The Autonomic Nervous System Flashcards
What are the 2 major divisions of the autonomic nervous system ?
The sympathetic nervous system and the parasympathetic nervous system
What are pre-ganglionic fibres ?
The fibres going from the CNS to the autonomic ganglia
What are post-ganglionic fibres ?
Fibres going from the ganglia to the target organs
Where do sympathetic fibres operate ?
They leave the CNS from the thoracic and lumbar regions (T1 - L2) or the thoracolumbar division
Where do parasympathetic fibres operate ?
They leave the CNS from the brain stem and sacral regions or the craniosacral division
What is the adrenal medulla ?
It is a specialised part of the sympathetic nervous system
It forms an endocrine gland
What is autonomic ‘tone’ ?
When autonomic innovation provides a basal level of activity in the tissues it innovates
Can autonomic tone be changed ?
It can either be increased or decreased to modulate activity of specific tissues
Summarise somatic nerves
Somatic nerves (motor neurones) go to voluntary effectors (skeletal muscle)
They only have 1 synapse
They use myelinated axons
The neurotransmitter is Ach.
Summarise autonomic nerves
Autonomic nerves go to non-voluntary effectors – such as smooth muscle, heart and glands . Neurotransmitters include ACh at the ganglia for both sympathetic and parasympathetic nervous system and noradrenaline at the post-ganglionic sympathetic nervous system
What is the American name for adrenaline ?
Epinephrine
What is the American name for noradrenaline ?
Norepinephrine
Summarise autonomic ganglia
In the sympathetic nervous system > there are short pre-ganglionic myelinated fibres or long post-ganglionic unmyelinated fibres and the ganglia are close to the spinal cord
In the parasympathetic nervous system > there are long pre-ganglionic fibres and short post-ganglionic fibres and the ganglia are close to the innervated structure
Summarise nicotinic acetylcholine receptors
- activated by acetylcholine
- ion channel linked
- blocked by hexamethonium
Summarise transmission at parasympathetic postganglionic nerve endings
Acetylcholine can increase or decrease the activity of the effector -
• heart - ACh decreases the rate of beating
• salivary glands - ACh increases rate of secretion