Respiratory system

Question 1

diagram of the lungs

Answer 1

1. mouth / nose
2. pharynx
3. larynx (voice box)
4. trachea
5. bronchi
6. bronchioles
7. alveoli
8. diaphragm

Question 2

how does gas exchange happen?

Answer 2

• happens in the alveoli
• o2 is respired in and enters the alveoli
• o2 is then diffused into the capillaries (the diffusion is easy as they are only one cell thick)
• co2 is exchanged from the RBCs with o2
• o2 binds with haemoglobin in the RBC to be carried around the body

Question 3

what is the normal breathing rate?

Answer 3

12 breaths per minute

Question 4

minute ventilation

Answer 4

volume of air inspired or expired in one minute

7.5l/min = volume at rest

minute ventilation increases during exercise as more o2 is required for working muscles

tidal volume x breathing frequency = minute ventilation

Question 5

tidal volume

Answer 5

volume of air inspired and expired per breath

0.5l = volume at rest

depth an frequency of breaths increase during exercise

Question 6

residual volume

Answer 6

volume of air that remains in the lungs after maximal expiration

1.2l = volume at rest

remains the same at rest and exercise

Question 7

expiratory reserve volume

Answer 7

volume of air that can be forcibly expired after a normal breath

volume at rest:
women = 0.8l
men = 1.1l

volume slightly decreases during exercise

Question 8

inspiratory reserve volume

Answer 8

amount of air that can be forcibly inspired after a normal breath

volume at rest:
women = 1.9l
men = 3.3l

volume decreases during exercise as BR increases

Question 9

4 factors of diffusion

Answer 9

1. high capillary density
2. high alveoli density
3. short diffusion distance due to thin membrane (1 cell thick)
4. blood travels slowly through the capillaries

Question 10

how does the nervous system regulate BR

Answer 10

SNS
- increases BR
- demand of o2 increases

PNS
- decreases BR
- helps body return back to rest state after exercise

Question 11

what mechanics of breathing increase inspiration?

Answer 11

pectorals minor and sternocleidomastoid
- further increases the thoracic cavity by lifting the sternum and ribcage

Question 12

what mechanics of breathing increase expiration?

Answer 12

intercostal muscles
- activated during exercise to pull the ribs in and out more forcefully to force air out of lungs

rectus abdominals
- aids respiration by contracting and increasing the intra-abdominal pressure and forces the diaphragm into a dome shape

Question 13

what is the sequence of breathing regulation?

Answer 13

• the 3 receptors (chemoreceptors, baroreceptors, proprioceptors) send an impulse to the medulla oblongata which activates the ICC (inspiratory control centre)
• the stretch receptors are activated to allow the lungs to expand and increase volume
• once the lungs have been fully stretched it stimulates the ECC (expiratory control centre) where it allows the lungs to relax and breath out