Reflexes

Question 1

What is a reflex?

Answer 1

involuntary, unconscious response to a stimulus

Question 2

What is a learned reflex?

Answer 2

Involuntary, unconscious response to a stimulus acquired through procedural learning and practice

Question 3

Describe the reflex arc.

List the different parts involved in the process.

Answer 3

neural pathway controlling a reflex, involuntary and unconscious response to a stimulus

• Receptor: Muscle spindle -> detects stimulus (change in internal/external environment)
• Afferent fibre: Muscle spindle afferent
• Integration center: Lamina IX of spinal cord
• Efferent fibre: a-motorneurones
• Effector: Muscle

Question 4

Which sensory neurone fibre type responds to muscle fibre proprioception?

Answer 4

IA ≈ Aa

Question 5

Which sensory neurone fibre type responds to Golgi tendon organ proprioception?

Answer 5

IB ≈ Aa

Question 6

Outline the process of the reflex arc in a GTO.

Answer 6

Length of muscle changes changing stretch of tendon (rate of change and tension)

Afferent sensory fibre Ib (Aa)

Integration centre at dorsal root and lamina IX of spinal cord

Interneurones

Anterior motor neurones via Aa motor fibres (extrafusal) and Ay motor fibres (intrafusal)

Effector ≈ Ay muscle spindle ad Aa motor unit changes

Question 7

Outline the process of the reflex arc in a Muscle Spindle.

Answer 7

Length of muscle changes changing stretch of tendon (rate of change and tension)

Afferent sensory fibre Ia (Aa)

Integration centre at dorsal root and lamina IX of spinal cord

Interneurones

Anterior motor neurones via Aa motor fibres (extrafusal) and Ay motor fibres (intrafusal)

Effector ≈ Ay muscle spindle ad Aa motor unit changes

Question 8

Give an example of a monosynaptic stretch reflex.

Answer 8

Knee jerk reflex