Longer Term Physiological Response to a Challenge Flashcards
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?
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
What is the restoration of red cell mass?
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
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
Erythropoietin Production
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,
fatigue.
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
and alveoli.
Cough, shortness of breath, weakness.
What are altitude sickness treatments?
All conditions improve with Immediate Descent
Oxygen
Medication
Specialised evacuation equipment
What is the cold?
Behavioural – shelter under fuselage, extra clothing
Peripheral Vasoconstriction
Shivering
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
oedema
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
increases
What’s Henry’s Law in terms of diving?
The diver inhales air under pressure( selfcontained, underwater, breathing apparatus – SCUBA); the deeper the dive, the more gas dissolves in the bloodstream.
What is Nitrogen Narcosis?
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.
