Flashcards in Longer Term Physiological Response to a Challenge Deck (23):
What's the short term response of blood loss?
By the baroreceptor reflex
What's the medium term response to blood loss?
Restoration of circulating volume. Mediated by anti-diuretic hormone, aldosterone and angiotensin II
What's the long term response to blood loss?
Restoration of red blood cell mass. Mediated by erythropoietin (EPO)
What is the baroreceptor response to haemorrhage?
Blood volume decreases
Blood pressure decreases
Baroreceptor activation decreases
Increased activation of sympathetic system
Increased cardiac contraction
Increased stroke volume
Increased heart rate
Increased Cardiac Output
Increased blood pressure
What is the restoration of red cell mass?
(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
What is Dalton's Law?
The pressure of a gas mixture is the sum of the partial
pressures of the individual components of the gas mixture.
Why does partial pressure of oxygen fall alongside?
As the proportion of oxygen is constant at 21%, as the
pressure falls so does the partial pressure of oxygen.
What are the respiratory adaptations to altitude?
Increased respiratory rate and depth (carotid bodies)
Limited by pCO2 levels
What are the blood adaptations to altitude?
Increased 2,3 BPG
What are the three types of altitude sickness?
Acute Mountain Sickness
High Altitude Cerebral Oedema
High Altitude Pulmonary Oedema
What are the symptoms of acute mountain sickness?
Headache, loss of appetite, nausea, vomiting, insomnia, dizziness,
What are the symptoms of high altitude cerebral oedema?
Probably end-stage of acute mountain sickness.
May lead to coma, irreversible neurological damage or death.
What are the symptoms of high altitude pulmonary oedema?
Fluid leaks from alveolar capillaries into the lung parenchyma
Cough, shortness of breath, weakness.
What are altitude sickness treatments?
All conditions improve with Immediate Descent
Specialised evacuation equipment
What is the cold?
Behavioural – shelter under fuselage, extra clothing
Secretion of adrenaline and thyroxine
What are the symptoms of frostbite?
Caused by freezing of tissue
Ice-crystals form in ECF, or in cells themselves
Cell membranes may be punctured
What happens when re heating after frostbite?
On re-warming, capillary damage leads leakage of fluid and
Red blood cells sludge in capillaries which leads to hypoxia in the tissues
What are the symptoms of hypothermia?
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.
What happens when diving, a high pressure problem?
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.
What's Boyle's Law?
Pressure x Volume = Constant
What is Henry's Law?
As pressure increases, the
solubility of a gas
What's Henry's Law in terms of diving?
The diver inhales air
under pressure( selfcontained,
breathing apparatus –
SCUBA); the deeper the
dive, the more gas
dissolves in the