Ch. 13 Central Nervous System

Ch. 13 Central Nervous System

IntroductionIntroduction

The CNS contains:– Brain - encased by

cranium– Spinal cord - encased

by vertebrae

The CNS contains:– Brain - encased by

cranium– Spinal cord - encased

by vertebrae

Coverings of the brain and spinal cordCoverings of the brain and spinal cordMeninges membranes between bone and soft tissue

– Dura mater – outermost, contains blood vessels Forms periostium of skull bones Forms partitions between lobes of brain and sinuses provides resistance to pathogens Prevents cerebral spinal fluid leaks

– Arachnoid mater – middle. Thin, avascular

– Pia mater – innermost, vascular, thin

– Attached to brain and spinal cord surface.

Spaces– Epidural-between dura mater and covering of spinal

cord.

– Subdural – between dura mater/arachnoid mater. Contains serous fluid

– Subarachnoid – between arachnoid and pia. Contains cerebrospinal fluid

Purpose – supportive cushion.

Meninges membranes between bone and soft tissue– Dura mater – outermost, contains blood vessels

Forms periostium of skull bones Forms partitions between lobes of brain and sinuses provides resistance to pathogens Prevents cerebral spinal fluid leaks

– Arachnoid mater – middle. Thin, avascular

– Pia mater – innermost, vascular, thin

– Attached to brain and spinal cord surface.

Spaces– Epidural-between dura mater and covering of spinal

cord.

– Subdural – between dura mater/arachnoid mater. Contains serous fluid

– Subarachnoid – between arachnoid and pia. Contains cerebrospinal fluid

Purpose – supportive cushion.

Structure of the Spinal cordStructure of the Spinal cord Description and location Structure

– 31 Segments with a pair of spinal nerves in each segment

– 8 cervical – 12 thoracic – 5 lumbar– 5 sacral– CX - in coccyx– Cervical enlargement– Lumbar enlargement– Plexus - clump– Grooves

Anterior media fissure Posterior median sulcus

– White matter – myelinated fibers – Gray mater - cell bodies and dendrites of

interneurons. (butterfly shaped)

Description and location Structure

– 31 Segments with a pair of spinal nerves in each segment

– 8 cervical – 12 thoracic – 5 lumbar– 5 sacral– CX - in coccyx– Cervical enlargement– Lumbar enlargement– Plexus - clump– Grooves

Anterior media fissure Posterior median sulcus

– White matter – myelinated fibers – Gray mater - cell bodies and dendrites of

interneurons. (butterfly shaped)

Function of the spinal cordFunction of the spinal cord

Functions– Transmit impulses– House spinal reflexes

Ascending (sensory) descending tracts (motor) Names of tracts – identify origin and

termination of fibers in tract (ex. Spinothalamic tract)

Functions– Transmit impulses– House spinal reflexes

Ascending (sensory) descending tracts (motor) Names of tracts – identify origin and

termination of fibers in tract (ex. Spinothalamic tract)

The myteries of the human brainThe myteries of the human brain

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The brainThe brain Introduction - largest part of

the nervous system 100 billion multipolar

neurons. Divisions

– Cerebrum – largest/higher mental functions

– Diencephalon – process sensory input

– Cerebellum-coordinates muscular activity

– Brainstem-coordinates/regulates visceral activities

Introduction - largest part of the nervous system

100 billion multipolar neurons.

Divisions– Cerebrum – largest/higher

mental functions– Diencephalon – process

sensory input– Cerebellum-coordinates

muscular activity– Brainstem-coordinates/

regulates visceral activities

The cerebrumThe cerebrum The largest part of the brain Surface of the brain is marked by

convolutions, sulci, fissures. Lobes of the brain are named

according to the bones they underlie. 2 hemispheres connected by Corpus

callosum– Convolutions, sulci, fissures– Lobes

Frontal Parietal Temporal Occipital

– Cerebral cortex - thin layer of gray mater - 75% of cell bodies

The largest part of the brain Surface of the brain is marked by

convolutions, sulci, fissures. Lobes of the brain are named

according to the bones they underlie. 2 hemispheres connected by Corpus

callosum– Convolutions, sulci, fissures– Lobes

Frontal Parietal Temporal Occipital

– Cerebral cortex - thin layer of gray mater - 75% of cell bodies

Functions of the cerebrumFunctions of the cerebrum

Higher brain functions– Interpretation of sensory input– Initiating voluntary muscular movement– Memory– Integrating information for reasoning– Consciousness– Language– Emotions

Higher brain functions– Interpretation of sensory input– Initiating voluntary muscular movement– Memory– Integrating information for reasoning– Consciousness– Language– Emotions

Functional regions of cerebral cortexFunctional regions of cerebral cortex Primary motor area-frontal lobes, anterior wall Broca’s area coordinates muscular activity for

speech Frontal eye field - controls eye and eye lid

movement Sensory areas - interpret sensory input,

produce feelings/sensations Association areas interpret sensory impulse,

reasoning, judgment, emotions, story memory Cross-over - right side controls left side of

body, etc. Interpretive areas-located where lobes come

together - higher intellectual processes. Damage

– Occipital lob - sight and images– Temporal lobe - recent memories - inability to

form long term memories.

Primary motor area-frontal lobes, anterior wall Broca’s area coordinates muscular activity for

speech Frontal eye field - controls eye and eye lid

movement Sensory areas - interpret sensory input,

produce feelings/sensations Association areas interpret sensory impulse,

reasoning, judgment, emotions, story memory Cross-over - right side controls left side of

body, etc. Interpretive areas-located where lobes come

together - higher intellectual processes. Damage

– Occipital lob - sight and images– Temporal lobe - recent memories - inability to

form long term memories.

Hemisphere dominanceHemisphere dominance

Both cerebral hemispheres receive/analyze Most people exhibit dominance of left or right

hemispheres. Left hemisphere is dominant in 90% Left hemisphere dominance usually results in

being right handed, etc. Non dominant hemisphere specialize in nonverbal

function, emotion control/intuitive thinking

Both cerebral hemispheres receive/analyze Most people exhibit dominance of left or right

hemispheres. Left hemisphere is dominant in 90% Left hemisphere dominance usually results in

being right handed, etc. Non dominant hemisphere specialize in nonverbal

function, emotion control/intuitive thinking

Ventricles and cerebrospinal fluidVentricles and cerebrospinal fluid Description - series of connective

cavities containing cerebrospinal fluid. Continuous with the spinal cord

Choroid plexuses– Specialized capillaries that Secrete

cerebrospinal fluid Comes from lateral ventricles Cerebrospinal fluid

– Nutritive– Protective

Pressure - normally constant. Infection /tumor can increase pressure - causes damage

Description - series of connective cavities containing cerebrospinal fluid. Continuous with the spinal cord

Choroid plexuses– Specialized capillaries that Secrete

cerebrospinal fluid Comes from lateral ventricles Cerebrospinal fluid

– Nutritive– Protective

Pressure - normally constant. Infection /tumor can increase pressure - causes damage

DiencephalonDiencephalon Location - above brain stem Contains:

– thalamus -sorts and directs sensory information - filters non-essential information

– Hypothalamus - maintains homeostasis/ linked to endocrine system

– Optic tracts and chasmas - connect sense of sight

– Infundibulum - attachment for pituitary– Pituitary gland - certain hormone

production.– Pineal gland - puts you to sleep– Limbic system - controls emotional

experience and expression Guides behavior that increases

chance of survival.

Location - above brain stem Contains:

– thalamus -sorts and directs sensory information - filters non-essential information

– Hypothalamus - maintains homeostasis/ linked to endocrine system

– Optic tracts and chasmas - connect sense of sight

– Infundibulum - attachment for pituitary– Pituitary gland - certain hormone

production.– Pineal gland - puts you to sleep– Limbic system - controls emotional

experience and expression Guides behavior that increases

chance of survival.

BrainstemBrainstem Consists of

– Midbrain- conveys impulses to and from other parts of the brain

Reflex centers

– Pons-between midbrain and medulla oblongata

Regulates rate and depth of breathing

Transmits impulses between brain and spinal cord

– Medulla oblongata - transmits ascending and descending impulses

– Controls visceral functions - cardiac center - heart rate, blood pressure control, respiratory center, cough and vomiting centers, sneezing

– Reticular formation-wakes up the cerebral cortex

Decreased activity results in sleep, increased - wakefulness

Filters sensory impulses If damaged, can’t wake from a

coma.

Consists of – Midbrain- conveys impulses to and

from other parts of the brain Reflex centers

– Pons-between midbrain and medulla oblongata

Regulates rate and depth of breathing

Transmits impulses between brain and spinal cord

– Medulla oblongata - transmits ascending and descending impulses

– Controls visceral functions - cardiac center - heart rate, blood pressure control, respiratory center, cough and vomiting centers, sneezing

– Reticular formation-wakes up the cerebral cortex

Decreased activity results in sleep, increased - wakefulness

Filters sensory impulses If damaged, can’t wake from a

coma.

Cerebellum Cerebellum Made of two

hemispheres connected in the middle.

Cerebellar cortex - gray matter

Communicates with others parts of cns.

Integrates sensory information about position of body parts and coordinates skeletal muscle activity to maintain posture.

Made of two hemispheres connected in the middle.

Cerebellar cortex - gray matter

Communicates with others parts of cns.

Integrates sensory information about position of body parts and coordinates skeletal muscle activity to maintain posture.

languagelanguage

Ability to speak/write words and ability to understand spoken/written words.

Speech center – areas in frontal, parietal, temporal lobes.

Left cerebral hemisphere contains speech centers in 90% of population

Aphasias - damage to speech centers - can’t speak.

Ability to speak/write words and ability to understand spoken/written words.

Speech center – areas in frontal, parietal, temporal lobes.

Left cerebral hemisphere contains speech centers in 90% of population

Aphasias - damage to speech centers - can’t speak.

EmotionsEmotions

Limbic system -known as the “emotional brain”

Medial surface of cerebrum and region called hippocampus

Connection to olfactory sense

Limbic system -known as the “emotional brain”

Medial surface of cerebrum and region called hippocampus

Connection to olfactory sense

MemoryMemory Cortex stores and retrieves short and long term

memory

Repetition is the key to transferring information from short to long term memory

If you don’t use it you lose it. Closely connected to limbic system Forgetting is the atrophy of a neural

connection that was created when learning took place.

Cortex stores and retrieves short and long term memory

Repetition is the key to transferring information from short to long term memory

If you don’t use it you lose it. Closely connected to limbic system Forgetting is the atrophy of a neural

connection that was created when learning took place.