Longer Term Physiological Response to a Challenge

Question 1

What’s the short term response of blood loss?

Answer 1

By the baroreceptor reflex

Question 2

What’s the medium term response to blood loss?

Answer 2

Restoration of circulating volume. Mediated by anti-diuretic hormone, aldosterone and angiotensin II

Question 3

What’s the long term response to blood loss?

Answer 3

Restoration of red blood cell mass. Mediated by erythropoietin (EPO)

Question 4

What is the baroreceptor response to haemorrhage?

Answer 4

Haemorrhage
Blood volume decreases
Blood pressure decreases
Baroreceptor activation decreases
Increased activation of sympathetic system
Increased cardiac contraction
Increased stroke volume
Increased heart rate
Arteriolar constriction
Increased TPR
Increased Cardiac Output
Increased blood pressure

Question 5

What is the restoration of red cell mass?

Answer 5

Hypoxia detected
(decrease O2, due to decrease RBC)
Increased EPO production
Stimulates erythropoiesis in bone marrow
Erythropoiesis (increase RBC)
Blood O2 level returned to normal, decreased EPO production

Question 6

What is Dalton’s Law?

Answer 6

The pressure of a gas mixture is the sum of the partial

pressures of the individual components of the gas mixture.

Question 7

Why does partial pressure of oxygen fall alongside?

Answer 7

As the proportion of oxygen is constant at 21%, as the

pressure falls so does the partial pressure of oxygen.

Question 8

What are the respiratory adaptations to altitude?

Answer 8

Increased respiratory rate and depth (carotid bodies)

Limited by pCO2 levels

Question 9

What are the blood adaptations to altitude?

Answer 9

Increased 2,3 BPG

Erythropoietin Production

Question 10

What are the three types of altitude sickness?

Answer 10

Acute Mountain Sickness
High Altitude Cerebral Oedema
High Altitude Pulmonary Oedema

Question 11

What are the symptoms of acute mountain sickness?

Answer 11

Headache, loss of appetite, nausea, vomiting, insomnia, dizziness,
fatigue.

Question 12

What are the symptoms of high altitude cerebral oedema?

Answer 12

Probably end-stage of acute mountain sickness.

May lead to coma, irreversible neurological damage or death.

Question 13

What are the symptoms of high altitude pulmonary oedema?

Answer 13

Fluid leaks from alveolar capillaries into the lung parenchyma
and alveoli.
Cough, shortness of breath, weakness.

Question 14

What are altitude sickness treatments?

Answer 14

All conditions improve with Immediate Descent
Oxygen
Medication
Specialised evacuation equipment

Question 15

What is the cold?

Answer 15

Behavioural – shelter under fuselage, extra clothing
Peripheral Vasoconstriction
Shivering
Secretion of adrenaline and thyroxine

Question 16

What are the symptoms of frostbite?

Answer 16

Caused by freezing of tissue
Ice-crystals form in ECF, or in cells themselves
Cell membranes may be punctured

Question 17

What happens when re heating after frostbite?

Answer 17

On re-warming, capillary damage leads leakage of fluid and
oedema
Red blood cells sludge in capillaries which leads to hypoxia in the tissues

Question 18

What are the symptoms of hypothermia?

Answer 18

Core body temperature < 35ºC
Mild hypothermia – intense shivering and confusion
Moderate hypothermia – drowsy, shivering stops
Paradoxical undressing – may be due to hypothalamic
dysfunction, or sudden vasodilation – vascular smooth muscle no longer able to constrict; blood diverts to
peripheries, so the person feels they are warm.

Question 19

What happens when diving, a high pressure problem?

Answer 19

In the same way that air
pressure decreases with
height, pressure at depth
increases due to the
weight of water pushing
down from above.
At 10m depth, the
pressure is 2 atmospheres
At 20m depth the
pressure is 3 atmospheres,
and so on.

Question 20

What’s Boyle’s Law?

Answer 20

Pressure x Volume = Constant

Question 21

What is Henry’s Law?

Answer 21

As pressure increases, the
solubility of a gas
increases

Question 22

What’s Henry’s Law in terms of diving?

Answer 22

The diver inhales air
under pressure( selfcontained,
underwater,
breathing apparatus –
SCUBA); the deeper the
dive, the more gas
dissolves in the
bloodstream.

Question 23

What is Nitrogen Narcosis?

Answer 23

Below about 30m depth
Due to effects of dissolved nitrogen in blood
Similar to alcohol intoxication
Risk of diver disregarding safety procedures
Resolves on moving to shallower depth.
Below 40m specialist equipment is used.