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MBS217 > Pathways > Flashcards

Pathways Flashcards

1
Q

What are tonic Receptors?

A

Always active,show little peripheral adaptation and are slow adapting Receptors reminds you of an injury long after it has occurred

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2
Q

What are phasic receptors?

A

Normally inactive
Become active after a short while whenever a change occurs
Provides information about the rate of change and intensity
And are fast adapting receptors

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3
Q

What are mechanoreceptors ?

A

Sensitive to stimuli that distort their plasma membranes
Contain mechanically gated ion channels whoose gates open or close in response to stretching,compression and twisting

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4
Q

What are the 3 classes of mechanoreceptors?

A

Tactile -provide sensations of touch,pressure and vibration
Baroreceptors-Detect pressure changes in the walls of blood vessels and in portions of digestive,reproductive and urinary tracts
Prioprioreceptors

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5
Q

What are the types of tactile receptors?

A

Tactile discs -Merkels disc’s extremely sesive to tonic Receptors
Tactile corpusules -perceive sensations of fine touch,pressure and low frequency vibrations
Root hair plexus -Across the body surface wherever hairs are located
Free nerve endings -Sensitive to pressure and touch

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6
Q

What is a first order neuron?

A

Delivers sensations from receptors to Cns
Located in dorsal root ganglion or cranial nerve ganglion

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7
Q

What is a second order neuron?

A

Delivers sensation from spinal cord to thalamus
May be located in spinal cord or brain stem

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8
Q

What is a third order neuron?

A

Second order neuron synapses with 3rd order neuron in the thalamus and delivers sensation from thalamus to sensory cortex

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9
Q

What are the 3 major somatic sensory pathways?

A

Spinothalamic
Posterior column
Spinocerebellar

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10
Q

What is the spinothalamic pathway?

A

Conscious of crude touch,pressure,pain and temperature
1st order-Synapse with 2 nd order neuron within posterior gray horns and these neurons enter spinal cord

2nd-ascending within anterior or lateral spinothalamic tracts
Ant-cary crude touch and pressure
Lat-pain and temp(referred pain)

3rd order-synapse in ventral nucleus group of thalamus

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11
Q

What is reffered pain?

A

Pain felt in an uninjured part of the body

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12
Q

What is the posterior column pathway?

A

Carries sensations for fine touch,pressure, vibration and proprioception
And the fasciculus gracillis and cutaneous tracts are involved
1st-Axons enter the spinal cord in the dorsal root ganglion and ascend to medulla oblongata where they join fasciculus grascillis or cuneatus
2nd-Axons cross over to opposite side of MO before entering medial lemniscus and ascend to thalamus
3rd-In the ventricular nuclei of the thalamus

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13
Q

What is the diffrence between dorsal column medial lenisical pathway and anterior spinothalamic tract?

A

Sensations
Final destination
Site of cross over
Location of neuron cell bodies

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14
Q

What are Brodmann Areas?

A

Region of the cerebral cortex and defined by its cytoarchitecture or histological structure and organization of cells

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15
Q

What is the spinocerebellar pathway?

A

It carries information from the muscle spindle golgi tendon and joint capsule

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16
Q

What does the cerebellum recieve proprioceptive information about?

A

Skeletal muscle
Tendons
Joints

17
Q

What are the spinocerebellar tracts?

A

Posterior and Anterior

18
Q

What are the posterior spinocerebellar tracts?

A

They contain 2nd order axons that do not cross over the opposite side of the spinal cord they just reach cerebellar cortex via inferior cerebellar punduncle

19
Q

What are the anterior spinocerebellar tracts?

A

It is dominated by 2nd order neurons that have crossed over
Sensations reach cerebellar cortex via superior cerebellar punduncle and many axons cross over and move up to cerebellum then crosses over again within cerebellum and synapsing on same side as original stimulus

20
Q

What are muscle spindles?

A

They are sensory receptors within the belly of a muscle and they consist of specialized muscle fibers that are covered in a connective tissue capsule and the detect changes in length and convey this information to Cns and information is processed by brain and determine the position of body parts

21
Q

What are intra fusal muscle fibers?

A

Each consists of a bundle of small skeletal muscle fibers and are surrounded by larger extra Futsal muscle fibers

22
Q

What do muscle spinsle fibers consist of?

A

Central part non contraction part
It receives sensory innervation
Peripheral part contractile part
Recieves motor innervention
When it contracts it causes stretch of central receptor

23
Q

What is the sensory region?

A

Central region of intrafusal fibers and has dendrites for sensory neurons and synapses into motor neurons in the anterior gray horn of spinal cord

24
Q

What is the muscle spindle innervated by?

A

Gamma motor neurons

25
Q

What is the function of a muscle spindle?

A

When ever a muscle is stretched the muscle spindle is stimulated
And it detects change in length of muscle fibers and rate of change at which muscles are stretched

26
Q

What are alpha motor neurons?

A

Axons of the sensory neurons synapse directly with motor neurons in the spinal cord and they are called alpha motor neurons

27
Q

What are gamma motor neurons m

A

Motor neurons that inerbate the intrafusal fibers
Their axons are called gamma efferents and they enable Cns to adjust the sensitivity of muscle spindle

28
Q

How is the muscle spindle excited?

A

By lengthening the whole muscle
Contractio of end portion of the intrafusal fibers

29
Q

What is the golgi tendon organ?

A

It is in the muscle tendon junction it is sensitive to tension and it monitors the tension and causes muscle to relax

30
Q

What does the cerebellum monitor?

A

Proprioceptive sensations
Visual information from the eyes
Balance sensations from inner ear as movements are under way

31
Q

How are motor activities modified and refined?

A

The motor cortex sends AP to LMN and these Ap from motor cortex will infirm the cerebellum of intended movement
The LMN in spinal cord sends AP to skeletal muscles which causes them to contact
Proprioceptive signals from skeletal muscles and joints to the cerebellum will convey information concerning the status of the muscles and structure being moved during contraction
Cerebellum becomes the comparator
Aps from cerebellum to spinal cord modify stimulation from motor cortex to LMN and Aps from cerebellum are sent to motor cortex to modify its motor activity

32
Q

What does stretching the central portion of the intrafusal fiber do?

A

It distorts the dendrites and stimulates the sensory neurons and increases the frequency of AP generation

33
Q

What does compressing the central portion of the intrafusal fiber do?

A

It will inhibit the sensory neuron and decrease frequency of AP generation

MBS217 (27 decks)

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