Neuroanatomy One

Question 1

What are the three major subdivisions of the peripheral nervous system?

Answer 1

sensory system

autonomic system- comprises of sympathetic and parasympathetic branches

Question 2

What are the main differences between the sympathetic and the autonomic branches?

Answer 2

somatic- only one neuron and one synapse, each muscle fiber is innervated by a single motor neuron and contains high density ionotropic receptors
autonomic nervous system- dual innervation, two neuron chains, expresses metabotropic receptors that produce multiple effects and amplify signals

Question 3

How does gross anatomy of the somatic and autonomic nervous system contribute to their primary functions?

Answer 3

• primary function of the somatic nervous system is the control of voluntary movement
• autonomic nervous system is able to generate much more diverse responses over multiple body systems

Question 4

What are two features of the sympathetic nervous system that allows for the coordinated activity of mutiple different body systems?

Answer 4

• sympathetic nervous system has very short preganglionic neurons that synapse very close to the spinal cord enabling sympathetic NS control of postganglionic neurons that are going to diverse targets
• the sympathetic nervous system has a long chain of ganglia that runs almost the full length of the spinal cord facilitating the transfer of signals between neurons

Question 5

Explain the differences in structure between and function between electrical and chemical stimuli:

Answer 5

• electrical synapses transmitted directly between neurons through gap junctions and are present mainly in the brain
• chemical synapses is a transmitter that binds directly to a specific receptor on the plasma wall of the other cell.

Question 6

What is the function of the botulism toxin?

Answer 6

• targets the NMJ causing flaccid paralysis

Question 7

What is the function of the tetanus toxin?

Answer 7

• targets the Renshaw cells inhibitory interneurons within the spinal cord

Question 8

What are the main sites of ACh transmission?

Answer 8

• somatic NS @ the NMJ

- parasympathetic nervous system at the pre and the psot ganglionic fibres

Question 9

What is the name of the transporter that uptakes glutamine?

Answer 9

SAT2 (system A transporter)

Question 10

Why are NMDA transporters only active when the cell is depolarised?

Answer 10

this is when the magnesium is able to dislodge itself

Question 11

What is the name of the antagonist to the glutamate NMDA transporter?

Answer 11

ketamine

Question 12

What is the main precursor for GABA receptors

Answer 12

glucose is the main precursor but glutamate is involved in synthesis as well

Question 13

What does domperidome do?

Answer 13

Blocks the D2 receptors

Question 14

What is the main precursor of the catecholamines? (dopamine, adrenaline, noradrenaline)

Answer 14

the main precursor of the caetacholamines is tyrosine

Question 15

What is the main precursor to serotonin?

Answer 15

tryptophan

Question 16

How does nitric oxide differ from other neurotransmitters?

Answer 16

1. Not stored in vesicles- generated as needed
2. Not released by calcium dependant exocytosis
3. Decays sponataneously
4. Does not interact with specific receptors
5. Acts as a retrograde messenger

Question 17

Explain on the most basic level the organisation of the lower motor neurons within the spinal cord:

Answer 17

• medial motor pool to axial/proximal

- lateral motor neuron pool is to the distal muscle

Question 18

Briefly explain the different types of muscle fibres within motor units:

Answer 18

• Slow- slow oxidative red fibres that contract very slowly to generate small forces
• Fast fatiguable- large, fast glycolytic fibres that contract very quickly
• Fast-fatigue resistant- fast oxidative red fibres, represent an intermediate between slow and fast fatiguable

Question 19

Explain the sequence of events that are involved in the myotatic patellar stretch reflex:

Answer 19

• simplest form of reflex that involves only one muscle fibre
• tapping patellar causes a signal to go to the spinal cord via the proprioceptive system that then causes the extensor to contract and the flexor to relax
• the net effect of this is that the limb will swing forwards
• note the spinal reflexes still function even if damage to the spinal cord has occurred

Question 20

What are muscles that are involved in the biceps tendon reflex?

Answer 20

• musculocutanous nerve C6-C8

Question 21

What are the muscles that are involved in the triceps reflex?

Answer 21

• radial nerve C7-T2

Question 22

What are the nerves that are involved in the patellar reflex?

Answer 22

• femoral nerve (L4-L6)

Question 23

Why are muscle innervated by both motor and gamma motor neurons?

Answer 23

it means when the muscle contracts the muscle spindle will also contract esnuring continuity of information

Question 24

State the role of 1a, 1b and II muscle spindles:

Answer 24

1a- provide information about length changes
1b- provide information about muscle tension- work by negative feedback ensuring that muscle tensions do not become too great
II- provide infomation about the static length of the fibres