Physiology 1 (Week 1) COPY

Question 1

What is internal respiration?

Answer 1

The intracellular mechanisms which consume O2 and produce CO2

Question 2

What is external respiration?

Answer 2

The sequence of events involved in gas exchange of O2 and CO2 between the external environment and body cells

Question 3

Describe the four stages of external respiration.

Answer 3

Ventilation - gas exchange between atmosphere and air sacs in the lungs
Gas exchange between alveoli and blood
Transport of gases between lungs and tissue
Exchange of gases between blood and tissue

Question 4

Explain Boyle’s Law.

Answer 4

At a constant temperature, the pressure exerted by a gas is inversely proportional to the gas volume

Question 5

Air flows down a ______ gradient.

Answer 5

pressure

Question 6

During inspiration, the intra-alveolar pressure is ___ ___atmospheric pressure.

Answer 6

less than

Question 7

Why do the thorax and lungs expand during inspiration?

Answer 7

Contraction of inspiratory muscles

Question 8

Name two forces which hold the thoracic wall and the lungs together.

Answer 8

1. Intrapleural fluid cohesiveness (water molecules attracted to one another)
2. Negative intrapleural pressure (transmural pressure gradient - lungs forced to expand, chest forced to squeeze inwards)

Question 9

Name three pressures important in preventing lung collapse.

Answer 9

1. Atmospheric pressure
2. Intra-alveolar pressure
   3, Intrapleural pressure

Question 10

Inspiration is an ____ process.

Answer 10

active

Question 11

What does inspiration depend on?

Answer 11

Muscle contraction

Question 12

What is the major inspiratory muscle?

Answer 12

The diaphragm

Question 13

When the diaphragm contracts, ____ volume increases vertically.

Answer 13

thorax , vertically

Question 14

Which muscles are responsible for lifting the ribs and moving the sternum anteriorly during inspiration?

Answer 14

External intercostal muscles

Question 15

How does an expansion of the lungs help during inspiration?

Answer 15

Expansion of the lungs –> greater lung volume –> decrease in intra-alveolar pressure by Boyle’s Law –> air travels into the alveoli down the pressure gradient

Question 16

Expiration is a ____ process.

Answer 16

passive

Question 17

What brings about expiration?

Answer 17

Relaxation of inspiratory muscles

Question 18

What name is given to the size reduction of the lungs and chest wall ‘back to normal’?

Answer 18

Recoil

Question 19

Recoil causes the intra-alveolar pressure to ____.

Answer 19

increase

Question 20

Why does recoil cause an increase in intra-alveolar pressure?

Answer 20

Decrease in volume –> Increase in pressure (Boyle’s Law)

Question 21

During expiration, air leaves the lungs ___ the pressure gradient.

Answer 21

down

Question 22

What is a pneumothorax?

Answer 22

Air in the pleural space

Question 23

Name a possible cause of a pneumothorax.

Answer 23

Disease

Stab wound

Question 24

A pneumothorax abolishes the ____ pressure gradient.

Answer 24

transmural

Question 25

What is a common consequence of a pneumothorax?

Answer 25

Lung collapse

Question 26

Why do the lungs recoil during expiration?

Answer 26

1. Elastic connective tissue in the lungs

2. Alveolar surface tension

Question 27

What is alveolar surface tension?

Answer 27

Attraction between water molecules at the air-liquid interface of an alveolus

Question 28

Alveolar surface tension produces a force which ____ the stretching of the lungs.

Answer 28

resists

Question 29

Why aren’t alveoli lined with water alone?

Answer 29

Surface tension would be too strong –> alveolar collapse

Question 30

Explain LaPlace’s Law.

Answer 30

Smaller alveoli have a greater tendency to collapse

Question 31

What is pulmonary surfactant?

Answer 31

A mixture of lipids and proteins which lines the alveoli.

Question 32

What type of alveoli secrete pulmonary surfactant?

Answer 32

Type II

Question 33

Pulmonary surfactant ___ alveolar surface tension.

Answer 33

lowers

Question 34

When do developing fetal lungs synthesise pulmonary surfactant?

Answer 34

Late in pregnancy

Question 35

Name the syndrome in which premature babies do not have enough pulmonary surfactant.

Answer 35

Respiratory distress syndrome of the newborn

Question 36

How would you tell a newborn had respiratory distress syndrome?

Answer 36

Strenuous inspiratory efforts

Question 37

A newborn with respiratory distress syndrome struggles to overcome ____ ____ ___ ___ and inflate their lungs.

Answer 37

high alveolar surface tension

Question 38

Explain alveolar interdependence.

Answer 38

If an alveolus starts to collapse, the surrounding alveoli STRETCH and then RECOIL to expand and open the collapsing alveolus.

Question 39

Name three forces which keep alveoli open.

Answer 39

1. Transmural pressure gradient
2. Pulmonary surfactant
3. Alveolar interdependence

Question 40

Name two forces which promote alveolar collapse.

Answer 40

1. Elasticity of connective tissue

2. Alveolar surface tension