PSC1002/L14 Respiratory System

Question 1

Give two functions of the respiratory system.

Answer 1

Exchange of gases
Regulation of body pH
Protection from inhaled pathogens and irritants
Vocalisation

Question 2

Which lung is divided into 3 lobes rather than 2?

Answer 2

Right lung

Question 3

What are the conducting systems comprised of? (2)

Answer 3

Upper respiratory tract - nasal cavity, pharynx, larynx
Lower respiratory tract - trachea, bronchi, bronchioles

Question 4

What is the respiratory zone comprised of?

Answer 4

Alveoli and capillary supply

Question 5

Give 3 functions of the nose and nasal cavity.

Answer 5

Warm and humidify air
Filter debris
Secrete antibacterial substances
Houses olfactory receptors
Enhances resonance of voice

Question 6

Give 3 functions of the pharynx.

Answer 6

Warm, humidify and filter air
Prevent food entering respiratory tract
Protects against mechanical stress

Question 7

Give 2 functions of the larynx.

Answer 7

Prevents food and liquid entering respiratory tract (epiglottis)
Sound protection

Question 8

How many secondary and tertiary bronchi are there?

Answer 8

5 secondary
18 tertiary

Question 9

What are goblet cells?

Answer 9

Mucus-secreting cells that form a continuous layer over surface of respiratory tract

Question 10

What are ciliated cells?

Answer 10

Cells that produce saline and sweep mucus upwards to pharynx

Question 11

What does the mucociliary escalator do?

Answer 11

Removes noxious particles from lungs

Question 12

Describe the saline secretion pathway in airway epithelial cells. (4)

Answer 12

NKCC brings Cl- into epithelial cells from ECF
Apical anion channels, including CFTR, allow Cl- to enter lumen
Na+ goes from ECF into lumen by paracellular pathway drawn by ECG
NaCl movement from ECF creates concentration gradient so water follows into lumen

Question 13

What structures keep the trachea open?

Answer 13

C-shaped cartilage rings

Question 14

What is the function of the posterior smooth muscle of the trachea?

Answer 14

Allows expansion of oesophagus during swallowing

Question 15

What 3 main histological changes occur as bronchi divide and get smaller?

Answer 15

Cartilage changes to complete and fewer rings
Epithelium changes to columnar cells
Amount of smooth muscle increases

Question 16

Describe the structure of a bronchiole. (3)

Answer 16

Non-ciliated epithelium
Smooth muscle layer
No cartilage

Question 17

Describe the structure of alveoli. (3)

Answer 17

Single epithelial cell layer
Supported by elastic fibres
Large SA for gas exchange

Question 18

Describe type I alveolar cells. (3)

Answer 18

90% of alveolar cells
Very thin
Gas exchange occurs

Question 19

Describe type II alveolar cells. (3)

Answer 19

Smaller
Thicker
Produce surfactant

Question 20

What is the function of macrophages with regards to alveoli?

Answer 20

Protect alveolar structures from non-filtered, small particles

Question 21

Briefly describe quiet breathing.

Answer 21

Inhalation - active contraction of diaphragm
Exhalation - passive relaxation of diaphragm

Question 22

Which muscles contract to raise the ribcage upwards and outwards? (2)

Answer 22

External intercostal muscles
Scalenes

Question 23

Define Boyle’s Law.

Answer 23

As volume of the contained increases, the pressure that the gas exerts on the container decreases

Question 24

Define atmospheric pressure.

Answer 24

Pull of gravity on air around us creates atmospheric pressure

Question 25

Describe intrapulmonary pressure. (3)

Answer 25

Air pressure within alveoli Rises and falls with inspiration and expiration Always eventually equalises with atmospheric pressure

Question 26

Define intrapleural pressure. (3)

Answer 26

Pressure found within pleural cavity Rises and falls with inspiration and expiration Does not equalise with atmospheric pressure

Question 27

What are pleural sacs? (2)

Answer 27

Two membranes of elastic connective tissue and capillaries Surrounds each lung

Question 28

What is pleural fluid? (3)

Answer 28

Very thin film of fluid within cavity Acts as lubricant to allow lung to move within thorax Maintains lung inflation at rest

Question 29

Describe the structure of the pleural sacs. (2)

Answer 29

Parietal pleura - outer layer fused to rib cage, diaphragm and other structures At hilium, parietal pleura turns over to create visceral pleura continuous with lung surface

Question 30

Why is intrapleural pressure less than atmospheric pressure?

Answer 30

The lungs and chest wall pull away from each other (elastic recoil)