131central nervous system

7/31/2019 131Central Nervous System

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Early

Developmental

Regions

Late Developmental

Regions

Structure Derived

from Regions

Thalamus


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Encephalons Development


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CNS: Bone and Connective Tissue

Brain is encased in bony skull or cranium

Spinal cord runs through vertebralcolumn

Meninges lies between bone and tissues Dura mater

Arachnoid membrane

Pia mater

Meningeal layers of the brain cushion and protect

delicate neural tissue


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CNS: Bone and Connective Tissue

Figure 9-4 (1 of 2)

Cerebral

hemispheres

Cerebellum

Cranium

Cervical spinalnerves

Cranium

Dura mater

Subdural

space

Subarachnoid

space

Pia mater

Arachnoid

membrane

Brain

(b) Meningeal layers of the brain cushion and

protect delicate neural tissue.

CENTRAL NERVOUS SYSTEM SECTIONAL VIEWS OF THE CNS

ANATOMY SUMMARY

Venous sinus

Dural Sinuses

drain CSFonly between dura


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CNS: Ventricles of the Brain

Figure 9-5a

ANATOMY SUMMARY

VENTRICLES OF THE BRAIN

Cerebrum

Lateral ventricles

Third ventricle

Fourth ventricle

Cerebellum

Central canal

Spinal cord

Lateral view Frontal view(a)


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CNS: Cerebrospinal Fluid

Figure 9-5b-d

ANATOMY SUMMARY

CEREBROSPINAL FLUID CIRCULATION

Choroid plexus

of third ventricle

Arachnoid

villi

Pia mater

(b)Sinus

Arachnoid

membrane

Arachnoid

membrane

Dura mater

Subarachnoid

space

Central canal

Choroid plexus

of fourth ventricle

Spinal cord

Cerebral

cortex

Endothelial

lining

Blood in

venous sinus

Fluid

movement

Arachnoid

villus

Dura mater

(inner layer)

Subdural

space

Arachnoid

membrane

Subarachnoid

space

Pia

mater

Cerebrospinal fluid

Bone of skull

Dura mater

(d)

Secreted continuously by choroid

plexus- consists of capillaries and

transporting epithelium

Selectively pumps sodium and

other solutes from plasma into

ventricles

Choroid plexus ventricles

subarachnoid space blood by villi on

arachnoid membrane


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CNS: Blood-Brain Barrier

Figure 9-6b


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CNS: Neural Tissue Metabolic Needs

Oxygen

Passes freely across blood-brain barrier

Brain receives 15% of blood pumped by heart

Glucose Brain responsible for about half of bodys glucose

consumption

Membrane transporters move glucose from plasma

into the brain interstitial fluid Progressive hypoglycemia leads to confusion,

unconsciousness, and death


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Spinal Cord:organization

Figure 9-7b

(b) Gray matterconsists of sensory and motor nuclei.

Dorsal root

ganglion

Ventral

root

Ventral

horn

Lateral

horn

Dorsal

horn

Visceral sensory nuclei

Somatic

sensory

nuclei

Autonomic

efferent

nuclei

Somatic

motor nuclei


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Spinal Cord: Anatomy

Propriospinal tracts remain within the cord

Figure 9-7c (1 of 2)


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Spinal Cord: Anatomy

Figure 9-7c (2 of 2)


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The Brain: Mid-Sagittal View

Figure 9-9c

Temporal

lobe

Parietal lobe

Occipital lobe

Frontal lobe

(c) Mid-sagittal view of brain

Cerebellum

Medulla oblongata

Pons

Corpus callosum

Thalamus

Cingulate gyrus

ANATOMY SUMMARY

ANATOMY OF THE BRAIN

Hypothalamus


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The Brain: Hypothalamus

Activates sympathetic nervous system

Maintains body temperature

Controls body osmolarity

Controls reproductive functions Controls food intake

Interacts with limbic system to influence behavior and

emotions

Influences cardiovascular control center in medulla oblongata Secretes trophic hormones that control release of hormones

from anterior pituitary gland


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The Brain: Gray Matter of the Cerebrum

Figure 9-11

Basal

ganglia

Lateral

ventricle

Corpus

callosum

Gray matter of

cerebral cortex

Tip of lateral

ventricle

Tracts of

white matter

Basal ganglia- involved in control of movement

Th B i C ll B di i th C b l


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The Brain: Cell Bodies in the Cerebral

Cortex Form Distinct Layers

Figure 9-12


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Brain Function: Reflex Pathways in the Brain

Figure 9-14

Sensory

input

Sensory

system

(reflex)

Integration

Behavioral

state system

Cognitive

system

(voluntary)

CNS

OutputMotor

system output

ResponsePhysiological

response or

behavior

Feedback

(a) A simple

neural reflex

(b) Behavioral state and cognition

influence brain output.


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Three systems influence output of motor

systems of the body

Sensory system which monitors external and

internal environments and initiates reflex

responses

Cognitive system resides in cerebral cortex

and is able to initiate voluntary responses

Behavioral state system- resides in brain nd

regulates sleep-wake cycles and other intrinsic

behaviors


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Brain Function: Cerebral Cortex From a functional viewpoint, it can be divided

into three specializations

Sensory areas

Sensory input translated into perception (awareness)

Monitors external and internal environment

Motor areas

Direct skeletal muscle movement

Association areas

Integrate information from sensory and motor areas Can direct voluntary behaviors

B i F ti F ti l A f th


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Brain Function: Functional Areas of the

Cerebral Cortex

Figure 9-15

Skeletal

muscle

movement

Visual

association

area

OCCIPITAL LOBE

Visual

cortex

Auditory

association area

Auditory

cortex

TEMPORAL LOBE

FRONTAL LOBE

Sensory association area

Olfactory cortex

Hearing

Vision

Smell

Prefrontal

association

area

Primary somatic sensory cortex

Motor association

area (premotor cortex)

Primary motor cortex

Gustatory cortexTaste

PARIETAL LOBE


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Speech

center

Writing

Auditory

cortex

(right ear)

LEFTHEMISPHERE

RIGHTHEMISPHERE

General

interpretive

center

(language and

mathematical

calculation)

Visual cortex

(right visual field)

C

O

R

P

U

S

C

A

L

L

O

S

U

M

LEFT HAND

Prefrontal

cortex

RIGHT HAND

Prefrontal

cortex

Spatial

visualization

and analysis

Auditory

cortex

(left ear)

Analysis

by touch

Visual cortex

(left visual field)

Figure 9-16

Brain Function: Cerebral Lateralization

Each lobe hasspecial

functions

Dominance (leftbrain-right braindominance)

Neural connections

exhibit plasticity


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Brain Function: Sensory Information

Special senses have devoted regions

Visual cortex

Auditory cortex

Olfactory cortex

Gustatory cortex

Processed into perception


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Brain Function: Motor Systemgoverns output from CNS

Three major types

Skeletal muscle movement

Somatic motor division

Neuroendocrine signals Hypothalamus and adrenal medulla

Visceral responses

Autonomic division

Voluntary movement

Primary motor cortex and motor association areas


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Brain Function: Behavioral State

Modulator of sensory and cognitive processes

Neurons collectively known as diffuse

modulatory systems

Originate in reticular formation in brain stem

Classified according to neurotransmitter they

secrete

Influence attention, motivation,sleep-wake cycles,

memory, motor control, mood and metabolic

homeostasis


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Brain Function: Behavioral State

Table 9-3

Brain Function: Diffuse Modulatory


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Systems Modulate Brain Function

Figure 9-19a-b

Thalamus

HypothalamusCerebellum

Locus coeruleus

(a) Norepinephrine

To basal

nuclei

Raphe

nuclei

(b) Serotonin

Functions: attention, arousal, sleep-wakecycles, learning, memory, anxiety,

pain, mood

Neurons originate: locus coeruleus of pons

Neurons terminate: cerebral cortex, thalamus,

hypothalamus, olfactory bulb,

cerebellum, midbrain, spinal cord

Functions: lower nuclei: pain, locomotion

upper nuclei: sleep-wake cycles

mood & emotional behaviors

such as aggression & depression

Neuron originate:raphe nuclei along brain stem

midline

Neurons terminate: lower nuclei: spinal cordupper nuclei: most of brain



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Systems Modulate Brain Function

Figure 9-19c-d

Substantia

nigra

Ventral

tegmental area

To basal

nuclei

Prefrontal

cortex

(c) Dopamine

Cingulate

gyrus

Fornix

Pontine

nuclei

(d) Acetylcholine

Functions: motor control

reward centers linked to

addictive behavior

Neurons originate: substantia nigra midbrain

ventral tegmentum midbrain

Neurons terminate: cortex

cortex & parts limbic system

Functions: sleep-wake cycles, arousal, learning,

memory, sensory information,

passing through thalamus

Neurons originate: base of cerebrum, pons, and

midbrain

Neuron terminate: cerebrum, hippocampus,

thalamus


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Figure 9-20a

Brain Function: States of Arousal

Electroencephalograms (EEGs) and the sleep

cycle

Reticular

activating

system keeps

conscious

brain awake


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Brain Function: Sleep

Four stages with two major phases Slow-wave sleep

Adjust body without conscious commands

REM sleep

Brain activity inhibits motor neurons to skeletal muscle,

paralyzing them

Dreaming takes place

Circadian rhythm Suprachiasmatic nucleus
http://www.youtube.com/watch?v=J7Y_qDGicgI&feature=relatedhttp://www.youtube.com/watch?v=J7Y_qDGicgI&feature=related


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Brain Function: Emotion and Motivation

The link betweenemotions and

physiological functions

Motivation- internalsignals that shape

voluntary behaviors common properties (drives)

1. create an internal state of CNSalertness or arousal

2. create goal-oriented behavior

3. capable of coordinating disparate

behaviors to achieve that goal

Figure 9-21


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Brain Function: Learning and Memory

Learning has two broad types

Associative

Nonassociative

Habituation

Sensitization

Memory has several types

Short-term and long-term

Reflexive and declarative


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Brain Function: Memory Processing

Figure 9-22


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Brain Function: Long-Term Memory

Table 9-4


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Brain Function: Language

Cerebral processing of spoken and visual

language

Damage to Wernickescauses receptive aphasia

Figure 9-23a(a) Speaking a written word

Readwords

Brocasarea

Motorcortex

Wernickesarea

Visualcortex


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Brain Function: Language

Damage to Brocas area causes expressiveaphasia

(b) Speaking a heard word

Hear

words

Brocas

area

Motorcortex

Wernickes

area

Auditory

cortex

131central nervous system

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