Low oxygen environments Flashcards
What are the conditions of deep-sea hydrothermal vents?
High pressure
outflow temp 350degrees celsius
ambient water 2degrees
some oxygen diffuses down
HYDROGEN SULPHIDE used as energy source by bacteria - chemosynthesis
some animals feed on bacteria - symbiotic relationships
DOMINATED BY ANNELID + POGONOPHORAN TUBEWORMS, BIVALVE MOLLUSCS + CRUSTACEA
SHORT LIVED
What are the adaptations of the pogonophoran tubeworm (Rifta pachyptila)?
internal bacteria for nutrition, supplying bacteria with sulphide, oxygen and carbon dioxide
no gut or mouth
tolerates anoxia for up to 60h
3 different high affinity heamoglobins
top half may be oxic, lower half anoxic
Upper region passes H2S down to bacteria, they use it and pass nutrients up
Describe the ability of Weddell seals in diving
dive up to 75 minutes
diving mammals store lots of O2 in blood
weddell seals have ability to store lots of O2 in tissues
can store around 4x more O2 per kg than human
70% in blood - 4x more heamoglobin
Spleanic contraction - allows more blood pumped into circulation - more heamoglobin in circulation
muscles loaded with MYOglobin- darker colour
anaerobic respiration, altered circulation - decreased flow to muscles, normal to vital organs
What is the problem of pressure?
sperm whales routinely dive to 400m = 40 atmospheres pressure
gasses subjected to such pressures tend to dissolve in blood
more nitrogen dissolves in blood causing nitrogen necrosis
How do diving mammals overcome this?
Lungs collapse within 100m of surface - alveolar collapse prevents gas exchange into blood, so no nitrogen can diffuse into blood
many ribs not attached to sternum for collapse
Lungs have elastic fibres - allows compression and re-expansion
What do native highlanders have in the way of adaptations?
Blood has higher affinity for O2 more readily at lungs
Larger lung volume (barrel chest)
Increased Heamoglobin
natives have tolerance to low CO2 (tolerance to hypocapnia)
what are the unaccustomed responses to altitude in term of ventilation of the lungs?
increase in ventilation (hyperventilation)
decrease in PCO2
Alkalosis (due to loss of CO2)
what adaptions do native highlanders have in terms of lung ventilation?
adjustment of HCO2 levels
can tolerate low CO2
increased ventilation sustained
what happens in acclimatized lowlanders in diffusion from lung air to blood?
hypoxia stimulates increased number of pulmonary capillaries to create a larger diffusion gradient
increased pulmonary circulation blood pressures via pulmonary resistance increase
What adaptations do native highlanders have in diffusion from lung air to blood?
larger lung volumes (barrel chest)
blood has higher affinity for O2 (left shift in oxygen dissociation curve of blood, picks up O2 more readily at lungs
what do native highlanders have in way of transport of oxygen in blood?
higher affinity for O2, left shift, picks up O2 more readily
relative number of blood cells is the same
