Topic 10 - Spinal reflexes

Question 1

What is the definition of a reflex?

Answer 1

a rapid, involuntary but sterotyped and co-ordinated response to a sensory stimulus.

Question 2

Describe spinal reflexes:

Answer 2

• Require stimulation (so not spontaneous)
• Quick (few synapses involved)
• Involuntary and automatic
• Stereotyped = occur the same way each time.
• SOMATIC reflexes are also called spinal reflexes as involve spinal cord circulatory.

Question 3

what are ‘extensors’ and ‘flexors’ in the patellar reflex?

Answer 3

Extensors = muscle causing limb to extend

Flexors =. muscle causing limb to flex (bend)

Question 4

What else is the the stretch reflex called?

Answer 4

The Myotactic reflex.

Question 5

What is GTO the golgi tendon organ for?

Answer 5

GTO is for tension detection.

• it is another kind of proprioceptor
• They detect muscle tension due to muscle contraction, not muscle stretch (which muscle spindles detect).
• The golgi tendon reflex is a negative feedback circuit - regulates muscle tension and protects muscle by preventing it contracting it too much.

Question 6

What is the flexor (withdrawal) reflex?

Answer 6

= a quick contraction of flexor muscles to withdraw a limb from injurious stimulus like heat or cut.

• reflex withdrawal when activation of nocioceptive sensory receptors.
• Is a polysynaptic reflex - Activation of multiple excitatory interneurons sustains the response:
• ’Parallel after-discharge circuit’… less synapses = quicker