Ventilation

Question 1

What kind of process is inspiration?

Answer 1

Active process.

Question 2

What happens during inspiration?

Answer 2

• Diaphragm contracts, flattening, and lowering.
• External intercostal muscles contract, moving ribs upwards and outwards.
• The volume of the thorax increases so the pressure in the thorax is reduced. It is now lower than the pressure of the atmospheric air, so air is drawn through the nasal passages, trachea, bronchi and bronchioles into the lungs. This equalises pressures inside and outside the chest.

Question 3

What kind of process is expiration?

Answer 3

Passive process.

Question 4

What happens during expiration?

Answer 4

• The muscles of diaphragm relax so it moves up.
• The external intercostal muscles relax so ribs move down and inwards.
• Elastic fibres in alveoli of the lungs return to their normal length.
• Due to all these changes the volume in the thorax is decreased.
• The pressure inside the thorax is greater than the pressure of the atmospheric air, so air moved out of the lungs until the pressure inside and out is equal again.

Question 5

How does a spirometer work?

Answer 5

1)The person breathes in and out through the mouth, via the mouthpiece ( must hold nose clip).

2) The air is trapped between the enclosed chamber between the float and the water.

3) When breathing in, the volume of air in the chamber decreases and the float drops.

4) When breathing out, the volume of air in the chamber increases and the float rises.

5) The float is attached to a pen which writes on the paper on the revolving drum, recording the breathing movements.

Question 6

What are the safety precautions when using spirometer?

Answer 6

• Make sure that there is soda lime being used, otherwise the person will be breathing in exhaled CO2.
• Make sure that the person using it is healthy, no underlying health conditions/cold/ asthma.
• Sterilise the mouthpart or use a new mouthpiece between different users.

Question 7

What happens when soda lime is used in a spirometer?

Answer 7

The carbon dioxide breathed out into the mouthpiece is absorbed, so it doesn’t reach the chamber.

Question 8

How do you calculate breathing rate?

Answer 8

60/time for 1 breath

or count the peaks on the graph

Question 9

What is the tidal volume?

Answer 9

The volume of air that moves into and out the lungs with each resting breathing.

Question 10

What is the vital capacity?

Answer 10

The volume of air that can be breathed in when the strongest possible exhalation is filled by the deepest possible intake of breath.

Question 11

What is the inspiratory reserve volume?

Answer 11

The maximum volume of air you can breathe in over and above a normal inhalation.

Question 12

What is the expiratory reserve volume?

Answer 12

The extra amount of air you can force out of your lungs over and above the normal tidal volume of air you breathe out.

Question 13

What is the residual volume?

Answer 13

The volume of air that is left in your lungs when you have exhaled as hard as possible.

Question 14

What is the total lung capacity?

Answer 14

vital capacity + the residual volume.