Respiratory control centre (RCC)

where is the RCC located?

In the medulla oblongata

what 2 centres is the RCC made up of?

• the inspiration centre

• the expiration centre

what happens in the inspiration centre?

• Has intercostal nerve and phrenic nerve which work together to control diaphragm and intercostals.  

• Works at both rest and exercise. 

what happens in the expiration control centre?

Only kicks in during exercise. 

what does the RCC do during exercise?

• uses the receptors to detect change:

• Chemoreceptors: detect ↑CO₂, ↑H⁺, ↓O₂

• Thermoreceptors: detect ↑blood temperature

• Proprioceptors: detect ↑muscle and joint movement

• These receptors stimulate the inspiratory centre (IC)

• IC increases force of diaphragm & external intercostals

• IC recruits sternocleidomastoid & pectoralis minor → ↑depth of inspiration

• Baroreceptors: monitor lung inflation

• Excessive stretch stimulates expiratory centre (EC)

• EC recruits internal intercostals & abdominals → forced expiration

• Combined IC & EC activity → ↑breathing rate and depth

what are the 4 receptors which help regulate the respiratory system during exercise and what do they measure?

• baroreceptors: located in lung tissue and bronchioles and inform the state of lung inflation. 

• proprioceptors: inform of motor activity in the muscles and joints. 

• thermoreceptors: inform of an increased blood temperature. 

• chemoreceptors: located in aorta and carotid arteries and pick up an increase in blood acidity, increases in CO2 conc and decrease in O2 conc. 

what does the RCC do during rest?

• IC is responsible for the rhythmic cycle of breathing.  

• Nerve impulses are generated and stimulate the inspiratory muscles causing them to contract via the: intercostal nerve to the external intercostals and the phrenic nerve to the diaphragm.  

• This causes thoracic activity volume to be increased.  

• Approx. 500ml of air will be inspired. 

• After approx. 2 seconds, stimulation stops and the inspiratory muscles relax. 

• Lung tissues recoil, causing passive expiration. 

• This will be repeated approx. 12-15 times per minute. 

• The expiratory centre is inactive during rest due to the natural relaxation of the diaphragm and external intercostals.  

when is the phrenic nerve stimulated and what does it cause?

• Stimulated by the inspiratory centre (IC) within the respiratory control centre when chemoreceptors detect ↑CO₂, ↑H⁺ and/or ↓O₂ (at exercise)

• Sends motor impulses to the diaphragm

• Diaphragm contracts and flattens

• Thoracic cavity volume increases

• Lung pressure decreases

• Air is drawn into the lungs, initiating and increasing inspiration

when is the intercostal nerve stimulated and what does it cause?

• Stimulated by the inspiratory centre (IC) within the respiratory control centre when chemoreceptors detect ↑CO₂, ↑H⁺ and/or ↓O₂ (at exercise)

• Sends motor impulses via the intercostal nerve to the external intercostal muscles

• External intercostals contract

• Rib cage moves up and out

• Thoracic cavity volume increases

• Lung pressure decreases

• Air is drawn into the lungs, increasing inspiration