THE BRAIN AND FIVE THE BRAIN AND FIVE SENSESSENSES

BRAIN- responsible for overseeing the daily BRAIN- responsible for overseeing the daily operations of the human body and for interpreting operations of the human body and for interpreting the vast amount of information recieves.the adult the vast amount of information recieves.the adult human body brain weighs an average of 1.4 kg or human body brain weighs an average of 1.4 kg or

about 2% of the total body weight.about 2% of the total body weight.

The Brain is the main switching unit of the The Brain is the main switching unit of the central nervous system;it is place to which central nervous system;it is place to which impulses flow and from which impulses impulses flow and from which impulses originate.originate.

Spinal Cord provides the link between the Spinal Cord provides the link between the brain and the rest of the bodybrain and the rest of the body

THE BRAIN HAS THREE MAIN PARTSTHE BRAIN HAS THREE MAIN PARTS CerebrumCerebrum CerebellumCerebellum

-Brain stem-Brain stem

-the brain is protected by bony covering called -the brain is protected by bony covering called the SKULLthe SKULL

- Wrapped in three layers of connective tissue Wrapped in three layers of connective tissue called the MENINGES.called the MENINGES.

The innermost layer which covers surface of The innermost layer which covers surface of the brain is the PIA MATER.the brain is the PIA MATER.

The ARACHNOID is thin,elastic,weblike The ARACHNOID is thin,elastic,weblike layer between the PIA MATER and DURA layer between the PIA MATER and DURA MATER.MATER.

The outer layer called the DURA MATER The outer layer called the DURA MATER composed of thick connective tissue.composed of thick connective tissue.

CEREBROSPINAL FLUID –space CEREBROSPINAL FLUID –space filled between the pia mater and the filled between the pia mater and the

arachnoid .arachnoid . CSF –is a clear liquid that protects the brain CSF –is a clear liquid that protects the brain

from mechanical injury by acting as schock from mechanical injury by acting as schock absorber.absorber.

VENTRICLES –Cerebrospinal fluid that VENTRICLES –Cerebrospinal fluid that separates the middle and inner meninges and separates the middle and inner meninges and fills four interconnected or cavities in the fills four interconnected or cavities in the brain.brain.

In order that brain perform its functions must In order that brain perform its functions must have constant supply of food and oxygen.have constant supply of food and oxygen.

PARTS OF THE BRAINPARTS OF THE BRAIN

THE CEREBRUM – control center of the brainTHE CEREBRUM – control center of the brain Largest and most prominent part of the human Largest and most prominent part of the human

brain.Brain is the cerebrum 85% OF THE WEIGHT brain.Brain is the cerebrum 85% OF THE WEIGHT OF HUMAN BRAIN.OF HUMAN BRAIN.

Responsible for all voluntary activities of the Responsible for all voluntary activities of the body,site of INTELLIGENCE,LEARNING AND body,site of INTELLIGENCE,LEARNING AND JUDGEMENT.JUDGEMENT.

It functions in It functions in language,conscious,thought,memory,personality language,conscious,thought,memory,personality development,vision and other sensations.development,vision and other sensations.

TWO HEMISPHERETWO HEMISPHERE

-The left and the right cerebral hemispheres.-The left and the right cerebral hemispheres.-There is a DEEP GROOVE that separates the -There is a DEEP GROOVE that separates the

two hemisphere- this are connected in the two hemisphere- this are connected in the region known as CORPUS CALLOSUMregion known as CORPUS CALLOSUM

-The right and left cerebral hemispheres are -The right and left cerebral hemispheres are linked by a bundle of neurons called a linked by a bundle of neurons called a TRACT.TRACT.

-It contains thick layers of unmyelinated neurons -It contains thick layers of unmyelinated neurons which look gray(GRAY MATER)which look gray(GRAY MATER)

FOUR REGIONSFOUR REGIONS

LOBES –These lobes are named for the skull LOBES –These lobes are named for the skull bones-FRONTAL,PARIETAL,TEMPORAL bones-FRONTAL,PARIETAL,TEMPORAL AND OCCIPITAL LOBES.AND OCCIPITAL LOBES.

Scientist have discovered that the left side of Scientist have discovered that the left side of the body SENDS sensations to the right the body SENDS sensations to the right hemisphere of the cerebrum and the right side hemisphere of the cerebrum and the right side of the body send its sensations to the left of the body send its sensations to the left hemisphere.hemisphere.

The right hemisphere associated with The right hemisphere associated with creativity and artistic ability while the left creativity and artistic ability while the left hemisphere with analytical and mathematical hemisphere with analytical and mathematical ability.ability.

Sometimes blood vessels in the brain blocked Sometimes blood vessels in the brain blocked by blood clots causing disorder called stroke.by blood clots causing disorder called stroke.

Two surfaces of cerebrumTwo surfaces of cerebrum

FOLDED OUTER SURFACE-CEREBRAL FOLDED OUTER SURFACE-CEREBRAL CORTEX and consists of GRAY CORTEX and consists of GRAY MATER(unmyelinated neuron)MATER(unmyelinated neuron)

INNER SURFACE –CEREBRAL MEDULLA INNER SURFACE –CEREBRAL MEDULLA –made up of bundles of MYELINATED –made up of bundles of MYELINATED AXONS . THE WHITE MATTER-MYLIN AXONS . THE WHITE MATTER-MYLIN GIVES WHITE MATER COLOR.GIVES WHITE MATER COLOR.

CEREBELLUMCEREBELLUM

Second largest part of the brain and is locate at the Second largest part of the brain and is locate at the back of the skull.back of the skull.

COORDINATES MUSCLE MOVEMENTCOORDINATES MUSCLE MOVEMENT CONTROLS BALANCE,POSTURE AND CONTROLS BALANCE,POSTURE AND

COORDINATIONCOORDINATION Receives sensory impulses from Receives sensory impulses from

muscles,tendons,joints,eyes and ears.muscles,tendons,joints,eyes and ears. Processes information about position and controls Processes information about position and controls

posture by keeping skeletal muscles in a constan state posture by keeping skeletal muscles in a constan state of partial contraction.of partial contraction.

This is a small CAULIFLOWER SHAPED This is a small CAULIFLOWER SHAPED STRUCTURE.STRUCTURE.

Function of the cerebellum is Function of the cerebellum is involuntary(NOT UNDER CONSCIOUS involuntary(NOT UNDER CONSCIOUS CONDITION).CONDITION).

BRAIN STEMBRAIN STEM

CONNECTS THE BRAIN AND SPINAL CONNECTS THE BRAIN AND SPINAL CORDCORD

Maintains life support,systems,consist of Maintains life support,systems,consist of diencephalon,medulla oblongata,pons,and the diencephalon,medulla oblongata,pons,and the midbrain.midbrain.

CONTROLS VITAL BODY PROCESSESS.CONTROLS VITAL BODY PROCESSESS. UPPER BRAIN STEM- DIECENPHALONUPPER BRAIN STEM- DIECENPHALON LOWER BRAIN STEM – MEDULLA LOWER BRAIN STEM – MEDULLA

OBLONGATA OBLONGATA

MEDULLA contains WHITE MATER-conducts MEDULLA contains WHITE MATER-conducts impulses between the spinal cord and brain.-also impulses between the spinal cord and brain.-also controls involuntary functions that include controls involuntary functions that include breathing,blood pressure,heart breathing,blood pressure,heart rate,digestion,swallowing and coughing.rate,digestion,swallowing and coughing.

Reticular activating system or reticular Reticular activating system or reticular formation(RAS) –other important part of the medulla- formation(RAS) –other important part of the medulla- RAS- HELP to allert or awakens the upper parts of RAS- HELP to allert or awakens the upper parts of the brain,including the cerebral cortex.-also helps to the brain,including the cerebral cortex.-also helps to control respiration and circulationcontrol respiration and circulation

PONSPONS

just above the medulla,the brainstem enlarges just above the medulla,the brainstem enlarges to form pons and it MEANS BRIDGE,mostly to form pons and it MEANS BRIDGE,mostly white mater that link bet the cerebral cortex white mater that link bet the cerebral cortex and the cerebellum.and the cerebellum.

Midbrain- above the pons and the smallest Midbrain- above the pons and the smallest division of the lower stem-areas involved division of the lower stem-areas involved hearing and vision.hearing and vision.

DIENCEPHALON(UPPER BRAIN DIENCEPHALON(UPPER BRAIN STEM)STEM)

Thalamus and hypothalamus-bet. Brain stem Thalamus and hypothalamus-bet. Brain stem and cerebrumand cerebrum

Thalamus- gray matter serves as switching Thalamus- gray matter serves as switching station for sensory input with the exception of station for sensory input with the exception of smell.smell.

It is the relay station of the brain stem where It is the relay station of the brain stem where sensory pathways in the spinal cord and brain sensory pathways in the spinal cord and brain stem form synapses on their way to cerebral stem form synapses on their way to cerebral cortex.cortex.

Hypothalamus-below the thalamus – control Hypothalamus-below the thalamus – control center for hunger,thirst,fatique,anger and body center for hunger,thirst,fatique,anger and body temperaturetemperature

Limbic systemLimbic system

Includes the thalamus and the hypothalamus Includes the thalamus and the hypothalamus some deeper parts are the cerebral cortex and some deeper parts are the cerebral cortex and the temporal lobes- an plays an important role the temporal lobes- an plays an important role in emotions,memory and motivation in emotions,memory and motivation

The seat of emotional interpretation.The seat of emotional interpretation.

SENSORY SYSTEMSENSORY SYSTEM

Sensory receptors react directly to stimulation Sensory receptors react directly to stimulation from the environment.from the environment.

Sense organs-receive information from the Sense organs-receive information from the environment.environment.

Examples of stimulation are ( LIGHT, Examples of stimulation are ( LIGHT, SOUND,MOTION,CHEMICAL PRESSURE, SOUND,MOTION,CHEMICAL PRESSURE, PAIN OF CHANGES IN THE PAIN OF CHANGES IN THE TEMPERATURE.TEMPERATURE.

SENSORY RECEPTORSSENSORY RECEPTORS

ARE NEURON THAT IS SPECIALIZED TO ARE NEURON THAT IS SPECIALIZED TO DETECT STIMULUS THEY RESPOND TO:DETECT STIMULUS THEY RESPOND TO:

Mechanoreceptors- respond to movement,pressure and Mechanoreceptors- respond to movement,pressure and tensiontension

Photoreceptors (RODS AND CONES)-respond to Photoreceptors (RODS AND CONES)-respond to variations to light.variations to light.

Chemoreceptors-respond to chemicalsChemoreceptors-respond to chemicals

Thermorecptors-respond to changes in temperatureThermorecptors-respond to changes in temperature

Pain receptors-respond to tissue damage-PAINPain receptors-respond to tissue damage-PAIN

FIVE SENSESFIVE SENSES

SIGHT-HEARING-SMELL-TASTE-TOUCHSIGHT-HEARING-SMELL-TASTE-TOUCH MOST FAMILIAR SENSE ORGANS ARE THE MOST FAMILIAR SENSE ORGANS ARE THE

EYES,EARS,NOSE,SKIN AND TASTE BUDSEYES,EARS,NOSE,SKIN AND TASTE BUDS THE RECEPTORS CONVERT THE ENERGY of a THE RECEPTORS CONVERT THE ENERGY of a

stimulus into an electrical energy that can travel in stimulus into an electrical energy that can travel in the NERVOUS SYSTEMSthe NERVOUS SYSTEMS

Messages from sense organs to CNS are in the form Messages from sense organs to CNS are in the form of Nerve impulses.of Nerve impulses.

Hearing and BalanceHearing and Balance

EAR is really two sense organ in one.not only EAR is really two sense organ in one.not only detect sound waves also senses the position of detect sound waves also senses the position of the head whether it is still moving in a straight the head whether it is still moving in a straight line or rotating.line or rotating.

Low-pitched-slow variationsLow-pitched-slow variations High –pitched-faster variationHigh –pitched-faster variation

EXTERNAL EAREXTERNAL EAR

Consists of the visible fleshly part helps to collect Consists of the visible fleshly part helps to collect sound and funnel into the AUDITORY sound and funnel into the AUDITORY CANAL(CONNECTS THE EXTERNAL EAR) with CANAL(CONNECTS THE EXTERNAL EAR) with the tympanic membrane also called eardrum.the tympanic membrane also called eardrum.

The AUDITORY CANAL- contains small hair and The AUDITORY CANAL- contains small hair and wax producing glands that prevent foreign objects wax producing glands that prevent foreign objects from entering the ear.from entering the ear.

Extends into the bone of the head and stops at the Extends into the bone of the head and stops at the eardrumeardrum

Sound variations strike the eardrum and Sound variations strike the eardrum and transmitted into three tiny bones.the transmitted into three tiny bones.the malleaus(HAMMER) incus (ANVIL) and malleaus(HAMMER) incus (ANVIL) and STAPES(stirrup)STAPES(stirrup)

THE STIRRUP TRANSFERS THE THE STIRRUP TRANSFERS THE VIBRATIONS TO A THIN MEMBRANE VIBRATIONS TO A THIN MEMBRANE CALLED OVAL WINDOW.CALLED OVAL WINDOW.

This membrane transmits the vibrations to the This membrane transmits the vibrations to the cochlea which begins the INNER EAR.cochlea which begins the INNER EAR.

The COCHLEA IS snail shaped consisting of The COCHLEA IS snail shaped consisting of fluid filled chambers that are separated by fluid filled chambers that are separated by membranes.membranes.

Organ of corti- middle chamberOrgan of corti- middle chamber These nerve impulses are carried to the brain These nerve impulses are carried to the brain

by the AUDITORY OR ACOUSTIC NERVEby the AUDITORY OR ACOUSTIC NERVE The ears also contain structures for detecting The ears also contain structures for detecting

stimulus that make us aware of our movement stimulus that make us aware of our movement and allow us to maintain our BALANCE.and allow us to maintain our BALANCE.

LOCATED WITHIN THE INNER EAR JUST LOCATED WITHIN THE INNER EAR JUST ABOVE THE COCHLEA ARE THREE ABOVE THE COCHLEA ARE THREE TINY CANALS THAT LIE AT THE RIGHT TINY CANALS THAT LIE AT THE RIGHT ANGLES TO EACH OTHER –semicicular ANGLES TO EACH OTHER –semicicular canals because they each make half a circle.canals because they each make half a circle.

The semicircular canals and two tiny sacs The semicircular canals and two tiny sacs located behing them helf us to sense balance or located behing them helf us to sense balance or equilibirum.equilibirum.

OtolithsOtoliths

ARE TINY RAINS OF CALCIUM ARE TINY RAINS OF CALCIUM CARBONATE AND PROTEIN.CARBONATE AND PROTEIN.

EYE- VISIONEYE- VISION

-The sense organ we use to sense light is the -The sense organ we use to sense light is the eyes.eyes.

Composed of three layers- outer layer-consists Composed of three layers- outer layer-consists of the sclera and cornea-middle choroid,ciliary of the sclera and cornea-middle choroid,ciliary body and iris-inner layer retinabody and iris-inner layer retina

SCLERA ( white of the eye)-MAINTAIN SCLERA ( white of the eye)-MAINTAIN SHAPE OF THE EYE AND PROVIDES SHAPE OF THE EYE AND PROVIDES ATTACHEMENT FOR THE MUSCLES ATTACHEMENT FOR THE MUSCLES THAT MOVE THE EYE.THAT MOVE THE EYE.

Cornea- front of the eye and forms a Cornea- front of the eye and forms a transparent layers and the part of the eye that transparent layers and the part of the eye that enters light.enters light.

AQUEOUS HUMOR- JUST INSIDE THE AQUEOUS HUMOR- JUST INSIDE THE CORNEA AND A SMALL CHAMBER CORNEA AND A SMALL CHAMBER FILLED WITH FLUID.FILLED WITH FLUID.

Choroid – back of the chamber ,contains blood Choroid – back of the chamber ,contains blood vessels of the eye,becomes a disk-liske vessels of the eye,becomes a disk-liske structure-IRISstructure-IRIS

DIAPHRAGM(iris)portion of the eye that DIAPHRAGM(iris)portion of the eye that gives your eye its color and control the amount gives your eye its color and control the amount of light entering the eye by altering the of light entering the eye by altering the diameter of the pupildiameter of the pupil

PUPIL – middle of the iris ,a small opening PUPIL – middle of the iris ,a small opening through which light enters the eye.-black disk through which light enters the eye.-black disk in the center of the eye-regulate the size of the in the center of the eye-regulate the size of the pupil controlling the amount of light to enter pupil controlling the amount of light to enter the eye.the eye.

LENSLENS

Behind the iris-light is focused by the lens Behind the iris-light is focused by the lens which cahnges shape when pulled by muscles which cahnges shape when pulled by muscles around its edges.around its edges.

Crystalin-cells that form the lens contain Crystalin-cells that form the lens contain special protein and is almost transparent and special protein and is almost transparent and allows light to pass through.allows light to pass through.

VITREAL CHAMBER-behind lensVITREAL CHAMBER-behind lens VITREOUS HUMOR-Transparent jelly-like VITREOUS HUMOR-Transparent jelly-like

fluidfluid

PHOTORECEPTORSPHOTORECEPTORS

CONVERT light energy into impulses that are carried CONVERT light energy into impulses that are carried to the CNS.to the CNS.

CONTAIN PIGMENT CALLED rhodopsin-respond CONTAIN PIGMENT CALLED rhodopsin-respond to wavelenghts of light.to wavelenghts of light.

TWO TYPES OF PHOTORECEPTORSTWO TYPES OF PHOTORECEPTORS 1.RODS –sensitive to all colors of light do not 1.RODS –sensitive to all colors of light do not

distinquish different colors.distinquish different colors. 2. CONES –sensitive than rods,do not respond 2. CONES –sensitive than rods,do not respond

differently to llight of different colors,producing differently to llight of different colors,producing color visioncolor vision

Optic nerveOptic nerve

Impulses leave the eye by way of optic nerve Impulses leave the eye by way of optic nerve and carried part of the brain known as the and carried part of the brain known as the optic lobe or occipital lobe-which interprets optic lobe or occipital lobe-which interprets the visual images and provides information the visual images and provides information about the external world.about the external world.

SMELLSMELL

The sense of smell is a chemical sense responsible of The sense of smell is a chemical sense responsible of smell called the olfactory receptors.smell called the olfactory receptors.

Located in the upper part of the nasal cavityLocated in the upper part of the nasal cavity Chemorecptors contain cilia that extend into the air Chemorecptors contain cilia that extend into the air

passages of the nose and react to chemicals in tha passages of the nose and react to chemicals in tha air.chemicals that come into contact with the air.chemicals that come into contact with the chemoreceptors stimulate them causing impulses to chemoreceptors stimulate them causing impulses to be sent to the brain by the OLFACTORY NERVEbe sent to the brain by the OLFACTORY NERVE

TASTETASTE

The sense of taste is a chemical senseThe sense of taste is a chemical sense Stimulated by the chemicals called Stimulated by the chemicals called

chemoreceptorschemoreceptors The sense organ detects taste.taste are the taste The sense organ detects taste.taste are the taste

buds not the tonque.buds not the tonque. Most 10,000 taste buds are embedded between Most 10,000 taste buds are embedded between

bumps called PAPILLAE on the tonque but bumps called PAPILLAE on the tonque but can also found on the rrrof of the mouth,on the can also found on the rrrof of the mouth,on the lips and in the throat.lips and in the throat.

TOUCHTOUCH

All regions of the body are sensitive to touchAll regions of the body are sensitive to touch SKIN - largest sense organs of the skinSKIN - largest sense organs of the skin mechanoreceptors – located throughout the mechanoreceptors – located throughout the

skin make it posible to sense of touch,pressure skin make it posible to sense of touch,pressure and tension.and tension.

TWO TYPES OF OF RESPOND;TWO TYPES OF OF RESPOND; THERMORECEPTORS –respond to touchTHERMORECEPTORS –respond to touch MECHANORECEPTORS –respond to tissue MECHANORECEPTORS –respond to tissue

damage which causes pain receptors.damage which causes pain receptors.