target? and effect?
Produced in the adrenal gland, targets the distal tubules and collecting duct, conserves Na and water, K+ secretion –> inc. BP
What effects do Angiotensin have?
Inc. vasoconstriction –> inc. BP, overlong term can cause fibrosis
Renal innervation is predominantly what type of fibers?
Alpha-adrenergic sympathetic
What are the three main innervation sites in the kidney and what are the effects?
- Renal arterioles –> Preglomerular vasoconstriction (can stop urine production during symp. activation)
- Renal tubular epithelium–>Inc. Na pump activity
- Juxtaglomerular apparatus –>renin secretion from juxtaglomerular cells
i.e. kidneys dont detect pain, ex. stone dont feel until swells and pressure is put on capsule
