Autonomic Nervous system

Question 1

What is the autonomic nervous system involved with?

Answer 1

Involuntary control e.g. heart rate, pupil dilations- these changes are occuring to ensure homeostasis is maintained

Question 2

Describe the different divisions of the peripheral NS + what they’re involved in?

Answer 2

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

Question 3

What is the difference between the afferent and efferent divisions of the peripheral NS?
+ what part is the autonomic NS is?

Answer 3

Efferent = carries info away from central NS
- autonomic NS = part of this division

Afferent = carries info towards the central NS

Question 4

What does the division between the parasympathetic NS and sympathetic NS depend on?

Answer 4

= Anatomical- depends where the cell body of the preganglionic nerve is in the CNS

Question 5

What is a preganglionic neuron?

Answer 5

A nerve that connects CNS to a ganglion- they are cholinergic

Question 6

Define: cholinergic

Answer 6

A nerve cell is cholinergic when acetylcholine acts as the neurotransmitter

Question 7

Define: ganglia

Answer 7

= cluster of cell bodies that form swelling on nerve trunks

Question 8

Define: Nerve fibre

Answer 8

= axon of a neuron

Question 9

Describe the difference between how the CNS and effector organs are connected in the somatic NS and autonomic NS

Answer 9

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

Question 10

Where is neurotransmitter released on a postganglion neuron?

Answer 10

Terminal boutons on postganglion neuron have collaterals (=branches) that have swellings called varicosities- where neurotransmitter is released

Question 11

What are the main neurons and neurotransmitters they release in the autonomic NS?

Answer 11

Pre-ganglionic = acetylcholine
Post-ganglionic = acetylcholine or noradrenaline- depending on nerve type
Both = NANC neurotransmitters/co-transmitters

Question 12

What is the difference between cholinergic and adrenergic transmission?

Answer 12

Adrenergic = adrenaline and noradrenaline

Cholinergic = acetylcholine

Question 13

What are NANC neurotransmitters?

Answer 13

non-adrenergic + non-cholinergic neurotransmitters

Question 14

What is the parasympathetic NS also known as and where are the cells bodies of preganglionic neurons located?

Answer 14

= Cranialsacral outflow
- cell bodies locates on cranial + sacral regions of CNS

Question 15

In the parasympathetic NS, are the postganglionic and preganglionic neurons long or short?

Answer 15

Pre = long
Post = short

Question 16

Describe the structure of the parasympathetic NS

Answer 16

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

Question 17

What is a plexus and how is it different to a ganglion?

Answer 17

= large network of nerve fibres
- ganglion = smaller plexus that can be found within a plexus

Question 18

What is the sympathetic NS also known as and where are the preganglionic cell bodies located?

Answer 18

= thoracolumbar region
- cell bodies located within thoracic + lumbar regions

Question 19

In the sympathetic NS, are preganglionic and postganglionic neurons long or short?

Answer 19

Pre = short
Post = long

Question 20

Describe the 3 main regions where a preganglionic neuron can form a synapse in the sympathetic NS

Answer 20

1. 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
2. Prevertebral ganglia- preganglionic cell body within CNS- its axon extends to abdominal cavity to form a synapse with a prevertebral ganglion
3. Adrenal medulla- some preganglionic neurones travel to adrenal medulla and form synapses with chromaffin cells

Question 21

Name 3 types of prevertebral ganglia

Answer 21

Coeliac
Superior mesentric
Hypogastric/inferior mesenteric

Question 22

What is the adrenal medulla and where is it located?

Answer 22

= small gland located on top of kidneys

Question 23

What are chromaffin cells?

Answer 23

= equivalent of postganglionic neuron within adrenal medulla