regulation of breathing

Question 1

where is the respiratory centre located

Answer 1

medulla oblongata

Question 2

2 main areas of respiratory centre

Answer 2

1. inspiratory centre - responsible for inspiration and expiration
2. expiratory centre - stimulates the expiratory muscles during exercise

Question 3

inspiratory centre

Answer 3

sends out nerve impulses via the phrenic nerve to the inspiratory muscles (diaphragm and external intercostals) to cause them to contract.

• this stimulation acts for approximately 2 seconds then the impulses stop and passive expiration occurs due to the elastic recoil of the lungs

Question 4

chemoreceptors

Answer 4

• detect change in C02 and acidity
• send impulse to the inspiratory centre to increase ventilation until the blood acidity has returned to normal
• the respiratory centre sends impulses down the phrenic nerve to stimulate more inspiratory muscles causing breathing to increase

Question 5

proprioreceptors

Answer 5

sensory receptors located in the joints and muscles that provide feedback to the respiratory centre to increase breathing during exercise

• send impulse to the inspiratory centre to increase ventilation until the blood acidity has returned to normal
• the respiratory centre sends impulses down the phrenic nerve to stimulate more inspiratory muscles causing breathing to increase

Question 6

baroreceptors

Answer 6

decrease in blood pressure detected by baroreceptors results in an increase in breathing rate

• send impulse to the inspiratory centre to increase ventilation until the blood acidity has returned to normal
• the respiratory centre sends impulses down the phrenic nerve to stimulate more inspiratory muscles causing breathing to increase

Question 7

stretch receptors

Answer 7

detect increase in stretch of lungs
- prevent over-inflation of lungs by sending impulses to the expiratory centre and then down the intercostal nerve to the expiratory muscles so expiration occurs

Question 8

the order of neural/ chemical control for inspiration is;

Answer 8

receptors -> medulla -> phrenic nerve -> diaphragm and external intercostals

Question 9

the order of neural/ chemical control for expiration is;

Answer 9

receptors -> medulla -> intercostal nerve -> abdominals and internal intercostals

Question 10

adrenaline

Answer 10

released in response to exercise

• before we start the brain send impulse to the renal glands which responds and pump adrenaline into the blood in anticipation of the increase need for oxygen and carbon dioxide exchange
• as a result breathing rate increases in preparation for exercise and the demand to take in more oxygen and remove more carbon dioxide

Question 11

5 effects of smoking

Answer 11

• irritation of trachea and bronchi
• reduces lung function and increases breathlessness caused by swelling and narrowing of the lungs’ airways
• smoke damages the cells lining the trachea and bronchi. These tiny cells have microscopic hair like cilia on their surface which help to push mucus out of lungs. When they are damaged, excess mucus builds up in the lung passages which leads to smokers cough
• damage alveoli which reduces efficiency of gaseous exchange which increases the risk of chronic obstructive pulmonary disease.
• affects oxygen transport as the carbon monoxide from cigarettes combines with haemoglobin in red blood cells much more readily than oxygen which reduces oxygen carrying capacity which increases breathlessness during exercise