Chapter 3D

Question 1

The tactile sensations include PITTV

Answer 1

pressure, itch, tickle, touch, vibration

Question 2

Cold thermoreceptors: activated by temperatures between 10 and 35°C.
* Warm thermoreceptors: activated by temperatures between 30 and 45°C. Less
abundant that cold receptors

Answer 2

ok

Question 3

What does the free nerve ending sense?

PIT CW

Answer 3

pain, itch, tickle, cold or warmth

Question 4

2 types of pain:

fast
slow

characteristics?

Answer 4

. Fast pain:

within 0.1 sec, acute, sharp, or pricking , not felt in deeper layers

2. Slow pain:
   second or more, chronic, burning,
   aching, or throbbing pain. can occur everywhere

Question 5

Superficial somatic pain: results from receptors on …

Answer 5

the skin

Question 6

Deep somatic pain: results from stimulation of receptors in …

Answer 6

skeletal muscles, joints,
tendons, and fascia.

Question 7

Visceral pain: results from stimulation of nociceptors in …

Answer 7

visceral organs.

Question 8

x allow us to recognize that parts of our
body belong to us (self).
* Kinesthesia is the perception of body movements.

Answer 8

proprioception

Question 9

There are three types of proprioceptors in the musculoskeletal system

Muscle spindles
tendon organs
Joint kinesthetic receptors

what do they do

Answer 9

Muscle spindles:

monitor changes in the length of skeletal
muscles, stretch reflexes

Tendon organs: at junction of a tendon, changes in muscle tension

3. Joint kinesthetic receptors: at Joint ligaments, adjust reflex inhibition of muscles when excessive strain
   is on the joint

Question 10

SO FAR, WE HAVE STUDIED THE SENSATIONS AND THEIR
RECEPTORS, BUT WHERE DOES THE INFORMATION
REACH THE BRAIN?

Answer 10

(primary somatosensory area )of the cerebral cortex (about the middle of the brain)

cerebellum (which looks like the small brain)

Question 11

First-order (primary) neurons are sensory neurons that conduct impulses from
…. receptors into …

Answer 11

somatic sensory
the brainstem or spinal cord

Question 12

Second-order (secondary) neurons conduct impulses from the …. to the …

Answer 12

brainstem or spinal
cord
thalamus (center of brain)

Question 13

Third-order (tertiary) neurons conduct impulses from the …. to the ….. on the same side. As the impulses reach the primary
somatosensory area, perception of the sensation occurs.

Answer 13

thalamus
primary
somatosensory area

Question 14

What does decussate mean?

Answer 14

cross over to the other side of the brain

Question 15

Because the axons of …
neurons decussate as they pass through
the brainstem or spinal cord, somatic
sensory information on one side of the
body is perceived by the primary
somatosensory area on the opposite
side of the brain.

Answer 15

second-order

Question 16

What is Sensory homunculus ?

Answer 16

it maps sensory signals from
the left side of the body in the somatosensory
area of the right cerebral hemisphere

The relative sizes of these regions in the
somatosensory area are proportional to the
number of specialized sensory receptors within
the corresponding part of the body

Question 17

Cerebellum receives most of proprioceptive impulses

true/false

Answer 17

true

Question 18

Somatic sensory impulses reach the cerebellum via two spinocerebellar tracts:

1. anterior spinocerebellar tract
2. posterior spinocerebellar tract

• Although they are not consciously perceived, sensory impulses conveyed to the
  cerebellum along these two path ways are critical for…

Answer 18

posture, balance, and
coordination of skilled movements.

Question 19

SUMMARY: what you should know

Somatic sensory (somatosensory) pathways relay information from somatic sensory
receptors to:
1. The primary somatosensory area in the cerebral cortex through first-, secondand thrid-order neurons:
* First: from somatic sensory receptors into the brainstem or spinal cord.
* Second: from the brainstem or spinal cord to the thalamus (relay center).
* Third: from the thalamus to the primary somatosensory area
Localization of somatic sensations occurs when nerve impulses arrive at the
primary somatosensory area.
Each region in this area receives sensory input from a different part of the
body

Answer 19

ok

Question 20

SUMMARY: what you should know

2. The cerebellum receives most of proprioceptive impulses: critical for posture,
   balance, and coordination of skilled movements.

Answer 20

ok

Question 21

SUMMARY

The somatic nervous system consists of somatic motor neurons that innervate the
skeletal muscles of the body.
* When a somatic motor neuron stimulates a skeletal muscle, it contracts; the effect is
always excitation.
* If somatic motor neurons cease to stimulate a skeletal muscle, the result is a paralyzed,
limp muscle that has no muscle tone.

Answer 21

ok

Question 22

SUMMARY

The somatic nervous system usually operates under voluntary (conscious) control.
Voluntary control of movement involves motor areas of the cerebral cortex that activate
somatic motor neurons whenever you have a desire to move.
* Exceptions: somatic motor neurons that innervate skeletal muscles involved in posture,
balance, breathing, and somatic reflexes (such as the flexor reflex) are involuntarily.
* The somatic nervous system can also receive sensory input from sensory neurons that
convey information for somatic senses (tactile, thermal, pain, and proprioceptive
sensations) or the special senses (sight, hearing, taste, smell, and equilibrium).
* All of these sensations normally are consciously perceived. In response to this sensory
information, somatic motor neurons cause the appropriate skeletal muscles of the body
to contract.

Answer 22

ok

Question 23

….. in the brain and spinal cord orchestrate all voluntary movements

Answer 23

neural circuits

Question 24

Ultimately, all excitatory and inhibitory signals that control movement converge on the
…… that extend out of the brainstem and spinal cord to innervate
skeletal muscles in the body

Answer 24

lower motor neurons

Question 25

These neurons are known as lower motor neurons (LMNs) because ....

Answer 25

they have their cell bodies in the lower parts of the CNS (brainstem and spinal cord):

Question 26

From the brainstem, axons of LMNs extend through ..... nerves to innervate skeletal muscles of the face and head. * From the spinal cord, axons of LMNs extend through .... nerves to innervate skeletal muscles of the limbs and trunk.

Answer 26

cranial nerves spinal nerves

Question 27

Lower motor neurons provide output from the CNS to skeletal muscle fibers. For this reason, they are also called the .... pathway

Answer 27

final common

Question 28

Axon of a single, myelinated somatic lower motor neuron extends from the CNS all the way to the skeletal muscle fibers in its motor unit. * Somatic nervous system stimulation always excites its effectors (skeletal muscle fibers). * Somatic motor neurons release only ....

Answer 28

acetylcholine

Question 29

Neurons in four distinct but highly interactive neural circuits participate in control of movement by providing input to lower motor neurons: 1. Local circuit neurons in brainstem and spinal cord 2. Upper motor neurons from cerebral cortex (pyramidal pathway) and brainstem (extrapyramidal pathway) 3. Basal nuclei neurons 4. Cerebellar neurons

Answer 29

ok

Question 30

...... area: the idea or desire to move a part of the body is generated and the information is processed and sent to the premotor area where a motor plan is developed. * .... cortex: is the major control region for the execution of voluntary movements. Electrical stimulation of any point in the primary motor area causes contraction of specific muscles on the opposite side of the body.

Answer 30

Premotor Primary motor

Question 31

What is the motor homunculus

Answer 31

This distorted muscle map of the body is called the motor homunculus

Question 32

control of movement by the cerebral cortex: X cells of the primary motor area of the cerebral cortex extend their axons to directly provide input to lower motor neurons. * The direct motor pathways consist of two pathways: 1. corticobulbar pathway: conducts impulses for the control of skeletal muscles [where?]. Some of the axons of the corticobulbar tract decussate; others do not. 2. corticospinal pathways: conduct impulses for the control of muscles of [where?].

Answer 32

X Pyramidal [in the head] [the limbs and trunk]

Question 33

Which of the following motor neurons fits this description? Originate in cerebral cortex (next, we will see that others upper motor neurons originate at brainstem). * Synapses with a lower motor neuron farther down in the CNS (brainstem or spinal cord). * Control the lower motor neurons: nerve action potential to occur in the axon of the upper motor neuron, followed by neurotransmitter release generates a graded potential in a lower motor neuron. Upper motor neuron in SNS (pyramidal pathway) Lower motor neuron in SNS (pyramidal pathway):

Answer 33

upper motor neuron

Question 34

Which of the following motor neurons fits this description? Originate in brainstem (cranial nerves ) or spinal cord (spinal nerves). * Inervate muscle directly. * Are under the influence of upper motor neurons: the graded potential triggers the formation of a nerve action potential and then release of the neurotransmitter at neuromuscular junctions (Chapter 4). Upper motor neuron in SNS (pyramidal pathway) Lower motor neuron in SNS (pyramidal pathway):

Answer 34

Lower motor neuron

Question 35

Lower motor neuron in SNS: The axons of motor neurons are non-myelinated/myelinated and have small/large diameters for fast/slow conduction of action potentials. * Always/not always excites its effectors (skeletal muscle fibers). * Release only acetylcholine/more than only acetylcholine.

Answer 35

- myelinated - large - fast - always - only acetylcholine

Question 36

CONTROL OF MOVEMENT BY THE CEREBRAL CORTEX: SUMMARY Voluntary movements are conveyed through the pyramidal tract, which arises from the pyramidal cell in the primary motor cortex. * The pyramidal system is a two neuron system consisting of upper motor neurons in the primary motor cortex and lower motor neurons. * Pyramidal tract divides into the corticospinal tract, which synapses with the lower motor neurons innervating the muscles in the limbs and trunk, and the corticobulbar tract, which synapses with the cranial nerves to control muscular movements of the face, head, and neck. * Damage to the pyramidal tract result in spastic paralysis

Answer 36

ok

Question 37

The pyramidal system provides voluntary control of all our muscular movements, but very roughly. * ....pathway refines the ”raw” movements provided by the pyramidal system and control involuntary movements.

Answer 37

Extrapyramidal

Question 38

The extrapyramidal system accompanies the pyramidal, but also acts on its own. true/false

Answer 38

true

Question 39

* Automations and involuntary movements are included in the extrapyramidal pathways. true/false

Answer 39

true

Question 40

* The extrapyramidal is not connected to the limbic system (emotions). true/false

Answer 40

false

Question 41

* In addition to the extrapyramidal pathway (motor centers in the brainstem), only one pathway contributes to the movement by affecting upper motor neurons: basal nuclei, cerebellum etc. true/false

Answer 41

multiple

Question 42

CONTROL OF MOVEMENT BY THE BRAINSTEM: INDIRECT OR EXTRAPYRAMIDAL PATHWAY * This pathway includes all/some somatic motor tracts other than the pyramidal tracts. * Motor centers in the brainstem convey action potentials to upper/lower motor neurons to cause involuntary/voluntary movements that regulate posture, balance, muscle tone, and reflexive movements of the head and trunk.

Answer 42

all lower involuntary