Exam 3: Salt/water Balance Flashcards
Osmolarity of ECF is monitored/adjusted by
Regulating water excretion in kidney in response to ADH
Major electrolyte in ECF
Na+
Renal mechanisms of Na+ balance
RAAS
Atrial natriuretic peptide
ADH contributes ___ to volume regulation
Directly
**Trumps osmolarity
Virtually all Na+ reabsorption in kidney is due to
Passive Na+ reabsorption following gradient
Active Na+ removal due to ATPase
Na+ coupled transport also reabsorbs
Glucose
AA
Phosphate
HCO3
(Water follows)
H2O is impermeable across
Ascending loop of Henle
Hormones that regulate NaCl/H2O
Antidiuretic hormone
RAAS
ANP
ADH AKA
Vasopressin
ADH signals kidney to
Conserve H2O
ADH is released when
Plasma osmolarity inc
Plasma volume dec 10-15%
Osmole receptors are very sensitive and ___% inc can stim ADH release
1-2%
Blood volume changes are sensed by _____ receptors
High and low pressure receptors
Response to ___ volume is an emergency response
Dec
ADH is a powerful vaso____ which targets
Constrictor; arteriolar smooth muscle (V1 receptor)
ADH via V2 receptor causes
Insertion of aquaporins
Aquaporins are H2O channels that
Make collecting duct permeable to H2O
Osmole receptors are found in
Circumventricular organs
- organum vasculosum
- subfonical organ
Axons from circumventricular organs project to ADH producing cells in
Hypothalamic supraoptin and paraventricular nuclei
Most potent osmolyte
NaCl
Dehydration and ADH
Inc osmolarity and dec volume stimulate ADH
Dec osmolarity and small dec in volume
Osmolarity kept constant
Dec osmolarity and LARGE dec in volume
Osmolarity sacrificed to maintain integrity of ciruclation
Diabetes insipidis
Large amounts of dilute urine
Central diabetes insipidis
Dec ADH production
Low circulating ADH
Nephrogenic diabetes insipidis
Dec response of kidney to ADH
Circulating ADH levels high
Syndrome of inappropriate ADH
Inc ADH secretion even if plasma osmolarity low
Syndrome of inappropriate ADH death occurs when
Profound dilution of plasma electrolytes
ADH cell bodies found in
Supraoptic nuclei
Oxytocin cell bodies found in
Paraventricular nuclei
ADH and oxytocin are secreted from nerve terminals in
Posterior pituitary
Supraoptic nuclei can make both
Oxytocin and ADH
ADH acts on principal cells in last ___ to inc H2O reabsorption, thus ___ body fluid osmolarity
DCT; dec (back to normal)
V2 receptor for ADH elicits response via
cAMP
CAMP causes insertion of aquaporin 2 which ____ the urine
Concentrates
V1 receptor is coupled to
Phospholipase C
Net result of ADH w/ V1 receptor
Contraction of vascular SM
Constrict arterioles
Inc TPR