Topic 5: Nervous System 3 - Integration and Control - Spinal Cord

Question 1

What does the sensory (afferent) division do?

Answer 1

• inputs info to brain and spinal cord (control centres)

Question 2

What does the brain and spinal cord do?

Answer 2

• integrates info and controls effectors through motor (efferent) division (output)

Question 3

Which is responsible for reflexes: The brain or spinal cord?

Answer 3

• spinal cord

Question 4

What are reflexes? (2)

Answer 4

• rapid automatic responses to stimuli
• usually protective

Question 5

What do reflexes need? (2)

Answer 5

• stimulus always cause the same motor response
• involves 2 or more neurons

Question 6

The reflex pathway or arc is a pathway of _____

Answer 6

impulses

Question 7

Reflex pathway diagram

Answer 7

`

Question 8

How are reflexes categorized? (3)

Answer 8

1. Effector
2. Which side of the body the sensory and motor neurons are located
3. Number of Synapses (and neurons) in arc

Question 9

What are the effectors in a reflex for somatic reflex?

Answer 9

skeletal muscle

Question 10

What are the effectors in a reflex for visceral (autonomic) reflex? (3)

Answer 10

• smooth, cardiac muscle
• glands

Question 11

reflexes are categorized based on which side of the body the sensory and motor neurons are. What is an ipsilateral reflex?

Answer 11

• sensory and motor neuron on same side

Question 12

reflexes are categorized based on which side of the body the sensory and motor neurons are. What is contralateral reflex?

Answer 12

• sensory and motor neuron on opposite sides

Question 13

Reflexes are categorized based of number of synapses and neurons in the arc. What is a monosynaptic reflex?

Answer 13

one synapse between 1 sensory and 1 motor neuron

Question 14

Reflexes are categorized based of number of synapses and neurons in the arc. What is a polysynaptic reflex?

Answer 14

• 2+ synapses between 3+ neurons

Question 15

What are 4 examples of SOMATIC spinal reflexes? (3)

Answer 15

1. stretch reflex
2. Flexor (withdrawal) reflex
3. Crossed extensor reflex

Question 16

Give an example of a stretch reflex. Then, name the
a) stimulus
b) receptor
c) effector
4) type of reflex

Answer 16

• knee jerk reflex where extensor muscle contracts
  a) stimulus is tapping patellar ligament, which stretches the quadricep femoris muscle
  b) receptor = muscle spindle (in quad)
  c) effetor = skeletal muscle (quad) which contracts
  d) ipsilateral and monosynaptic

Question 17

Give an example of a flexor (withdrawal) reflex. Then, name the
a) stimulus
b) receptor
c) effector
4) type of reflex

Answer 17

• in leg
  a) stimulus is stepping on a nail
  b) receptor = touch, pressure, pain
  c) effector is hamstrings (flexors) which contracts
  d) ipsilateral and polysynaptic

Question 18

Give an example of a crossed extensor reflex. Then, name the
a) stimulus
b) receptor
c) effector
4) type of reflex

Answer 18

• ex in leg
  a) stimulus is stepping on a nail
  b) receptor = touch, pressure, pain
  c) effector = quad fem in opposite leg (extensor) which contracts
  d) contralateral and polysynaptic

Question 19

What is the purpose of a crossed extensor reflex in the leg?

Answer 19

keeps you from falling down when withdrawal (flexor) reflex occurs

Question 20

Somatic spinal reflexes also include reciprocal inhibition. What is that? (2)

Answer 20

-muscle (or group) contracts (AGONIST)
- at the same time, antagonist is prevented from contracting due to inhibitory interneurons firing

Question 21

What is an example of reciprocal inhibition? (3)

Answer 21

• in stretch reflex
• quadriceps femoris (agonist) contracts
• hamstrings (antagonists) contraction inhibited

Question 22

Give an example of an autonomic Spinal reflex, and name
a) stimulus
b) receptor
c) division of NS and location
d) effector

Answer 22

• Micturition reflex in urinary bladder
  a) stimulus is stretch of bladder
  b) receptor - stretch receptors in bladder wall
  c) CNS in sacral segment of spinal cord (PSNS)
  d) effector = detrusor muscle (wall of bladder) which contracts and internal urethral sphincter opens (both are smooth muscle)