Introduction and Anatomy

Question 1

Explain the functions of the respiratory system

Answer 1

Gas exchange
Acid base balance
Protection from infection (URT has lymphatic tissue which scans for pathogens and can initiate a response. Cilia and mucous prevent pathogens getting into LRT)
Communication via speech (air moves across vocal cords - learn to control on expiration as develop)

Question 2

Explain the importance of gas exchange

Answer 2

Cellular respiration: burn O2 to release energy and acquire CO2 (toxic waste product).

Question 3

Explain how the cardiovascular and respiratory systems are both involved in gas exchange

Answer 3

The respiratory system acquires O2 and removes CO2 via gas exchange.
The cardiovascular system transports oxygen to tissues from the lungs and transports CO2 away from tissues to the lungs.
This process is called external respiration.

Question 4

What is external respiration?

Answer 4

The movement of gases between the air and body cells

Question 5

Explain the process of external respiration

Answer 5

Gas exchange occurs in the lungs.
O2 moves from inspired air to the blood in the lungs
CO2 moves from the blood to air which is expired.
The pulmonary artery travels AWAY from the heart to the lungs and carries deoxygenated blood to the lungs containing CO2.
The pulmonary vein travels from the lungs TOWARDS the heart and carries oxygenated blood away from the lungs.
Oxygen is then taken around the body via systemic circulation.
Via systemic capillaries, O2 is taken up by cells and CO2 is removed from cells.

Question 6

Explain how the cardiovascular and respiratory systems are integrated in terms of increased energy demand by working muscle.

Answer 6

Increased energy demand by working muscle leads to: 
RESPIRATORY: 
Increased rate of depth of breathing
Substrate (O2) acquisition
Waste (CO2) disposal 

CARDIOVASCULAR:
Increased heart rate and contraction force
Substrate delivery to muscle via blood
Waste removal via blood

Question 7

In a steady state, how is the net volume of oxygen in the lungs exchanged per unit time proportional to to net volume exchanged in tissues?

Answer 7

Equal.

Same applies for CO2.

Question 8

Why is it important that in a steady state, the net volume of a specific gas exchanges per unit time is equal to the net volume exchanged in tissues?

Answer 8

Prevents build up of CO2 or O2 in circulation which would inhibit gas exchange.
Ensures demand = supply.

Question 9

State the average volumes of gas exchanged per minute.

Answer 9

250ml of oxygen is consumed

200ml of carbon dioxide is produced

Question 10

What is the average breathing rate at rest?

Answer 10

10-20 breaths per minute

Question 11

What is the breathing rate at maximum exercise in adults?

Answer 11

40-45 breaths per minute

Question 12

Describe the function of the mouth and nose.

Answer 12

Air enters the URT via the mouth and nose.
The nose has a bigger surface area to volume ratio than the mouth so air dries out less easily.
The nose starts off the process of making air SATURATED and MOIST (this is needed for gas exchange to occur). (This process id continued by the respiratory tree).
The nose also scans the air with lymphoid tissue and mucus and cilia prevent pathogens going further down the respiratory tree.

Question 13

Describe the function of the pharynx

Answer 13

Where air travels after the nose.

Pharynx is shared with GI tract

Question 14

Briefly describe the structure and function of the larynx

Answer 14

Contains vocal cords that vibrate to produce sound

Question 15

Describe the structure and function of the trachea

Answer 15

Transports air from larynx to bronchi.
Supported by incomplete rings of cartilage.
Bifurcates into bronchi at sternal notch.

Question 16

List the organs of the URT

Answer 16

Nasal cavity
Mouth
Pharynx
Layrnx

Question 17

List the organs of the LRT

Answer 17

Trachea
Bronchi
Lungs

Question 18

Describe the structure of the right lung in terms of lobes, fissures and secondary bronchi

Answer 18

3 LOBES: superior, middle and inferior
FISSURES: superior and middle lobes separated by horizontal fissure, middle and inferior lobes separated by oblique fissure
3 SECONDARY BRONCHI: one for each lobe

Question 19

Describe the structure of the left lung in terms of lobes, fissures and bronchi

Answer 19

2 LOBES - superior and inferior
FISSURES: lobes separated by horizontal fissure
2 SECONDARY BRONCHI

Question 20

Describe the difference in structure between the right and left bronchi and its clinical consequences

Answer 20

The RIGHT main bronchus is more vertical than the LEFT.

This means aspirated foreign bodies commonly lodge here

Question 21

Describe the branching of the respiratory tree

Answer 21

Trachea
2 primary bronchi (1 per lung)
Secondary bronchi (3 in right lung, 2 in left lung)
Bronchioles
Alveoli

Question 22

State how patency is maintained in the trachea

Answer 22

Potency maintained by C shaped rings of cartilage

Question 23

State how patency is maintained in the primary and secondary bronchioles

Answer 23

Cartilage rings

Question 24

State how patency is maintained in the bronchioles

Answer 24

Physical forces in the thorax

Question 25

State the function of the alveoli

Answer 25

Gas exchange

Question 26

After the trachea branches into bronchi, how many more times do the bronchi branch until the alveoli are reached?

Answer 26

22 times

Question 27

State the relationship between airway diameter and branching

Answer 27

As branching increases, airway diameter decreases.

Question 28

Describe the relationship between airway diameter and resistance to airflow

Answer 28

As diameter increases, resistance to airflow decreases.
HOWEVER, most resistance to airflow occurs in the UPPER airways because there are many bronchioles, meaning that the surface area of the bronchioles is much greater than that of the trachea. Therefore there is much more congestion of air in the trachea, as many small molecules are feeding into one large airway, whereas in the bronchioles, a few small molecules are feeding into many small airways.

Question 29

Describe the structure of alveoli

Answer 29

Alveoli are contained in lung lobules
Each alveoli is surrounded by elastic fibres and a capillary network
Thin walls
Macrophages (gather residual dirt and escape to pharynx or lymph nodes)

Question 30

Describe the two types of cells (pneumocytes) in alveoli

Answer 30

Type 1 cells:
gas exchange (always directed abutted to capillaries)
97% of alveolar surface
Simple squamous epithelium

Type 2 cells:
surfactant production

Question 31

Why do elastic fibres never separate an alveolus from its capillaries?

Answer 31

So there is no barrier for gas exchange

Question 32

Describe the function of the elastic fibres surrounding each alveolus.

Answer 32

When elastic fibres recoil, the alveoli contract. This is a passive process as no energy is needed since the energy has been invested in stretching the elastic on inspiration.

Question 33

Why can gas exchange no take place further up the respiratory tree?
What is this space called and what is its function?

Answer 33

The walls are too thick - only alveoli have thin enough walls.
The upper airways are referred to as the anatomical dead space. Function: air conduction only.

Question 34

List the components of the lining of the respiratory tract

Answer 34

Epithelium 
Glands 
Lymph nodes
NUTRITIVE blood vessels
Cilia 
Mucous producing goblet cells

Question 35

What happens to the epithelium as you move down the respiratory tree?

Answer 35

Becomes more squamous
Mucous cells lost (before cilia)
Cilia lost

Question 36

State where mucous is produced and its function.

Answer 36

Produced in sub epithelial glands and goblet cells.

Function: moistens air and traps particles, providing a large surface area for cilia to act on.