Physiology

Question 1

What is respiration controlled by?

Answer 1

Resp centre in the medulla oblongata, and the carotid bodies situated at the carotid bifrucations

Question 2

What does the medullary centre do?

Answer 2

Senses any change in CO2 concentration in the cerebrospinal fluid, and modifies respiration by nervous stimulation of respiration muscles and the diaphragm

Question 3

What do the carotid bodies do?

Answer 3

monitor partial pressure of O2 in the blood, and then stimulate the resp centre through the glossopharyngeal nerves

Question 4

In response to what can carotid bodies become hyper plastic?

Answer 4

chronic arterial hyperaemia e.g. in high-altitude dwellers, pulmonary emphysema, diffuse pulmonary fibrosis

Question 5

How is air drawn into the lungs?

Answer 5

By contraction of the diaphragm and intercostal muscles, creating a -ve intrapleural pressure

Question 6

How is air expelled from the lungs?

Answer 6

When D and IC relax, due to the action of gravity and elasticity in the lung connective tissue

Question 7

What is lung compliance?

Answer 7

The stiffness of the lungs, a measure of the change in volume per uni change in pressure - therefore a measure of compressibility. e.g. in pulmonary fibrosis lungs can’t be easily compressed so compliance is decreased

Question 8

What is dead space?

Answer 8

The proportion of inspired air not involved with gas exchange