Lungs - A1

Question 1

What is the path that air takes when travelling to the lungs?

Answer 1

Air travels down the trachea -> bronchi -> bronchioles -> alveoli

Question 2

What does the trachea have that provides structure and support?

Answer 2

The trachea has rings of cartilage which help to prevent the trachea from collapsing in on itself.

Question 3

What are the alveolus and what is their purpose?

Answer 3

The alveolus are mini air sacs that are used as a gas exchange surface.

Question 4

What are the alveolus lined with?

Answer 4

The alveolus are lined with epithelium (outermost layer) which are one cell thick.

Question 5

What are endothelium cells?

Answer 5

Line the inside of a cell.

Question 6

What are the alveolus covered in?

Answer 6

A network of capillaries.

Question 7

Approximately how many alveoli are in each lung and what is the benefit of this?

Answer 7

There are approx. 350 million in each lung and they provide a large surface area for gas exchange.

Question 8

What is the trachea?

Answer 8

A wide tube that carries air to the bronchus.

Question 9

What is the effect of cartilage on the trachea?

Answer 9

There are about 20 rings of hard cartilage that keep the air passage open due to pressure changes. The rings are C-shaped, separated by muscle and elastic tissue. The soft tissue allows the trachea to be flexible and to stretch.

Question 10

What are the bronchus?

Answer 10

The bronchus(2 bronchioles) are the first branch off the trachea and allows passage of air into the bronchioles.

Question 11

What else do the bronchus have that is similar to the trachea?

Answer 11

They also have cartilage in their walls to keep them open.

Question 12

What are the bronchioles?

Answer 12

They’re smaller branches of the bronchus and end in clusters of alveoli. The smaller bronchioles have only muscle and elastic fibres so that they can contract and relax easily during ventilation.

Question 13

What type of cells need the most ATP?

Answer 13

Active muscle cells, cells producing useful substances(e.g. hormones or enzymes) and brain cells.

Question 14

What does ventilation consist of?

Answer 14

• inspiration and expiration
  -Controlled movements of the diaphragm, internal and external intercostal muscles

Question 15

What is the thoracic cavity?

Answer 15

The area where the lungs sit.

Question 16

Describe the process of inspiration.

Answer 16

• The diaphragm contracts and flattens, and the external intercostal muscles contract and move the ribcage upwards and outwards - increasing the volume of the thoracic cavity.
  -This increase in volume decreases the pressure in the thoracic cavity to below atmospheric pressure.
  -This causes air to flow into the lungs from an area of high to low pressure down a pressure gradient.

Question 17

Describe the process of expiration.

Answer 17

-The diaphragm relaxes and domes upwards, and the external intercostal muscles relax and cause the ribcage to move downwards and inwards.
-This decreases the volume of the thoracic cavity, which increases the pressure to above atmospheric pressure.
-air is then forced down a pressure gradient and out of the lungs.

Question 18

What is forced expiration?

Answer 18

-Expiration can be forced, for example when blowing out a candle
-During forced expiration, external intercostal muscles relax(as before) and internal intercostal muscles contract.
-This causes the ribcage to be pulled in and down further
-The two sets of intercostal muscles are antagonistic(opposite).

Question 19

What does Fick’s Law state?

Answer 19

The rate of diffusion is directly proportional to the surface area multiplied by the concentration gradient, divided by the diffusion distance.

Question 20

What are three things all gas exchange surfaces have?

Answer 20

Large surface area, large concentration gradient, short diffusion distance.

Question 21

What features must gas exchange sites(alveoli) have?

Answer 21

-Moist
-Thin - the alveolar epithelium is only 1 cell thick. This means that there is a short diffusion pathway, which speeds up diffusion.
-Permeable.
-Have a large surface area - millions of alveoli, meaning there’s a large S.A. for diffusion/gas exchange.
-Good blood supply(also ventilation) - maintains a steep concentration gradient of oxygen and carbon dioxide between the alveoli and the capillaries.

Question 22

What happens to oxygen in the alveolus?

Answer 22

Oxygen diffuses down a concentration gradient through the alveolus epithelium and then through the capillary endothelium, and then binds to haemoglobin.

Question 23

What are the measures of lung function?

Answer 23

Tidal volume, ventilation rate, forced expiratory volume1 , forced vital capacity1

Question 24

What is tidal volume?

Answer 24

The volume of air in each breath - 0.4 dm(cubed) and 0.5dm(cubed) for adults.

Question 25

What is ventilation rate?

Answer 25

The number of breaths per minute - usually around 15 (for adults).

Question 26

What is forced expiratory volume1 ?

Answer 26

The maximum volume of air that can be breathed out in 1 second.

Question 27

What is forced vital capacity1 ?

Answer 27

The maximum volume of air it is possible to breathe forcefully out of the lungs after a deep breath.

Question 28

What is pulmonary ventilation?

Answer 28

The volume of air breathed in per minute.

Question 29

What is the equation for pulmonary ventilation?

Answer 29

Pulmonary ventilation = ventilation rate X tidal volume

Question 30

What would happen to the numbers in the pulmonary ventilation equation during exercise?

Answer 30

They would increase.

Question 31

What happens when there is a reduced rate of gas exchange in alveoli?

Answer 31

-Less oxygen can diffuse into the bloodstream
-Body cells receive less oxygen so rate of aerobic respiration decreases.
-Less energy released so sufferers feel tired and weak.