ATC Water Physiology 2

Question 1

What happens to central blood volume when a person is immersed to the neck in water?

Accepted Answer

It increases by about 700 mL

Answer

Hydrostatic pressure pushes peripheral blood toward the thorax, raising central blood volume by roughly 700 mL.

Question 2

Which hormone's release is suppressed during neck-deep immersion, contributing to diuresis?

Accepted Answer

Antidiuretic hormone (ADH)

Answer

Increased central blood volume suppresses ADH (and renin/aldosterone), increasing urine output.

Question 3

Compared with land, resting heart rate during thermoneutral neck-deep immersion typically:

Accepted Answer

Decreases slightly

Answer

Increased stroke volume from greater venous return lets heart rate fall slightly at rest.

Question 4

Approximately how much does stroke volume increase with immersion to the neck?

Accepted Answer

25-35%

Answer

Stroke volume rises roughly 25-35% due to higher preload from hydrostatic pressure.

Question 5

Which statement about vital capacity during chest-deep immersion is correct?

Accepted Answer

It decreases roughly 6-12%

Answer

Hydrostatic pressure on the chest wall and increased thoracic blood volume reduce vital capacity.

ATC - Aquatic Therapy Certification Practice Test