21.neural control and coordination

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1 Presented by B.Prabhakar Principal JNV. Panchmahal (Guj)

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Presented by

B.PrabhakarPrincipal

JNV. Panchmahal(Guj)

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NEURAL CONTROL AND COORDINATIONNEURAL CONTROL AND COORDINATION HomeostasisHomeostasis to be maintained. to be maintained. CoordinationCoordination:- process through which two :- process through which two

or more organs interact and complement the or more organs interact and complement the functions of one another.functions of one another.

1. Neural control and coordination1. Neural control and coordination2. Chemical control and coordination.2. Chemical control and coordination.

in this chapter we study thein this chapter we study the neural system of humanneural system of human mechanism of neural coordination mechanism of neural coordination

(nerve (nerve impulse)impulse) synapse and impulse conductionsynapse and impulse conduction physiology of reflex actionphysiology of reflex action

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NEURAL SYSTEMSNEURAL SYSTEMS

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HUMAN NEURAL SYSTEMHUMAN NEURAL SYSTEMCentral Neural SystemCentral Neural System

include Brain and -include Brain and -Spinal cordSpinal cord

Peripheral Neural Peripheral Neural SystemSystem

-include all the nerves-include all the nervesA. Somatic neural A. Somatic neural

system and system and B. Autonomic neural B. Autonomic neural

system- it is further system- it is further divided intodivided intoa. a. sympathetic neural sympathetic neural

systemsystemb. Parasympathetic b. Parasympathetic

neural sysneural sys

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The Sympathetic Nervous System The Parasympathetic Nervous System

"fight" or take "flight" (run away)

"rest" and "digest"

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Types of nerve fibresTypes of nerve fibresI.I. a.a. AfferentAfferent:- transmit impulses from :- transmit impulses from

tissues to CNStissues to CNSb. b. EfferentEfferent:- from CNS to concerned :- from CNS to concerned peripheral tissues/ organsperipheral tissues/ organs

II.II. a. a. Sensory and Sensory and B. MotorB. Motor

III.III. Myelinated and unmyelinated nerve Myelinated and unmyelinated nerve fibrsfibrs

IV.IV. Uni, bi and multipolarUni, bi and multipolar neurons. neurons.

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Bipolar Neurons have two processes extending from the cell body i.e., one axon and one dendrite (examples: retinal cells, olfactory epithelium cells).

unipolar cells cell body with one axon only (found in embryonic stage)

Multipolar Neurons with one axon and two or dendrites. (examples: cerebral cortex).

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100 billion (100,000,000,000) neurons in the human brain

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TRANSMISSION OF IMPULSE

SYNAPSESYNAPSE:- a nerve impulse is :- a nerve impulse is transmitted from one neuron to another transmitted from one neuron to another through junctions called synapse.through junctions called synapse.

Two type of synapses, electrical and Two type of synapses, electrical and chemical synapses.chemical synapses.

Transmission of synapse in myelinated Transmission of synapse in myelinated nerve fiber is called saltatory nerve fiber is called saltatory conduction. It is faster than in non conduction. It is faster than in non myelinated nerve fibre.myelinated nerve fibre.

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SYNAPSE

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SYNAPTIC TRANSMISSION

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CENTRRAL NERVOUS CENTRRAL NERVOUS SYSTEMSYSTEM

Acts as command and control.Acts as command and control. It controls the voluntary movements.It controls the voluntary movements. Functioning of involuntary organs.Functioning of involuntary organs. ThermoregulationThermoregulation Human behaviour.Human behaviour. Also site for processing of vision, hearing, Also site for processing of vision, hearing,

speech, memory, intelligence, emotions speech, memory, intelligence, emotions and thoughtsand thoughts..

SkullSkull Cranial meninges- pia, arachnoid and Cranial meninges- pia, arachnoid and

duramaterduramater..

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Brain can be divided intoBrain can be divided into i. Fore brain ii. Midbrain. Ii. Hind i. Fore brain ii. Midbrain. Ii. Hind brainbrain

i. FORE BRAIN.i. FORE BRAIN.1.it consists of cerebrum, 1.it consists of cerebrum, thalamus and thalamus and hypothalamus.hypothalamus.

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HUMAN BRAIN

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The word "cortex" comes from the Latin word for "bark" (of a tree). This is because the cortex is a sheet of tissue that makes up the outer layer of the brain.

The right and left sides of the cerebral cortex are connected by a thick band of nerve fibers called the "corpus callosum."

In higher mammals such as humans, the cerebral cortex looks like it has many bumps and grooves. A bump or bulge on the cortex is called a gyrus (the plural of the word gyrus is "gyri") and a groove is called a sulcus (the plural of the word sulcus is "sulci").

Functions:

Thought Voluntary

movement Language Reasoning Perception

Cerebral Cortex

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Functional Divisions of the Cerebral Cortex

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• The thalamus receives sensory information and relays this information to the cerebral cortex.

• The cerebral cortex also sends information to the thalamus which then transmits this information to other areas of the brain and spinal cord.

Functions:

Sensory Integration Motor Integration

Thalamus

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One important function of One important function of the hypothalamus is the the hypothalamus is the control of body control of body temperature. temperature.

The hypothalamus acts like The hypothalamus acts like a "thermostat" by sensing a "thermostat" by sensing changes in body changes in body temperature and then temperature and then sending out signals to sending out signals to adjust the temperature.adjust the temperature.

The hypothalamus also The hypothalamus also controls the pituitary. controls the pituitary.

Functions:

Body Temperature Emotions Hunger Thirst

Circadian Rhythms

Hypothalamus

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HIPPOCAMPUSHIPPOCAMPUSThe hippocampus is The hippocampus is one part of the limbic one part of the limbic system that is system that is important for memory important for memory and learning. and learning.

Functions:

Learning Memory

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Limbic System • The limbic system (or the limbic

areas) is a group of structures that includes inner parts of cerebral hemispheres, the amygdala, the hippocampus etc.

• These areas are important for controlling the emotional response to a given situation.

• The hippocampus is also important for memory.

• Limbic system + hypothalamus-involved in regulation of sexual behaviour, expression of emotional reactions (pleasure, rage, fear) and motivation.

Functions:

Emotional Behavior

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MIDBRAINMIDBRAIN Located between hypothalamus of forebrain and Located between hypothalamus of forebrain and

pons of hindbrain.pons of hindbrain. The dorsal portion of midbrain consists four The dorsal portion of midbrain consists four

round swellings called corpora quadrigeminaround swellings called corpora quadrigemina . . Functions:Functions:

Vision Vision Audition Audition Eye Movement Eye Movement Body MovementBody Movement

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Midbrain and hindbrain form the brain stem.

Functions:

Breathing Heart Rate

Blood Pressure

Brain stem

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Hind brain consists pons, cerebellum and medulla.

Cerebellum divided into hemispheres and has a cortex that surrounds these hemispheres. Medulla connected to spinal cord.

Controls respiration, cardiovascular reflexes and gastric secretions.

Functions:

Movement Balance Posture

HIND BRAIN-Cerebellum

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Reflex action and reflex and reflex arcarc

Reflex actionReflex action:- :- The process of response to The process of response to a stimulus that occurs involuntarily.a stimulus that occurs involuntarily.

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HUMAN EYE

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The RetinaCross-section of eye

Ganglion cell layer

Bipolar cell layer

Receptor layer

Pigmentedepithelium

Ganglion axons

Cross section of retina

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Retina up-close

Light

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STRUCTURE OF EYESTRUCTURE OF EYE Three layers sclera, choroid and retina.Three layers sclera, choroid and retina. The anterior portion of sclera is cornea.The anterior portion of sclera is cornea. Choroid forms ciliary body, iris and pupilChoroid forms ciliary body, iris and pupil Retina contains three layers of cells-ganglion cells, bipolar Retina contains three layers of cells-ganglion cells, bipolar

cells and photoreceptor (Rods and cones) cells.cells and photoreceptor (Rods and cones) cells. Photoreceptor cells contain photopigments viz., rhodopsin Photoreceptor cells contain photopigments viz., rhodopsin

and iodopsin.and iodopsin. There are three types of cones that respond to red, green There are three types of cones that respond to red, green

and blue.and blue. Blind spot for optic nerve to leave and blood vessels to enter.Blind spot for optic nerve to leave and blood vessels to enter. Fovea is present in yellowish pigmented spot called macula Fovea is present in yellowish pigmented spot called macula

lutea.lutea. Fovea contains only cones hence visual activity is highestFovea contains only cones hence visual activity is highest Aqueous chamber with aqueous humor and vitreous Aqueous chamber with aqueous humor and vitreous

chamber with vitreous humor.chamber with vitreous humor.

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Mechanism of visionMechanism of vision

Light rays- cornea and lens- retina Light rays- cornea and lens- retina generates impulses in rods and cones- generates impulses in rods and cones- opsin and retinol of photo pigment opsin and retinol of photo pigment dissociates- result in change in opsin dissociates- result in change in opsin structure cause membrane structure cause membrane permeability changes it results p.ds. permeability changes it results p.ds. generated in photoreceptor cells generated in photoreceptor cells action potential in ganglion cells through action potential in ganglion cells through bipolar cells optic nerve bipolar cells optic nerve visual cortex area of brain image visual cortex area of brain image recognized based on earlier memory and recognized based on earlier memory and experience. experience.

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THE EARTHE EAR Ear perform two sensory functions.Ear perform two sensory functions.

– i.Hearing i.Hearing – ii. Maintenance of body balance –ii. Maintenance of body balance – – three major sections of the earthree major sections of the ear

Outer ear consists pinna, external auditory meatusOuter ear consists pinna, external auditory meatussebaceous glands( wax secreting), fine hairs, sebaceous glands( wax secreting), fine hairs, tympanic membranetympanic membrane

Middle ear:-three ear ossicles malleus, incus and Middle ear:-three ear ossicles malleus, incus and stapes.stapes.

Stapes Is attached to oval window of cochlea.Stapes Is attached to oval window of cochlea. Eustachian tube connects the middle ear cavity with Eustachian tube connects the middle ear cavity with

the pharynx. Equalize pressure on either side of the pharynx. Equalize pressure on either side of eardrum.eardrum.

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THE HUMAN EARTHE HUMAN EAR

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Inner ear called labyrinth consists two parts.Inner ear called labyrinth consists two parts. Bony and membranous labyrinth.Bony and membranous labyrinth. Fluid are endolymph and perilymph.Fluid are endolymph and perilymph. Coiled portion of labyrinth is called cochlea.Coiled portion of labyrinth is called cochlea. Space above scala media is scala vestibuli and Space above scala media is scala vestibuli and

below scala tympani.below scala tympani. Organ of corti located on basalar membrane, Organ of corti located on basalar membrane,

contains hair cells, act as auditory receptors.contains hair cells, act as auditory receptors. Above hair cellsAbove hair cells is tectorial membrane.is tectorial membrane. Inner ear also contain vestibular apparatus, above Inner ear also contain vestibular apparatus, above

cochlea.cochlea. Semicircular canals and otolith organ (saccule and Semicircular canals and otolith organ (saccule and

utricle)utricle)

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COCHLEA

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Projected part of s.c.canal is Projected part of s.c.canal is crista ampullaris having hair cells.crista ampullaris having hair cells.Saccule and utricle contain a Saccule and utricle contain a projecting ridge called macula.projecting ridge called macula.Crista and macula are the specific Crista and macula are the specific receptors of the vestibular receptors of the vestibular apparatus for balance and apparatus for balance and posture of body. posture of body.

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MECHANISM OF HEARING1.1. The sound waves are directed towards the The sound waves are directed towards the

ear canal by the pinna.ear canal by the pinna.2.The waves that enter the canal are 2.The waves that enter the canal are

concentrated and made to strike against concentrated and made to strike against the tympanum.the tympanum.

3. The vibrations are picked up by the malleus 3. The vibrations are picked up by the malleus on the other side.on the other side.

4.These vibrations are transmitted to the 4.These vibrations are transmitted to the fenestra ovalis via the incus and the fenestra ovalis via the incus and the stapes.stapes.

5.The vibrations that strike the oval window 5.The vibrations that strike the oval window are amplified 22 times more than those that are amplified 22 times more than those that struck the tympanumstruck the tympanum..

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MECHANISM OF HEARING6. These vibrations travel along the 6. These vibrations travel along the

vestibular canal to the end of the cochlea vestibular canal to the end of the cochlea and then to the tympanic canal. The and then to the tympanic canal. The vibrations are also transmitted via the vibrations are also transmitted via the Reisnner's membrane to the basilar Reisnner's membrane to the basilar membrane and then to the tympanic canal.membrane and then to the tympanic canal.

7. From the basilar membrane the vibrations 7. From the basilar membrane the vibrations are picked up by the sensory hair cells of are picked up by the sensory hair cells of the organ of corti and transmitted as action the organ of corti and transmitted as action potentials to the neurons of the auditory potentials to the neurons of the auditory nerve fibers.nerve fibers.

8.The action potentials are then transmitted 8.The action potentials are then transmitted as nerve impulses to the auditory cortex of as nerve impulses to the auditory cortex of the brain through the auditory nervethe brain through the auditory nerve..