Respiratory System Under Stress Flashcards
How do divers hold their breath for 20 min after flooding their body with oxygen for 20 minutes?
Inducing the diving reflex, cold water on the face and bradycardia slow heart rate and redirecting blood to the brain and essential organs and away from the peripheral tissues etc
What are your body’s response to free diving?
Apnea, hypertension, bradycardia, splenic contraction
What causes the bends (decompression sickness)?
For every 10 m that you go under, pressure increases by 1 atm. A lot of air in your lungs, nitrogen (other gases too) dissolves under pressure and goes into the blood. Like a soda water bottle (under pressure with cap on CO2 is in solution, as soon as you reduce the pressure to atmosphere, it comes out of solution). Causes bubbles which causes nerve problems, embolism, etc.
What are adverse effects of barotrauma?
Blurred vision, retinal detachments, ruptured eardrums, collapsed lungs and then ruptured lungs from barotrauma during ascent, the bends, drowning
What are sperm whale non-resp. adaptations so that they can dive for 2 hrs exceeding 2300 m?
No effects from the bends or rapid ascent from the depths.
Peripheral tissue metabolism down to conserve O2; CV adaptations O2 directed to brain, more circulating O2 less in lungs; splenic contraction to release RBCs, more RBCs in blood; high blood to body ratio
* highly compressible lungs & thorax, FRC 10% of TLC, lung anatomy enables the expulsion of air out of gas exchange regions under immense pressure, inc. haemoglobin myoglobin??
What happens with resp. at high altitude?
Low pO2 (even though still 21% of atmosphere), 21% less pressure at altitude, inspired oxygen (760 mm Hg= 1 atm), as increase altitude atm. pressure drops- inspired oxygen drops, causes pulmonary vasoconstriction (part of V/Q mismatch thing), to try and get more oxygen in animals and humans try to hyperventilate, but you're blowing off CO2, no CO2 drive to stimulate breathing, so you get severe respiratory alkalosis, dizziness, etc. Blunted respiratory drive- adaptations to altitude leads to blunted resp. drive * Whale bronchioles have cartilage and bigger mass of smooth muscle.
What are resp. issues at high altitude?
Pulmonary oedema (vasoconstriction, low levels of oxygen at high altitudes, so you get pulmonary hypertension- increase BP in pulmonary circulation, causes fluid to leak out of blood vessels- increases diffusion between alveolar and blood), cerebral oedema (increased cerebral pressure), cor pulmonale (heart problems caused by vasoconstriction in the lungs; right side of the heart has to pump out at high pressures- lung is vasoconstricted due to hypoxaemia- right side of the heart has to push against high pressure bed)
What is Brisket Disease?
High mountain disease in cattle; common in angus cattle. Hypoxic vasoconstriction stimulated by hypobaric hypoxia leads to pulmonary hypertension- a reflection of the usual physiologic means to achieve V/Q mismatching.
Hypertensive vascular remodelling, cor pulmonale and cardiac failure.
Heart has marked right ventricular hypertrophy and dilation; the cardiac apex is displaced to the left making the enlarged heart appear round.
Bar-headed geese
Birds can tolerate arterial pCO2 of < 10 mm Hg caused by hyperventilation.
Adaptations- skeletal and cardiac muscles better supplied with O2, more homogenous capillary spacing, higher proportion of mitochondria, more oxidative fibres than water fowl, Hb more efficient O2 loading (more affinity for O2 (Hb that is) than normal birds), larger lungs, hyperventilate in response to severe hypoxia
Why? Fly over the Himalayas for better feed (from India)
What happens in an elite horse athlete with inspiration, HR, PCV, pO2, pCO2?
Huge differential. pO2 rest 95%/ exercise 55%; pCO2 rest 42%/exercise 52%. pO2 goes way down in the blood in horses. Problem.
Why do horses become hypoxaemic in exercise?
V/Q mistmatch, diffusion limitation (HR went up to 240- blood is going through the lungs so quickly, the RBC don’t have time to get the oxygen because it takes time to diffuse through the barrier- so doesn’t get completely oxygenated- O2 doesn’t bind with Hb), R-L shunt (bronchiole circulation- goes to resp. tissues not involved in gas exchange- dilute the blood out a bit- using up the oxygen- put it back in the pulmonary veins that go back to the heart)
Diffusion limitation is the major factor that causes hypoxaemia in an exercising horse
