Respiratory

Question 1

Outline how oxygen is transported in the blood (2)

Answer 1

Transport of oxygen in haemoglobin in the form of
oxyhaemoglobin
Oxygen dissolved in blood plasma

Question 2

Process of oxygen diffusion at the alveoli during exercise. (4)

Answer 2

Oxygen diffuses down the concentration gradient from the alveoli to the blood
Is a high ppO2 in the alveoli
During exercise muscles use more oxygen
So lower ppO2 in the blood

Question 3

Describe the mechanics of breathing for inspiration at rest (4)

Answer 3

Diaphragm contracts or flattens
Rib cage up and out
Increasing the volume of the thoracic cavity
Forcing air into the lungs / air enters the lungs

Question 4

Describe the mechanics of breathing for inspiration during exercise (5)

Answer 4

The diaphragm flattens or contracts with greater force
Additional muscles are recruited e.g. sternocleidomastoid
The rib cage moves up and out further (than at rest)
Volume of the thoracic cavity increases more (than at rest)
More air enters the lungs

Question 5

Explain why a trained athlete will have a lower minute ventilation at rest than an untrained individual (3)

Answer 5

More efficient oxygen transportation
Higher Red blood cell count
Lower breathing frequency

Question 6

Compare the process of gas exchange at the muscles during exercise to resting conditions (5)

Answer 6

During exercise the ppO2 is lower in muscles than at rest
During exercise the ppCO2 is higher in muscles than at rest
There is a steeper diffusion / concentration gradient during exercise
More O2/CO2 diffuses/moves at a faster rate during exercise
Oxyhaemoglobin dissociation curves shifts to right during exercise or Bohrshift

Question 7

Assess how changes in the pressure gradient affect oxygen diffusion at the working muscles during exercise (5)

Answer 7

Gradient is steeper/increased
PpO2 in working muscles is reduced/lower
(Reason) Because the working muscles are using more
O2 for aerobic respiration/energy system
More O2 diffuses into the muscle

Question 8

Assess how changes in the dissociation of oxyhaemoglobin affect oxygen diffusion at the working muscles during exercise (4)

Answer 8

The oxyhaemoglobin dissociation curve shifts to the right/Bohr shift
There is an increase in CO2 /acidity / temperature
or decrease in pH
(Effect) causing reduced saturation of haemoglobin
with O2
More oxygen available for diffusion to the muscle

Question 9

What are the resting values for BR and TV

Answer 9

BR - 11-15 bpm
TV - 500ml

Question 10

Contrast the mechanics of expiration at rest with the mechanics of expiration during exercise (5)

Answer 10

Internal intercostals/ Rectus abdominus contract during exercise but not at rest
Rib cage come downwards and inwards more quickly/further during exercise than at rest
Diaphragm relaxes shape more quickly in exercise than at rest
Volume in thoracic cavity decreases more during exercise than at rest
Pressure in thoracic cavity increases more during exercise than at rest
Air expired faster during exercise than at rest

Question 11

Explain the roles of the sternocleidomastoid in the mechanics of breathing during exercise

Answer 11

Lift the rib cage/ sternum further up and out (than at rest)
Increases the volume of the thoracic cavity further (than
at rest)
Reduces pressure in the thoracic cavity more (than at rest)
More air inspired (than at rest)

Question 12

Explain the roles of the internal intercostal muscles in the mechanics of breathing during exercise

Answer 12

Pull the rib cage/ sternum further/ faster in and down
(than at rest)
Reduces the volume of the thoracic cavity further (than at rest)
Increases pressure in the thoracic cavity more (than at rest)
More air expired (than at rest)

Question 13

During a 5000 metre race, the athlete’s tidal volume increases. Explain how neural control of breathing
causes this to happen (2)

Answer 13

Inspiratory centre stimulates nerves/motor neurones to increase depth of breathing
Phrenic nerve stimulates diaphragm to contract more strongly

Question 14

Analyse the changes in the mechanics of breathing as exercise increases which would enhance the performance of an endurance swimmer (4)

Answer 14

Diaphragm contracts with more force which increases the volume of thoracic cavity more
Causing a greater decrease in pressure in the lungs which means more air enters lungs
Expiration becomes an active process to increase breathing rate
Greater volumes of air in means more O2 to working muscles

Question 15

Tidal volume changes during exercise and recovery. Describe the role of proprioceptors in the control of
these changes

Answer 15

During exercise - proprioceptors detect motor activity
Send messages to respiratory control centre
During recovery - proprioceptors detect that movement has stopped