44 - Regulation of respiration. Respiratory centre and breathing rhythm. Chemical control of respiration. Reflex control of respiration. Effects of the cerebral cortex on respiration.

sections

respiratory centre

chemical control of respiration

reflex control of respiration

effects of cerebral cortex on respiration

respiratory centre

• The area from which nerve impulses are sent is located in the brainstem and is referred to as the respiratory center. in medulla oblongata and pons.

• It is divided into three major parts:

  • sensory signals into the respiratory centre from peripheral chemoreceptors, baroreceptors and all types of receptors in the lung

  • The basic rhythm of respiration is generated mainly in the dorsal respiratory centre

• The respiratory center consists of groups of neurons in the brain stem that are functionally divided into three areas:

  1. The medullary rhythmicity area in the medulla oblongata.- controls basic rhythm of respiration

  2. The pneumotaxic area in the pons- helps to coordinate the transition between inspiration and expiration, limits inspiration so expiration takes place

  3. The apneustic area in the pons- stimulates inspiratory area to prolong inspiration, thus inhibiting expiration

chemical control of respiration

• Central chemoreceptors - in the medulla oblongata, highly sensitive to blood concentration of CO2

• CO2 immediately forms new H+ ions which in turn stimulates the chemosensitive area, resulting in a strong increase in respiratory centre activities

• Peripheral chemoreceptors - in the aortic body and common carotid arteries, sensitive to changes in CO2 and O2 levels in blood

• This mechanism responds when blood O2 drops too low. chemoreceptors transmit nervous signals to the brain to help regulate respiratory activity.

reflex control of respiration

• This reflex is responsible for protecting the lung from overinflating.

• baroreceptors- Stretch receptors are located in the wall of bronchi and once activated, they send stimuli through the vagus nerve into the dorsal respiratory centre and the pneumotaxic centre of the brainstem.

• The stretch receptors activate a feedback response, which leads to inhibition of inspiration.

effects of cerebral cortex on respiration

• respiration can be affected by higher brain conditions such as emotional state via limbic system, or temperature via hypothalamus or free will.

• Voluntary or conscious control of respiration is provided via the cerebral cortex, although chemoreceptors are capable of overriding it.