Response to Being Stranded

Question 1

What is the short term response to blood lose?

Answer 1

Baroreceptor reflex

Question 2

What is the medium term response to blood loss?

Answer 2

Anti-diuretic hormone, aldosterone and angiotensin 2 (promotes secretion of the previous two) are all involved in retaining water to increase blood volume

Question 3

What is the long term response to blood loss?

Answer 3

Erythropoetin stimulates bone marrow to produce red blood cells

Question 4

What is the problem with being at a higher altitude in terms of PO2?

Answer 4

The atmopsheric pressure of air is lower so therefore the partial pressure of oxygen in the arterial blood is lower

Question 5

Why would the respiratory rate increase at high altitude?

Answer 5

Activation of the peripheral chemoreceptors by hypoxic drive (oxygen receptors rather than carbon dioxide receptors are activated)

Question 6

Apart from in long term response to blood loss when else is erythropoetin secreted?

Answer 6

Due to chronic hypoxia at high altitude

Question 7

What happens to haemoglobin at high altitude?

Answer 7

Since PO2 is decreased the % of hb saturated with oxygen decreases as it is being released

Question 8

What causes the release of oxygen from Hb?

Answer 8

Increased secretion of 2-3 bisphosphoglycerate

Question 9

What secretes BPG?

Answer 9

Red blood cells produced it as a by product in metabolism

Question 10

At a given PO2 what % oxygen release do high levels of BPG cause?

Answer 10

10%

Question 11

What causes the increase in BPG levels in red blood cells at altitude?

Answer 11

Thyroid and growth hormones

Question 12

Why would an increase is BPG be beneficial at high altitude?

Answer 12

Increase O2 delivery to the tissues

Question 13

What is the long term response to injuries i.e. fractures

Answer 13

Secretion of cortisol

Question 14

What is cortisol?

Answer 14

A glucocorticoid that promotes glucose production, mutes the immune system and increases reponse to catecholamines and angotension II

Question 15

What are the initial responses to cold conditions?

Answer 15

Peripheral vasoconstriction to prevent blood cooling and shivering to make muscles generate heat

Question 16

What eventually happens after a long time of cold exposure?

Answer 16

Vasodilation when constriction is reduced

Question 17

What are the consequences of lack of protein due to starvation?

Answer 17

Breakdown of protein from the liver and skeletal muscles (spares the heart and brain)

Question 18

What are the consequences of lack of carbohydrates due to starvation

Answer 18

Gluconeogensis (converts protein to glucose) caused by glucagon

Question 19

What happens once carbohydrate stores have been depleted?

Answer 19

Fats are broken down into fatty acids and ketone bodies (starvation ketosis)

Question 20

What does lowered plasma glucose cause in times of starvation?

Answer 20

Glucagon secretion to promote glucose breakdown from protein and promotes fat breakdown

Question 21

Why is fat breakdown beneficial?

Answer 21

Produces keto acids to be used by the brain

Question 22

Why cant you drink salt water?

Answer 22

because it is so concentrated when you drink it it increases the osmolarity of the blood and draws blood out of the cells which shrinks them and cause mlafunction

Question 23

Why cant you drink large amounts of water?

Answer 23

Dilutes plasma electrolytes and water entering cells are the extracelluar water conc is higher than the intraceullar which results in cell swelling and in the brain leads to swelling and death

Question 24

Why are marathon runners particulary at risk when it comes to drinking too much water?

Answer 24

Cause they are already losing their plasma electrolytes through their sweat

Question 25

What is the problem with breathing air higher than normal atmospheric pressure?

Answer 25

Henrys law states more gas will be dissolved if the pressure is higher - if this is rapid bubbles can form in solution (decompression)

Question 26

What is the consequence of decompression bubbles?

Answer 26

Joint pain and if the CNS is affected cause lead to paralysis and death

Question 27

What type of people have the most problem with decompression sickness?

Answer 27

Divers when they are ascending back to the surface

Question 28

How would divers avoid decompression sickness?

Answer 28

Rising back up slowly with breaks and then going into a hyperbaric chamber

Question 29

What depth of water is twice atmospheric pressure?

Answer 29

10m deep

Question 30

What is another problem apart from decompression involved in breathing air under high pressure?

Answer 30

N2 Narcosis

Question 31

What is N2 Narcosis?

Answer 31

Nitrogen is an inert gas but at high pressures have anaesthetic effects

Question 32

How do deep sea divers get around n2 narcosis?

Answer 32

They use helium which is inert even at high pressure