Introduction to Neuroscience

Question 1

How is the PNS divided?

Answer 1

Somatic PNS - controls motor and sensory functions of the body wall, - skin + skeletal muscles

Autonomic Nervous System - Sympathetic + Parasympathetic

Question 2

Direction of Afferent Axons + Efferent Axons + Interneurons?

Answer 2

• Towards the CNS
• Away from the CNS
• CNS neurons that synapse with other CNS neurons in the brain and spinal cord.

Question 3

Where does the CNS end

Answer 3

At the margins of the spinal cord.

The dorsal and ventral roots emerging from the spinal cord are part of the PNS.

Question 4

Describe Spinal Nerves?

Answer 4

• They both contain afferent and efferent axons.
• Bundled into fascicles surrounded by perineurium.
• Whole nerve is in a tough epineurium
• individual axons are wrapped with myelin and endoneurium

Question 5

Neuron regeneration?

Answer 5

Peripheral nerve axons can regenerate after injury.

Compromised by aberrant axon sprouting - neuropathic pain

Question 6

Why can’t CNS neurons regenerate?

Answer 6

can’t regenerate over long distances, because:

• inhibitory molecules in CNS not PNS
• absence of guidance cues stimulating axon growth during development
• loss of intrinsic axon growth by the neuron.

Question 7

Spinal cord Anatomy -

Answer 7

Grey matter = neuronal cell bodies

White matter = ascending and descending axon tracts to and from brain.

Question 8

Fast Reflex Requires

Answer 8

Somatic input to the spinal cord.
Motor outputs from SC required only.
They have to be intact.

Question 9

Concious Registering

Answer 9

• Sensory inputs activates further sensory neurons in the grey matter.
• These transmit action potentials to the sensorimotor cortex of the brain
• sensorimotor cortex of the brain extends axons downwards (descending tracts) to synapse with spinal motor neurons