Lecture Human anatomy and physiology - Chapter 12: The central nervous system (part c)

Chapter 12 - The central nervous system (part c), in this chapter you will learn about the following: Functional brain systems, limbic system, limbic system: emotion and cognition, reticular formation, reticular formation: RAS and motor function, electroencephalogram (EEG), brain waves,...and other contents.

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PowerPoint ® Lecture Slides

prepared by Vince Austin, Bluegrass Technical

and Community College

C H A P T E R

12

The Central Nervous

System:

Part C

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Functional Brain Systems

span wide areas of the brain

• Reticular formation

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Limbic System

hemispheres and diencephalon

cerebral structures that encircle the brain

stem

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Corpus callosum Septum pellucidum

•Fornix

•Anterior commissure

Cerebral tures of the limbic system

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Limbic System

expressions, assesses danger, and elicits the fear response

emotions via gestures, and resolves mental conflict

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Limbic System: Emotion and Cognition

lobes, therefore:

consciously understand to be happening

richness in our lives

memory

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Reticular Formation

brain stem

• Medial (large cell) group of nuclei

• Lateral (small cell) group of nuclei

hypothalamus, thalamus, cerebral cortex,

cerebellum, and spinal cord

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Reticular Formation: RAS and Motor Function

it conscious and alert

• Filters out repetitive and weak stimuli (~99% of all stimuli!)

unconsciousness (coma)

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Reticular Formation: RAS and Motor Function

motor functions

• Respiratory centers

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Visual impulses Reticular formation

Auditory impulses

Radiations

to cerebral cortex

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Electroencephalogram (EEG)

brain function

between various cortical areas

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Brain Waves

frequency measured as Hertz (Hz)

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Types of Brain Waves

• Alpha waves (8–13 Hz)—regular and rhythmic, amplitude, synchronous waves indicating an “idling” brain

low-• Beta waves (14–30 Hz)—rhythmic, less regular

waves occurring when mentally alert

• Theta waves (4–7 Hz)—more irregular; common in children and uncommon in adults

• Delta waves (4 Hz or less)—high-amplitude waves seen in deep sleep and when reticular activating

system is damped, or during anesthesia; may

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Alpha waves—awake but relaxed

Beta waves—awake, alert

Theta waves—common in children

Delta waves—deep sleep

(b) Brain waves shown in EEGs fall into four general classes.

1-second interval

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Brain Waves: State of the Brain

disease, and the chemical state of the body

lesions, tumors, infarcts, infections,

abscesses, and epileptic lesions

evidence of death

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Epilepsy

fall stiffly, and have uncontrollable jerking

impairments

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Epileptic Seizures

expression goes blank

broken due to intense contractions, may experience loss of bowel and bladder control, and severe biting of the tongue

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Control of Epilepsy

skin of the chest can keep electrical activity of the brain from becoming chaotic

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processing (memory, logic, judgment, etc.)

syncopy) is a signal that brain function is

impaired

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Consciousness

behavior in response to stimuli

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person can be aroused by stimulation

patterns)

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Sleep

first 30–45 minutes of sleep

and then REM sleep begins abruptly

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REM: Skeletal

muscles (except ocular muscles and diaphragm) are actively inhibited; most dreaming occurs.

NREM stage 1:

Relaxation begins;

EEG shows alpha waves, arousal is easy.

NREM stage 2: Irregular

EEG with sleep spindles (short high- amplitude bursts); arousal is more difficult.

NREM stage 3: Sleep

deepens; theta and delta waves appear;

vital signs decline.

NREM stage 4: EEG is

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Sleep Patterns

reflect a natural circadian (24-hour) rhythm

mediates, dreaming sleep

the hypothalamus time the sleep cycle

REM and NREM sleep

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(b) Typical progression of an adult through one night’s sleep stages

Awake REM Stage 1 Stage 2 Non

REM Stage 3

Stage 4

Time (hrs)

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Importance of Sleep

• Slow-wave sleep (NREM stages 3 and 4) is

presumed to be the restorative stage

• People deprived of REM sleep become moody and depressed

• REM sleep may be a reverse learning process where superfluous information is purged from the brain

• Daily sleep requirements decline with age

• Stage 4 sleep declines steadily and may disappear after age 60

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Language

• Basal nuclei

• Broca’s area and Wernicke’s area (in the

association cortex on the left side)

• Analyzes incoming word sounds

• Produces outgoing word sounds and grammatical structures

involved with nonverbal language components

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—temporary holding of information; limited to seven or eight pieces of information

capacity

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Outside stimuli

General and special sensory receptors

Data transfer influenced by:

Excitement Rehearsal Association of old and new data Long-term

memory (LTM)

Data permanently lost

Automatic memory

Data unretrievable

Temporary storage (buffer) in

cerebral cortex

Short-term memory (STM)

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Transfer from STM to LTM

• Emotional state—best if alert, motivated,

surprised, and aroused

memories

stored in LTM

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Categories of Memory

memory, and emotional memory

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Brain Structures Involved in Declarative

Memory

function in consolidation and access to

memory

memory formation and retrieval

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Basal forebrain Prefrontal cortex Taste

Thalamus Touch

Association cortex

Sensory input

Medial temporal lobe (hippocampus, etc.)

(a) Declarative

memory circuits

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Brain Structures Involved in Nondeclarative Memory

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Thalamus Premotor

cortex

Substantia nigra

Association

cortex

Basal nuclei

Sensory and

motor inputs

Premotor cortex

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Molecular Basis of Memory

• During learning:

dendrites

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potentiation, or LTP) is crucial

receptors, opening calcium channels in

postsynaptic terminal

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proteins of the postsynaptic terminal and

presynaptic terminal (via release of retrograde messengers)

for synthesis of synaptic proteins, in presence

of CREB (cAMP response-element binding

protein) and BDNF (brain-derived

neurotrophic factor)

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Protection of the Brain

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Meninges

sinuses

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Skin of scalp Periosteum

Falx cerebri (in longitudinal fissure only)

Blood vessel Arachnoid villusPia mater

Arachnoid mater

Dura mater

Meningeal Periosteal

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Dura Mater

(around the brain) separate to form dural sinuses

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Dura Mater

brain

• Falx cerebri—in the longitudinal fissure;

attached to crista galli

• Falx cerebelli—along the vermis of the

cerebellum

• Tentorium cerebelli—horizontal dural fold over cerebellum and in the transverse fissure

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Falx cerebri

Superior sagittal sinus

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Arachnoid Mater

subdural space

vessels

sagittal sinus and permit CSF reabsorption

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Skin of scalp Periosteum

Falx cerebri (in longitudinal fissure only)

Blood vessel Arachnoid villusPia mater

Arachnoid mater

Dura mater

Meningeal Periosteal

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Pia Mater

tissue that clings tightly to the brain

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Cerebrospinal Fluid (CSF)

signals

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sagittal sinus

Arachnoid villus

Subarachnoid space Arachnoid mater Meningeal dura mater Periosteal dura mater

Right lateral ventricle (deep to cut)

CSF is produced by the choroid plexus of each ventricle

1

CSF flows through the ventricles and into the subarachnoid space via the median and lateral apertures

Some CSF flows through the

2

1

2 3

4

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Choroid Plexuses

and a layer of ependymal cells

composition of the CSF and help cleanse CSF

by removing wastes

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Cavity of CSF forms as a filtrate

containing glucose, oxygen,

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(a) Astrocytes are the most abundant

CNS neuroglia.

Capillary

Neuron

Astrocyte

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Blood-Brain Barrier: Functions

• Allows nutrients to move by facilitated diffusion

• Allows any fat-soluble substances to pass,

including alcohol, nicotine, and anesthetics

and the hypothalamus, where it is necessary

to monitor the chemical composition of the

blood

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Homeostatic Imbalances of the Brain

force brain stem through the foramen magnum, resulting in death

associated with traumatic head injury

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• Cerebrovascular accidents (CVAs)(strokes)

blockage of a cerebral artery by a blood clot

deficits

episodes of reversible cerebral ischemia

approved treatment for stroke

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• Degenerative brain disorders

disease of the brain that results in dementia

dopamine-releasing neurons of the substantia nigra

caused by accumulation of the protein huntingtin that leads to degeneration of the basal nuclei and cerebral cortex

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