Reflexes Flashcards

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1
Q

Sensory Modality

A

Type of stimulus activating a particular receptor

touch, pressure, pain, temperature, light

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2
Q

Adequate Stimulus

A

Type of energy a receptor normally responds to

Causes a generator potential (mVolts)

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3
Q

Mechanoreceptors

A

Adequate Stimulus - Pressure, Stretch, Deformation
Activates Stretch-Sensitive ion channels causing ion flow across the membrane
Respond to mechanical stimuli

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4
Q

Proprioceptors

A

Mechanoreceptors in joints and muscles
Signal Body, Limb position and movement in space
Control Voluntary Movement

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5
Q

Nociceptors

A

Pain (Noxious) Stimuli - Tissue damage and heat

Free Nerve Endings

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6
Q

Transduction in Sensory Receptors involves?

A

Opening or Closing Ion Channels

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7
Q

Pacinian Corpsule

A

Senses Vibration

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8
Q

Ruffini Corpsule

A

Skin Stretch

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9
Q

Merkel Receptors

A

Sense steady pressure and texture

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10
Q

Meissners Corspule

A

Respond to flutter and stroking movement

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11
Q

Mechanoreceptor Adaptation

A

Respond only to change or novel event

Signal the onset of stimulus

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12
Q

Rapidly Adapting Receptors

A

Pacinian corpuscles

Meissner corpuscles

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13
Q

Slowly Adapting Receptors

A

Merkel’s Disks

Ruffini Endings

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14
Q

Non Adapting Receptors

A

Nociceptors - free nerve endings

Its Important not to ignore painful stimuli

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15
Q

Pacinian corpuscle Structure

A
A myelinated nerve
with a naked nerve ending
enclosed by a connective tissue capsule
of layered membrane lamellae
separated by fluid
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16
Q

Pacinian corpuscle Action

A
Mechanical Stimulus deforms capsule 
Nerve Ending is Stretched 
Ion Channels Open
Local Depolirisation
Generator Potential
APs Fire 
Fluid Redistribution in capsule rapidly dissipates stimulus
17
Q

Receptive field

A

Stimuli in a specific area activates somatic sensory neuron

18
Q

Acuity

A

Ability to locate a stimulus on the skin and differentiate it from another closeby

19
Q

Lateral Inhibition

A

Sharpening sensory information
In spinal cord for cutaneous information
Contrast bw relevant and irrelevant stimuli
Inhibition of Lateral neurons in 2ry neuron
High precision information components use it

20
Q

Sensory Information goes?

A

Brain
Via thalamus to somatosensory cortex
Sensitive areas occupy greater cortical space

21
Q

Muscle Spindles

A
Monitor Rate of change of muscle length 
and muscle length 
Control Reflexes and Voluntary movement
Ends shorten but central area doesnt so it stretches
In parallel to muscle fibres
22
Q

Golgi tendon organs

A

Monitor tension.stretch on tendons
Stretch receptors
In series with muscle fibres

23
Q

Joint Receptors

A

Monitor Joint angle, rate of angular movement and tension on the joint.

24
Q

Intrafusal Fibers

A

Muscle Fibres with specialised sensory and motor intervention
Contained within a capsule
Central Area has no contractile material
Gamma Motor Neuron from CNS contract the ends contain contractile sarcomeres

25
Q

Intrafusal + Extrafusal Fibers

A

Form a muscle spindle

26
Q

Extrafusal Fibers

A

Contractile Skeletal muscle fibres

Alpha Motor Neuron from CNS

27
Q

Ia Afferent Nerves

A

Wrap around the centre of intrafusal fibres forming Anulospiral Endings

28
Q

Tendons are affected greatly by?

A

Contractile Strength

Less by passive stretch since they are inelastic

29
Q

Stretch Reflex

A

Initially Muscle Stretches
1) Directly activates the a-motor neurones to the muscle which is stretched - (AGONIST) so it contracts
Monosynaptic Reflex
Negative Feedback Loop
2) RECIPROCAL INHIBITION
Spindle Afferents connect with active inhibitory interneurones which decrease activation of a-motorneurones to the antagonist which then relaxes
3) Spindle afferent connects with somatosensory brain