respi phys

Question 1

what is tidal volume?

Answer 1

volume of air inhaled/exhaled during quiet breathing

Question 2

what is forced expiratory volume (FEV1)?

Answer 2

amount of air expired in the first 1s

Question 3

what is forced vital capacity?

Answer 3

maximum volume of air exhaled after maximal inspiration

Question 4

what are the factors affecting ventilation?

Answer 4

1. area of lungs available for diffusion
2. thickness of alveoli epithelium
3. diffusion constant of gas
4. partial pressures of gas
5. V/Q matching

Question 5

what are the 4 variables in Fick’s Law?

Answer 5

1. area of lungs available for diffusion
2. thickness of alveoli epithelium
3. diffusion constant (solubility) of gas
4. partial pressures of gas

Question 6

how is O2 transported in the blood?

Answer 6

1. reversibly bound to haemoglobin (MAIN)
2. dissolved in plasma

Question 7

how will an increase in pH affect the O2/Hb dissociation curve?

Answer 7

shift left
increase pH –> decreased [H+] –> less O2 offloaded –> increased O2 affinity

Question 8

how will an increase in 2-3,DPG affect the O2/Hb dissociation curve?

Answer 8

shift right

Question 9

how will CO affect the O2/Hb dissociation curve?

Answer 9

shift left

Question 10

how is CO2 transported in the blood?

Answer 10

1. as bicarbonate ions in plasma
2. bound to Hb
3. dissolved in plasma

Question 11

Does the ventral respiratory group (VRG) or dorsal respiratory group (DRG) modulate rhythm?

Answer 11

DRG

Question 12

how does the pneumotaxic centre of the pons regulate ventilation?

Answer 12

inhibits inspiration

Question 13

how does the apneustic centre of the pons regulate ventilation?

Answer 13

stimulates inspiration

Question 14

Does the ventral respiratory group (VRG) or dorsal respiratory group (DRG) generate rhythm?

Answer 14

VRG

Question 15

what is the hering breuer reflex?

Answer 15

stretch receptors stimulated by lung expansion –> send inhibitory inputs to medulla to prevent overinflation of lungs

Question 16

where are central chemoreceptors located at?

Answer 16

medulla of brain

Question 17

where are peripheral chemoreceptors located at?

Answer 17

carotid bodies and aortic arch

Question 18

what changes to PCO2, PO2 and [H+] do peripheral chemoreceptors respond to?

Answer 18

1. increase pCO2 (respiratory acidosis)
2. decrease pO2 (hypoxia)
3. increase [H+] (metabolic acidosis)

Question 19

what is the haldane effect?

Answer 19

Hb has higher affinity for CO2 when not oxygenated

Question 20

what is dead space?

Answer 20

inhaled air does not get to gas exchanging areas

Question 21

A group of 15‐year‐old boys are having a competition to see how long they can hold their breath.
They find that they can hold their breath longer if they hyperventilate before each attempt.

What is the explanation for this phenomenon?

A. They load extra oxygen which reduces their respiratory drive.
B. They open previously non‐functioning alveoli.
C. There is a reflex fall in metabolic rate that reduces O2 consumption.
D. They lower arterial PCO2 which reduces their respiratory drive.
E. It decreases their blood pH which reduces their respiratory drive.

Answer 21

D. They lower arterial PCO2 which reduces their respiratory drive.