Somatic Nervous System

Question 1

Is the somatic nervous system voluntary or involuntary?

Answer 1

Voluntary

Question 2

What are the primary functions of the somatic nervous system?

Answer 2

• Sensory perceptions
• Special senses
• Connecting to skeletal muscles

Question 3

Complete the sentence:
Nerves are collections of…

Answer 3

Neurones

Question 4

Which part of the CNS does the somatic nervous system communicate with?

Answer 4

The somatomotor cortex.

Question 5

What are the components of the somatic nervous system?

Answer 5

• Cell body located in the CNS (often in the spinal cord)
• The motor neurone is part of the PNS and runs to skeletal muscle
• Neurone releases ACh (always excitatory)

Question 6

How does the signal transduction route work in the somatic nervous system?

Answer 6

• Incoming information from afferent neurones is coordinated in the CNS (spinal cord)
• Somatomotor cortex helps to programme the motor response too.
• Efferent nerves transmit impulses from the CNS to skeletal muscles causing contraction.

Question 7

Where is the somatomotor cortex located?

Answer 7

Within the cerebral cortex

Question 8

How is a signal transported through the somatic system? (E.g., use a fly bite on the skin)

Answer 8

• Sensory receptor in the skin detects flies biting
• Sensory (afferent) neurone conducts nerve impulse to the CNS
• Ascending neurone in CNS carries info to cerebral cortex. Brain plans a response.
• Impulse conducted from upper motor neurone of the somatomotor cortex to the lower spinal neurone.
• Impulse sent to skeletal muscle which contracts.

Question 9

What is the definition of a reflex arc?

Answer 9

The neural pathway mediating a reflex action.

Question 10

Complete the sentence:
Reflexes that output to skeletal muscles use the same nerve pathways as the … even though they are not voluntary.

Answer 10

Somatic nervous system.

Question 11

What is the function of somatosensory receptors?

Answer 11

They detect pain, temperature, touch and body position.

Question 12

For each of the following receptors, state where they are found and what they detect:
1) Golgi tendon organs
2) Muscle spindles
3) Meisnners corpuscles
4) Merkel’s disks
5) Pacinian corpuscles
6) Ruffini corpuscles
7) Free nerve endings

Answer 12

1) Tendons - stretch
2) Muscles - stretch
3) Skin - light touch
4) Skin - light touch and texture
5) Skin - Pain and deep pressure
6) Skin, joints, ligaments - stretch + proprioception
7) Skin, deep tissues, organs - pain + temp