Nervous system

Question 1

Name the divisions of the nervous system

Answer 1

a. CNS – brain and spinal cord
b. PNS – all other nerves
i) SOMATIC nervous system: “voluntary”
1) Sensory component
2) Motor component
ii) AUTONOMIC nervous system: “involuntary”
1. Sympathetic: sight, flight, freeze
- Sensory component
- Motor component
2. Parasympathetic: rest and digest
a. Sensory component
b. Motor component

Question 2

What is a basic reflex arc

Answer 2

Simple segmental reflex: involves CNS as spinal cord but not brain.
1. Stimulus, sensory neurone, interneurone (relay), motor neurone, effector

Question 3

What does myelination provide?

Answer 3

electrical insulation. Allows salatary conduction where impulse jumps between nodes of ranvier, allowing a faster impulse travel.

Question 4

What are the main fibre types in the PNS

Answer 4

A fibres = large, fast , myelinated.
A delta = small, lightly myelinated.
C = smallest, slowest.

Question 5

How is the autonomic nervous system arranged?

Answer 5

Splits to sympathetic (middle of spinal cord) and parasympathetic (top of spinal cord)
Sympathetic nerves located more closesly to spinal cord for faster response.

Question 6

What is a ganglion

Answer 6

structure containing cell bodies, linked to synapses. Connect synapses

Question 7

What is the myelination ususally like in the ANS ganglions?

Answer 7

Pre-ganglionic neurone in ANS usually myelinated.

Post-ganglionic neurone in ANS usually unmyelinated.

Question 8

what are the 4 options for motor pathway of autonomic reflex?

Answer 8

1. skin/sweat glands – many pre gang neurone synapse in sympathetic trunk. Post ganglionic neurone later all synapse individually. 2. heart - has single synapse in symp trunk. Post ganglionic neurone has single synapse later.
2. guts - pre gang neurone passes straight thourgh symp trunk and synapses in a smaller trunk. Post gang neurone synapses to guts later. 4. adrenal medulla – neurone passes straight through the symp trunk and synapses directly
   within adrenal medulla.

Question 9

What are the:
a) lenghts
b) myelination
c) neurotransmitter 
in the sympathetic and parasympathetic nervous system?

Answer 9

Sympathetic –
1. Shorter myelinated preganglionic neurone. Releases Ach.
2. Longer unmyelinated postganglionic neurone. Releases Ach.
Parasympathetic
1. Longer myelinated preganglionic neurone. Releases Ach
2. Shorter unmyelinated postganglionic neurone. Releases Ach.

Question 10

How is the PNS arranged?

Answer 10

Somatic and autonomic (para and sympathetic)

Question 11

What is the main difference between the somatic and autonomic nervous systems

Answer 11

i. S – one neuron from spinal cord to muscle (no pre/post ganglionic)
ii. Autonomic – typically 2 peripheral components: post and pre ganglion

Question 12

What are the pre and post ganglionic nerves like in autnomic

Answer 12

1. Pre ganglionic = from spinal cord to ganglion = myelinated
2. Post ganglionic = ganglion to tissue (e.g. heart) = unmyelinated

Question 13

Contrast a smooth muscle (ANS) with skeletal (SNS)

Answer 13

• Somatic skeletal NMJ- one motor comes in and innovates a few skeletal muscles. Myelinated
> Autonomic- nerves come in and innovate several different cells and ALSO bunch of cells and innovating autonomic motor neuron comes in and releases neurotransmitter across length, all act on muscle all way along neuron- graded contractions

Question 14

Which part of the spinal cord do the parasympathetic neurones come from?

Answer 14

1. cranial and sacrel area, nothing from middle of spinal cord

Question 15

Which part of the spinal cord do the sympathetic neurones come from?

Answer 15

Thoracic segment 1 (T1) to Lumbar segment 2 (L2)