Kidney functions- regulation and quantification Flashcards
Kidney functions include?
excretion, ABB maintenance, metabolic and endocrine functions
Physiological basis of urine formation includes…?
glomerular and tubular filtration
What is glomerular filtration?
Filtration of plasma through 3 layers that make up the glomerular membrane.
Name layers of glomerular membrane?
- endothelial cells of the capillary wall
- basement membrane
- and the inner layer of Bowman’s capsule (podocytes)
What is tubular filtration?
occurs when the glomerular liquid passes into the renal tubules.
What happens under glomerular filtration?
Volume of the liquid decreases (secondary urine) and the composition gets changed by processes of reabsorbtion and secretion.
Which system does the glomerulus represent?
A high pressure system, the high hydrostatic pressure facilitates filtration.
Which system does the peritubular capillaries contribute to?
A low pressure system, the low hydrostatic pressure facilitates reabsorption from the tubulus.
Filtration can be inflluenced by?
- altered renal blood flow
- changes in hydrostatic pressure (glomerular capillaries)
- alterations in systemic BP
- Constriction of vas afferens or efferens
- changes of HP in Bowmans capsule
- alterations in plasma protein concentration
- changes in permeability of glomerula capillaries
- changes in the effective filtration surface
- obstruction in ureter, edema in kidney capsule etc.
What is RAAS ?
Renin-angiotensin-aldosterone system –> is a hormone system that regulates blood pressure and fluid balance.
Granular cell function in kidneys?
Internal baroreceptors
Which cells are sentisitve to NaCl?
Macula densa cells –>area of closely packed specialized cells lining the wall of the distal tubule.
What happens when there is a fall in NaCl concentration or BP in afferent arteriole?
Granular cells start producing the hormone renin.
What are Granular cells innervated by, and what does this enable?
The sympatic nervous system, enables a reflex response to BP failure by stimulating renin secretion.
What induces renin production?
Fall of :
- conc. of NaCl
- ECF volume
- Blod pressure
What happens with renin after secretion?
Acts as an enzyme and by cleavage it activates angiotensinogen –> angiotensin I
What is angiotensionogen?
A precursor, plasma protein synthesized in liver
What happens with angiotensin I?
It passes through the lungs during circulation, and there it gets converted to angiotensin II.
Which enzyme converts angiotensin I –> angiotensin II?
ACE –> angiotensin converting hormone, produced by endothelial cells of lung capillaries.
Function of angiotensin II?
a active hormone causing vasoconstriction and increases BP. It is also the primary stimulus for aldosterone secretion.
What is aldosterone and where is it produced?
Promotes the synthesis of Na+/K+ carriers in the distal and collecting tubules of the kidney. It increases Na+ reabsorption followed by water reabsorbtion –> produced in adrenal cortex.
Agonist of angiotensin II?
Vasopressin/ADH –>both is constrictors of the systemic arterioles –> incr. BP
What is ANP, and where is it produced?
Atrial natriuretic peptide, produced in the right atria of the heart in response to being streched by Na+ retention, expansion of the ECF and increase in atrial BP
what is ANP’s role in the RAAS system?
it promotes in turn natriuretic, diuretic, and hypotensive effects to help correct the original stimuli that resulted in it’s release. –>promotes excretion of water and sodium from the kidneys when their level gets too high
