Physiology 6 (easy) Flashcards
Secretion stimulated by water-deficit and inhibited by water excess
ADH
Dominant factor controlling thirst and vasopressin secretion
Hypothalamic osmoreceptors
(ADH release also affected by activation of left atrial stretch receptors but hypothalamic osmoreceptors = most important)
Atrial pressure and ADH release
Decreased atrial pressure INCREASES ADH release
What happens when stretch receptors are stimulated in the GI tract
Causes feed-forward inhibition of ADH
Nicotine and ADH?
Stimulates ADH release
Alcohol and ADH
inhibits ADH
How is salt imbalance manifested
Change in extracellular volume
Which organ produces angiotensin converting enzyme?
The lung
Where is K+ absorbed
Normally, ~90% of K+ is reabsorbed in the early regions of the nephron (mainly the proximal tubule)
When aldosterone is absent the rest is reabsorbed in the distal tubule (therefore, no K+ is excreted in the urine)
An increase in plasma K+ stimulates what?
Stimulates adrenal cortex = aldosterone
Aldosterone stimulates secretion of K+
What controls renin release from granular cells in the JGA?
Reduced pressure in afferent arteriole
More renin released, more Na+ reabsorbed, blood vol. increased, blood pressure restored.
Macula densa cells sense the amount of NaCl in the distal tubule
If NaCl reduced, more renin released, more Na+ reabsorbed
Increased sympathetic activity as a result of reduced arterial blood pressure
Granular (renin-secreting) cells directly innervated by sympathetic nervous system, causes renin release.
Where is ANP stored and when is it released?
- stored in atrial muscle cells
- released when they are strethced
- promote excretion of Na+ and diuresis to reduce plasma volume
Difference between water and osmotic diuresis
Any loss of solute in the urine must be accompanied by water loss (osmotic diuresis), but the reverse is not true; water diuresis is not necessarily accompanied by equivalent solute loss.
How is erythropoiesis regulated?
If O2 too low:
- kidney produces erythropoeitein
- this stimulates stem cells in bone marrow to produce more red blood cells
pH of arterial blood
7.45
