Day 2 5/13/15

Question 1

Normal [Na] in ECF

Answer 1

135-145 mM

Question 2

Adding Na to the ECF causes a ________ in the ECF volume.

Answer 2

• increase
• due to the two-fold greater volume of the cellular over the ECF compartment, gains (or losses) of sodium from the ECF result in two-fold greater changes in ECF volume than they do in ECF sodium concentration

Question 3

Feedback Loop for Na Regulation via Aldosterone

ECF Na loss causes:

Answer 3

• shift of ECF water to cells
• dec. ECF volume
• dec. MAP
• inc. baroreceptor reflexes
• inc. renin
• AgII
• inc. aldosterone synthesis/secretion in adrenal cortex
• inc. Na reabsorption in distal tubule and collecting duct
• addition of ingested Na to ECF

Question 4

Water Regulation ADH Feedback Loop

Severe sweating causes:

Answer 4

• dec. ECF volume, dec in L atrial filling pressure, inc. in baroreceptor reflex to hypothalamus
• inc. ECF osmolarity, inc. activation of hypothalamic osmoreceptors
• both pathways above:
• inc. activation of ADH sythesizing neurons
• inc. secretion of ADH from posterior pituitary
• inc. water reabsorption in late distal tubule and collecting duct
• add ingested water to ECF

Question 5

Sweat is:

Answer 5

hypotonic

Question 6

Volume vs Osmolarity: Healthy Pt

Answer 6

• for normal osmolarity, changes in ECF volume have little effect on ADH levels
• ECF water regulation is primarily an osmoregulatory system with an emergency low-volume override.

Question 7

Volume vs Osmolarity: Sick Pt

Answer 7

• when ECF volume falls severely, changes in osmolarity have large effect on ADH levels
• ECF water regulation is primarily an osmoregulatory system with an emergency low-volume override.

Question 8

Atrial Natriuretic Factor

Answer 8

• present in atrial cardiocytes
• granular contents are released upon inc. in ECF volume
• leads to inc. in urine produciton
• targets include: ADH block, dec. ADH secretion, dec. renin release, block of aldosterone

Question 9

Inc. ECF Volume Results in:

Answer 9

• inc. distension of atria
• relsease of ANP (atrial natriuretic peptide) granule contents from atrial cardiocytes
• active ANP reaches targets throughout body, which aid in inc. production of urine