Respiratory System

Question 1

State the two key functions of the respiratory system

Answer 1

1. Allows gas exchange between the body and external environment
2. Oxygen is taken in and transported to cells, while carbon dioxide is removed

Question 2

State the three levels of gas exchange in the lungs and their components (structure and function)

Answer 2

1. Cell level - Gas exchange occurs by diffusion across alveolar and capillary endothelial cells
2. Tissue Level - The alveolar-capillary network consists of thin, one cell-thick walls that allow for efficient diffusion of gases
3. Organ Level - The lungs provide a large surface area for gas exchange, facilitated by their branching structure and elastic properties

Question 3

How does breathing (ventilation) maintain efficient gas exchange?

Answer 3

The diaphragm and intercostal muscles create pressure changes to draw are in and expel it

Question 4

How does blood flow maintain efficient gas exchange?

Answer 4

Capillaries surrounding alveoli rapidly transport oxygenated blood to the body and return deoxygenated blood for gas exchange

Question 5

How does the alveolar structure maintain efficient gas exchange?

Answer 5

The alveoli have a large surface area, thin walls, and a moist lining, which maximises the rate of diffusion of gases

Question 6

Name 4 characteristics that increase gas exchange

Answer 6

1. Very thin walls (one cell thick alveoli and capillaries)
2. Moist
3. Rich blood supply
4. Large surface area

Question 7

What parts of the respiratory system have a mucous lining?

Answer 7

The nasal cavity + upper airways

Question 8

What cells create the mucous and where are these cells found?

Answer 8

Goblet cells (secrete a clear, sticky mucous). These goblet cells are found on the epithelial lining of the airways.

Question 9

What is the purpose of mucous?

Answer 9

To trap dirt particles and microbes before they enter the lungs.

Question 10

Where does air enter and leave from the body?

Answer 10

Nose/Mouth

Question 11

What does the nose do to air as it enters the body?

Answer 11

Cleans, warms and moistens before entering the body

Question 12

Where is lysozyme found?

Answer 12

The nasal secretions contain an anti-bacterial enzyme – lysozyme

Question 13

State in order, the structure of the Bronchial Tree

Answer 13

1. Larynx
2. Trachea
3. Bronchus
4. Bronchiole
5. Alveoli

Question 14

Describe the physical characteristics of the Larnyx

Answer 14

A box-like structure constructed from nine cartilages + is the entrance to the trachea + lungs

Question 15

What is the entrance to the Larynx protected by?

Answer 15

The eppiglotis

Question 16

What does the Larnyx house?

Answer 16

The vocal chords (or vocal folds)

Question 17

What are the trachea and bronchi reinforced with?

Answer 17

With C-shaped rings of cartilage (these prevent the tubes from collapsing during inhalation)

Question 18

What are the upper airways lined with?

Answer 18

Ciliated mucous membrane

Question 19

What does the Cilia do?

Answer 19

Sweep up the dirty mucous up the trachea + into the throat

Question 20

Where do the Bronchioles terminate?

Answer 20

The bronchioles terminate in microscopic clusters of air sacs - the alveoli

Question 21

What takes place in the alveoli?

Answer 21

Gas exchange

Question 22

What is breathing?

Answer 22

Breathing (sometimes referred to as ventilation) is the process of moving air into and out of the lungs

Question 23

What is the purpose of breathing?

Answer 23

The purpose of breathing is to exchange oxygen and carbon dioxide between the lungs and the air

Question 24

What characteristics make the Alveoli a good place for gas exchange?

Answer 24

Like all exchange surfaces, the alveoli:
-are very thin
-have a large surface area
-are moist
-have a rich blood supply

Question 25

State the sequence for inhalation:

Answer 25

1. Diaphragm contracts and flattens ○ The diaphragm is a dome-shaped muscle at the base of the lungs. ○ When it contracts, it flattens downward. 2. Intercostal muscles contract ○ The external intercostal muscles (between the ribs) contract. ○ This causes the rib cage to move upward and outward. 3. Thoracic cavity volume increases ○ The movement of the diaphragm and ribs enlarges the thoracic cavity. ○ This increase in volume reduces the pressure inside the thoracic cavity (also called intrathoracic or intrapulmonary pressure). 4. Air pressure in lungs becomes lower than atmospheric pressure ○ Because pressure inside the lungs is now lower than the air outside the body, a pressure gradient is created. 5. Air flows into the lungs ○ Air moves into the lungs from the outside to equalize the pressure. It enters through the nose/mouth → trachea → bronchi → bronchioles → alveoli.

Question 26

What is the pleura and what is its function?

Answer 26

a membrane that covers the surface of the lungs and lines the inside of the chest, containing a thin layer of pleural fluid between its layers that holds the lungs against the chest wall and allows them to slide along the wall during breathing

Question 27

Why does air flow into the lungs during inhalation?

Answer 27

The contraction of the diaphragm and external intercostal muscles increases the volume of the chest cavity, which expands the lungs and causes the air pressure inside them to be lower than the atmospheric pressure, causing air to rush in (from high to low pressure)

Question 28

Why does air flow out of the lungs during exhalation?

Answer 28

Because the diaphragm and external intercostal muscles relax, which reduces the volume of the chest cavity and lungs, making the air presure in the lungs greater than the atmospheric pressure, pushing air from high to low pressure (out)

Question 29

Why does oxygen diffuse into the blood at the alveoli?

Answer 29

The concentration of oxygen is higher in the alveoli than in the blood, causing oxygen to diffuse into the blood, this concentration gradient is maintained by constant blood flow and the movement of air into and out of the alveoli

Question 30

Why does carbon dioxide diffuse out of the blood at the alveoli?

Answer 30

The concentration of carbon dioxide is higher in the blood than in the alveoli, causing it to diffuse out into the air, this concentration gradient is maintained by constant blood flow and the movement of air into and out of the alveoli

Question 31

How does emphysema affect gas exchange?

Answer 31

causing the alveoli to lose their elasticity and break down, which reduces the internal surface area of the lung and makes ventilation difficult, thereby impairing the efficient transfer of oxygen into and carbon dioxide out of the blood (caused by long-term exposure to tobacco smoke and pollutants)

Question 32

What is lung cancer and how does it affect the lungs?

Answer 32

-uncontrolled division of cells, leading to the development of a mass, or tumour, typically beginning in the walls of the air passages, usually the bronchi -causing irritation of the mucous membrane -results in excessive mucus production, leading to trapped mucus and the rupture of alveoli -reducing the internal surface area for gas exchange and making ventilation difficult

Question 33

How do infections like pneumonia and tuberculosis affect gas exchange?

Answer 33

-causes inflammation and secretions of fluid and mucus into the alveoli -reduces the amount of air they can contain and decreases the internal surface area available for gas exchange, making breathing difficult

Question 34

How does asthma affect the airways?

Answer 34

causes the smooth muscles to contract, inflammation to thicken the lining, and mucus to fill the air passages, all of which narrow the airways and lead to difficulty breathing

Question 35

How does Cystic fibrosis affect gas exchange?

Answer 35

causes the production of excessive, thick mucus primarily in the lungs, which reduces the amount of air alveoli can contain and decreases the internal surface area available for gas exchange, making breathing difficult

Question 36

How does Lou Gehrig’s disease (motor neurone disease) affect breathing?

Answer 36

causes paralysis of the diaphragm, which prevents the lungs from expanding and thus impairs ventilation

Question 37

State the order by which air enters the body to the blood

Answer 37

1. Nose/Mouth 2. Pharynx 3. Larynx 4. Trachea 3. Bronchi (c-shaped cartilage rings, smooth muscle) 4. Bronchioles (smooth muscle) 5. Alveoli