Understanding:
• The autonomic nervous system controls involuntary processes in the body using centres in the brainstem
The human nervous system can be organised into several sub-divisions:
- Firstly, the nervous system can be divided into the central nervous system (brain and spine) and peripheral nervous system
- The peripheral nervous system (PNS) can be divided into the sensory (afferent) pathway or the motor (efferent) pathway
- The motor pathway can be subdivided according to whether the response is voluntary (somatic) or involuntary (autonomic)
The autonomic nervous system controls involuntary processes in the body using centres located mostly within the brainstem
- Sympathetic nerves release noradrenaline (adrenergic) to mobilise body systems (‘fight or flight’ responses)
- Parasympathetic nerves release acetylcholine (cholinergic) to relax body systems and conserve energy (‘rest and digest’)
Divisions of the Nervous System
Application:
• Swallowing, breathing and heart rate as examples of activities coordinated by the medulla
The medulla oblongata is a part of the brainstem responsible for coordinating many autonomic (involuntary) activities
- This includes the regulation of body activities such as swallowing, breathing and heart rate
Sympathetic Responses (‘Fight or Flight’)
- Decreases salivary release and blood flow to the gut in response to swallowing
- Increases ventilation rate and dilates airways in response to a reduction in blood pH (caused by increased levels of CO2)
- Increases heart rate by raising the normal sinus rhythm of the pacemaker of the heart
Parasympathetic Responses (‘Rest and Digest’ / ‘Feed and Breed’)
- Increases salivary release and blood flow to the gut in response to swallowing
- Lowers ventilation rate and constricts airways in response to an increase in blood pH (caused by lower levels of CO2)
- Reduces heart rate (via vagus nerve) by lowering the normal sinus rhythm of the pacemaker of the heart
Autonomic Control of Body Systems
