Body Water

Front 1

1. What are the two drivers of thirst?
2. Which is also termed dehydration thirst
3. Which is also termed EC depletion thirst

Back 1

1. Osmotic and volume
2. Osmotic
3. volume

Front 2

1. Withhold H2O -> ^ Posm -> thirst -> H2O intake -> Posm drosps ot normal - descrip of?
2. ↓ ECF or ↓ BV with no change in Posm → thirst. description of?

Back 2

1. Osmotic thirst
2. Volume thirst

Front 3

1. Which thirst type is most sensitive?
2. Posm that thirst begins at?
3. Mech of this type of thirst?

Back 3

1. Osmotic thirst
2. 290-295 mOsm/L, 2% increase from 286
3. ^ Posm exerts a hypertonic effect and decreases ICF volume of the brain cells that elicit thirst

Front 4

1. Where are receptors of osmotic thirst located?
2. effect of injection of hyperosmotic solution in this area?
3. Effect of destruction of this area?

Back 4

1. hypothalamus, near those that control ADH release
2. Thirst - a hypotonic soln does not illicit thirst
3. no thirst ever

Front 5

1. Type of thirst that has a high threshold, less sensitive, requires a 10% or more decrease in volume
2. controlof this type of thirst?

Back 5

1. Volume thirst, explains why blood donors are not thirsty
2. Control is through volume receptors which keep thirst tonically inhibited; thirst will result when there is decreased stimulation of the receptors

Front 6

1. Where are low pressure thirst receptors?
2. High pressure thirst receptors?
3. What is a dipsogen?

Back 6

1. atria nd large v in thorax; ↓ BV → ↓ inhibitory signals to brain → thirst
2. Aortic arch and carotid sinuses; ↓ BV → ↓ arterial pressure → ↓ inhibitory signals to brain → thirst
3. Agent that produces thirst

Front 7

1. 3 things that ^ renin release?
2. Is response to osmotic thirst greater in conditions of hypo or hypervolemia?

Back 7

1. renal baroreceptor of the afferent arteriole; NaCl sensor of the macula densa of the DCT; direct stim via renal symp. n.
2. Hypovolemia

Front 8

1. Water output is controlled by what hormone (produced where?)
2. How does it increase water output?
3. 2 mech that control ADH secretion?

Back 8

1. ADH, vasopressing in the posterior pituitary
2. increase the water permeability of the collecting duct which increases renal H2O reabsorption
3. Osmotic and volume (same idea as prev.)

Front 9

Osmotic control response for ADH Release:
1. If pOSM ^?
2. If pOSM decreases
3. receptors controlling osmotic release of ADH are located where?

Back 9

1. ADH ^
2. ADH decreases
3. supraoptic and paraventricular nuclei of the hypothalamus prob in response to change in cell size i.e. hypertonic injection, cell shrinks ^ thirst

Front 10

1. 2 major factors that control ECF Na+ [ ]
2. What is the most sensitive control for ADH release?

ADH is really sensitive in a hypovolemic state, less sensitive in a hypervolemic state

Back 10

1. Thirst and ADH; since 90% of osmolarity of ECF is due to Na+ salts; [Na] is adjusted w/ solvent rather than changing the amount of solute
2. Osmotic control; 1% or less change in Posm will lead to a change in ADH secretion if pOSM>280

Front 11

1. threshold for ADH release?
2. Posm [ ] at which ADH has its maximal effect on the renal tubule?
3. Does thirst or ADH secretion occur first?
3 e.g. of a cooperative control system

Back 11

1. 280, below this, no ADH is released
2. 295 Posm, or 5 pg/mL of ADH, gives max urine [ ]
3. ADH secretion will max out b4 you become extremely thirsty (involuntary first then voluntary)

Front 12

1. effect of ↓ BV and/or ↓ BP on ADH?
2. % decrease in BV to increase ADH release?
3. Effect of ADH on body after it is already maximally concentrating urine?

Back 12

1. ^ ADH secretion
2. 10%
3. a potent vasoconstrictor hence alternate name vasopressin

Front 13

ADH can be secreted in response to nausea, stress, nicotine
Secretion is decreased by ethanol, swallowing

Back 13

...

Front 14

1. Condition charac. by a high flow of dilute urine and thirst due to complete or partial failure of ADH secretion or failure of kidney to respond to ADH
2. 3 types of 1?

Back 14

1. Diabetes insipidus
2. Psychogenic, hypothalamic, nephrogenic

Front 15

1. A thirst disorder due to CNS trauma or psych. factors (Schizo), person always thirsty, low pOSM
2. most common type, defect in ADH secretory mech due to CNS trauma or tumor, low or no ADH
3. no defect in ADH secretion but renal tubule is not responsive to ADH

Back 15

1. Psychogenic, person drinks so much they shut off ADH
2. Hypothalamic or central
3. Neprhogenic - inheritied or due to renal disease or drug therapy, ADH is normal or high

Front 16

1. increasins Posm would cause a response in which types of DI?
2. injection of ADH would cause a response in which types of DI?
3. If no response to ^ Posm and response to ADH injection which DI is it?

Back 16

1. only the psychogenic, by withholding H2O or ^ hypertonic NaCl
2. Psychogenic and hypothalamic but not nephrogenic
3. Central/hypothalamic

Front 17

SIADH syndromes:
1. ADH leak - continual leakage of ADH into plasma due to hypothalamic oversecretion or ectopic
2. Rand. secretion - rdm not linked to osmotic or volume factors; due to CNS problems or ectopic

Back 17

3. Reset osmoreceptor ctrl - ADH regulated around too low a Posm b/c threshold is decreased; due to hypovolemia, malnutrition pregnancy, 1st 2 mo
4. Increased renal sensitivity to ADH - drug induced or direct renal tubular problem (nephrogenic Syndrome of inappropriate antidiuresis)