Regulation Of Kidney Function Flashcards
How is the functioning of the kidneys monitored?
Which structures are involved?
Efficiently monitored and regulated by hormona feedback mechanisms.
Hypothalamus, JGA, and to a certain extent, the heart.
How are osmoreceptors in the body activated?
Changes in
Blood volume
Body fluid volume
Ionic concentration
What does activated osmoreceptors do?
An excessive loss of fluid from the body can activate these receptors which stimulate the hypothalamus to release antidiuretic hormone (ADH) or vasopressin from the neurohypophysis.
Function of ADH
How is it suppressed
ADH facilitates water reabsorption from latter parts of the tubule, thereby preventing diuresis.
ADH can also affect the kidney function by its constrictory effects on blood vessels. This causes an increase in blood pressure. An increase in blood pressure can increase the glomerular blood flow and thereby the GFR.
An increase in body fluid volume can switch off the osmoreceptors and suppress the ADH release to complete the feedback.
How are the JG cells activated?
What do they then release?
What is the function of the substance released?
Fall in glomerular blood flow/glomerular blood pressure/GFR
Renin
Converts angiotensin in blood to angiotensin I and further to angiotensin II
Which is a powerful constrictor in the Renin Angiotensin mechanism?
What is its function?
Angiotension II
Angiotensin II, being a powerful vasoconstrictor, increases the glomerular blood pressure and thereby GFR.
Angiotensin II also activates the adrenal cortex to release Aldosterone. Aldosterone causes reabsorption of Na+ and water from the distal parts of the tubule. This also leads to an increase in blood pressure and GFR.
What substance is released when blood flow to atria of the heart is increased?
What is its function?
Atrial Natriuretic Factor (ANF)
ANF can cause vasodilation (dilation of blood vessels) and thereby decrease the blood pressure. ANF mechanism, therefore, acts as a check on the renin-angiotensin mechanism.
