Lecture 17

Question 1

Define Somatic information transmission. (give examples)

Answer 1

Stuff we are aware of, have control over. [muscle movement (efferent) and sensory information (afferent) - nose, ears, eyes etc.]

Question 2

Define Autonomic information transmission. (give examples)

Answer 2

Stuff we are not aware of and don’t have control over. [muscle - heart beating (efferent) and sensory information - blood pressure, respiratory rate, heart rate etc (afferent)].

Question 3

Where is the cell body and axons located for the somatic efferent division?

Answer 3

• Cell bodies are located in the spinal cord (CNS).

- Axons are located in the spinal nerves (PNS).

Question 4

What is the effector?

Answer 4

The thing the nerves go to and control. (e.g. muscle fibres)

Question 5

What is the anatomical organisation of the somatic motor (efferent)?

Answer 5

• 1 neuron (from the spinal cord- CNS) with its myelated axon (PNS) making a synapse with a muscle fibre.
• neuron is the pre-synaptic cell
• muscle fibre is the post-synaptic cell.

Question 6

What is the name of the junction between a somatic motor neuron and muscle fibre(s)?

Answer 6

Neuromuscular junction (NMJ).

Question 7

What is the chemical neurotransmitter used in the somatic motor (efferent)?

Answer 7

Acetylcholine (ACh).

Question 8

What is a motor unit?

Answer 8

Includes 1 motor neuron + all the muscle fibre(s) it contacts.

ONLY 1 MOTOR NEURON ( MUSCLE CAN ONLY BE TOLD TO DO 1 THING AT A TIME)

Question 9

How many neurons are involved in the autonomic nervous system and where are each of their cell bodies and axons located.

Answer 9

2 Neurons involved

• Neuron 1 has its cell body in the spinal cord (CNS) and its axon is the PNS.
• Neuron 2 has its cell body and its axon in the PNS.

Question 10

What is the Autonomic ganglion?

Answer 10

Collection of the cell bodies of peripheral neurons involved in the autonomic division of the nervous system.

Question 11

What is the anatomical organisation of the autonomic nervous system?

Answer 11

Neuron 1 from the CNS forms synapse with the autonomic ganglion which is in the PNS.

Neuron 2 from the autonomic ganglion then forms a synapse with the effector (e.g. muscle).

Question 12

Which neurons are myelated in the autonomic nervous system of the nervous system?

Answer 12

• Neuron 1 is myelated

- Neuron 2 is not myelated

Question 13

What are the 2 classifications of both neuron 1 and neuron 2 in the autonomic nervous system?

Answer 13

Neuron 1 - Pre-synaptic & Pre-ganglionic.

Neuron 2 - Post-synaptic & post-ganglionic.

Question 14

What Neurotransmitter are used by both neurons?

Answer 14

Neuron 1 - Acetylcholine (ACh)

Neuron 2 - Acetylcholine (ACh) or noradrenaline (NE) - (ONLY NEURON TO USE 2 DIFFERENT NEUROTRANSMITTERS).

Question 15

What are the 2 types of autonomic efferents? (define them)

Answer 15

Sympathetic - used for stressful responses

Parasympathetic - used in restful situations

Question 16

What are the effects of both the Sympathetic and Parasympathetic autonomic efferents?

Answer 16

Sympathetic:

• increases heart rates
• increases blood flow to muscles (constricts blood vessels to skin and viscera)
• decreases gastric motility
• decreases salivation
• increases pupil size
• increases sweating

Parasympathetic:

• decreases heart rate
• increase gastric motility
• decreases pupil size
• increases salivation

Question 17

What are the structural and neurotransmitter differences between sympathetic and parasympathetic nervous systems?

Answer 17

Sympathetic nervous system:

• Sympathetic ganglion close to the CNS = short axon of neuron 1 and long axon of neuron 2
• Uses noradrenaline / norepinephrine. (NE)

Parasympathetic nervous system:

• Parasympathetic ganglion further away from the CNS = long axon of neuron 1 and short axon of neuron 2.
• Uses Acetylcholine. (ACh)

Question 18

Where does the Sympathetic nervous system leave from the CNS and what is the position of the ganglia?

Answer 18

• Axons of the Pre-ganglonic cells leave the CNS from the Thoracolumbar levels of the spinal cord. (between T1 and L2)
• Axons extend a short distance (as sympathetic ganglia are located close to the CNS)
• Sympathetic ganglia form a chain (sympathetic chain)
• Synapse and cell body of the post-ganglionic neuron is located in the sympathetic ganglion.

Question 19

Describe the sympathetic chain ganglia and where they are located.

Answer 19

• 21-23 pairs (depending on height)
• Located along the sides of the vertebral column
• Place where the pre-ganglionic neuron (neuron 1) synapses with the post-ganglionic neuron. (neuron 2)

Question 20

What are the 2 types of sympathetic ganglia?

Answer 20

Chain ganglia:

• 21-23 pairs
• alongside the vertebral column

Collateral ganglia:

• 3 main collateral ganglia
• not included in the chain of ganglia

Question 21

Where does the Parasympathetic nervous system leave from the CNS and what is the position of the ganglia?

Answer 21

• Axons of the pre-ganglionic neurons leave from the cranial (brainstem) and sacral (spinal cord) levels. (craniosacral nerves)
• Pre-ganglionic axons extend a long distance (as the parasympathetic ganglia are located further away from the CNS and closer to the effector organs).