DHUBS 2 - WEEK 11 - EXAM

Question 1

What occurs in a crossed cord reflex?
o What would happen in the right tricep and bicep with activation of the left
bicep?

Answer 1

In addition to Ia afferent fibres exciting the alpha motor neurones for their own muscle, interneurones modulate other motor neurones
E.g. Activation of the right biceps will cause inhibition of the right triceps
- The antagonist is inhibited (right triceps)
- The contralateral antagonist is facilitated (left triceps)
- The contralateral agonist is inhibited (left bicep)

Question 2

What is an example of a polysynaptic reflex?

Answer 2

Withdrawal reflex:
Also known as the flexor reflex, this reflex occurs when you pull away from a painful stimulus, such as when you touch something hot.

Question 3

What receptors influence postural reflexes?

Answer 3

Proprioceptors in the muscles and joints
Cutaneous receptors in the skin
Vestibular receptors in the ear
Visual receptors in the retina of the eye
Auditory receptors in the ear

Question 4

What is the difference between short and long latency reflexes?
o What pathways and systems are utilized for each type?

Answer 4

Long latency reflexes allow for more integrated responses to postural perturbations.
Short latency reflexes allow for rapid responses to postural perturbations (20-45 ms).

Long latency reflexes utilise brainstem pathways, including inputs from the vestibular system, visual system and proprioceptive system.

Short latency reflexes utilise spinal cord pathways, including monosynaptic muscle stretch and polysynaptic crossed cord reflexes.

Question 5

Free nerve endings may respond to what type of stimuli?

Answer 5

• Pressure
• Chemicals
• Temperature

Question 6

What are free nerve endings commonly associated with?

Answer 6

Pain sensation.

Question 7

What is the difference between exteroceptors and interceptors?
Give examples of each.

Answer 7

Exteroceptors transduce information from the external environment.
- Light for vision
- Pressure for touch

Interoceptors transduce information from the internal environment.
- Stretch receptors from the gut
- Blood pressure receptors in the aorta

Question 8

What are the primary actions of each of the eye muscles?

Answer 8

Lateral rectus - Abduction

Medial rectus - Adduction

Superior rectus - Elevation, Intorsion, Adduction

Inferior rectus - Depression, Extorsion, Adduction

Superior oblique - Intorsion, Depression, Abduction.

Inferior oblique - Extorsion, Elevation and Abduction.

Question 9

What are the differences between rods and cones?
Where are each one more densely located, and what do they do?

Answer 9

Rods detect light. Rods are found in the peripheral retina and are better at detecting motion and low light vision.

Cones detect colour. Cones are found more densely in the macula where there is better clarity of vision and colour.