Neurology Lecture 1 Part 2. Central Nervous System Brain Spinal Cord Control center for entire...

Neurology

Lecture 1Part 2

Central Nervous System

• Brain• Spinal Cord• Control center for

entire system

Brain

• Skull– Ridged vault

• Plates and Fissures– Occipital – Parietal– Temporal– Frontal

The Meninges

• Function– Support– Protect– Nourish

• Dura mater• Arachnoid

– Choroid Plexus– Cerebral-spinal fluid

(CSF)

• Pia Mater

Brain – 3 main areas

• Cerebrum– Coordination of stimuli

• Brainstem– Midbrain– Pons– Medulla oblongata

• Cerebellum– Control muscle

movement

Cerebrum

• Cerebral cortex• Rt. & Lt. hemisphere• Receives & analyze

impulses• Control voluntary

movement• Stores knowledge

4 Major Lobes

• Frontal• Parietal• Temporal• Occipital

Frontal Lobe - Cerebrum

• Personality• Intellectual functioning• Conceptualization• Abstraction• Affect• Judgment• Inhibitions• Write

Parietal Lobe - Cerebrum

• Perception & interpretation of sensory info

• Recognize body parts• Sensation• Spatial relationships

Temporal Lobe - Cerebrum

• Memory (short term)• Hearing• Taste• Smell• Auditory integration• Understanding spoken word• Behavior and emotional

control

Occipital Lobe - Cerebrum

• Visual center• Understanding of

written language

Basal Ganglia

• Deep within the cerebrum

• Function– Control postural

adjustments (subconscious)

– Fine motor movements (esp. hands & lower ext.)

Speech Centers

• Broca’s Area– Frontal lobe– Controls verbal &

expressive speech– Coordinates the mouth,

tongue and larynx– Damaged can not

speak

Speech Centers

• Wernicke’s area– Temporal lobe– Responsible for

reception and understanding of language

– Damage can not understand speech

Left-side Brain

• Verbal communication• Linguistics /language• Arithmetical• Calculating• Analytical• Problem solving• Reading• Writing

Right-side Brain

• Geometric• Spatial• Visual• Patterns• Music• Perception of physical

environment• Art• Non-verbal communication• Spiritual

Corpus Callosum - Cerebrum

• Responsible for transmission of info from one side of the brain to the other

Diencephalon

• Thalamus– Translates impulses into

• Pain• Temperature• Touch sensation• Pleasant and

unpleasant feelings– Complex reflex

movement

Diencephalon

• Hypothalamus– Nervous + endocrine

system– Feelings of rage /anger– Temperature– Sleep– Thirst– Appetite/hunger– Respiration– Blood pressure– Osmolarity of body fluids

Diencephalon

• Pituitary Gland– Endocrine system– Master gland

Cerebral Cortex / Cerebrum

• All stored information• 4 speech centers• Motor & sensory areas• Vision & hearing

Cerebral Cortex / Cerebrum

• CNS produces electrical waves

• EEG

Brainstem

• Connects brain with spinal cord

• Structures– Midbrain

• Upper brain stem• Motor movement• Postural reflexes• Relay for sight and

hearing

Brainstem

• Structures– Midbrain– Pons

• Btw midbrain and medulla

• Pneumotaxic center– Medulla oblongata

Brainstem

• Medulla oblongata– Below ponds– Vital reflexes– Cardiac center– Respiratory center– Cough, swallowing,

hiccupping vomiting– Pyramidal tracts

Cerebellum

• Lesser brain• Controls skeletal

muscles coordinated movement, equilibrium and erect posture

Spinal Cord – CNS

• Continuous with brain stem

• Extend to L-1orL-2• Filum Terminal• Lumbar Punctures

L3-4

Spinal Cord - CNS

• Divided into Rt & Lt hemispheres

Peripheral Nervous System

• Contains– Cranial nerves– Spinal nerves

• Location• Function

– Sensory impulses from PNS CNS

– Motor response from CNS PNS

• Key word:– Nerves

Peripheral Nervous System

• Consists of– 12 pairs of cranial

nerves– 31 pairs of spinal nerves

• Cervical = 8• Thoracic = 12• Lumbar = 5• Sacral = 5• Coccygeal = 1

Peripheral Nervous System

• Myelin Sheath– Insulation– Increases velocity of

impulse

Spinal Nerves

• Dorsal/Posterior Horn– Sensory

• Vental/Anterior Horn– Motor

Thought Question

When the doctor checks your reflexes in your leg: Does the impulse:

A. travel to you spinal cord brain Brain says kick impulse to your spinal cord impulse to your knee kick OR

B. Impulse travel to your spinal cord spinal cord says kick impulse back to knee kick

Spinal Reflexes

• Forms reflex arc• Automatic

PNS Somatic & Autonomic NS

• Somatic NS– Acetylcholine speeds impulses– Connects CNS to skin & skeletal muscles – Conscious activities - Voluntary

• Autonomic NS– Connects CNS to visceral organs– Unconscious activates– Divided

• Sympathetic nervous system• Parasympathetic nervous system

Schematic Diagram of the Peripheral Nervous System

PNS comprised of Cranial and Spinal Nerves

Somatic Nervous SystemProcess: VoluntaryFunction: Respond to changes in external environmentEffector site: skeletal muscle

Autonomic Nervous systemProcess: InvoluntaryFunction: Respond to changes in the internal environmentEffector sites: Internal organs

Sympathetic NS Parasympathetic NS

Autonomic Nervous System

Sympathetic Nervous System

Chemical Process: AdrenergicFunction: EnergizeScope of Response: Global

Parasympathetic Nervous SystemChemical Process: CholinergicFunction: StabilizeScope of Response: Local

Sympathetic NS Parasympathetic NS

Rate Heart rate

Constricts Abd. muscles

Dilates

Dilates Vessels of Skeletal muscles

0

Dilates Bronchi Constricts

secretions Lung secretions

secretions

Peristalsis

Salivary secretions

Sympathetic NS Parasympathetic NS

Closes Anal sphincter Opens

Relaxes Bladder Contracts

Closes Urinary sphincter

Opens

Dilate Pupil Constrict

far vision Eye accommodatio

n

near vision

secretions Pancreas secretions

Release glucose

Liver 0

secretions Adrenal Medulla

0

Cerebrospinal fluid (CSF)

• The ventricles manufacture and absorb CSF – primarily choroid plexus

• Circulated in the subarachnoid space

CSF Function

• Cushion• Carries nutrients• Helps maintain inter-

cranial pressure

CSF Characteristics

• Colorless• Average: 100-150

cc• Contains

– H2O– Glucose– Na+

– Cl-

– K+

– No RBC’s– WBC – (trace 0-5)

Circulation of brain and spinal cord

• 2 internal carotid arteries

Circulation of brain and spinal cord

• 2 internal carotid arteries

• Vertebral arteries

Circulation of brain and spinal cord

• 2 internal carotid arteries

• Vertebral arteries• Circle of Willis

Brain circulation

• Does not store nutrients• Can adjust own blood flow

in response to BP– Increase CO2

• Vasodilate– Decrease O2

• Vasodilate – Decrease in pH

• Vasodilate

• Large amounts of O2

Blood brain barrier

What do we know about capillaries?

• Permeable / thinBrain capillaries lined with

endothelial cells tight junction

Permeability of Blood Brain Barrier

Permeable:• O2• CO2• WaterSlight Permeable:• Electrolytes• GlucoseImpermeable to:• Most drugs• proteins