Thermoregulation

Question 1

Define SIADH

Answer 1

Syndrome of inappropriate anti-diuretic hormone secretion

Question 2

Describe what changes to extracellular fluid concentration and volume during exercise-induced dehydration?

Answer 2

Increase in osmolality (concentration) in ECF.

Limited change in volume as fluid moves from the ICF to ECF.

Question 3

What are normal sodium and potassium concentrations in intracellular and extracellular fluid?

Answer 3

ECF sodium = 135-145 mol/L
ECF potassium = 4.5-5.5 mmol/L
ICF sodium = 5 mmol/L
ICF potassium = 150-170 mmol/L

Question 4

Does a higher sweat loss rate increase or decrease sweat sodium concentration, and why?

Answer 4

• increase
• sodium reabsorbed in sweat gland duct
• higher sweat loss rate, less transit time for sodium reabsorption