LO4: Respiratory system

Question 1

Structure

Answer 1

When you breathe, air enters your body through your mouth and nasal cavity.
It passes through your pharynx, past your epiglottis, and down your trachea.
The trachea branches into two bronchi (left and right); each bronchi breaks down further into smaller bronchioles (like a tree’s roots branching out).
At the end of each bronchiole lies a group of alveoli.
The alveoli is the place where the O2 diffuses into the blood and CO2 back to the lungs.

Question 2

Inspire at rest

Answer 2

The external intercostal muscles of the ribs must contract, as does the diaphragm in the abdomen.
The contraction increases the volume of the lungs, which reduces the pressure of the air inside the lungs.
The pressure of air is higher outside the body, so it rushes in through the mouth and nose to fill the lungs until the pressure is equalised.

Question 3

Expire at rest

Answer 3

The intercostal muscles and diaphragm must relax. As lungs are not now being stretched, they return to original size.
This in turn increases the pressure of air inside the lungs compared to outside. The air is forced out.

Question 4

Breathing during exercise (Inspire)

Answer 4

The same process when at rest, but additional muscles help to increase the volume of the lungs. Sternocleidomastoid, scalene and pectoralis major help to pull the clavicle upwards & outwards. Clavicle is the bone that internal intercostals pull against.

Question 5

Breathing during exercise (Expire)

Answer 5

Breathing out during physical activity is much more involved. Rather than passively relaxing, the ribcage is forced downwards and inwards by the internal intercostal muscles. The rectus abdominus helps to force the diaphragm upwards. These actions reduce the volume of the lungs, increasing the pressure inside them and therefore forcing air out quicker.

Question 6

Gaseous exchange at the alveoli

Answer 6

The exchange of oxygen and carbon dioxide in the lungs is described as external respiration because gases exchanged within the atmosphere. The air we breathe in is made up of 21% oxygen, 78% nitrogen & 0.04% carbon dioxide. The remainder is other gases and pollution.

Question 7

Tidal Volume (TV)

Answer 7

The volume of air inspired or expired per breath- approx 500ml during breathing at rest

Question 8

Frequency (f)

Answer 8

Also known as the ‘rate’, the number of breaths taken in 1 minute- you take approx 12-15 breaths when you breathe at rest.

Question 9

Minute Ventilation (VE)

Answer 9

The volume of air inspired or expired in 1 minute

Question 10

Formula for Minute ventilation (VE)

Answer 10

VE = TV x f

Question 11

Inspiratory reserve volume (IRV)

Answer 11

The volume of air available that could be inspireed after tidal volume.

Question 12

Expiratory reserve volume (ERV)

Answer 12

The volume of air available that could be expired after tidal volume

Question 13

Residual volume (RV)

Answer 13

The volume of air that is left in the lungs after total forced expiration.

Question 14

Vital Capacity (VC)

Answer 14

The total volume of air that can be inspired and expired

Question 15

Total Lung Capacity (TLC)

Answer 15

The total volume of lungs at maximum inflation

Question 16

Formula for Total Lung Capacity

Answer 16

TLC = RV + VC

Question 17

Short-term effects of exercise on respiratory system

Answer 17

Increases the volume of air inspired in one breath.
Increases the frequency of breaths in 1 minute.
Increased breathing rate
Increased tidalvolume

Question 18

Long-term effects of exercise on respiratory system

Answer 18

Increases the number and diameter of the capillaries around the alveoli.
As muscles power respiration, they respond in the same way as skeletal muscles.
The diaphragm & intercostal muscles grow stronger, enabling them to lift the rib cage higher, allowing more air in to the lungs.
They are also able to contract with a greater force increasing the pressure differences.