Na_H20 Balance

Question 1

ANP functions

Answer 1

increases Na and H2O excretion 
increases FGR (via afferent VD and efferent VC
inhibits Na reabs in CD
inhibits renin 
inhibits ald
systemic VD
inhibit ADH

Question 2

Urodilatin

Answer 2

secreted by DCT and CD in response to increased arterial pressure and ECF volume

decrease Na reabs and H20 reabs in CD

NO systemic effects

Question 3

PGE2

Answer 3

increases GFR via dilation
Decrease na reabs in the TAL and CD

net= increased Na excretion

Question 4

AVP release

Answer 4

2 major stimuli:

1) Hyperosmolarity
2) Volume depletion

osmoreceptors are the most important

Question 5

Osmoregulation

Answer 5

Plasma Osm is sensed by hypothalamic osmoreceptors

• –>ADH and thirst
• –>affects urin Osm and water intake

Question 6

Volume regulation

Answer 6

adequate tissue perfusion is sensed (ECV) by the macula densa, afferent arterioles, atria, and carotid sinus

• –>RAAS, ANP, NE, ADH
• –>Urinary Na, Thirst

Question 7

Atonic (flaccid neuropathic) bladder

Answer 7

caused by destruction of sensory inputs from bladder to sacral cords (DM, crush, syphilis, MS)

no more stretch information —>overflow incontinence—>distends muscle, becomes thin walled

Question 8

denvervated hypertrophic areflexic bladder

Answer 8

destruction of afferent and efferent fibers
no sensory or stimulatory/ inhibitory signals

contractions cease–>bladder becomes flaccid and distended initially, but later the muscle develops spontaneous and uncoordinated activity, muscles become hypertrophic

Question 9

automatic spacitc neuropathic bladder

Answer 9

severing of the spinal cord above sacral micturition center—>no more communication to CNS—>no more SNS inhibitory outflow—>acutely there is flaccid bladder due to lack of micturition reflex, later on there is exaggerated micturition reflex with frequent voiding

Question 10

Uninhibited neurogenic bladder autonomic dysreflexia

Answer 10

caused by destruction of the tracts carrying the inhibitory SNS outputs

micturition center is continually stimulated
–>continual voiding with detrusor hypertrophy and reduced bladder capacity

Question 11

UTI

Answer 11

bladder and urethral irritation from the infection

uninhibited contraction of detrusor muscle with facilitation of the micturition reflex

increase urinary frequency and urgency and leak

Question 12

dilutional hyponatremia

Answer 12

Retention of fluid (or exs fluid intake) dilutes plasma concentration of Na decreases (absolute Na stays the same)

can cause brain to swell

Question 13

Pseudo hyponatremia

Answer 13

artifact of other problem that causes blood values to seem hyponatremic, but Na conc is really unchanged

hyponatremia with low serum Osm

high osmolar gap

hyperlipidemia, hyperproteinemia, hypercholesterolemia,

Question 14

The three causes of hyponatremia

Answer 14

1) CHF (due to increased renin, NE, ADH—>retention of water)
2) SIADH
3) Reset omostat

Question 15

causes of hypernatremia

Answer 15

1) Increased water loss (fever, sweat, central or nephrogenic DI, osmotic diuresis, diarrhea)
2) hypertonic NaCl or NaCO3- admin

Question 16

Sympathetic innervation to bladder

Answer 16

T10-12
Pass thru hypogastric plexus
contract internal sphincter
relax detrusor

Question 17

PSNS innervation to the bladder

Answer 17

S2-4
pass thru the pelvic splanchnic n.
contract detrusor
relax internal sphincter

Question 18

Somatic innervation to the bladder

Answer 18

S2-4
travel with pudendal n.
contract external sphincter

Question 19

innervation to the ureter

Answer 19

PSNS increases the peristaltic contractions in the ureter

SNS decrease this