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Central Nervous System

Brain 

 

I). Ventricles

brain ventricles

1). Several large ‘spaces’ filled with cerebrospinal fluid.

2). Cerebrospinal Fluid forms a liquid cushion in and around the brain and spinal cord that is constantly drained and replaced.

 

II). Cerebral Hemispheresbrain animation

cerebral hemeispheres
cerebral hemispheres

A). 2 Lobes

B). The cerebrum divides into:

i). frontal

ii). parietal

iii). temporal

iv). occipital

v). insula: forms part of the floor

C). The sections form regions

basal nuclei

1). Basal nuclei

bulletregulating attention
bulletstarting, stopping and monitoring movements.
bulletinhibits movements

2). Cerebral White Matter:

bulletcommunication between:
bulletCerebral cortex and the lower CNS
bullethemispheres

3). Cerebral Cortex

    a).  Superficial layer

    b).  mind

bulletawareness of self
bulletcommunication
bulletmemory
bulletunderstanding

   c).  Convolutions

bulletgyri
bulletsulci
bulletfissures
bullet

    d).  Cerebral Dominance

1). Left side has greater control but not exclusive control over language, math, and logic.

2). Right side has greater control visual-spatial skills, intuition, emotion, and artistic skills.

    e).  Motor & Sensory control

bulletmotor areas
bulletsensory areas
bulletassociation areas

concerned with sensory input of the opposite side of the body

2 hemispheres are not equal in function

No functional area acts alone.

 

ffunctional areas of the brain
functional areas of the brain

i). Functional Area:  Motor areas:

Found: posterior part of the Frontal Lobe

bulletInclude voluntary movements, repetitious movements, motor speech and voluntary eye movements.
bulletOperates left to right: .
sensory and motor divsions of the brain

ii). Sensory Areas:

Found in the parietal, temporal, & occipital lobes.

Conscious awareness of sensation.

Sensory areas:

1). Spatial discrimination: Parietal lobe

bulletskeletal muscles and skin and identifies region being stimulated.

2). Somatosensory association: Parietal lobe--

bullet object being felt to produce an understanding.

3). Visuals Areas: Occipital Lobe

bulletInformation from the eyes. Information from the right eye is mapped in the left visual cortex and vice versa.
bulletAlso interprets visual stimuli using past visual experience

4). Auditory Areas: Temporal Lobe---

bulletInformation on pitch, rhythm, and loudness in interpreted and perceived as sound.
bulletMemories of sound are stored for reference.

5). Olfactory Cortex: Frontal Lobe & Temporal--

bulletolfactory signals and perceives smells.

6). Gustatory Cortex: Parietal Lobe

bulletTaste

7). Vestibular Cortex: Insula & Temporal Lobe

bullet" Equilibrium" Position of the head in space.

iii). Association Areas

Communicates between the primary sensory areas and the motor areas and other areas to:

bulletanalyze
bulletrecognize
bulletact

on input in reference to past experience.

1.) All of the sensory areas are connected to specific association areas

2.). Prefrontal Cortex: Anterior Frontal Lobes

bulletIntellect, complex learning, recall and personality, 
bulletabstract ideas, reasoning, concern for others

3). Language Areas: Temporal Lobe

bulletLanguage dominant side:
bulletNon-language dominant side:

4). General Interpretation Area: Found in one hemisphere only

bulletintegrates all signals into a single thought or understanding.

5). Visceral Association Area: Insula

bulletConscious perception of sensations from the internal organs. (ie. full bladder)

 

III). Diencephalon

diencephalon

 

A). Thalamus

bulletGateway to the cerebral cortex
bulletImpulses from all of the senses converge at a specific receptor and are edited or synchronized before traveling to the cortex.
bulletfunctions in motor activities, cortical arousal, learning & memory.

B). Hypothalamus

bulletLocated below thalamus.
bulletMain visceral control center. Functions in:

1). Autonomic control center  

2). Center for emotional response:

3). Body thermostat  

4). Regulation of food intake  

5). Regulation of water balance  

6). Regulation of circadian rhythm  

7). Controls endocrine system  

C). Epithalamus

1). Pineal gland

2). Choroid plexus

IV). Brain Stem

Brain Stem Brain Stem

Rigid, preprogrammed, automatic behaviors for survival. (primitive behaviors)

A). Midbrain

Under the diencephalon forming the cerebral peduncles.

Functions in:

1). Visual reflexes 

2). Auditory relay  

3). Startle reflex 

4). Releases dopamine.

5). Limb flexion.

B). Pons

Transmits nerves from the medulla oblongata and the cerebrum, and from the cerebrum to the cerebellum, and the peripheral nerves to higher functions.

C). Medulla Oblongata (m.o.)

Functions to:

1). Sends ascending impulses through the brain stem and to higher functions 

2). Controls heart rate.

3). Vasomotor control that contract blood vessels.

4). Respiratory center regulates rate and depth of breathing.

 

V). Reticular Formation (r.f.)

reticular formation

Network that is scattered through the brain stem connecting the brainstem, cerebellum and cerebrum with ascending and descending tracts.

 When sensory information reaches the r.f., it activates or arouses the cerebral cortex.

Decrease r.f. results in sleep.

bulletIt filters sensory information.
bulletInhibits some reflexes.
bulletCoordinates muscle activity

 

VI).  Cerebellum

A).  Anatomy

bulletLocated posterior and inferior to the cerebrum under the occipital lobe.
bulletoverlapping sensory maps of the body.
bulletAll the fibers in and out control the same side of the body. (ipsilateral)
bulletno direct connection to the cerebral cortex

B).  Functions:

C).  Needs to:

bulletplan
bulletcoordinate
bulletexecute movement
bulletmaintain balance

D).  Processes

1). Cerebral cortex sends message of intent to initiate voluntary muscle movement.

2). Receives information on body position and muscle tension and visual input.

3). Calculates best way to coordinate muscles

4). Cerebellum sends "blueprint" of movement to cerebral motor cortex.

5). Also sends stimulus to the midbrain and thus the spinal cord

VII). Limbic System

 Structures located throughout the cerebral hemisphere & diencephalon.

Function:

bulletEmotional feeling brain
bullet recognizes angry, fearful expressions and assesses danger &elicits fear response.
bulletExpresses emotions and resolves mental conflict.
bulletConnects with prefrontal lobe so there is a strong relationship between feelings and cognitive thought.
bulletOutput relayed through the hypothalamus.

brain animation

 

VIII). Protection of the Brain

A). Skull

B). Cerebral Spinal Fluid: Forms a cushion

C). Meninges

1). Consists of 3 connective tissue membranes external to the central nervous system.

layers of the meninges

2).  Layers of the Meninges

i) Dura Mater

bulletTough meninx (meninges layer)
bullet2 layered fibrous connective tissue.

ii). Arachnoid Mater

bulletForms the subdural space under the dura mater.

iii). Pia Mater

bulletDelicate connective tissue that clings to the brain.

IX). Blood-Brain Barrier

Capillaries in the brain are the least permeable in the entire body

(However in some areas it is very porous ie. hypothalamus)

Glucose, amino, acids, and electrolytes move freely however toxins, metabolic wastes etc. do not.

Fats and fat-soluble molecules move freely.

This includes various drugs & alcohol