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The Brain

Occupies cranial cavity, covered by membranes, fluid and bones of the skull.

The cerebrum

- largest part of the brain.

Cerebral hemispheres

- divided into right and left.

Longitudinal fissure

- deep groove that divides.

Diencephalon

-area between the cerebral hemispheres and the brain stem. Includes thalamus and hypothalamus

Brain stem-

connects the cerebrum and diencephalon with the spinal cord.

Midbrain

- superior portion of brain stem

Pons

- inferior to midbrain

Medulla oblongata

- pons connects midbrain with medulla

Foramen magnum

- medulla connects the brain with the spinal cord through large opening at base of the skull.

Cerebellum

- (little brain) located immediately below the posterior part of the cerebral hemispheres, connected with cerebrum, brain stem and spinal cord by means of the pons.

Meninges-

3 layers of connective tissue that surround both the brain and spinal cord to form a complete enclosure.

Dura mater

- outermost - thickest, toughest (hard mother) has 2 layers and outer layer is fused to bones of cranium.

Dural sinuses

venous channels for drainage of blood coming from the brain tissue.

Arachnoid

middle layer of meninges. Loosely attached by weblike fingers. Allows space for movement of CSF cerebrospinal fluid.

Pia mater

innermost layer around the brain ,Attached to nervous tissue of the brain and spinal cord. Follows all contours.,Delicate connective tissue. ,Holds blood vessels,Supply nutrients and oxygen to brain and spinal cord.

Cerebrospinal fluid

Clear liquid that circulates in and around the brain and spinal cord.

Function of CSF

to support nervous tissues, cushion shocks, carries nutrients to cell, transports waste away.,Flows out into subarachnoid space of the meninges.

Arachnoid villis

rojections through which fluid returns to blood.

Ventricles

- 4 spaces within the brain.

Choroid plexus

-vascular network in each ventricle- forms CSF by filtration of the blood and by cellular secretion.

Horns-

extensions into lobes of cerebrum

Foramina-

openings for communication.

Cerebral aquaduct-

continues down from 3rd ventricle- small canal.

Cerebral Hemispheres: Divided into 4 lobes:

frontal, parietal, temporal and occipital lobes.

Insula-

small 5th lobe- deep within each hemisphere-

Cerebral cortex-

outer nervous tissue of the cerebral hemisphere is gray matter. Arranged in folds. Thin layer of gray matter- most highly evolved portion of brain, Responsible for conscious thought,reasoning, and abstract mental functions.

Gyri-

elevated portions of folds.

Sulci- (sulcus)

Raised areas are separated by shallow grooves

Central sulcus-

lies between frontal and parietal lobes of each hemisphere at right angles to the longitudinal fissure.

Lateral sulcus-

curves along the side of each hemisphere and separates the temporal lobe from the frontal and parietal lobes.

White matter-

Internally- cerebral hemispheres are made of white matter.Consists of myelinated fibers that connect the cortical areas of each other with other parts of the nervous system.

Basal nuclei-basal ganglia-

masses of gray matter located deep within each cerebral hemisphere.,Work w/cerebral cortex to regulate body movement, muscles of facial expression.

Dopamine-

neurotransmitter secreted by neurons of basal nuclei.

Corpus callosum-

band of white matter located at bottom of longitudinal fissure.,Band is a bridge between right and left hemisphere. ,Permits impulses to cross from one side to the other.

Internal capsule-

compact band of myelinated fibers that carries impulses between the cerebral hemispheres and the brain stem.

Vertical fibers

make up internal capsule

cerebral cortex-

layer of gray matter forms surface of each cerebral hemisphere-impulses are received and analyzed.

Functions of Cerebral Cortex

Activities form the basis of knowledge. ,Memory- information can be recalled on demand.,Thought processes such as association, judgment and discrimination.,Conscious deliberation and voluntary actions

Frontal lobe-

larger in humans- lies anterior to the central sulcus.

Frontal Lobe Functions

Primary motor area- provides conscious control of skeletal muscles.,2 areas important in speech.

Parietal lobe-

occupies superior part of each hemisphere and lies posterior to the central sulcus.,Gyrus just behind the central sulcus in this lobe contains:

Parietal Lobe Functions

Primary sensory area- impulses from the skin : touch, pain, and temperature are interpreted. ,Estimation of distances, sizes and shapes take place here. Greater the sensation the more involved cortex is.

Temporal lobe-

inferior to lateral sulcus, fold under the hemisphere on each side.

Temporal Lobe Functions:

auditory area- receiving and interpreting impulses from the ear.Olfactory area- sense of smell- located in medial part of temporal lobe. Stimulated by impulses arising from receptors in the nose.

Occipital lobe- l

ies posterior to theparietal lobe and extends over the cerebellum.

Occipital lobe functions

Visual receiving area and visual association area, Interprets impulses arising from the retina of the eye.

Auditory areas-

lie in temporal lobe-

Auditory receiving area-

detects sound impulses transmitted from the environment

Auditory association area

- interprets sounds.

Speech comprehension area-

wernicke area- functions in speech recognition and the meaning of the words.auditory

Motor areas-

for spoken and written communication- lie anterior to the most inferior part of the frontal lobe's motor cortex.

Motor speech area.

- broca area- Speech muscles in the tongue, soft palate, and larynx controlled here.

Motor aphasia-

difficulty producing speech ( if damage to this area)

Written speech center-

lies anterior to cortical area that controls arm and hand muscles. motor

Ability to write words-

last phase of development of learning words and their meanings.Motor

Visual areas-

occipital lobe's cortex.

Functions of Occipital lobe cortex

Visual images of language are received. Visual area lies anterior to receiving cortex, then interprets these visual impulses as words. Ability to read with understanding develops in this area.

Memory-

mental faculty for recalling ideas.

Initial stage-

sensory signals are retained for a short time.

Short term memory

- retention bits of information for a few seconds or perhaps a few minutes. After that time information is lost unless reinforced.

Long term memory-

storage of information that can be recalled at a later time.

Fibrils form at

the synapses in the cerebral cortex. ,Enables impulses to travel more easily from one neuron to another.

Diencephalon-

interbrain- is located between the cerebral hemispheres and the brain stem.,Includes thalamus and hypothalamus. 2 parts of the thalamus form the lateral walls of the third ventricle.

Thalmus

All sensory impulses travel through the thalamus.

Role of thalamus

is to sort out the impulses and direct them to particular areas of the cerebral cortex.

Hypothalmus-

Located in the midline area inferior to the thalamus and forms the floor of the third ventricle.

Hypothalmus Helps maintain

homestasis by controlling body temperature, water balance, sleep, appetite and some emotions such as fear and pleasure.

Hypothalmus Controls-

Sympathetic and parasympathetic, controls pituitary, Influences heartbeat, Contraction and relaxation of blood vessels. ,Hormone secretion,Other vital body functions.

The Brain Stem

Composed of midbrain, pons and medulla oblongata.

Midbrain

Inferior to the center of the cerebrum.,Forms superior part of brain stem.

Mid brain Gray Matter

-Four rounded masses, hidden by cerebral hemispheres form superior part of midbrain.,Four bodies act as centers for reflexes involving,Eyes, and ears.

Midbrain White matter - anterior of midbrain

- conducts impulses between higher centers of cerebrum and lower centers of pons, medulla, cerebellum and spinal cord.

Crainial nerves III and IV

originate from midbrain.

The Pons

Lies between the midbrain and the medulla ,Anterior to the cerebellum ,Composed of myelinated nerve fibers which connect the tow halves of the cerebellum with the brain stem,

Pons is an Important connecting link

between cerebellum and rest of nervous system.

Pons regulates

Reflex- involuntary actions- some regulating respiration.

Cranial nerves V through VIII

originate from Pons.

Medulla Oblongata

Located between the pons and the spinal cord. ,Appears white externally because of myelinated nerve fibers., Internally contains collection of cell bodies( gray matter) called Nuclei or centers. Vital centers.

Medulla Oblongata Controls

Respiratory center- Cardiac center- Vasomotor center Controls blood flow and blood pressure.

Hair Follicle

Composed of Keratin , not living, Filament, slender, dead, epidermal tissue

Hair All over the body except

soles of feet

Arrector pili

surrounds base of hair, band of muscle, contracts- goose bumps-Cells add color pigment to hair.

Hair is Protection

for eyes and nose

Hair follicles

are located Deep in dermis and subcutaneous tissue.

Nails

Dead, Cutaneous plates , made of keratin - produced by cells that originate in the outer layer of the epidermis, Protection- for toes and fingers

Nails originate

in outer part of epidermis

1. Affect

*Emotional state- can be created by nervous system. To have an influence on or affect a change in.

2. Arachnoid

*middle layer of meninges. Resembling a cobweb. Used of the arachnoid membrane covering the brain and spinal cord.

3. Auditory

**pertaining to sense of hearing. Of or relating to hearing, the organs of hearing, or the sense of hearing.

4. Brain Stem

**portion of brain that connects the cerebrum with the spinal cord, contains the midbrain, pons, medulla oblongata. the stemlike portion of the brain connecting the cerebral hemispheres with the spinal cord.

5. Cerebrum

**largest part of brain. the main portion of the brain, occupying the upper part of the cranial cavity; its two hemispheres, united by the corpus callosum, form the largest part of the central nervous system in humans.

6. Cerumen

earwax; the waxlike substance found within the external meatus of the ear.

7. Cutaneous

**skin pertaining to the skin.

8. Dura mater

**outermost layer of meninges the outermost, toughest of the three meninges (membranes) of the brain and spinal cord.

9. Effect

**response to a stimuli, the result produced by an action.

10. Equilibrium

**state of balance. the condition of balance between varying, shifting, and opposing forces that is characteristic of living processes.

11. Grey Matter

**nervous tissue, composed of unmyelinated fibers and cell bodies. Brownish-gray nerve tissue, especially of the brain and spinal cord, composed of nerve cell bodies and their dendrites and some supportive tissue.

12. Hypothalmus

** region controls pituitary, maintains homeostasis. The part of the brain that lies below the thalamus, forming the major portion of the ventral region of the diencephalon, and that regulates bodily temperature, certain metabolic processes, and other autonomic activities.

13. Motor

**efferent neurons, fibers that carry impulses from the central nervous system out to muscles and glands. Causing or producing motion.

14. Neurology

** study of diseases of nervous system. the branch of medicine that deals with the nervous system, both normal and in disease.

15. Olfactory

*cranial nerve, sense of smell. Receptors in nasal muscosa. Of, relating to, or contributing to the sense of smell.

16. Orbit

Eye socket. the bony cavity containing the eyeball and its associated muscles, vessels, and nerves.

17. Receptor

Specialized cell or ending of sensory nerve that can be excited by a stimulus. a sensory nerve ending that responds to various stimuli.

18. Refraction

** bending of light rays as they travel through a medium other than air. the deviation of light in passing obliquely from one medium to another of different density.

19. Sensory

**neurons that carrie impulses from receptors, to the brain and spinal cord. Transmitting impulses from sense organs to nerve centers; afferent.

20. Synapse

**point of junction between 2 neurons or between a neuron and an effector. Carries Out a response to stimulus. (leaping)the site of functional apposition between neurons, where an impulse is transmitted from one to another, usually by a chemical neurotransmitter released by the axon terminal of the presynaptic neuron.

21. Thalmus

**region of brain located in diencephalon- A large ovoid mass of gray matter situated in the posterior part of the forebrain that relays sensory impulses to the cerebral cortex.

22. White Matter

Whitish nerve tissue, especially of the brain and spinal cord, consisting chiefly of myelinated nerve fibers. ** nervous tissue composed of myelinated fibers.

Nervous System-

coordinates and controls the body, then communicates with systems, That will conduct responses to internal and external changes.

Functions of Nervous system

Reacts to internal and external changes,Links with environment,Center of mental processes., Reacts in split seconds. Processes information and sends it to an appropriate area.

CNS- -central nervous system

Brain, spinal cord

PNS- pheripheral nervous system-

spinal nerves, cranial nerves

Somatic

Effectors areskeletal muscles, Controlled voluntary, conscious will.

Autonomic- automatic-

involuntary-,Activities of visceral organs

Autonomic Nervous System Processes:

Hormonal feedbacks, visceral , controls smooth muscle, heart glands, peristalsis, digestive juices.

Autonomic breaks into

Sympathetic, Parasympathetic

Role of nervous system:

Detects and responds to stimuli, Brain and spinal cord act as switiching centers,Nerves carry messages to and from centers.

Neurons:

Functional cells of nervous system, Extremely specialized

Structure of a neuron

Cell body,Nucleus, Cell fibers,Dendrites,Axons

Neuron Nerve cells are

transmitter cells

Dendrites-

nerve fibers move toward the cell.

Axons-

nerve fibers that carry away from the cell.

This equals neuron-

dendrites and axons

Types of neurons:

Can be sensory or motor

Nerve tissue:

neurons a lot of them together form bundles = nerve fibers.

Nerve Fibers are like

a conducting core

Afferent-

sensory- impulses -Electrical charge- goes toward central nervous systems- Incoming

Efferent

-motor- comes away from CNS- outgoing

Interneuron-

mixed combo of sensory and motor ( central neurons and associative) found ONLY in CNS.

Afferent- Sensory-

single dendrite -single axon

dendrite-

can be up to 3ft. long.,Sent to brain, interpret, response. Stimulus happens within seconds

Dendrite orginates in

receptor.

Receptors are

end organs- internal and external-, all information send to brain and right back out (effector).Touch, pain, hot and cold. Etc.

Efferent-motor-

long axon and 3-5 dendrites, Myelin sheath- Nerve fibers are covered with Myelin.

Myelin is an

insulator.

Myelin Covered by

neurilemma - connective tissue,Regenerates nerve tissue.

***CNS does not have

nurilemma- cannot regenerate.

Synapse- junction-

Gap between nerve tissue-,Impulse will jump across,Electricity- junction point for transmission of nerve impulses.

Synapse Needs neurotransmitters:

ephinenphrine(norephinephrine), acetycoline,(adrenaline) noradrenaline, Need chemical to send it to the brain.

Gray Matter

- concerned with brain and spinal cord, unmyelinated; no neurilemma, Taking impulses across selected synapses,Tissue, cell bodies of these neurons are scattered throughout., Several cell bodies- constantly conducting.,Hit with stimuli all the time. Brain very active

White Matter

Myelinated, Concerned with impulses along fibers which goes both ways. Spinal cord- has tracks- bundles of nerve fibers which have the same origin and termination and function.

Nervous system at work

Electrical impulses sent along neuron fibers and transmitted between cells at junctions.

Meninges:

Connective tissue - 3 layers, surround brain and spinal cord, forms a closed system

Duramater-

outermost layer, thickest, toughest, protection.,In spine- lines vertebrae,In brain- skull splits to allow passage of blood

Arachnoid membrane-

cobweb-w/spaces in between- to hold fluid

Subarachnoid space-

cerebral, spinal fluid.-CSF

Pia mater-

allows for blood supply to the brain.,Directly attached to the cord and the brain.,Will dip in and out of brain- into all of those depressions.Extremely delicate. - a lot of vessels.

Cerebrlspinal Fluid

Cushion, protect, transport nutrients and waste ( away.) Supports nervous tissue, cushions from shock

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