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Physiology > Reflexes > Flashcards

Reflexes Flashcards

1
Q

What are the 2 classifications of reflexes?

A

Somatic (muscle) or autonomic (saliva).

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2
Q

What is the orderly sequence of events which reflexes are involved with?

A

Reflex Arc

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3
Q

What are the two types of reflexes (synaptic)?

A

Monosynaptic or polysynaptic.

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4
Q

What is a reflex?

A

A reflex is an involuntary stereotyped coordinated response to a stimulus.

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5
Q

What is the result when a muscle is stretched?

A

Reflex contraction, muscle ‘fights back’

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6
Q

What do these correlate to?

(a) Sensory receptor
(b) Afferent nerve fibre
(c) Synapse

A

(a) Muscle spindle
(b) IA afferents
(c) Spinal cord

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7
Q

What do these correlate to?

(d) Motor fibers
(e) Effector organ contracts

A

(d) alpha motor neuron

(e) Skeletal muscle

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8
Q

What is a reflex an example of?

A

Negative feedback

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9
Q

What does a mechanoreceptor respond to ?

A

A mechanoreceptor responds to stretch, and therefore responds to length changes in the muscle.

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10
Q

What are mechanoreceptors composed of?

A

Of Intrafusal and muscle fibers which lie parallel to EXTRAFUSAL FIBERS.

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11
Q

What are the two components at the centre and poles of the intrafusal fibers?

A

They have non-contractile centres and some contractile tissue at either end (poles.

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12
Q

What are the 2 types of intrafusal fibers?

A 
Nuclear Bag (jumbled)
Nuclear Chain (tidy, rolls)
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13
Q

What is spinal innervation - motor innervation? (DEFINITION)

A

This is when gamma (y) motor neurons innervate intrafusal fibers of the muscle spindle.

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14
Q

What nerve endings does sensory innervation involve?

A

Primary, annulospiral nerve endings, which are Type 1a afferents - detect amount of muscle stretch

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15
Q

What are two characteristics about primary, annulospiral nerve endings which are type 1a afferents. Speed and size?

A

They are rapidly conducting myelinating neurons.

They are larger than Type II

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16
Q

What are three characteristics (speed, covering, response) of secondary flower spray endings , what type are they?

A

These type two afferent; secondary flower spray endings are static in response, myelinated and are SLOWER conducting neurons in comparison to type 1a.

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17
Q

What do primary annulospiral nerve endings mainly innervate(intrafusal fibers)?

A

BOTH (I) nuclear bag and chain fibers - type II mainly CHAIN FIBERS

18
Q

What is an example of how the postsynaptic reflex is activated?

A

Activated in response to a painful stimulus - therefore; a protective reflex.
Very rapid response.

19
Q

What reflex supports the body weight against gravity as you move away from the stimulus that triggered the polysynaptic reflex?

A

The crossed extensor reflex.

20
Q

Where does the golgi tendon organ reflex arc lie?

Mechanoreceptor

A

It lies at the junction between tendon and muscle.
It is very sensitive to muscle tension.
Tendon detects tension

21
Q

Where do GTO lie in correlation with the muscle?

A

In series.

22
Q

What innervates the GTO collagen of tendon?

A

The nerve terminals

23
Q

How is sensory information sent in the GTO reflex arc? Describe the size of these fibers?

A

Sensory information is sent via the 1b afferents.

These have a large diameter and are rapidly conducting fibers

24
Q

During muscle contraction for example biceps muscle when holding an object what does the GTO detect?Where is this information sent to and what happens?

A

It detects tension in contracting muscle.
Sensory information is carried into the spinal cord.
Here is where it then synapses with an interneuron.

25
Q

What happens if the tension on the muscle becomes excessive? relevant to the GTO.

A

If tension becomes excessive this can result in INHIBITION of contracting muscle (motor neuron) and therefore reflex relaxation.
This may be a protective reflex (polysynaptic) as it can prevent excessive force on the muscle.

26
Q

What is the final common pathway also referred to as neurone wise?

A

Lower motor neurons.

27
Q

How does sensory information enter the brain?

A

Via the dorsal route, the back of the brain.

28
Q

Do all skeletal muscles have spindles?

A

Yes, some have more than others.

29
Q

What innervates the extrafusal motor neurons?

A

The alpha motor neurons.

30
Q

What is the main function of the GTO (Golgi tendon organs)?

A

To be protective from excessive force in the muscle via inhibition.

31
Q

Muscle spindles and gto are both?

A

Mechanoreceptors.
These are also proprioceptors these are tension/force detectors - (make us aware of the body position sense. An awareness of the body position)

32
Q

Why are stretch reflexes important?

A

These reflexes are important in the overall maintenance of normal posture and balance as reflexes allow for rapid autonomic adjustments as required by the muscle.

33
Q

Where are muscle spindles and stretch reflexes especially prominent?

A

In the anti-gravity muscles, also neck muscles and in muscles where fine control is required.
These prevent over stretching by initiating reflex contraction.

34
Q

What does the golgi tendon organ prevent against?

A

The excessive force generation in a muscle.

35
Q

Why is the GTO important feedback control wise?

A

It is important in the control of muscle length in response to a load and so can help prevent jerky movements and thus have a damping or smoothing effect.

36
Q

Where are upper motor neurons made?

A

In the brain.

37
Q

What do the impulses of the UMN do to the LMN?

A

Either facilitate or inhibit.

38
Q

What does damage to LMN lead to?

A

A reduced/absent stretch reflexes and a FLACCID PARALYSIS.

39
Q

What is the purpose of the cell body in the spinal cord located from where the axon travels out directly to the skeletal muscle?

A

To stimulate it to contract.

40
Q

Where are LMN stimulated from?

A

The UMN

41
Q

How many muscle fibres do the LMN supply?

A

from 1 to perhaps hundreds (the motor unit

Physiology (5 decks)

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