week 12- environmental sickness

Question 1

boyles law

Answer 1

Boyle’s law states that the volume of gas is oppositely proportional to pressure, given temperature is constant. As such, if gas pressure is doubled, gas volume would be halved.

Question 2

Henry’s law

Answer 2

The amount of gas that dissolves at a certain temperature is the same as the partial pressure of gas in contact with liquid.
Henry’s law states that the quantity of gas that dissolves into a liquid at a given temperature is directly proportional to the partial pressure of gas in contact with the liquid. This explains how inert (chemically inactive) gas is taken up when breathing at depth, and therefore is important in the understanding of decompression sickness and nitrogen narcosis.

Question 3

decompression sickness

Answer 3

Decompression sickness occurs when divers surface too quickly after being at depth. Nitrogen bubbles form in the blood stream; however, the mechanism of formation is unknown. The bubbles may form either directly in tissues, or in the circulatory system (typically, the low-pressure venous circulation). They are thought to obstruct flow directly, leading to ischaemia. Additionally, air-blood and air-endothelial interfaces initiate inflammatory & thrombotic processes, altering the permeability of endothelium. This may result in third-spacing of fluid.

Question 4

type 1 decompression sickness

Answer 4

. Type 1 is a “pain only” decompression sickness, involving joints, extremities & skin. The pain is described as deep pain, unrelieved & unchanged with movement. Poorly localised/difficult-to-describe back or abdominal pain may indicate signs of spinal cord involvement. The pain is thought to be caused by bubbles creating distention in ligaments or fascia, bubbles at the ends of long bones

Question 5

type 2 decompression sickness

Answer 5

Type 2 involves the CNS (mainly spinal cord in divers), vestibular symptoms (“staggers”), & cardiopulmonary symptoms (“chokes”).