Ch 15 Sensory pathways and the somatic nervous system

Question 1

Describe the receptive field. (Figure 15-2)

Answer 1

The area receptive to stimuli monitored by a single receptor cell.

Question 2

General sense receptors are typically the

Answer 2

dendrites of sensory neurons.

Question 3

The conversion of a sensory input to a change in membrane potential in the receptor is known as

Answer 3

transduction

Question 4

A reduction in sensitivity in the presence of a constant stimulus is referred to as

Answer 4

adaptation

Question 5

How do we become aware of the sensation of touch?

Answer 5

General sensory receptors send information to the primary somatosensory cortex.

Question 6

Receptor specificity can arise from __________.

Answer 6

the presence of accessory cells
the structure of the receptor cell
the presence of structures that protect the receptor cell

Question 7

You cannot tell when your small intestines shift position as food enters because you do not have any ________ there.

Answer 7

proprioceptors

Question 8

Receptors in your stomach that determine when food enters because the pH changes would be classified as

Answer 8

chemoreceptors

Question 9

Mechanoreceptors that respond to changes in blood pressure are called

Answer 9

baroreceptors.

Question 10

We are constantly bombarded by a variety of stimuli inside and outside of our bodies. Why are we not overwhelmed by sensory information?

Answer 10

A very tiny percentage of incoming sensory information is received by the cerebral cortex.

Question 11

Pain is to ________ as cold is to _______

Answer 11

nociceptors; thermoreceptors

Question 12

Receptive characteristics

Answer 12

1. Specificity
2. Field
3. Tonic (slow) + phasic (fast)
4. Transduction (convert stimulus to change in membrane potential which leads to AP)

Question 13

Classification of receptor

Answer 13

• stimulus type => name usually define what it is
• location => where stimulus arise

Question 14

What impact the specificity of receptors & how?

Answer 14

Structural complexity
• Free nerve endings
• connective tissue layers around nerve endings
• accessory structures

Question 15

Define Receptive field?

Answer 15

It’s the size that localize the stimulus.
E.g: two-point discrimination

Question 16

Generator potential

Answer 16

If receptor is sensory neuron and when depolarization reach threshold AP generated

Question 17

Receptor potential

Answer 17

When receptor is other type of cell and not neuron in this case graded potential can alter the rate Of NTs release by sensory receptor cell

Question 18

Key features of neural pathways

Answer 18

1. multi-neural-> 2-3 to relay info
2. Spatial relationships among fibers
3. Most decussate (cross sides)
4. Paired symmetrically both R & L sides

Question 19

Immediate involuntary response

Answer 19

Processing centers in the spinal cord or brainstem may direct an immediate reflex response even before sensations reach the cerebral cortex.

Question 20

Voluntary response

Answer 20

The voluntary response, which is not immediate, can moderate, enhance, or supplement the relatively simple involuntary reflexive response.

Question 21

next half start at 21 deck

Key features for neural pathways

Answer 21

=> multi-neural (2-3)
=> Most exhibit spatial relationships
among fibers that reflect mapping
=> Most decussate (cross sides) at
some point
=> Pathways are paired symmetrically

Question 22

define immediate involuntary response

Answer 22

Processing centers in the spinal cord or brainstem may direct immmediate reflex response even before sensation reach cerebral cortex

Question 23

voluntary response

Answer 23

it is not immediate, can moderate, enhance, or supplement the relatively simple involuntary response.

Question 24

name the three pathways for somatic sensory information (SSP)

Answer 24

Posterior column pathway
Spinocerebellar pathway
–posterior/anterior tracts
spinothalamic pathway
–lateral/ anterior

Question 25

explain somatic sensory pathways

Answer 25

• Ascending tracts
• Associated with white matter of spinal
  cord
• Two have 3rd order neurons

Question 26

what are the stimulus for spinothalamic pathway

Answer 26

-provide sensation from the poorly localized touch, pain, and pressure

Question 27

explain the pathway for spinothalamic

Answer 27

First-order neuron => enter spinal cord at the posterior horns on second-order neuron
second => the interneuron cross to the opposite side of the spinal cord.
Third => the interneuron synapse in the primary somatosensory cortext

Question 28

define somatotopy

Answer 28

the functional mapping of the somatosensory cortex. also called ‘homunculus’ mean ‘‘little man’’

Question 29

how map area is divided for different regions in the somatosensory cortex.

Answer 29

like caricature => size of the devoted region for body parts is proportional to the density of the sensory input received from that region.

Question 30

Posterior column pathway

Answer 30

It carries highly localized fine touch, pressure, vibration, and proprioception. also known as posterior column- medial lemniscus pathway

Question 31

bague explanation of spinothalamic

Answer 31

• Inputs come from many
  different types of sensory
  receptors
• May make multiple synapses
  in brainstem
• Aware of stimulus, but have
  difficulty localizing precisely

Question 32

vague explanation of posterior column pathway

Answer 32

• Inputs come from a single or a
  few related types of sensory
  receptor
• Information sorted by 1)
  nature of stimulus and 2)
  body region involved
• Localize stimulus
  precisely on body surface

Question 33

Spinocerebellar pathway

Answer 33

The cerebellum receives proprioceptive information about the position of the skeletal muscles, tendons, and joints along this pathway.

Question 34

Posterior spinocerebellar tract

Answer 34

it contains the axons that do not cross over the opposite side of the spinal cord.
It reach to cerbellar cortex by the inferior cerebellar peduncle of that side.

Question 35

Anterior spinocerebellar pathway

Answer 35

these are dominated by axons that have over to the opposite side of the spinal cord.

Question 36

Adaptation of SSP

Answer 36

it can reduce the amount of sensory
information reaching the CNS (peripheral adaptation) and cerebral cortex (central adaptation)

Question 37

Frequency and pattern of action potentials of SSP

Answer 37

it provides information about the stimulus such as strength duration and variation

Question 38

labeled lines and preception about SSP

Answer 38

• The labeled line that is activated tells the brain about the type of stimulus and where it is coming from
• Your perception of the nature of the stimulus depends on the path it takes in the CNS

Question 39

Visceral sensory pathway

Answer 39

• Visceral sensory information is collected by
  interoceptors monitoring visceral tissues and organs:
  (Primarily within thoracic and abdominopelvic cavities
  => goes to medulla oblongata

Question 40

what are the interoceptors

Answer 40

Interoceptors include:
nociceptors,
baroreceptors,
thermoreceptors,
tactile receptors,
chemoreceptors

Question 41

Referred pain

Answer 41

not localised enough as many neurons from multiple places merge into one neuron.
visceral pain info travel similae route as somatic pain info.

Question 42

key features of somatic motor pathways SMP

Answer 42

• contraction of skeletal muscles
• centers in cerebrum, diencephalon, and brainstem.
• conscious or unconscious reflexive control

Question 43

what motor neurons include in SMP

Answer 43

1. Upper motor neuron – cell body in CNS
   processing center
2. Lower motor neuron – cell body in
   brainstem or spinal cord, axon extends out
   of CNS

Question 44

major Somatic motor pathways

Answer 44

=> corticospinal pathway
=> Lateral Pathway
=> Medial Pathway

Question 45

Corticospinal Pathway

Answer 45

=> Upper motor neuron descend to spinal cord without synapsing
=> associated with fine and fast skilled movements
=> axons in the corticospinal tracts cross to the opposite side either in brainstem or spinal cord.
=> heavily myelinated

Question 46

Lateral pathways

Answer 46

=> related to limbs
=>helps control distal limb muscles
that perform precise movements
=> it controls subconscious movements of muscle tone & body posture.

Question 47

Medial pathways

Answer 47

=> helps control gross movements
of trunk and proximal limb
muscles
=> lower limbs and head position

Question 48

Basal ganglia

Answer 48

Subconscious adjustment and modification of voluntary motor commands

Question 49

cerebellum

Answer 49

=> Coordinates complex somatic motor patterns
=> adjust out of the other somatic motor centers in brain and spinal cord.

Question 50

role of cerebellum and basal ganglia in the somatosensory/motor pathways

Answer 50

Adjusting the activity of motor pathways
often involves stimulating or inhibiting
1) motor nuclei
2) the primary motor cortex