(c) Fundamentals of the Nervous System & Nervous Tissue (Q2,P6) Flashcards

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1
Q

Nervous System Functions

A

Master control and communication system
1) Gathers information – sensory input
2) Processes and interprets sensory input
3) Dictates a response - motor output

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2
Q

Basic Divisions of the Nervous System

A

Central Nervous System
Peripheral Nervous System

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3
Q

Central Nervous System (CNS)

A

Integrating and command center
2 Divisions: Brain, Spinal Cord

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4
Q

Peripheral Nervous System (PNS)

A

Consists of nerves extending from brain and spinal cord
Cranial nerves – 12 pairs
Spinal nerves – 31 pairs
- Peripheral nerves link all regions of the body to the CNS; responsible for getting info to cns and putting out info to the body

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5
Q

Sensory (afferent) signals

A
  • signals that come from outside stimuli and tell your brain what they are sensing, such as temperature
  • Picked up by sensor receptors
  • signals directed TOWARD the CNS
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6
Q

Motor (efferent) signals

A

innervate muscles and glands
Signals travel AWAY from the CNS

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7
Q

Main Cell Types of Nervous Tissue

A

1) Supporting cells (neuroglial cells) – nonexcitable; Surround and wrap neurons
2) Neurons – transmit electrical signals (excitable); Body has billions of neurons

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8
Q

Special Characteristics of the Neuron

A

1) Longevity – can live and function for a lifetime; usually can’t be restored
2) Do not divide – fetal neurons lose their ability to undergo mitosis; neural stem cells are an exception
3) High metabolic rate – require abundant oxygen and glucose

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9
Q

Three Main Parts of a Neuron

A

1) Cell Body
2) Dendrites
3) Axons

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10
Q

Cell Body of a Neuron

A

Contains usual organelles plus other structures

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11
Q

Dendrites

A
  • Extensively branching from the cell body
  • Function as receptive sites (carry electric signals to the cell body)
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12
Q

Axons

A
  • Neuron has only one
  • portion of a nerve cell (neuron) that carries nerve impulses away from the cell body.
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13
Q

Ganglia

A

Clusters of cell bodies

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14
Q

Synapses

A
  • Site at which neurons communicate
  • Signals pass across synapse in one direction
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15
Q

Nerves

A
  • cordlike organs in the PNS
  • Consists of numerous axons wrapped in connective tissue
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16
Q

Myelin Sheaths

A
  • Axons is surrounded by myelin sheaths
  • Surround thicker axons
  • Form an insulating layer; Prevent leakage of electrical current to ensure it goes in the proper direction
  • Increase the speed of impulse conduction
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17
Q

Types of Nerve Coverings

A

1) Endoneurium: layer of delicate connective tissue surrounding the axon
2) Nerve Fascicles: groups of axons bound into bundles
3) Perineurium: connective tissue wrapping surrounding a nerve fascicle
4) Epineurium: whole nerve is surrounded by tough fibrous sheath

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18
Q

Directional Terms Unique to the CNS

A

1) Rostral: toward the nose
2) Caudal: toward the tail

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19
Q

4 Regions of the Brain

A
  • Cerebral hemispheres
  • 3 parts of Diencephalon
  • 3 parts of Brain stem
  • Cerebellum
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20
Q

3 parts of Diencephalon

A

thalamus, hypothalamus, epithalamus

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21
Q

3 parts of the Brain stem

A

midbrain, pons, and medulla oblongata

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22
Q

What are the Ventricles of the Brain?

A

Expansions of the brain’s central cavity
Filled with cerebrospinal fluid produced by vessels called the CHOROID PLEXUSES
Ventricles are Continuous with each other
Ventricles are Continuous with the central canal of the spinal cord

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23
Q

4 Ventricles of the Brain

A

1)Lateral ventricles
2) Third ventricle
3) Cerebral aqueduct
4) Fourth ventricle

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24
Q

Lateral ventricles

A

located in cerebral hemispheres, anterior in the brain

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25
Q

Third ventricle

A
  • lies in diencephalon
  • Connected with lateral ventricles by interventricular foramen – also called the “Foramen of Monro”
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26
Q

Cerebral aqueduct/“Aqueduct of Sylvius”

A

connects 3rd and 4th ventricles

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27
Q

4th Ventricle

A

– lies in hindbrain
- Connects to the central canal of the spinal cord and subarachnoid space
- LATERAL APERTURE – foramen of Luschke
- MEDIAN APERTURE– foramen of Magendie

28
Q

Fissures of the Cerebral Hemispheres

A

Fissures: deep grooves – separate major regions of the brain
1) Transverse fissure – separates cerebrum and cerebellum
2) Longitudinal fissure – separates cerebral hemispheres

29
Q

Grooves and Ridges of the Cerebral Hemispheres

A

Sulci – grooves on the surface of the cerebral hemispheres; increases surface area of cerebrum
Gyri – twisted ridges between sulci

30
Q

Sulci of the Cerebral Hemispheres

A

Deeper sulci divide cerebrum into lobes
Lobes are named for the skull bones overlying them

1) Central sulcus: Separates frontal and parietal lobes
2) Parieto-occipital sulcus: Separates the occipital from the parietal lobe
3) Lateral sulcus: Separates temporal lobe from parietal and frontal lobes
There are 2

31
Q

Insula

A

deep within the lateral sulcus (one of the lobes of the brain)

32
Q

Basic Structure of the Cerebral Hemispheres (to remember)

A
  • 5 lobes in each hemisphere
    ** Fissures separate major brain region
    ** Sulci separate parts of each hemisphere
33
Q

Primary Tissue Layers (Matter) of the Cerebral Hemispheres

A

1) Cerebral cortex (gray matter – external layer)
2) Cerebral white matter (deep to the cortex)
3) Deep gray matter of the cerebrum (basal ganglia; found deep within the cerebral white matter)

34
Q

Cerebral Cortex

A
  • Home of our conscious mind
  • Enables us to:
    Be aware of ourselves and our sensations; Initiate and control voluntary movements; Communicate, remember, and understand
  • Composed of gray matter
  • Folds in cortex – triples its size to increase surface area
  • Approximately 40% of brain’s mass
  • 3 Functional Areas: Motor areas, Sensory areas, Association areas
35
Q

Brodmann areas

A

52 structurally distinct areas; divide up various functions of the cerebral cortex

36
Q

Types of Tracts of Cerebral White Matter

A

1) Commissures
2) Association Fibers
3) Projection Fibers

37
Q

Commissures

A

composed of commissural fibers (not the same as neurons); cross hempospheric connections
- Allows communication between cerebral hemispheres (right with the left)
- Corpus callosum – the largest commissure

38
Q

Association fibers

A

Connect different parts of the same hemisphere

39
Q

Projection fibers

A

run vertically between the cerebral hemispheres and the brain stem and spinal cord

40
Q

Deep Gray Matter of the Cerebrum

A

Consists of:
Basal ganglia – involved in MOTOR CONTRL
Basal forebrain nuclei – associated with MEMORY; usually the last to develop (that’s why we don’t have memory up to a certain point)

41
Q

The Diencephalon

A
  • Forms the center core of the forebrain
  • Surrounded by the cerebral hemispheres
  • Composed of three paired structures:
    Thalamus, hypothalamus, and epithalamus (front to back)
  • Primarily composed of GRAY MATTER
42
Q

The Diencephalon – The Thalamus

A

Is the “gateway” to the cerebral cortex
Nuclei organize and amplify or tone down signals

  • Makes up 80% of the diencephalon
  • Contains approximately a dozen major nuclei
  • Afferent impulses converge on the thalamus; all info from perifial system goes through the thalamus; discriminates against important and unimportant symbols
43
Q

The Diencephalon – The Hypothalamus

A

Pituitary gland projects inferiorly
Contains approximately a dozen nuclei
MAIN VISCERAL CONTROL CENTER of the body

Controls MANY involuntary functions (these are not all)
1) Regulation of body temperature
2) Regulation of hunger and thirst sensations
3) Control of the autonomic nervous system (heartrate, breathing, etc)
4) Regulation of sleep-wake cycles

44
Q

The Diencephalon – The Epithalamus

A
  • Forms part of the “roof” of the third ventricle
  • Consists of a tiny group of nuclei
  • Includes the pineal gland (pineal body)
    The pineal gland…
    Secretes the hormone melatonin
    Under influence of the hypothalamus
45
Q

Functions of the Pineal Gland

A

Secretes the hormone MELATONIN
Under influence of the hypothalamus

46
Q

The Brain Stem

A
  • Includes the midbrain, pons, and medulla oblongata

Several general functions
- Produces automatic behaviors necessary for survival
- Passageway for all fiber tracts running between the cerebrum and spinal cord
- Heavily involved with the innervation of the face and head;10 of the 12 pairs of cranial nerves attach to it

47
Q

The Cerebellum

A

Located dorsal to the pons and medulla
Smoothes and coordinates body movements
Helps maintain equilibrium
Maintains posture (sitting or standing)

48
Q

Protection of the Brain

A

The brain is protected from injury by:
The skull
Meninges
Cerebrospinal fluid
Blood-brain barrier

49
Q

Protection of the Brain – Meninges

A
  • Cover and protect the CNS
  • Enclose and protect the vessels that supply the CNS
  • Contain the cerebrospinal fluid
  • Three Layers: Dura mater,Arachnoid mater,Pia mater
50
Q

The Dura Mater

A
  • Strongest of the meninges
  • Composed of two layers: 1)Periosteal layer 2) Meningeal layer
  • Two layers are fused except to enclose the dural sinuses
51
Q

The Arachnoid Mater

A
  • a type of Meninges
  • Located beneath the dura mater
  • Subdural space; Potential space between dura and arachnoid mater
  • Subarachnoid space
    Filled with CSF; Contains the blood vessels that supply the brain
52
Q

The Pia Mater

A
  • a type of Meninges
  • Delicate connective tissue
  • Clings tightly to the surface of the brain; Follows all convolutions of the cortex
53
Q

Protection of the Brain – Cerebrospinal Fluid (CSF)

A

Provides a liquid cushion for the brain and spinal cord
The brain “floats” in CSF
Formed in CHOROID PLEXUSES in the brain ventricles

54
Q

Protection of the Brain – Blood-Brain Barrier

A
  • Prevents most blood-borne toxins from entering the brain; Impermeable capillaries
  • Not an absolute barrier: oxygen pass through; Allows alcohol, nicotine, and anesthetics
55
Q

Autonomic nervous system (ANS)

A
  • Part of the Peripheral Nervous System
  • Regulates visceral functions:Heart rate, blood pressure, digestion, urination

ANS has two divisions
1) Parasympathetic – “Resting and digesting”
2) Sympathetic – “Fight, flight, and fright response” Activates adrenal glands

56
Q

Spinal Nerves

A
  • 31 pairs – contain thousands of nerve fibers
  • All Connect to the spinal cord
  • Named for point of issue from the spinal cord (1 pair per vertebra)
    8 pairs of cervical nerves (C1-C8)
    12 pairs of thoracic nerves (T1-T12)
    5 pairs of lumbar nerves (L1-L5)
    5 pairs of sacral nerves (S1-S5)
    1 pair of coccygeal nerves (Co1)
57
Q

Conus medullaris

A

the inferior end of the spinal cord

58
Q

Filum terminale

A

long filament of connective tissue (keeps spinal cord connected)
Attaches to the coccyx inferiorly

59
Q

Cervical and lumbar enlargements

A

Where nerves for upper and lower limbs arise
(spinal cord)

60
Q

Cauda equina

A

collection of nerve roots
(spinal cord)

61
Q

Denticulate ligaments

A

anchor spinal cord to vertebrae

62
Q

spinal dural sheath

A
  • only one layer
  • an extension of the dura mater that surrounds the spinal nerves of the spinal cord
63
Q

The Spinal Cord

A

Runs through the vertebral canal of each vertebrae
Extends from the foramen magnum to the level of the vertebra L1 or L2
Protected by vertebra bone, meninges, and CSF
Dura mater of the spinal cord

64
Q

choroid plexus

A

a network of blood vessels in each ventricle of the brain. It is derived from the pia mater and produces the cerebrospinal fluid

65
Q

What is a plexus?

A

branching network of intersecting nerves

66
Q

Dura Mater, Arachnoid Mater, Pia Mater

A

Three layers of membranes known as meninges protect the brain and spinal cord