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Flashcards in Reflex Movement Deck (18)
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1

What are the different types of movements

Involuntary actions - reflexes
Semi-automatic actions
Voluntary actions

2

Describe involuntary actions

No conscious element - involuntary
Centred on:
- Spinal cord (spinal nerves)
Brainstem (cranial nerves)
Stereotyped response
Monosynaptic circuit
Rapid, short latency (delay)

3

How many synapses do reflex arcs have

1 central synapse so its a monosynaptic arc

4

How is matter arranged in the spinal cord

Central grey matter surrounded by white matter

5

What are the components of a reflex pathway

Stimulus
Receptor
Afferent (sensory neurone)
Synapse(s)
Efferent (motor) neuron
Effector (muscle, gland)
Response

6

Why is the intermediate horn important

Important for the thoracic and lumbar regions as this is the main source of output for sympathetic nervous system

7

Describe the interneurone

Isn’t always necessary
Can recruit motor neurones
Path is slower as the pathway isn’t monosynaptic

8

Give examples of somatic reflex receptors in the tendon jerk reflex

Proprioceptor endings
Group 1a muscle afferents
Homonymous motor neurons

9

Give examples of somatic reflex receptors in cutaneous reflexes

Mechanoreceptor endings
Nociceptor endings

10

Give examples of some other somatic reflex receptors

Chemoreceptors
Photoreceptors

11

Describe the ankle jerk reflex

Hammer tap to Achilles’ tendon stretches spindles within gastrocnemius
Action potentials conducted along 1a muscle afferents to spinal cord
Monosynaptic activation of motor neurons of gastrocnemius muscle
APs travel along Aa motor axon
Gastrocnemius muscle contracts and foot extends

12

Describe the jaw jerk reflex

Hammer tap to chin stretches spindles of jaw elevator muscles (masseter, temporalis, medial pterygoid)
APs conducted along 1a muscle afferents to brainstem
Monosynaptic activation of motor neurones of jaw elevator muscles
APs travel along A motor axon, jaw elevator muscles contract and jaw jerks upwards, closing the mouth

13

What are the protection mechanisms of somatic reflexes

Escape mechanism
Prevention of muscle overloading
Prevention of inadvertent foreign body ingestion
Digestive aid

14

Describe the flexion withdrawal reflex

Noxious stimuli activates As and C fibres which activate interneurone which send info through the spinothalamic pathway causing the recruitment of motor neurons which allow a flexion withdrawal reflex
Conscious element involved

15

Describe muscle loading in jaw muscles

No golgi tendon organs in jaw muscles
Bite force controlled by increasing loading of PDL
Afferents inhibit jaw elevator muscle motor neurones
Anaesthesia of molars increases maximum bite force

16

Describe the pharyngeal reflex

Mechanoreceptor afferent from the posterior part of the tongue/soft palate causes stimulation of glossopharyngeal afferent fibres
Afferents terminate in the caudal part of the spinal trigeminal nucleus (SpVn)
Interneurone project from the SpVn to the nucleus ambiguous (X motor nucleus)
E afferents terminate in the muscles they innervates

17

What can salivary reflexes cause

Increased salivary flow

18

What stimuli can activate salivary reflexes

Gustatory (taste) stimuli
Visual, olfactory stimuli
Chewing forces