21.Neural Control and Coordination
Download as PPT, PDF32 likes19,009 views
The document discusses the structure and function of the human neural and sensory systems. It describes the central nervous system including the brain, spinal cord, and peripheral nervous system. It explains the divisions of the brain including the forebrain, midbrain, and hindbrain. It also discusses the autonomic nervous system and its sympathetic and parasympathetic divisions. Additionally, it summarizes the structure and function of the eye and ear as sensory organs.
21.Neural Control and Coordination
- 2. 22 NEURAL CONTROLAND COORDINATIONNEURAL CONTROLAND COORDINATION HomeostasisHomeostasis to be maintained.to be maintained. CoordinationCoordination:- process through which two or:- process through which two or more organs interact and complement the functionsmore organs interact and complement the functions of one another.of one another. 1. Neural control and coordination1. Neural control and coordination 2. 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 (nervemechanism of neural coordination (nerve impulse)impulse) synapse and impulse conductionsynapse and impulse conduction physiology of reflex actionphysiology of reflex action
- 4. HUMAN NEURAL SYSTEMHUMAN NEURAL SYSTEM Central Neural SystemCentral Neural System include Brain and -Spinalinclude Brain and -Spinal cordcord Peripheral NeuralPeripheral Neural SystemSystem -include all the nerves-include all the nerves A. Somatic neural systemA. Somatic neural system andand B. Autonomic neuralB. Autonomic neural system- it is furthersystem- it is further divided intodivided into a.a. sympathetic neuralsympathetic neural systemsystem b. Parasympatheticb. Parasympathetic neural sysneural sys 44
- 5. 55 The Sympathetic Nervous System The Parasympathetic Nervous System "fight" or take "flight" (run away) "rest" and "digest"
- 6. 66 Types of nerve fibresTypes of nerve fibres I.I. a.a. AfferentAfferent:- transmit impulses from:- transmit impulses from tissues to CNStissues to CNS b.b. EfferentEfferent:- from CNS to concerned:- from CNS to concerned peripheral tissues/ organsperipheral tissues/ organs II.II. a.a. Sensory andSensory and B. MotorB. Motor III.III. Myelinated and unmyelinated nerveMyelinated and unmyelinated nerve fibrsfibrs IV.IV. Uni, bi and multipolarUni, bi and multipolar neurons.neurons.
- 7. 7 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).
- 8. 8 100 billion (100,000,000,000) neurons in the human brain
- 9. 9
- 10. 10
- 11. 11
- 12. 1212 TRANSMISSION OF IMPULSETRANSMISSION OF IMPULSE SYNAPSESYNAPSE:- a nerve impulse is:- a nerve impulse is transmitted from one neuron to anothertransmitted from one neuron to another through junctions called synapse.through junctions called synapse. Two type of synapses, electrical andTwo type of synapses, electrical and chemical synapses.chemical synapses. Transmission of synapse in myelinatedTransmission of synapse in myelinated nerve fiber is called saltatorynerve fiber is called saltatory conduction. It is faster than in nonconduction. It is faster than in non myelinated nerve fibre.myelinated nerve fibre.
- 13. 1313 SYNAPSE
- 15. 1515 CENTRRAL NERVOUSCENTRRAL 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 andspeech, memory, intelligence, emotions and thoughtsthoughts.. SkullSkull Cranial meninges- pia, arachnoid andCranial meninges- pia, arachnoid and duramaterduramater..
- 16. 1616 Brain can be divided intoBrain can be divided into i. Fore brain ii. Midbrain. Ii. Hindi. Fore brain ii. Midbrain. Ii. Hind brainbrain i. FORE BRAIN.i. FORE BRAIN. 1.it consists of cerebrum,1.it consists of cerebrum, thalamus andthalamus and hypothalamus.hypothalamus.
- 17. 17 HUMAN BRAIN
- 18. 18 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
- 19. 19 Functional Divisions of the Cerebral Cortex
- 20. 20 • 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
- 21. 2121 One important function ofOne important function of the hypothalamus is thethe hypothalamus is the control of body temperature.control of body temperature. The hypothalamus acts likeThe hypothalamus acts like a "thermostat" by sensinga "thermostat" by sensing changes in bodychanges in body temperature and thentemperature and then sending out signals to adjustsending out signals to adjust the temperature.the temperature. The hypothalamus alsoThe hypothalamus also controls the pituitary.controls the pituitary. Functions: Body Temperature Emotions Hunger Thirst Circadian Rhythms Hypothalamus
- 22. 2222 HIPPOCAMPUSHIPPOCAMPUS The hippocampus isThe hippocampus is one part of the limbicone part of the limbic system that issystem that is important for memoryimportant for memory and learning.and learning. Functions: Learning Memory
- 23. 23 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
- 24. 2424 MIDBRAINMIDBRAIN Located between hypothalamus of forebrain andLocated between hypothalamus of forebrain and pons of hindbrain.pons of hindbrain. The dorsal portion of midbrain consists fourThe dorsal portion of midbrain consists four round swellings called corpora quadrigeminaround swellings called corpora quadrigemina.. Functions:Functions: VisionVision AuditionAudition Eye MovementEye Movement Body MovementBody Movement
- 25. 25 Midbrain and hindbrain form the brain stem. Functions: Breathing Heart Rate Blood Pressure Brain stem
- 26. 26 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
- 27. 2727 Reflex actionReflex action and reflexand reflex arcarc Reflex actionReflex action:-:- The process of response to aThe process of response to a stimulus that occurs involuntarily.stimulus that occurs involuntarily.
- 28. 28 HUMAN EYE
- 29. 29 The Retina Cross-section of eye Ganglion cell layer Bipolar cell layer Receptor layer Pigmented epithelium Ganglion axons Cross section of retina
- 31. 3131 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, bipolarRetina 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., rhodopsinPhotoreceptor cells contain photopigments viz., rhodopsin and iodopsin.and iodopsin. There are three types of cones that respond to red, greenThere 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 maculaFovea 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 vitreousAqueous chamber with aqueous humor and vitreous chamber with vitreous humor.chamber with vitreous humor.
- 32. 3232 Mechanism of visionMechanism of vision Light rays- cornea and lens- retinaLight rays- cornea and lens- retina generates impulses in rods and cones-generates impulses in rods and cones- opsin and retinol of photo pigmentopsin and retinol of photo pigment dissociates- result in change in opsindissociates- result in change in opsin structure cause membranestructure cause membrane permeability changes it results p.ds.permeability changes it results p.ds. generated in photoreceptor cellsgenerated in photoreceptor cells action potential in ganglion cells throughaction potential in ganglion cells through bipolar cells optic nervebipolar cells optic nerve visual cortex area of brain imagevisual cortex area of brain image recognized based on earlier memory andrecognized based on earlier memory and experience.experience.
- 33. 3333 THE EARTHE EAR Ear perform two sensory functions.Ear perform two sensory functions. – i.Hearingi.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 meatus sebaceous glands( wax secreting), fine hairs, tympanicsebaceous glands( wax secreting), fine hairs, tympanic membranemembrane Middle ear:-three ear ossicles malleus, incus andMiddle 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 theEustachian tube connects the middle ear cavity with the pharynx. Equalize pressure on either side of eardrum.pharynx. Equalize pressure on either side of eardrum.
- 34. 3434 THE HUMAN EARTHE HUMAN EAR
- 35. 35
- 36. 3636 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 andSpace 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, aboveInner ear also contain vestibular apparatus, above cochlea.cochlea. Semicircular canals and otolith organ (saccule andSemicircular canals and otolith organ (saccule and utricle)utricle)
- 37. 37 COCHLEA
- 38. 3838 Projected part of s.c.canal isProjected part of s.c.canal is crista ampullaris having hair cells.crista ampullaris having hair cells. Saccule and utricle contain aSaccule and utricle contain a projecting ridge called macula.projecting ridge called macula. Crista and macula are the specificCrista and macula are the specific receptors of the vestibularreceptors of the vestibular apparatus for balance andapparatus for balance and posture of body.posture of body.
- 39. 3939 MECHANISM OF HEARINGMECHANISM OF HEARING 1.1. The sound waves are directed towards theThe sound waves are directed towards the ear canal by the pinna.ear canal by the pinna. 2.The waves that enter the canal are2.The waves that enter the canal are concentrated and made to strike againstconcentrated and made to strike against the tympanum.the tympanum. 3. The vibrations are picked up by the malleus3. The vibrations are picked up by the malleus on the other side.on the other side. 4.These vibrations are transmitted to the4.These vibrations are transmitted to the fenestra ovalis via the incus and thefenestra ovalis via the incus and the stapes.stapes. 5.The vibrations that strike the oval window5.The vibrations that strike the oval window are amplified 22 times more than thoseare amplified 22 times more than those that struck the tympanumthat struck the tympanum..
- 40. 4040 MECHANISM OF HEARINGMECHANISM OF HEARING 6. These vibrations travel along the6. These vibrations travel along the vestibular canal to the end of the cochleavestibular canal to the end of the cochlea and then to the tympanic canal. Theand then to the tympanic canal. The vibrations are also transmitted via thevibrations are also transmitted via the Reisnner's membrane to the basilarReisnner's membrane to the basilar membrane and then to the tympanicmembrane and then to the tympanic canal.canal. 7. From the basilar membrane the vibrations7. From the basilar membrane the vibrations are picked up by the sensory hair cells ofare picked up by the sensory hair cells of the organ of corti and transmitted asthe organ of corti and transmitted as action potentials to the neurons of theaction potentials to the neurons of the auditory nerve fibers.auditory nerve fibers. 8.The action potentials are then transmitted8.The action potentials are then transmitted as nerve impulses to the auditory cortex ofas nerve impulses to the auditory cortex of the brain through the auditory nervethe brain through the auditory nerve..