11- Physiology Explains (2) Flashcards
What is the mnemonic for the adrenal cortex layers?
GFR - ACD
What hormones are mainly produced in the zona glomerulosa of the adrenal cortex?
Mineralocorticoids, mainly aldosterone
What hormones are mainly produced in the zona fasciculata of the adrenal cortex?
Glucocorticoids, mainly cortisol
What hormones are mainly produced in the zona reticularis of the adrenal cortex?
Androgens, mainly dehydroepiandrosterone (DHEA)
What stimulates the release of renin?
Reduced renal perfusion and low sodium levels
What does renin hydrolyze to form?
Angiotensin I
What factors stimulate renin secretion?
Low blood pressure, hyponatremia, sympathetic nerve stimulation, catecholamines, erect posture
What converts angiotensin I to angiotensin II?
ACE (angiotensin-converting enzyme) in the lungs
What are the effects of angiotensin II?
Vasoconstriction leading to raised blood pressure, stimulation of thirst, stimulation of aldosterone and ADH release
What stimulates the release of aldosterone?
Raised angiotensin II levels, potassium levels, and ACTH levels
What does aldosterone cause in the distal tubule?
Retention of sodium in exchange for potassium and hydrogen ions
Where does iron absorption primarily occur?
Duodenum and upper jejunum
What percentage of dietary iron is typically absorbed?
About 10%
Which form of iron is more readily absorbed: ferrous iron or ferric iron?
Ferrous iron
What happens to ferrous iron during absorption?
It is oxidized to form ferric iron, which combines with apoferritin to form ferritin
What factors can increase iron absorption?
Vitamin C and gastric acid
How is iron transported in the plasma?
Bound to transferrin
Where is iron stored in the body?
Ferritin (or haemosiderin) in the bone marrow
How is iron excreted from the body?
Lost via the intestinal tract following desquamation
What is the typical volume of pancreatic secretions per 24 hours?
1000-1500ml
What is the distribution of iron in the body?
Total body iron 4g
70% in hemoglobin, 25% in ferritin and haemosiderin, 4% in myoglobin, and 0.1% in plasma iron
What is the pH of pancreatic secretions?
8
Which cells in the pancreas produce enzymes?
Acinar cells
Name some enzymes produced by acinar cells.
Trypsinogen, procarboxylase, amylase, elastase