K6 - Control of Body-fluid volume and Osmolarity Flashcards
what does antidiuretic mean?
decrease urinary production and output
what is produced by the hypothalamus and stored in the posterior pituitary gland?
ADH
what controls the release of ADH from the pituitary into the blood?
hypothalamus
what stimulates ADH secretion?
water-deficit (dehydrated)
what inhibits ADH Secretion?
water- excess
what Effect does ADH have on water permeability of distal tubule and collecting duct
Increases permeability of luminal membrane to H2O by inserting new
water channels
what are the symptoms of the diabetes insipidus?
- large volumes of dilute urine
- constant thirst
what is the treatment for diabetes insipidus?
ADH replacement
What is the most important stimulus for ADH release?
Hypothalamic osmoreceptors
what also effects ADH release?
activation of left atrial stretch receptors
What does decreased atrial pressure do in terms of ADH release?
increases ADH release
what effect does nicotine have on ADH release?
stimulates it
What effect does alcohol have on ADH release?
inhibits it
What does a increase in osmolarity do to thirst?
increase thirst
What does an increase in ADH do to plasma volume?
increase
What is important for long term regulation of blood pressure?
Regulation of extracellular fluid volume
What is the amount of Na+ filtered regulated by?
regulation of GFR
what does Na excreted equal?
Na filtered - Na reabsorbed
what regulates the amount of Na reabsorbed?
renin-angiotensin-aldosterone system
where is the Steroid hormone secreted by the adrenal cortex?
aldosterone
when is aldosterone secreted?
- In response to rising [K+] or falling [Na+] in the blood
2. activation of the renin-angiotensin system
what does aldosterone do?
Stimulates Na+ reabsorption and K+ secretion
what % of K+ is reabsorbed in the early regions of the nephron
90%
what directly stimulates adrenal cortex?
increase in [K+]plasma
in terms of K+ what does aldosterone stimulate?
secretion of K+
What does a decrease in plasma [Na+] promote?
promotes the indirect secretion of aldosterone by means of the juxtaglomerular apparatus
Explain the control of renin release from the granular cells in 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.
What part of the kidney is renin released from?
granular cells
what do Abnormal increases in R-A-A system cause?
hypertension
What do ACE inhibitors do?
stop fluid & salt retention and arteriolar constriction
what hormone is produced by the heart and stored in the atrial smooth muscle cells?
Atrial natriuretic peptide (ANP)
what causes the release of ANP?
when atrial smooth muscle cells are mechanically stretched due to an increase in the circulating plasma volume
how does ANP decrease plasma volume?
ANP promotes excretion of Na+ and diuresis
