Respiratory System

Question 1

Lung Compliance

Answer 1

Elastic resistance of the lungs. Max compliance would be when you need the lease amount of airflow for min

Question 2

Tidal Volume Definition and normal value

Answer 2

Amount of air displaced in a normal breath. 500ml

Question 3

Vital Capacity def and normal value

Answer 3

Total lung capacity - residual volume. 5500ml

Question 4

Inspiratory and Expiratory reserve volume

Answer 4

Amount of air left in the lung after normal breath.

Question 5

Functional residual capacity

Answer 5

The total volume of air left in the lung after a normal expiration. 3500ml.

Question 6

Total Lung Capacity def and normal value

Answer 6

amount of air you can have in the lungs, 7300ml.

Question 7

Residual volume def and normal value

Answer 7

Amount of air left in the lungs after full expiration. 1800ml.

Question 8

Inspiratory capacity def and normal value

Answer 8

Total amount of air you can inspire after normal expiration. 3800ml.

Question 9

Volume of anatomic dead space

Answer 9

150ml

Question 10

Total ventilation per minute and alveolar ventilation.

Answer 10

Total: 7500 ml/min Alveolar: 5250 ml/min

Question 11

Pulmonary blood flow per minute.

Answer 11

5000 ml/min

Question 12

Factors affecting airway resistance

Answer 12

Airway diameter Obstruction (causing turbulence) Dynamic compression of airways Smooth Muscle Contraction

Question 13

Elastic and airway resistance

Answer 13

Elastic resistance: Resistance to the stretch of lung tissue and the air-liquid interface lining the alveoli. Airway Resistance: Resistance due to friction between layers of flowing air and between the air and the airway walls

Question 14

Restrictive vs Obstructive lung disease

Answer 14

In restrictive, it is difficult to breath in due to difficulty to expand the lungs. In obstructive, there is a blockage in the lung or increased airway resistance.

Question 15

Receptors in the Lung (4) and their role

Answer 15

Stretch Irritant Juxtapulmonary - detect pulmunary embolism, inflamation, oedemas Proprioreceptors - detects load in respiratory muscles.

Question 16

Hering Breuer reflex and deflation reflex

Answer 16

Hering Breuer: inflation inhibits inspiration Deflation reflex: deflation augments inspiration

Question 17

hypercapnia

Answer 17

excess CO2

Question 18

Hypoxia

Answer 18

Low O2

Question 19

Location of Central Chemoreceptors

Answer 19

Ventrolateral surface of medulla, exit of C9 and C10. In between cerebrospinal fluid and BBB.

Question 20

Normal Conc of CO2 and O2 in deoxygenated blood

Answer 20

CO2: 46mmHg O2: 40mmHg

Question 21

Normal conc of CO2 and O2 in oxygenated blood

Answer 21

CO2: 40mmHg O2: 100mmHg

Question 22

Shunt

Answer 22

Blocked airway -> no ventilation to those alveoli

Question 23

Dead space

Answer 23

Blocked vessel -> no blood going through system

Question 24

Dynamic compression

Answer 24

In forced expiration, when intrapleural pressure is larger than alveolar pressure so lung collapses into itself

Question 25

Effect of surfacant

Answer 25

Decreases surface tension (reduces the pressure difference needed to allow the lung to inflate. And hence increases compliance (volume change per unit of pressure) Also controls alveolar size: if the alveoli is too big, it will have less surfacant, so more surface tension and it will take more time to inflate than shorter alveoli. So it also keeps the rate of inflation constant over all alveoli.

Question 26

Role of alveolar type 1 and type 2 cells

Answer 26

Type 1 : form the alveoli air fluid interface Type 2 : produces surfactant and maintains cells.

Question 27

Inspiratory muscle obligate

Answer 27

Diaphragm Scalenes External intercostal Parasternal intercostal muscles

Question 28

Expiratory muscles

Answer 28

Internal intercostal muscle External and internal oblique muscles Rectum abdominis Transversus abdominis

Question 29

Components of surfactant

Answer 29

Phospholipids and surfactant proteins

Question 30

FEV1 vs FVC

Answer 30

FEV1: forced expiratory volume in 1 sec FVC: Forced vital capacity (total amount of air released)

Question 31

Effect of obstructive and restricitve lung disease on FEV1 and FVC

Answer 31

Question 32

Water vapour pressure in the lungs

Answer 32

6.3 kPa

Question 33

Difference between O2 and CO2 diffusing across air fluid interface

Answer 33

CO2 diffuses at 85% the rate of O2, CO2 is much more soluble than O2 so it equals out.

Question 34

Factors influencing diffusion of gases across interface

Answer 34

Membrane thickness and area.

Question 35

Max oxygen capacity of blood

Answer 35

300 ml/ L

Question 36

Why a right to left shunt is dangerous for oxygen partial pressure

Answer 36

Because a right to left shunt causes a decrease in O2 content which causes a large decrease in partial pressure.

Question 37

Explain why arterial PaCO2 is often normal or low with right to left shunts and VA/Q mismatching

Answer 37

In right to left shunt, increase in ventilation due to low O2 but this just further decreases CO2 content and does nothing about O2 because there is a shunt anyways.

Question 38

Define a shunt

Answer 38

Blood does not get ventilated

Question 39

Why is the pO2 in blood after ventilation not exactly equal to Avleolar pO2?

Answer 39

Because of natural left to right shunts

Question 40

Explain how hypoxic vasoconstriction helps reduce VA/Qmismatch

Answer 40

Vessels in areas of poor ventilation constrict, increasing the blood flow to better ventilated areas.

Question 41

List the causes of arterial hypoxia and explain how each is likely to affect arterial PaCO2.

Answer 41

Causes: Low inspired pO2 (e.g. altitude) Hypoventilating: causes low O2 and only one that causes high CO2 (e.g. overdose) Diffusion imparement: difficulty of gas exchange (e.g. pulmunary oedema) Right to left shunt (in lung or heart) Ventilation perfusion mismatch (e.g. emphysema) ALL others can blow off that pCO2 except hypoventilation

Question 42

Main CNS control of ventilation and location

Answer 42

Pre Botzinger complex (medulla)

Question 43

Main role of pons and medulla and what information they collect

Answer 43

Question 44

Effect of ventilation on increased CO2

Answer 44

Question 45

Effect of pH on ventilation

Answer 45

Acidosis: ventilation is much higher even at low doses of PCO2 Alkalosis: Ventilation is much lower even at high doses of pCO2

Question 46

Location of peripheral chemoreceptors

Answer 46

Aortic arch and biffurcation of common carotid artery

Question 47

Role of central chemoreceptors

Answer 47

Monitor CSF pH

Question 48

What is peripheral and central cyanosis

Answer 48

Peripheral cyanosis: reduced blood flow in a region leading to bleuish tint in periphery. Central cyanosis: hypoxaemia in arteries, so low oxygen overall

Question 49

3 ways carbon dioxide is transported in the blood

Answer 49

1. dissolved in the blood 2. carbamino compounds 3. In RBC by becoming bicarbonate aided by enxyme carbonic anhydrase. Bicarbonate leaves RBC and enters it again for reverse reaction at the lungs.

Question 50

Haldane effect

Answer 50

At any given pCO2, the amount of CO2 carried by blood will be higher because deox blood is more able to take CO2.

Question 51

How much CO2 is added to about 100ml of blood

Answer 51

4ml

Question 52

Answer 52

Question 53

Answer 53