Somatic Sensory And Motor Pathways

Front 1

What are sensory receptors?

Back 1

specialized cells that provide the central nervous system with information about conditions inside or outside the body

Front 2

Where are general sensory receptors located?

Back 2

throughout the body

Front 3

Where do sensory pathways begin and end?

Back 3

they begin at peripheral receptors and end in the CNS, usually in the diencephalon or cerebral hemispheres

Front 4

What is the information carried by a sensory pathway called?

Back 4

a sensation

Front 5

What is perception?

Back 5

our concious awareness of a sensation

Front 6

What is the relationship between a receptive field and localizing a stimulus?

Back 6

the larger the receptive field, the poorer your ability to localizee the stimulus

Front 7

What is sensory modality?

Back 7

A unique sensation

ex. pain vs. pressure vs. light

Front 8

What are the two classes of sensory modalities?

Back 8

1. general senses
-somatic
-visceral
2. special senses

Front 9

What are the four steps in the process of sensory and motor pathways?

Back 9

1. stimulation
2. transduction
3.. generation of nerve impulse
4. integration

Front 10

What are the simplest receptors?

Back 10

dendrites of sensory neurons

Front 11

Why do dendrites of sensory receptors exhibit little receptor specificity?

Back 11

they can be stimulated by a large variety of stimuli

Front 12

What alters the sensitivity and specificity of a free nerve ending?

Back 12

its location and presence of accessory structures

Front 13

What are the three sensory receptor locations?

Back 13

exteroceptors, interoceptors, proprioceptors

Front 14

Where are exteroceptors activating stimuli?

Back 14

at or near the body surface, external environment, touch, pressure, vibration, thermal, pain

Front 15

Where are interoceptors activating stimuli?

Back 15

in blood vessels, visceral organs, nervous system, internal environment, not consciously perceived, felt as pressure or pain

Front 16

Where are proprioceptors activating stimuli?

Back 16

in muscles, tendons, joints. could be body position, muscle length and tension, joint motion and position

Front 17

What are the five types of stimulus detected?

Back 17

mechanreceptors, thermoreceptors, nociceptors, chemoceptors, osmoreceptors

Front 18

How many different types of mechanoreceptors are there in the body?

Back 18

six

Front 19

Describe mechanoreceptors.

Back 19

detect mechanical pressure like touch, vibration, pressure, proprioception, blood vessels and organ stretch

Front 20

What do thermoreceptors detect

Back 20

changes in temp

Front 21

What type of receptrs are nociceptors?

Back 21

pain from physical or chemical damage to tissue

Front 22

What do chemoreceptors respond to?

Back 22

chemicals in body fluids

Front 23

What do osmoreceptors respond to?

Back 23

osmotic pressure of body fluids

Front 24

How can receptors for general senses be classified?

Back 24

by function and sensitivtiy

Front 25

What are the two types of responses to stimulation?

Back 25

tonic or phasic

Front 26

Compare tonic and phasic receptors.

Back 26

tonic recepts are always active and producing action potentials. when the stimulus increass or decreases, the rate of action potential generation changes. A phasic receptor is normally inactive but becomes active for a short time in response to changes in conditions they are monitoring

Front 27

Compare peripheral and central adaptation.

Back 27

peripheral adaptation-level of receptor activity changes
central adaptation-occurs along sensory pathways in the CNS and involves inhibition of the nuclei on this pathway

Front 28

What are the six different types of tactile receptors?

Back 28

1. free nerve endings
2. root hair plexus
3. tactile discs and merkel cells
4. tactile corpuscles
5. lamellated corpuscles
6. ruffini corpuscles

Front 29

Where are free nerve endings found?

Back 29

everywhere in the skin and other tissues

Front 30

What do free nerve endings detect?

Back 30

touch and pressue

Front 31

What type of tactile receptor respons to tickles, itches, and light touch?

Back 31

free nerve endings

Front 32

What type of fiber does free nerve endings info travel on?

Back 32

Type C-unmyelinated
2 m/sec

Front 33

Where are Meissners corpuscles found?

Back 33

nonhairy parts of the skin; abundant in fingertips and lips

Front 34

What do Meissners corpuscles detect?

Back 34

spatial locations of touch, movment of an object over an area, low frequency vibration

Front 35

Where are Merkel's discs found?

Back 35

Hairy and non-hairy parts of the skin

Front 36

Do Meissners corpuscles adapt quickly or slowly?

Back 36

quickly

Front 37

What do Merkels discs detect?

Back 37

sensations of continuous touch of objects against the skin

Front 38

Do Merkels discs adapt quickly or slowly?

Back 38

slowly

Front 39

What do Meissners and Merkels detect together?

Back 39

localizing touch sensations and determining an objects texture

Front 40

Where are root hair plexuses found

Back 40

the hair end organ

Front 41

What sensation is detected by a root hair plexus?

Back 41

initial body contact and subsequent movements

Front 42

Describe Ruffini's corpuscles structure.

Back 42

multibranched, encapsulated nerve endings

Front 43

Where are Ruffini's corpuscles located?

Back 43

deep layers of the skin and deeper internal tissues

Front 44

What sensation is detected by Ruffini's corpuscles?

Back 44

deep pressure

Front 45

Do Ruffinis corpuscles adapt very quickly or very slowly?

Back 45

very slowly

Front 46

Do root hair plexuses adapt very quickly or very slowly

Back 46

very quickly

Front 47

Where are pacinian corpuscles located?

Back 47

immediately beneath the skin

Front 48

What type of stimulation do pacinian corpuscles detect?

Back 48

rapid local compression; pulsing or high frequency vibrating stimuli

Front 49

What type of fibers do meissners, merkels, ruffinis, and pacinian travel?

Back 49

AB fibers
30-70 m/sec

Front 50

What are the three sets of neurons long the somatic sensory pathways?

Back 50

first order, second order, and third order

Front 51

Where do first order neurons originate and synapse?

Back 51

they originate in somatic receptors into the brain stem or spinal cord

Front 52

Where are second order neurons located?

Back 52

from teh brain stem and spinal cord to the thalamus for conscious awareness

Front 53

What happens to the axons in the brain stem or spinal cord before they ascend to the hypothalamus?

Back 53

they cross over to the other side

Front 54

Where are third order neurons located?

Back 54

synapse with second order neurons in the thalamus to the primary somatosensory area of the cortex on the same side

Front 55

Impulses headed for the cortex travel along what two pathways?

Back 55

posterior column or spinothalamic pathway

Front 56

Impulses headed for the cerebellum travel along what pathway?

Back 56

the spinocerebellar pathway

Front 57

Is the anterior or posterior spinocerebellar tract responsible for axons that have crossed over from the other side of the spinal cord?

Back 57

anterior

Front 58

What type of sensations does the posterior column pathway carry to the cerebral cortex?

Back 58

fine touch, vibration, pressure, and proprioception

Front 59

Describe the patway of an action potentialin the posterior column pathway.

Back 59

first order neuron travels up the spinal cord, synapses with second order neuron, crosses over to opposite medial lemniscus, synapes with thierd order neuron in the ventral nuclei of the thalamus, third order neuron brings info to the primary sensory cortex

Front 60

Where does the sensory info decussate in a posterior column pathway?

Back 60

the medulla oblongata

Front 61

What types of sensations does the spinothalamic pathway take to the primary sensory cortex?

Back 61

localized crude touch, pressure, pain, and temperature

Front 62

What are the two tracts of the spinothalamic pathway?

Back 62

anterior and lateral

Front 63

What sensations does the anterior spinothalamic tract of the spinothalamic pathway carry?

Back 63

crude touch and pressure

Front 64

What sensations does the lateral spinothalamic tracts of the spinothalamic pathway carry?

Back 64

pain and temperature

Front 65

In the spinocerebellar pathway, when does information coross over?

Back 65

ONLY if the information comes from the RIGHT side

Front 66

What type of information does the cerebellum recieve from the spinocerebellar pathway?

Back 66

proprioceptive input from Golgi tendon organs, muscle spindles, and joint capsules

Front 67

How many synapses are there in the spinocerebellar pathway?

Back 67

one

Front 68

How many motor neurons does the somatic motor pathways always involve?

Back 68

at least two

Front 69

Where does an upper motor neuron's cell body lie?

Back 69

in a CNS processing center

Front 70

Where does a lower motor neurons cell body lie?

Back 70

in the nucleus of a brain stem or spinal cord

Front 71

What pathway provides voluntary control over skeletal muscles?

Back 71

corticospinal

Front 72

What are the nuclei of the medial pathway?

Back 72

superior and inferior colliculi, reticular formation, vestibular nucleus

Front 73

What are the nuclie of lateral pathway?

Back 73

the red nuclei

Front 74

what does the lateral pathway help control?

Back 74

the distal lim muscles that perform more precise movements

Front 75

What does the medial pathway help control?

Back 75

gross movements of the trunk and proximal limb muscles

Front 76

What is the relationship between the distance of a motor center from the cortex to the complexity and variability of the motor activities there?

Back 76

the closer a motor center is to the cerebral cortex, the more complex and variable the motor activities will be

Front 77

What happen when you make a conscious decision to perform a specific movement?

Back 77

information is relayed from the frontal lobes to the motor association areas, then these areas relay the information to the cerebellum and basal nuclei

Front 78

What happens once the movemtn begins?

Back 78

th emoter association areas send instructions to the primary motor cortex

Front 79

What is referred pain?

Back 79

the sensation of pain in a part of the body other than its actual source

Front 80

What does the SNS provide?

Back 80

conscious and subconscious control over the skeletal muscles of the body