8.3

Question 1

What makes up the spinal cord?

Answer 1

White matter (myelinated axons)
Grey matter (cell bodies, glia, neurons, unmyelinated axons)
Central canal (flow of CSF)
Dorsal root (sensory input, afferent)
Ventral root (motor output, efferent)

Question 2

What is the communication pathway of the spinal cord?

Answer 2

2 way communication pathway
Ascending tract (sensory)
Descending tract (motor)
Conducts signalling between the brain and rest of the body

Question 3

How is the spinal cord organised?

Answer 3

• Dorsal Horn (somatic and visceral sensory nuclei)
• Ventral Horn (somatic motor nuclei)
• lateral horns (visceral motor nuclei)
• grey commissure (joining the two sides of spinal cord, unmyelinated axons)

Question 4

What are the two types of nerves?

Answer 4

Cranial and spinal nerves

Question 5

What are cranial nerves?

Answer 5

Exit bia the brain
12 pairs
Primarily innervate regions of head and neck

Question 6

What are spinal nerves?

Answer 6

• Exit via the spinal cord
• 31 pairs
• mixed nerves (sensory, somatic, autonomic)
• innervate the rest of the body

Question 7

Describe sensory neurons

Answer 7

• afferent
• body to the CNS
  Sensory receptors —> peripheral nerves —> spinal cord and brain

Question 8

Describe motor neurons

Answer 8

• efferent
• CNS to the body
  Brain and spinal cord —> peripheral nerves —> effector organs
• motor commands instructing movement

Question 9

What are the 5 sensory receptors?

Answer 9

Thermo-receptors (temperature)
Mechano-receptors (touch, pressure, vibrations)
Chemoreceptors (chemical stimuli)
Photo-receptors (light)
Nociceptors (pain)

Question 10

Describe chemoreceptors

Answer 10

• respond to chemical changes in the environment
• potential stimuli (pH, CO2 and O2 levels)
  Present in the medulla oblongata, carotid bodies and aortic bodies

Question 11

Describe baroreceptors

Answer 11

Mechanorecerptors
Detect changes in pressure
Regulate visceral (autonomic) function

Question 12

Describe proprioception

Answer 12

• sense ones own body position
• guided by proprioceptors (specific nerve receptors, present in muscle, tendons and joints)
• corrective movement in response to sensory feedback
• disturbed in many biological disorders
• utilised in the sobriety test

Question 13

Describe visceral sensations

Answer 13

• Communication between the viscera (internal organs) and the CNS
• stimuli are detected by: mechano, Chemo and Baro receptors
• alert the NS to disruption in homeostasis

Question 14

What are reflexes?

Answer 14

An essential protective mechanism
- rapid, immediate action to sensory stimuli
- occur via the spinal cord (circumvent the brain, occur prior to conscious perception

Question 15

What are the 4 classifications of reflexes?

Answer 15

Development (innate, Acquired)
Nature of response (somatic, visceral)
Complexity of the circuit (monosynaptic, polysynaptic)
Processing site (spinal, intersegmental, cranial)