What is produced by lung tissue to be used in lungs-
Ans. is 'c' i.e., Surfactant * Among the given options, two substances are formed in lung-i) Surfactant: Used by lungs alveoli to reduce surface tension.ii) Angiotensin II: ACE in lungs convert angiotensin I to angiotensin II. But angiotensin II mainly acts on blood vessels, kidney and adrenal cortex. Actions of angiotensin II are -# Vasoconstriction : - The most prominent action of agniotensin II.# Increased secretion of aldosterone from zona glomerulosa of adrenal cortex. Aldosterone cause Na+ retention.# Kidney : - Angiotensin II constricts both afferent and efferent arterioles, thereby reducing both GFR and RBF. However, the efferent arterioles are more sensitive to angiotensin II. Hence, angiotensin II causes greater constriction of the efferent arterioles, thereby increasing the filtration fraction. There is ncreased Na+ and water reabsorption as a result of increased aldosterone and ADH secretion, as well as by direct effect of angiotensin II in increasing Na+ reabsorption in proximal tubules, loop of Henle, distal tubules and collecting tubules.# Central effects : - Angiotensin II acts through angiotensin receptors present in the subfornical organ (SFO) and organ vasculosum of lamina terminalis to increase thirst. Angiotensin II also acts on area postrena of the brain to bring about an increased sympathetic discharge that causes increased release of norepinephrine in postganglionic sympathetic neurons.
Angiotensin I
Renin
Surfactant
Angiotensin II
Respiratory System