Autonomic Nervous system Flashcards
What is the autonomic nervous system involved with?
Involuntary control e.g. heart rate, pupil dilations- these changes are occuring to ensure homeostasis is maintained
Describe the different divisions of the peripheral NS + what they’re involved in?
Peripheral NS split into
- Somatic NS = conscious control of skeletal muscle
- autonomic NS = involuntary control of all other organs + tissues
Autonomic NS = involuntary control of all other organs + tissues- split into:
- Parasympathetic NS = conscious control of skeletal muscle
- Sympathetic NS = fight or flight response
- Enteric NS = nerves within gut
What is the difference between the afferent and efferent divisions of the peripheral NS?
+ what part is the autonomic NS is?
Efferent = carries info away from central NS
- autonomic NS = part of this division
Afferent = carries info towards the central NS
What does the division between the parasympathetic NS and sympathetic NS depend on?
= Anatomical- depends where the cell body of the preganglionic nerve is in the CNS
What is a preganglionic neuron?
A nerve that connects CNS to a ganglion- they are cholinergic
Define: cholinergic
A nerve cell is cholinergic when acetylcholine acts as the neurotransmitter
Define: ganglia
= cluster of cell bodies that form swelling on nerve trunks
Define: Nerve fibre
= axon of a neuron
Describe the difference between how the CNS and effector organs are connected in the somatic NS and autonomic NS
Somatic = singular myelinated neuron extends from CNS to effector
Autonomic = 2 neuron chain:
1. Preganglionic neuron- cell body found within spinal cord and axon extends to form synapse within a ganglion with post-ganglionic neuron
2. Post-ganglionic neuron axon extends from ganglion to effector organ
Where is neurotransmitter released on a postganglion neuron?
Terminal boutons on postganglion neuron have collaterals (=branches) that have swellings called varicosities- where neurotransmitter is released
What are the main neurons and neurotransmitters they release in the autonomic NS?
Pre-ganglionic = acetylcholine
Post-ganglionic = acetylcholine or noradrenaline- depending on nerve type
Both = NANC neurotransmitters/co-transmitters
What is the difference between cholinergic and adrenergic transmission?
Adrenergic = adrenaline and noradrenaline
Cholinergic = acetylcholine
What are NANC neurotransmitters?
non-adrenergic + non-cholinergic neurotransmitters
What is the parasympathetic NS also known as and where are the cells bodies of preganglionic neurons located?
= Cranialsacral outflow
- cell bodies locates on cranial + sacral regions of CNS
In the parasympathetic NS, are the postganglionic and preganglionic neurons long or short?
Pre = long
Post = short
Describe the structure of the parasympathetic NS
Number of different neurons involved:
- Pre-ganglionic cell body within cranial region- axon extends to form synapses with ganglia that are close or within the effector
- Sacral region- sacral nerve axons extends within pelvic region + forms a plexus, which have ganglia within this network and in pelvic tissues
What is a plexus and how is it different to a ganglion?
= large network of nerve fibres
- ganglion = smaller plexus that can be found within a plexus
What is the sympathetic NS also known as and where are the preganglionic cell bodies located?
= thoracolumbar region
- cell bodies located within thoracic + lumbar regions
In the sympathetic NS, are preganglionic and postganglionic neurons long or short?
Pre = short
Post = long
Describe the 3 main regions where a preganglionic neuron can form a synapse in the sympathetic NS
- Paravertebral sympathetic chain = chain of ganglia close to spinal cord- axons can enter this chain and can travel up or down before forming a synapse
- Prevertebral ganglia- preganglionic cell body within CNS- its axon extends to abdominal cavity to form a synapse with a prevertebral ganglion
- Adrenal medulla- some preganglionic neurones travel to adrenal medulla and form synapses with chromaffin cells
Name 3 types of prevertebral ganglia
Coeliac
Superior mesentric
Hypogastric/inferior mesenteric
What is the adrenal medulla and where is it located?
= small gland located on top of kidneys
What are chromaffin cells?
= equivalent of postganglionic neuron within adrenal medulla
