Chapter 15 Neural Integration I

Question 1

Sensory Receptors are?

Answer 1

Specialized cells that monitor specific conditions in the body or external environment

Question 2

Sensory Pathways

Answer 2

Deliver somatic and visceral sensory information to their final destinations inside the CNS using:
- nerves
- nuclei
- tracts

Question 3

Somatic Motor Commands

Answer 3

Travel from motor centers in the brain along somatic motor pathways of:
- motor nuclei
- tracts
- nerves

Question 4

General Senses?

Answer 4

temperature
pain
touch
pressure
vibration
proprioception

Question 5

Special Senses?

Answer 5

Olfaction (smell)
Vision (sight)
Gustation(taste)
Equilibrium(balance)
Hearing

Question 6

Pain Receptors

Answer 6

also called nociceptors (monitoring pain)
Common in the:
- superficial portions of the skin
- joint capsules
- within the periostea of bones
- around the walls of blood vessels
Free nerve endings with large receptive fields
(( Smaller the receptive field the more sensitive))
((Larger the receptive field the less sensitive))

Question 7

Nociceptors

Answer 7

May be sensitive to:
- extremes of temperature
- mechanical damage
- dissolved chemicals, such as chemicals released by injured cells

Question 8

Type A and Type C Fibers

Answer 8

Type A they move fasters (carries sharp burning type pain)
Type C Slow dull pain. not life threatening

Question 9

Myelinated Type A Fibers

Answer 9

Carries fast pain, or prickled pain such as injection or deep cut
Sensations reach the CNS quickly and often trigger somatic reflexes
Relayed to the primary sensory cortex and receive conscious attention

Question 10

Type C

Answer 10

Carry sensations of slow pain and aching pain
caused a generalized activation

Question 11

Thermoreceptors

Answer 11

Temperature receptors
- are free nerve endings located in:
- the dermis
- skeletal muscles
- the liver
- the hypothalamus

Question 12

Temperature sensations

Answer 12

Conducted along the same pathways that carry pain sensations

Question 13

Mechanoreceptors

Answer 13

Sensitive to stimuli that distort their cell membranes
Contain mechanically regulated ion channels whose gates open or close in response to:
- stretching
- compression
- twisting
- or other distortions of the membrane

Question 14

what are the 3 classes of mechanoreceptors?

Answer 14

Tactile receptors:
- provide sensations of touch, pressure, and vibration
Baroreceptors:
- detect pressure changes in the walls of blood vessels and in portions of the digestive, reproductive, and urinary tracts
Proprioceptors:
-monitor the positions of joints and muscles
- there most structurally and functionally complex of general sensory receptors

Question 15

Fine touch

Answer 15

extremely sensitive
have a relatively narrow receptive field
Provide detailed information about a source of stimulation, including:
- its exact location
- shape
- texture
- movement

Question 16

Crude touch

Answer 16

• have relatively large receptive fields
• provide poor localization
• give little information about the stimulus

Question 17

Chemoreceptors

Answer 17

Located in the:
- Carotid bodies: near the origin of the internal carotid arteries on each side of the neck
- aortic bodies:
– between the major branches of the aortic arch
- receptors monitor Ph, carbon dioxide, and oxygen levels in arterial blood

Question 18

Somatic Sensory Pathways

Answer 18

Carry sensory information from the skin, the musculature of the body wall, head, neck, and limbs

Question 19

3 Major Somatic Sensory Pathways

Answer 19

1. The posterior column pathway
2. the anterolateral pathway
3. the spinocerebellar pathway

Question 20

Posterior Column pathway

Answer 20

Carries sensations of highly localized (“fine”) touch, pressure, vibration, and proprioception.

Question 21

Ability to Determine stimulus

Answer 21

precisely where on the body a specific stimulus originated depends on the projection of information from the thalamus to the primary sensory cortex

Question 22

Sensory Information

Answer 22

From toes arrives at one end of the primary sensory cortex
From the head arrives at the other:
- when neurons in one position of your perjury sensory cortex are stimulated you become aware of sensations originating at a specific location

Question 23

Sensory Homunculus

Answer 23

Functional map of the primary sensory cortex

Question 24

The Anterolateral Pathway

Answer 24

Provides conscious sensations of pressure, pain, and temperature
Separated in the anterior spinothalamic tract and lateral spinothaalmic tract

Question 25

Posterior Gray horns

Answer 25

In anterolateral pathway, axons of first order sensory neurons enter spinal cord and synapse on second-order neurons within posterior gray horns

Question 26

Axons of Interneurons

Answer 26

Cross to the opposite side of the spinal cord before ascending

Question 27

Sensations Bound for Cerebral Cortex

Answer 27

Ascend within the anterior or lateral spinothalamic tracts
- the anterior spinothalamic tracts carry pressure sensations
- the lateral spinothalamic tracts carry pain and temperature sensations

Question 28

Tracts End

Answer 28

• At third-order neurons in the ventral nucleus group of the thalamus
• after the sensations have been sorted and processed, they are relayed to primary sensory cortex

Question 29

Strong Visceral Pain

Answer 29

Sensations arriving at segment of spinal cord can stimulate interneurons that are part of anterolateral pathway
- activity in interneurons leads to stimulation of primary sensory cortex, so an individual feels pain in specific part of body surface:
- also called referred pain

Question 30

Referred Pain

Answer 30

• The pain of a heart attack is frequently felt in the left arm
• the pain of appendicitis is generally felt first in the area around the navel and then in the right lower quadrant

Question 31

the spinocerebellar pathway

Answer 31

Cerebellum receives proprioceptive information about position of skeletal muscles, tendons, and joints

Question 32

Motor Commands

Answer 32

• issued by the CNS
• Distributed by somatic nervous system (SNS) and autonomic nervous system (ANS)
• SNS controls contractions of skeletal muscles
• ANS controls visceral effectors, such as smooth muscle, cardiac muscle, and glands

Question 33

Somatic Motor Pathways

Answer 33

Always involve at least 2 motor neurons:
- upper motor neuron (cell body lies in a CNS processing center)
- lower motor neuron (cell body lies in a nucleus of the brain stem or spinal cord)

Question 34

Upper Motor Neuron

Answer 34

• Synapses on the lower motor neuron
• Innervates a single motor unit in a skeletal muscle: activity in upper motor neuron may facilitate or inhibit lower motor neuron

Question 35

Lower Motor Neuron

Answer 35

Triggers a contraction in innervated muscle:
- only axons of lower motor neuron extends outside CNS
- destruction of or damage to lower motor neuron eliminates voluntary and reflex control over innervated motor unit

Question 36

Corticospinal Pathway

Answer 36

• Sometimes called the pyramidal tract
• Provides voluntary control over skeletal muscles:
• system begins at pyramidal cells of primary motor cortex
• axons of these upper motor neurons descend into brain stem and spinal cord to synapse on lower motor neurons that control skeletal muscles

Question 37

3 pairs of Descending Tracts

Answer 37

The corticospinal pathway contains 3 pairs of descending tracts:
- corticobulbar tracts
- lateral corticospinal tracts
- anterior corticospinal tracts

Question 38

Corticobulber tracts

Answer 38

• provides conscious control over skeletal muscles that move the eye, jaw, face, and some muscles of neck and pharynx
• innervate motor centers of medial and lateral pathways

Question 39

The Pyramids

Answer 39

As they descend, corticospinal tracts are visible along the ventral surface of medulla oblongata as pair of thick bands, the pyramids.

Question 40

Motor Homunculus

Answer 40

-Primary motor cortex corresponds point by point with specific regions of the body
- cortical areas have been mapped out in diagrammatic form

Question 41

Proportions of Motor Homunculus

Answer 41

Homunculus provides indication of degree of fine motor control available:
-hands, face, and tongue, capable of varied and complex movements
- appear very large, while trunk is relatively small
- these proportions are similar to sensory homunculus

Question 42

Somatic Motor Commands

Answer 42

Several centers in cerebrum, diencephalons, and brain stem may issue somatic motor commands as result of processing performed at subconscious level

Question 43

Primary Fucntions

Answer 43

These nuclei and tract are grouped by their primary functions:
- components of medial pathways help control gross movements of trunk and proximal limb muscles
- components of lateral pathways help control distal limb muscles that perform more precise movements