Reflexes + Autonomic Physiology

Question 1

Describe the stretch reflex

Answer 1

• Found in all muscle

1. Direct contact with motoneurones in stretched muscle causing rapid contraction of agonist muscle (monosynaptic reflex)
2. Agonist contracts, antagonist muscle reflexes (reciprocal inhibition)
3. Spindle efferent firing also travels up dorsal columns to thalamus and somatosensory cortex

Question 2

Reflex mediated by Golgi tendon organs

Answer 2

• Inverse stretch reflex

Question 3

Ipsilateral reflex

Question 4

Contralateral reflex

Question 5

Role of interneurones

Answer 5

• Reduces motor neurone firing (muscle relaxes rapidly)

Question 6

Flexor-withdrawal reflex

Answer 6

1. Activity in the flexor muscle affected
2. Antagonist extensors are inhibited
3. Excitatory interneurones cross spinal cord and excite the contralateral extensors
4. Other interneurones cross spinal cord and excite the contralateral extensors

Question 7

Roles of higher centres in reflexes

Question 8

Anatomy of sympathetic and parasympathetic branches of ANS

Answer 8

Sympathetic: thoracic (1-2) and lumbar (1-5)
Parasympathetic: cranial ( 3,7,9,10 ) and sacral (2 -4)

Question 9

Neurotransmitters of autonomic innervention

Answer 9

Acetylcholine

+ nor adrenaline

Question 10

Receptors of autonomic innervention

Answer 10

Acetylcholine - cholinergic (nicotinic + muscarinic)

Noradrenaline - adrenergic (a +b)

Question 11

Functional aspects of autonomic intervention

Question 12

Effect of autonomic intervention on major organs

Answer 12

Eye ~ contracts sphincter to make pupil smaller, eye focuses close up
Heart ~ decrease heart rate, little effect On strength of contraction
Lungs ~ smooth muscle contract and constricts airways

Question 13

Simple autonomic reflexes

Answer 13

• Spinal reflexes
• have higher control