ch4 respiratory system

Question 1

4 parts of the respiratory system

Answer 1

• Nose
• Trachea/windpipe
• Bronchi
• Lungs

Question 2

Nose structure

Answer 2

• The lining of the nasal cavity is convoluted and lined with mucous membranes.
• As the air passes over the membranes it is warmed and humidified.
• There are also hairs and mucus lining the nose.
• These trap debris, preventing it from reaching the lungs.

Question 3

Define:

Pharynx

Answer 3

The region from the nasal cavity to the top of the trachea and oesophagus. Air travels through it before being diverted into the trachea by the epiglottis.

Question 4

Epiglottis

Answer 4

A flap of elastic cartilage in the pharynx.
- During inhalation, the epiglottis covers the oesophagus, guiding the air into the trachea.
- When swallowing, the epiglottis covers the larynx, preventing food from entering it.

Question 5

Define:

Larynx

Answer 5

A cartilage structure joining the pharynx and trachea. It contains the vocal chords.

Question 6

Define:

Vocal chords

Answer 6

Mucous membranes that are able to vibrate as air passes over them.

Question 7

Function of:

Trachea

Answer 7

Carries air into and out of the lungs.

Question 8

Trachea structure

Answer 8

Made up of C-shaped cartilage rings that hold the structure open.
- This ensures that air can always pass through it.
- At its base, it splits into two branches.
- One branch takes air into one lung.
- The epithelial lining of the trachea produces mucus, which traps dust and debris, preventing it from entering the lungs.
- The cilia that also line the trachea can move in a wave-like motion to take mucus and debris up to the pharynx so that it can be swallowed and digested.

Question 9

Describe:

Bronchi

Answer 9

• At the end of the trachea, the structure splits into two primary bronchi - one for each lung.
• These then split further into secondary bronchi which take the air into each lobe of the lung.
• The secondary bronchi continue to divide, forming tertiary bronchi.

Question 10

Bronchi structure and function

Answer 10

• C-shaped cartilage rings. As the bronchi get smaller, the cartilage is more stretched out, and muscle and elastin form more of the structure.
• Cilia and mucus work together to trap and move dust and other particles from the airways.

Question 11

Define

Bronchioles

Answer 11

Tiny branches of air tubes in the lungs.

Question 12

Why don’t bronchioles contain cartilage?

Answer 12

This allows bronchioles to control the flow of air in the lungs, expanding when the body needs more oxygen.

Question 13

Bronchioles structure

Answer 13

• When the tertiary bronchi divide, they form smaller airways called bronchioles.
• These continue to split out until they end in millions of terminal bronchioles.
• They do not contain cartilage
• Cilia and mucus are also present in the bronchioles, protecting the lungs from contaminants.

Question 14

Lungs

Answer 14

• The two lungs take up the whole of the chest cavity, except for the space between them.
• Each lung is divided into lobes.Left lung: two lobesRight lung: three lobes

Between these two layers of pleura, there is a thin layer of pleural fluid, which holds the lungs against the inside of the chest wall and allows them to slide along the wall when breathing.

Question 15

Pleura

Answer 15

Membrane that covers the surface of the lungs and also lines the inside of the chest.

Question 16

Mediastinum

Answer 16

The space between the two lungs, occupied by the heart and blood vessels.

Question 17

Visceral pleura

Answer 17

Covers the surface of the lungs.

Question 18

Parietal pleura

Answer 18

Lines the inside of the chest.

Question 19

Alveoli

Answer 19

Tiny air sacs at the end of bronchioles. They are the functional units of the lungs.

Question 20

Alveoli structure

Answer 20

• Folded to increase surface area to volume ratio.
• Wall is one cell thick: distance over which the gases travel is less - shorter diffusion distance.
• Highly vascularised: for greater exchange surface.
• Moist: increases diffusion rate (although oxygen and carbon dioxide are not that soluble).
• Both the blood (moving) and ventilation allows maintenance of concentration gradient for efficient gas exchange.

Question 21

Alveoli function

Answer 21

This is where gases move between the blood in the capillaries and the air in the alveoli.
Alveoli are the surface of gaseous exchange, allowing a net flow of oxygen to pass from the airways into the blood, and carbon dioxide to pass from the blood into the airways.

Question 22

Define and describe:

Breathing/ventilation

Answer 22

• The process by which air is moved into and out of the lungs.
• Air moves from places of higher pressure to places of lower pressure, therefore air flows into and out of the lungs due to differences in air pressure.
• The diaphragm and intercostal muscles work together to change the volume and therefore the pressure of the lungs, resulting in airflow into or out of the lungs.

Question 23

Define and describe:

Inspiration

Answer 23

• The process of taking air into the lungs.
• For air to flow into the lungs, the pressure of the air in the lungs must be less than the atmospheric pressure outside the body.
• Therefore, to breathe we must decrease the pressure in the lungs.
• Increase volume of lungs = decrease pressure of lungs

Question 24

How is the volume of the lungs increased?

Answer 24

1. Diaphragm muscles contract and diaphragm lowers/becomes flatter.
2. External intercostal muscles contract and ribcage moves up and out
3. This increases the volume of the chest cavity.
4. As the pleura adheres to the internal wall of the chest cavity, the lungs expand with the expanding chest cavity.
5. Lungs expand = increased lung volume.
6. Increased lung volume = air pressure inside the lungs is lower than the pressure outside the body.
7. Air flows in through the nose and trachea until the pressure becomes equal.

Question 25

Define and describe:

Expiration

Answer 25

The process of air leaving the lungs. Decreasing the volume of the lungs.

Question 26

How is the volume of the lungs decreased?

Answer 26

1. Diaphragm mucles relax and diaphragm moves up/returns to its dome shape
2. External intercostal muscles relax and ribcage moves down and in under its own weight.
3. This reduces the volume of the chest cavity.
4. And thus the volume of the lungs.
5. Decreased lung volume = air pressure in the lungs is greater than the pressure outside the body.
6. Air flows out through the trachea and nose until the pressures are equal.