mark wrote:
Quote:
5. The carotid bodies:
a. have a smaller blood supply per gram than the brain
b. are more influenced by oxygen tension than by oxygen content
c. are stimulated by a fall in pH
d. are stimulated by a fall in their blood flow
e. contain baroreceptors
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a F b T c T d T e F
The carotid bodies are situated above the bifurcation of the carotid artery. Together with the aortic bodies they act as peripheral chemoreceptors and are imprortant in the regulation fo breathing. They have the highest blood flow per 100g tissue in the body (total blood flow 0.05ml/min, equivanet to 2l/100g tissue/min cf brain 750ml/min, 50mln/100g/min). Because of such a high blood supply dissolved oxygen is enough to provide their oxygen requirements. Hencs they are sensitive to reduced oxygen delivery (either reduced oxygen tension or reduced cardiac output) or impaired utilisation of oxygen (cyanide posioning).Rate of discharge increases when paO2 falls below 13.3Kpa. They are not sensitive to reduced O2 content eg reduced oxygen carrying capacity in anaemia and CO posioning. They are sensitive to reduced arterial pH or increased paCO2.
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