201

Question 1

Central Nervous System (CNS)

Answer 1

consists of the brain and spinal cord

Question 2

The peripheral nervous system (PNS)

Answer 2

consists of all nervous tissue outside the CNS. Components of the PNS include nerves and sensory receptors.

Question 3

Nervous system divisions

Answer 3

• Nervous system is dived into CNS and PNS
• CNS receives input for the sensory branch of the PNS, interprets is and then out puts signals to the motor brand of the PNS

Question 4

PNS divisions

Answer 4

• is divided into Sensory and Motor divisions
• Motor division is dived into somatic and autonomic
• autonomic is dived into sympathetic and parasympathetic

Question 5

The PNS is divided into a sensory (afferent) division and a motor (efferent) division.

Answer 5

• The sensory division conveys sensory input into the CNS from sensory receptors.
• The motor division conveys motor output from the CNS to effectors (muscles and glands).

Question 6

The efferent (motor) division of the PNS is further subdivided into a somatic nervous system and an autonomic nervous system.

Answer 6

• somatic nervous system (conveys motor output from the CNS to skeletal muscles only)
• autonomic nervous system (conveys motor output from the CNS to smooth muscle, cardiac muscle, and glands).

Question 7

The autonomic nervous system in turn is divided into a sympathetic division, parasympathetic division, and enteric plexuses.

Answer 7

The enteric plexuses in the wall of the digestive canal regulate the smooth muscle and glands of the digestive canal

Question 8

The nervous system helps maintain homeostasis and integrates all body activities.

Answer 8

it does this by sensing changes (sensory function), interpreting them (integrative function), and reacting to them (motor function).

Question 9

Nervous tissue consists of

Answer 9

neurons (nerve cells) and neuroglia.

Question 10

Neurons have the property of electrical excitability

Answer 10

and are responsible for most unique functions of the nervous system: sensing, thinking, remembering, controlling muscle activity, and regulating glandular secretions.

Question 11

Most neurons have three parts.

Answer 11

1-The dendrites are the main receiving or input region
2-The cell body, Integration occurs in the cell body, which includes typical cellular organelles.
3-the Axon, responsible for output which propagates nerve impulses toward another neuron, a muscle fiber, or a gland cell.

Question 12

Synapses

Answer 12

the site of functional contact between two excitable cells. Axon terminals contain synaptic vesicles filled with neurotransmitter molecules.

Question 13

slow axonal transport and fast axonal transport

Answer 13

systems for conveying materials to and from the cell body and axon terminals.

Question 14

On the basis of their structure, neurons are classified as

Answer 14

• multipolar,
• bipolar,
• unipolar or pseudounipolar.

Question 15

Neurons are functionally classified as

Answer 15

• sensory (afferent) neurons,
• motor (efferent) neurons,
• interneurons

Question 16

Sensory neurons carry sensory information into the CNS.

Answer 16

Motor neurons carry information out of the CNS to effectors (muscles and glands).

Question 17

Interneurons

Answer 17

located within the CNS between sensory and motor neurons.

Question 18

Neuroglia

Answer 18

support, nurture, and protect neurons and maintain the interstitial fluid that bathes them.

Question 19

Neuroglia in the CNS consist of

Answer 19

• astrocytes
• oligodendrocytes
• microglial cells
• ependymal cells

Question 20

Neuroglia in the PNS consist of

Answer 20

• Schwann cells

- satellite cells.

Question 21

Two types of neuroglia produce myelin sheaths:

Answer 21

Oligodendrocytes myelinate axons in the CNS, and Schwann cells myelinate axons in the PNS.

Question 22

White matter consists of aggregates of myelinated axons

Answer 22

gray matter contains cell bodies, dendrites, and axon terminals of neurons unmyelinated axons, and neuroglia.

Question 23

In the spinal cord, gray matter forms an H-shaped inner core that is surrounded by white matter.

Answer 23

In the brain, a thin, superficial shell of gray matter covers the cerebral and cerebellar hemispheres

Question 24

Neurons communicate with one another

Answer 24

• using graded potentials, which are used for short-distance communication only
• nerve impulses, which allow communication over long distances within the body.

Question 25

The electrical signals produced by neurons and muscle fibers rely on four kinds of ion channels:

Answer 25

• leak channels
• ligand-gated channels
• mechanically gated channels
• voltage-gated channels.

Question 26

Leak channels

Answer 26

• Gated channels that randomly open and close.

- Found in nearly all cells, and dendrites, cell bodies, and axons of all types of neurons.

Question 27

Ligand-gated channels Gated channels

Answer 27

• open in response to binding of ligand (chemical) stimulus.
• found on dendrites of some sensory neurons such as pain receptors and dendrites and cell bodies of interneurons and motor neurons.

Question 28

Mechanically gated channels

Answer 28

• open in response to mechanical stimulus (such as touch, pressure, vibration, or tissue stretching).
• found on Dendrites of some sensory neurons such as touch receptors, pressure receptors, and some pain receptors.

Question 29

Large nerve fibers

Answer 29

transmit impulses faster than small ones do

Question 30

Which of the following cell types can conduct action potentials?

1) smooth muscle cells
2) cardiac muscle cells
3) neurons
4) neuroglia
5) skeletal muscle cells

Answer 30

all the above

Question 31

Which of the following cell types can produce action potentials when stimulated?

1) smooth muscle cells
2) cardiac muscle cells
3) neurons
4) neuroglia
5) skeletal muscle cells

Answer 31

1,2,3,5

Question 32

Which one of the following is NOT found in the central nervous system?

a. myelinated fibers
b. unmyelinated fibers
c. neurolemma
d. oligodendrocytes
e. astrocytes

Answer 32

C neurolemma is not part of the CNS

Question 33

How is the resting membrane potential of -70mv (millivolts) best interpreted?

Answer 33

the inside of the fiber is 70mv more negative than the outside

Question 34

The sodium pump:

Answer 34

actively transports sodium out of the cell

Question 35

During the absolute refractory period a second action potential response can be produced:

Answer 35

never

Question 36

A large number of nerve fibers running together within the central nervous system is referred to as a:

Answer 36

tract

Question 37

gray matter contains mostly

Answer 37

neuron cell bodies and synapses

Question 38

Cerebrospinal fluid is found between the:

Answer 38

pia and archnoid

Question 39

Transmission across a chemical synapse is always in the same direction

Answer 39

true

Question 40

A spinal puncture places the needle tip in the:

Answer 40

subarchnoid space

Question 41

The anterior gray columns contain:

Answer 41

cell bodies of motor neurons

Question 42

: reflex arc

Answer 42

is the simplest unit capable of detecting a stimulus and causing a response

Question 43

The vital centers for control of heart, respiration and blood pressure are located in the:

Answer 43

medulla oblongata

Question 44

The major control systems for balance and posture in the body as well as muscular coordination are located in the:

Answer 44

cerebellum

Question 45

The most important central mechanism for temperature regulation is contained in the:

Answer 45

hypothalamus

Question 46

corpus callosum

Answer 46

is the nerve fibers that connect the Hemispheres of the cerebrum

Question 47

A resting membrane potential exists across the plasma membrane of excitable cells that are unstimulated (at rest).

Answer 47

The resting membrane potential exists because of a small buildup of negative ions in the cytosol along the inside surface of the membrane, and an equal buildup of positive ions in the extracellular fluid along the outside surface of the membrane.

Question 48

A typical value for the resting membrane potential of a neuron is −70 mV.

Answer 48

A cell that exhibits a membrane potential is polarized.

Question 49

The resting membrane potential is determined by three major factors:

Answer 49

(1) unequal distribution of ions in the ECF and cytosol;
(2) inability of most cytosolic anions to leave the cell;
(3) electrogenic nature of the Na+/K+ ATPases.

Question 50

Graded Potentials

Answer 50

1. A graded potential is a small deviation from the resting membrane potential that occurs because ligand-gated or mechanically gated channels open or close.
2. A hyperpolarizing graded potential makes the membrane potential more negative (more polarized).
3. A depolarizing graded potential makes the membrane potential less negative (less polarized).
4. The amplitude of a graded potential varies, depending on the strength of the stimulus.

Question 51

Action Potentials all-or-none principle

Answer 51

• if a stimulus is strong enough to generate an action potential, the impulse generated is of a constant size.
• A stronger stimulus does not generate a larger action potential.
• Instead, the greater the stimulus strength above threshold, the greater the frequency of the action potentials.

Question 52

During an action potential, voltage-gated Na+ and K+ channels open and close in sequence.

Answer 52

This results first in depolarization, the reversal of membrane polarization (from −70 mV to +30 mV). Then repolarization, the recovery of the resting membrane potential (from +30 mV to −70 mV), occurs.

Question 53

During the first part of the refractory period (RP), another action potential cannot be generated at all (absolute RP);

Answer 53

a little later, it can be triggered only by a larger-than-normal stimulus (relative RP).

Question 54

an action potential travels from point to point along the membrane without getting smaller,

Answer 54

it is useful for long-distance communication

Question 55

Nerve impulse propagation in which the impulse “leaps” from one myelin sheath gap to the next along a myelinated axon is saltatory conduction

Answer 55

. Saltatory conduction is faster than continuous conduction.

Question 56

Axons with larger diameters conduct nerve impulses at higher speeds than do axons with smaller diameters.

Answer 56

The intensity of a stimulus is encoded in the frequency of nerve impulses and in the number of sensory neurons that are recruited.

Question 57

A synapse is the functional junction between one neuron and another, or between a neuron and an effector such as a muscle or a gland.

Answer 57

The two types of synapses are electrical and chemical.

Question 58

A chemical synapse produces one-way information transfer—

Answer 58

from a presynaptic neuron to a postsynaptic neuron.

Question 59

An excitatory neurotransmitter is one that can depolarize the postsynaptic neuron’s membrane, bringing the membrane potential closer to threshold.

Answer 59

An inhibitory neurotransmitter hyperpolarizes the membrane of the postsynaptic neuron, moving it further from threshold.

Question 60

hyperpolarized = more negavite

Answer 60

depolarized = less negative

Question 61

There are two major types of neurotransmitter receptors:

Answer 61

ionotropic receptors and metabotropic receptors.

Question 62

ionotropic receptor contains a neurotransmitter binding site and an ion channel.

Answer 62

A metabotropic receptor contains a neurotransmitter binding site and is coupled to a separate ion channel by a G protein

Question 63

Neurotransmitter is removed from the synaptic cleft in three ways:

Answer 63

diffusion, enzymatic degradation, and uptake by cells (neurons and neuroglia

Question 64

If several presynaptic end bulbs release their neurotransmitter at about the same time

Answer 64

, the combined effect may generate a nerve impulse, due to summation. Summation may be spatial or temporal

Question 65

The postsynaptic neuron is an integrator.

Answer 65

It receives excitatory and inhibitory signals, integrates them, and then responds accordingly.

Question 66

Both excitatory and inhibitory neurotransmitters are present in the CNS and the PNS.

Answer 66

A given neurotransmitter may be excitatory in some locations and inhibitory in others

Question 67

Neurotransmitters can be divided into two classes based on size: (1) small-molecule neurotransmitters (acetylcholine, amino acids, biogenic amines, ATP and other purines, nitric oxide, and carbon monoxide), and (2) neuropeptides, which are composed of 3 to 40 amino acids.

Answer 67

(1) small-molecule neurotransmitters (acetylcholine, amino acids, biogenic amines, ATP and other purines, nitric oxide, and carbon monoxide), and
(2) neuropeptides, which are composed of 3 to 40 amino acids.

Question 68

Neurons in the central nervous system are organized into networks called neural circuits.

Answer 68

Neural circuits include simple series, diverging, converging, reverberating, and parallel after-discharge circuits.

Question 69

The nervous system exhibits plasticity (the capability to change based on experience)

Answer 69

it has very limited powers of regeneration (the capability to replicate or repair damaged neurons).

Question 70

Neurogenesis, the birth of new neurons from undifferentiated stem cells, is normally very limited. Repair of damaged axons does not occur in most regions of the CNS.

Answer 70

Axons and dendrites that are associated with a neurolemma in the PNS may undergo repair if the cell body is intact, the Schwann cells are functional, and scar tissue formation does not occur too rapidly

Question 71

The spinal cord is protected by

Answer 71

• vertebral column,
• meninges,
• cerebrospinal fluid,
• denticulate ligaments

Question 72

The three meninges are coverings that run continuously around the spinal cord and brain.

Answer 72

They are the

• dura mater
• arachnoid mater
• pia mater.

Question 73

The spinal cord begins as a continuation of the medulla oblongata and ends at about the second lumbar vertebra in an adult.

Answer 73

The spinal cord contains cervical and lumbosacral enlargements that serve as points of origin for nerves to the limbs

Question 74

The tapered inferior portion of the spinal cord is the conus medullaris

Answer 74

from which arise the filum terminale and cauda equina

Question 75

Spinal nerves connect to each segment of the spinal cord by two roots.

Answer 75

• the posterior root contains sensory axons

- the anterior root contains motor neuron axons.

Question 76

The anterior median fissure and the posterior median sulcus

Answer 76

partially divide the spinal cord into right and left sides.

Question 77

The gray matter in the spinal cord is divided into horns, and the white matter into funiculi.

Answer 77

In the center of the spinal cord is the central canal, which runs the length of the spinal cord

Question 78

Parts of the spinal cord observed in transverse section are the gray commissure; central canal; anterior, posterior, and lateral gray horns; and anterior, posterior, and lateral white funiculi, which contain ascending and descending tracts. Each part has specific functions

Answer 78

gray commissure; central canal; anterior, posterior, and lateral gray horns; and anterior, posterior, and lateral white funiculi, which contain ascending and descending tracts. Each part has specific functions

Question 79

The 31 pairs of spinal nerves are named and numbered according to the region and level of the spinal cord from which they emerge. There are 8 pairs of cervical, 12 pairs of thoracic, 5 pairs of lumbar, 5 pairs of sacral, and 1 pair of coccygeal nerves.

Answer 79

• 8 pairs of cervical
• 12 pairs of thoracic
• 5 pairs of lumbar
• 5 pairs of sacral
• 1 pair of coccygeal nerves

Question 80

Spinal nerves typically are connected with the spinal cord by a posterior root and an anterior root.

Answer 80

All spinal nerves contain both sensory and motor axons (they are mixed nerves).

Question 81

Three connective tissue coverings associated with spinal nerves are the endoneurium, perineurium, and epineurium.

Answer 81

endoneurium, perineurium, and epineurium.

Question 82

. Branches of a spinal nerve include the posterior ramus, anterior ramus, meningeal branch, and communicating rami.

Answer 82

The anterior rami of spinal nerves, except for T2–T12, form networks of nerves called plexuses.

Question 83

Anterior rami of nerves T2–T12 do not form plexuses and are called intercostal nerves.

Answer 83

They are distributed directly to the structures they supply in intercostal spaces.

Question 84

dermatomes

Answer 84

Sensory neurons within spinal nerves serve specific, constant segments of the skin

Question 85

Cervical Plexus

Answer 85

1. The cervical plexus is formed by the roots (anterior rami) of the first four cervical nerves (C1–C4), with contributions from C5.
2. Nerves of the cervical plexus supply the skin and muscles of the head, neck, and upper part of the shoulders; they connect with some cranial nerves and innervate the diaphragm.

Question 86

Brachial Plexus

Answer 86

1. The roots (anterior rami) of spinal nerves C5–C8 and T1 form the brachial plexus.
2. Nerves of the brachial plexus supply the upper limbs and several neck and shoulder muscles.

Question 87

Lumbar Plexus

Answer 87

1. The roots (anterior rami) of spinal nerves L1–L4 form the lumbar plexus.
2. Nerves of the lumbar plexus supply the anterolateral abdominal wall, external genitals, and part of the lower limbs.

Question 88

Sacral and Coccygeal Plexuses

Answer 88

1. The roots (anterior rami) of spinal nerves L1–L5 and S1–S4 form the sacral plexus.
2. Nerves of the sacral plexus supply the buttocks, perineum, and part of the lower limbs.
3. The roots (anterior rami) of the spinal nerves S4–S5 and the coccygeal nerves form the coccygeal plexus.
4. Nerves of the coccygeal plexus supply the skin of the coccygeal region.

Question 89

Spinal Cord Physiology

Answer 89

1. The white matter tracts in the spinal cord are highways for nerve impulse propagation. Along these tracts, sensory input travels toward the brain, and motor output travels from the brain toward skeletal muscles and other effector tissues. Sensory input travels along two main routes in the white matter of the spinal cord: the posterior funiculi and the spinothalamic tract. Motor output travels along two main routes in the white matter of the spinal cord: direct pathways and indirect pathways.

Question 90

A second major function of the spinal cord is to serve as an integrating center for spinal reflexes. This integration occurs in the gray matter.

Answer 90

A reflex is a fast, predictable sequence of involuntary actions, such as muscle contractions or glandular secretions, which occurs in response to certain changes in the environment. Reflexes may be spinal or cranial and somatic or autonomic.

Question 91

components of a reflex arc

Answer 91

• sensory receptor
• sensory neuron
• integrating center
• motor neuron
• effector

Question 92

Somatic spinal reflexes include

Answer 92

the stretch reflex, the tendon reflex, the flexor reflex, and the crossed extensor reflex; all exhibit reciprocal innervation

Question 93

A two-neuron or monosynaptic reflex arc consists of one sensory neuron and one motor neuron.

Answer 93

A stretch reflex, such as the patellar reflex, is an example.

Question 94

A polysynaptic reflex arc contains sensory neurons, interneurons, and motor neurons

Answer 94

tendon reflex, flexor (withdrawal) reflex, and crossed extensor reflexes are examples.

Question 95

Several important somatic reflexes are used to diagnose various disorders.

Answer 95

patellar reflex, Achilles reflex, Babinski sign, and abdominal reflex

Question 96

major parts of the brain

Answer 96

• brainstem
• cerebellum
• diencephalon
• cerebrum

Question 97

The brain is protected by

Answer 97

cranial cavity bones and the cranial meninges

Question 98

The cranial meninges are continuous with the spinal meninges.

Answer 98

From superficial to deep, they are the dura mater, arachnoid mater, and pia mater

Question 99

Blood flow to the brain

Answer 99

internal carotid and vertebral arteries.

Question 100

Any interruption of the oxygen or glucose supply to the brain can result in weakening of, permanent damage to, or death of brain cells.

Answer 100

The blood–brain barrier causes different substances to move between the blood and the brain tissue at different rates and prevents the movement of some substances from blood into the brain

Question 101

Cerebrospinal Fluid

Answer 101

1. Cerebrospinal fluid is formed in the choroid plexuses and circulates through the lateral ventricles, third ventricle, fourth ventricle, subarachnoid space, and central canal. Most of the fluid is absorbed into the blood across the arachnoid granulations of the superior sagittal sinus.
2. Cerebrospinal fluid provides mechanical protection, chemical protection, and circulation of nutrients

Question 102

The medulla oblongata is continuous with the superior part of the spinal cord and contains both sensory tracts and motor tracts.

Answer 102

• It contains a cardiovascular center, which regulates heart rate and blood vessel diameter (cardiovascular center), and a medullary respiratory center, which helps control breathing.
• It also contains the gracile nucleus, cuneate nucleus, gustatory nucleus, cochlear nuclei, and vestibular nuclei, which are components of sensory pathways to the brain.

Question 103

Also present in the medulla is the inferior olivary nucleus

Answer 103

-this provides instructions that the cerebellum uses to adjust muscle activity when you learn new motor skills. —–Other nuclei of the medulla coordinate vomiting, -swallowing, sneezing, coughing, and hiccupping.

Question 104

The medulla also contains nuclei associated with these nerves

Answer 104

vestibulocochlear (VIII), glossopharyngeal (IX), vagus (X), accessory (XI), and hypoglossal (XII) nerves

Question 105

The pons is superior to the medulla

Answer 105

It contains both sensory tracts and motor tracts.

Question 106

Pontine nuclei relay nerve impulses related to voluntary skeletal movements from the cerebral cortex to the cerebellum.

Answer 106

The pons also contains the pontine respiratory group, which helps control breathing

Question 107

Vestibular nuclei, which are present in the pons and medulla, are part of the equilibrium pathway to the brain.

Answer 107

Also present in the pons are nuclei associated with the trigeminal (V), abducens (VI), and facial (VII) nerves and the vestibular branch of the vestibulocochlear (VIII) nerve

Question 108

The midbrain connects the pons and diencephalon and surrounds the aqueduct of the midbrain.

Answer 108

• It contains both sensory tracts and motor tracts. The superior colliculi coordinate movements of the head, eye, and trunk in response to visual stimuli;
• the inferior colliculi coordinate movements of the head, eyes, and trunk in response to auditory stimuli.
• The midbrain also contains nuclei associated with the oculomotor (III) and trochlear (IV) nerves.

Question 109

A large part of the brainstem consists of small areas of gray matter and white matter called the reticular formation,

Answer 109

which helps maintain consciousness, causes awakening from sleep, and contributes to regulating muscle tone

Question 110

The Cerebellum

Answer 110

1. The cerebellum occupies the inferior and posterior aspects of the cranial cavity. It consists of two lateral hemispheres and a medial, constricted vermis.
2. It connects to the brainstem by three pairs of cerebellar peduncles.
3. The cerebellum smooths and coordinates the contractions of skeletal muscles. It also maintains posture and balance.

Question 111

The diencephalon surrounds the third ventricle

Answer 111

it consists of the thalamus, hypothalamus, and epithalamus.

Question 112

The thalamus is superior to the midbrain and contains nuclei that serve as relay stations for most sensory input to the cerebral cortex.

Answer 112

It also contributes to motor functions by transmitting information from the cerebellum and corpus striatum to the primary motor cortex of the cerebrum. In addition, the thalamus plays a role in maintenance of consciousness

Question 113

The hypothalamus is inferior to the thalamus. It controls the autonomic nervous system, produces hormones, and regulates emotional and behavioral patterns (along with the limbic system).

Answer 113

The hypothalamus also contains a feeding center and satiety center, which regulate eating, and a thirst center, which regulates drinking. In addition, the hypothalamus controls body temperature by serving as the body’s thermostat. Also present in the hypothalamus is the suprachiasmatic nucleus, which regulates circadian rhythms and functions as the body’s internal biological clock

Question 114

The epithalamus consists of the pineal gland and the habenular nuclei.

Answer 114

The pineal gland secretes melatonin, which is thought to promote sleep and to help set the body’s biological clock

Question 115

The cerebrum is the largest part of the brain.

Answer 115

Its cortex contains cerebral gyri, cerebral and interlobar sulci, and cerebral fissures

Question 116

The cerebrum is the largest part of the brain.

Answer 116

Its cortex contains cerebral gyri, cerebral and interlobar sulci, and cerebral fissures

Question 117

The cerebral hemispheres are divided into four lobes:

Answer 117

• frontal
• parietal
• temporal
• occipita

Question 118

The white matter of the cerebrum

Answer 118

is deep to the cortex and consists primarily of myelinated axons extending to other regions as association, commissural, and projection fibers.

Question 119

The corpus striatum consists of several groups of nuclei in each cerebral hemisphere.

Answer 119

They help initiate and terminate movements, suppress unwanted movements, and regulate muscle tone

Question 120

The limbic system encircles the upper part of the brainstem and the corpus callosum.

Answer 120

It functions in emotional aspects of behavior and memory

Question 121

cerebral cortex

Answer 121

• sensory areas of the allow perception of sensory information.
• motor areas control the execution of voluntary movements.
• association areas are concerned with more complex integrative functions such as memory, personality traits, and intelligence.

Question 122

primary motor cortex, which controls voluntary contractions of specific muscles or groups of muscles

Answer 122

premotor cortex sends impulses to the primary motor cortex that plan movements that cause specific groups of muscles to contract simultaneously and sequentially

Question 123

the frontal eye field controls voluntary scanning movements of the eyes

Answer 123

Broca’s area, which controls production of speech

Question 124

The somatosensory association area

Answer 124

permits you to determine the exact shape and texture of an object simply by touching it and to sense the relationship of one body part to another. It also stores memories of past somatic sensory experiences

Question 125

Cranial Nerves: Overview

Answer 125

1. Twelve pairs of cranial nerves originate from the nose, eyes, inner ear, brainstem, and spinal cord.
2. They are named primarily based on their distribution and are numbered I–XII in order of attachment to the brain.

Question 126

Olfactory (I) Nerve

Answer 126

1. The olfactory (I) nerve is entirely sensory.

2. It contains axons that conduct nerve impulses for olfaction (sense of smell).

Question 127

Optic (II) Nerve

Answer 127

1. The optic (II) nerve is purely sensory.

2. It contains axons that conduct nerve impulses for vision.

Question 128

Oculomotor (III), Trochlear (IV), and Abducens (VI) Nerves

Answer 128

1. The oculomotor (III), trochlear (IV), and abducens (VI) nerves are the cranial nerves that control the muscles that move the eyeballs.
2. They are all motor nerve

Question 129

Trigeminal (V) Nerve

Answer 129

1. The trigeminal (V) nerve is a mixed cranial nerve and the largest of the cranial nerves.
2. It conveys touch, pain, and thermal sensations from the scalp, face, and oral cavity and controls chewing muscles and middle ear muscle.

Question 130

Facial (VII) Nerve

Answer 130

1. The facial (VII) nerve is a mixed cranial nerve.
2. It conveys taste from anterior two-thirds of the tongue as well as touch, pain, and thermal sensations from skin in the external acoustic meatus; it also controls muscles of facial expression and middle ear muscle; promotes secretion of tears; and promotes secretion of saliva.

Question 131

Vestibulocochlear (VIII) Nerve

Answer 131

1. The vestibulocochlear (VIII) nerve is a sensory cranial nerve.
2. It conveys sensory information for audition (hearing) and equilibrium (balance

Question 132

Glossopharyngeal (IX) Nerve

Answer 132

1. The glossopharyngeal (IX) nerve is a mixed cranial nerve.
2. It conveys taste from posterior one-third of tongue, proprioception from some swallowing muscles, and touch, pain, and thermal sensations from the skin of external ear and upper pharynx; monitors blood pressure and oxygen and carbon dioxide levels in blood; assists in swallowing; and promotes secretion of saliva.

Question 133

Vagus (X) Nerve

Answer 133

1. The vagus (X) nerve is a mixed cranial nerve.
2. It conveys taste from the epiglottis, proprioception from throat and voice box muscles, touch, pain, and thermal sensations from skin of external ear, and sensations from thoracic and abdominal organs; monitors blood pressure and oxygen and carbon dioxide levels in blood; promotes swallowing, vocalization, and coughing, motility and excretion of digestive canal organs, and constriction of respiratory passageways; and decreases

Question 134

Accessory (XI) Nerve

Answer 134

1. The accessory (XI) nerve is a motor cranial nerve.

2. It controls movements of the head.

Question 135

Hypoglossal (XII) Nerve

Answer 135

1. The hypoglossal (XII) nerve is a motor cranial nerve.

2. It promotes speech and swallowing

Question 136

Development of the Nervous System

Answer 136

1. The development of the nervous system begins with a thickening of a region of the ectoderm called the neural plate.
2. During embryological development, primary brain vesicles form from the neural tube and serve as forerunners of various parts of the brain.
3. The telencephalon forms the cerebrum, the diencephalon develops into the thalamus and hypothalamus, the mesencephalon develops into the midbrain, the metencephalon develops into the pons and cerebellum, and the myelencephalon forms the medulla.

Question 137

Aging and the Nervous System

Answer 137

1. The brain grows rapidly during the first few years of life.
2. Age-related effects involve loss of brain mass and decreased capacity for sending nerve impulses.

Question 138

Comparison of Somatic and Autonomic Nervous Systems

Answer 138

• somatic nervous system operates under conscious control

- ANS usually operates without conscious contro

Question 139

Sensory input for the somatic nervous system is mainly from the somatic senses and special senses

Answer 139

sensory input for the ANS is from interoceptors, in addition to somatic senses and special senses.