Resp. Physiology

Question 1

4 main functions of the respiratory system

Answer 1

Gas exchange, acid base balance, protection from infection via goblet cells and lymphoid tissues, and communication via speech

Question 2

Oxygen is required for:

Answer 2

aerobic respiration, produce CO2 as a waste product

Question 3

Deoxygenated blood:

Answer 3

returns to heart via the venous system, goes through right side of the heart through pulmonary artery

Question 4

Pulmonary circulation

Answer 4

takes blood form heart to lungs

Question 5

Pulmonary veins

Answer 5

carry oxygenated blood from lungs to the heart

Question 6

In a steady state, what is the net volume of gas exchanged in the lungs per unit time

Answer 6

250ml/min O2

200ml/min CO2

Question 7

What is:
normal respiration rate
max respiration rate

Answer 7

12-18

40-45

Question 8

How many lobes does:
right lung have
left lung have

Answer 8

3

2

Question 9

Describe the respiratory tree

Answer 9

Trachea - which bifurcates at sternal angle into
2 primary bronchi (left and right)
Primary bronchi then split twice on the left and thrice on the right (supplying each lobe) giving rise to secondary bronchi
Secondary bronchi keep dividing till they become bronchioles
Bronchioles end in alveoli
Alveoli - site of gas exchange

Question 10

Name structures of the upper respiratory tract

Answer 10

Nasal cavity
Tongue
Pharynx 
Vocal cords
oesophagus 
Larynx

Question 11

Name structures of the lower respiratory tract

Answer 11

Trachea
Right lung, right bronchus
Left lung, left bronchus
Diaphragm

Question 12

What is the clinical significance of the right bronchus

Answer 12

Slightly more vertical trajectory - aspirated foreign bodies get commonly lodged into right bronchus

Question 13

What maintains the patency of the airway in primary, secondary and tertiary bronchi

Answer 13

C-shaped cartilage

Question 14

What maintains the patency of bronchioles

Answer 14

physical force in thorax

Question 15

Bronchial smooth muscle activity…

Answer 15

…can affect airway diameter, thus resistance to airflow

Question 16

Contraction of bronchial smooth muscle

Answer 16

decreases diameter and increases resistance

Question 17

Relaxation of bronchial smooth muscle

Answer 17

increases diameter, decreases resistance

Question 18

Which type of cells make up the bulk of the alveoli?

Answer 18

Type 1 cells

Question 19

Which cell types produces surfactant

Answer 19

Type 2 cells

Question 20

What are 3 functions of mucous?

Answer 20

Moistens air
Traps particles
Provides large S.A for cilia to act on

Question 21

What are the functions of elastic fibres?

Answer 21

They cover surface of alveoli, allowing them to stretch during inspiration and use elastic energy to recoil during expiration

Question 22

What is Boyle’s law?

Answer 22

Pressure exerted by a gas is inversely proportional to its volume

Question 23

What kind of muscle is the diaphragm?

Answer 23

Skeletal muscle - it separates thoracic cavity from abdominal cavity

Question 24

Name the layers of the pleura and what they line

Answer 24

Visceral pleura - attached to outer surface of lungs
Parietal pleura - attached to the inner surface of thoracic cavity

both are continuous with one another
thin layer of intrapleural fluid is found between the two layers

Question 25

Name 2 functions of pleural fluid

Answer 25

1. Allows membranes to slide across each other (providing frictionless movement)
2. Holds membranes together i.e. provides cohesive force. This holds the lungs against the ribs and the diaphragm

Question 26

What is pleurisy?

Answer 26

Inflammation of pleura

Question 27

Gasses always move..

Answer 27

from high pressure to low pressure

Question 28

Muscles of inspiration:

Answer 28

External intercostal muscles
Diaphragm
Sternocleidomastoid
Scalenes

Question 29

Muscles of expiration

Answer 29

Passive process but in severe respiratory load use internal intercostal muscles and abdominal muscles

Question 30

Describe mechanics of breathing in relation to diaphragm, volume and pressure

Answer 30

Diaphragm contracts and flattens increasing the dimensions of the thoracic cavity superiorly and inferiorly
This decreases pressure - air moves in from high pressure to low pressure
Breathing out - diaphragm relaxes - decreasing thoracic volume

Question 31

What is the function of intercostal muscles in relation to breathing? What do they act on?

Answer 31

Act on ribs and sternum
elevate ribs, increasing lateral dimensions of thoracic cavity thus increasing volume and decreasing pressure
increase anterior/posterior dimensions

Question 32

Asthma

Answer 32

Increased resistance due to over-reactive constriction of bronchial smooth muscle
Mainly affect expiration

Question 33

What is intra-thoracic alveolar pressure? P(A)

Answer 33

Pressure inside lungs

Can be positive or negative compared to atmospheric pressure

Question 34

What is intra-pleural pressure? P(ip)

Answer 34

Pressure inside pleural cavity - always negative (in healthy lungs)

Question 35

What is trans-pulmonary pressure? P(T)

Answer 35

Difference between alveolar and intra-pleural pressure

Always positive

Question 36

What are the P(A) pressure changes during normal breathing cycle:

1. No air movement
2. Inspiration
3. Expiration

Answer 36

1. P(A) = 0 (same as atmospheric pressure)
2. P(A) = negative
   3, P(A) = postive

Question 37

How does intra-pleural pressure change in breathing cycle?

Answer 37

Always negative
More negative during inspiration
Less negative during expiration