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Human Nervous System
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Human Nervous System

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  1. Human Nervous System A giant network of nerve cells or neurones Functions: Sensory -involves the sensory receptors, detect stimuli from internal or external and initiate nerve impulses Integrative -the nerve impulses sent to the CNS, processed, analysed, stored and make decisions for appropriate response Motor -carry out information from CNS and transmitted to an effector; muscles and glands


  3. Human Nervous System CNS BRAIN A B D C E

  4. A: Cerebrum Right hemisphere Left hemisphere Controls movements of the right side of the body Controls movements of the left side of the body Carries out integrative functions before commanding motor response Coordinate activities of other parts of the brain Receives sensory input

  5. Cerebral Cortex Outer region, highly folded Direct voluntary movement of muscles Creating sensory perception (see,hear,smell, taste, touch) Higher mental abilities ( learning, memory, reasoning, language skills, imagination, artistic talent and personality traits)

  6. B: Thalamus Sorting information which goes in and comes out of the cerebral cortex Integrates the information that is carried out by sensory receptors to the cerebrum by enhancing some signals and blocking others

  7. C: Cerebellum Coordinate movements Receive information from sensory receptors regarding the position of the body and from the cerebrum

  8. D: Hypothalamus Maintain homeostasis Regulate sleep, hunger, body temperature, water balance and blood pressure Controls the pituitary gland which secretes hormones that influence other glands and body functions

  9. E: Medulla Oblongata Regulating hearbeat, breathing and vasoconstriction Reflex centres for vomiting, coughing, sneezing, hicupping and swallowing

  10. Human Nervous System CNS SPINAL CORD U T V W X Y


  12. Human Nervous System CNS SPINAL CORD Central Canal Central Canal P Dorsal Root Ganglion Q R Dorsal Root Spinal Nerve S T Ventral Root V Grey matter U White matter

  13. Human Nervous System CNS SPINAL CORD Placed in vertebral column Surrounded by cerebrospinal fluid; cushions the cord and provide nutrients Grey Matter : consists cell bodies of nerve cells White Matter : myelin-coated axons of neurons , extended up and down the spinal cord Dorsal Root : consists the axons of afferent neurones which conduct impulses from sensory receptors to the spinal cord Dorsal Root Ganglion : consists cell bodies of afferent neurones

  14. Human Nervous System CNS SPINAL CORD Ventral Root : consists of axons of efferent neurones, conduct impulses away from spinal cord to effectors

  15. Human Nervous System CNS SPINAL CORD Functions Process certain types of sensory information Send out impulses via response Reflex actions

  16. The Neurones

  17. The Neurones 4 distinct parts of a neurone DENDRITES AXON CELL BODY SYNAPTIC TERMINALS Integrate signals and coordinates metabolic activities Conduct signals towards the cell body Conduct nerve impulses away from cell body Transmit signals to muscle cells, gland cells or the dendrites of another neurone Dendrite of afferent neurone have special membrane adaptations – produce signals in response to specific stimuli(pressure, light,heat) Long and thin fibre extends outward from the cell body Contains nucleus and other organeles Insulated by myelin-sheath; protect & insulates axon, speed up the conduction of impulses

  18. The Neurones This is a structure of an : Afferent neurone Dendrites It carries impulses from receptors to the brain and the spinal cord

  19. The Neurones This is a structure of an : Efferent neurone It carries impulses from the brain and the spinal cord to effector

  20. The Neurones This is a structure of an : Interneurone It conveys impulses between various part of the brain and spinal cord Participate in integrative functions It transmits impulses between afferent neurones and efferent neurones Transmits impulses from one side of the spinal cord to the other side Transmits impulses from the brain to the spinal cord or vice versa

  21. TRANSMISSION OF INFORMATION ALONG NEURONES Transmission of information in the form of: Electric Signals known as: Nerve Impulses A wave of positive charge travels along the axon to the synaptic terminal A neurone will not transmit an impulse unless: The stimulation is strong enough Once the magnitude of the stimulation reaches a tresheld level, impulse is generated that travels the entire length of the axon

  22. THE TRANSMISSION PATHWAY OF INFORMATION Chain of events that takes place from the time you hear the doorbell ring until you open the door. Sound of the doorbell The sound reach at the eardrum Receptors in the ear produce impulses in afferent neurones The nerve impulses pass from afferent neurones to interneurones in the brain

  23. THE TRANSMISSION PATHWAY OF INFORMATION The brain interprets the impulses from many interneurones and you realise the doorbell is ringing. The brain decides that the door should be open Nerve impulses are transmitted from interneurones to efferent neurones then to muscles Muscles of leg contract and relax: walk to the door, Muscle of arm- reach the knob to open the door

  24. TRANSMISSION OF INFORMATION ACROSS SYNAPSES Synaptic Vesicle Mitochondria Dendrite Synaptic Cleft Receptor Axon Synaptic Terminal Myelin sheath Postynaptic Membrane Presynaptic Membrane

  25. TRANSMISSION OF INFORMATION ACROSS SYNAPSES An electrical impulse reaches the presynaptic cleft Synaptic vesicle releases neurotransmitter into to synaptic cleft Electrical signal is converted into chemical signal

  26. TRANSMISSION OF INFORMATION ACROSS SYNAPSES Neurotransmitter diffuse across the synaptic cleft, bind to receptor that is attached to the postsynaptic membrane

  27. TRANSMISSION OF INFORMATION ACROSS SYNAPSES Chemical signal is converted back into electrical signal Neurotransmitter is rapidly broken down by enzyme OR taken up again by synaptic vesicle to be recycled The electric signal is transmitted along the dendrite of neighbouring neurone

  28. THE IMPORTANCE OF SYNAPSES Controlling and integrating nerve impulses that are transmitted by stimulated receptors Allow nerve impulses to be transmitted only in one direction

  29. TYPES OF ACTIONS VOLUNTARY ACTION INVOLVING SKELETAL MUSCLE INVOLUNTARY ACTION INVOLVING SKELETAL MUSCLE Governed by : Involved : Cerebral Cortex 1. Afferent Neurone 1. Afferent Neurone Reflex Action Walking UNDER CONSCIOUS CONTROL 2. Spinal Cord 2. Efferent Neurone Touching a hot stove Talking 3. Efferent Neurone 4. Interneurone Scratching Knee jerk reflex Digging ur NOSE

  30. The nerve pathway in a reflex action is called Reflex Arc A rapid and involuntary response to stimuli is called Reflex The significance of reflexes Get the hell out of a dangerous situation Protective functions: sneezing, blinking of eyes, swallowing Response is processed rapidly without waiting instruction from the brain

  31. INVOLUNTARY ACTION INVOLVING SKELETAL MUSCLE Skin touches a hot object Reflex arc involved: Afferent Neurone Interneurone Spinal Cord Efferent Neurone

  32. INVOLUNTARY ACTION INVOLVING SKELETAL MUSCLE Dorsal Ganglion Root Knee-jerk Reflex/Patellar Afferent Neurone Efferent Neurone Afferent Neurone Patella Quadriceps Efferent Neurone Tendon Sensory receptor


  34. AUTONOMIC NERVOUS SYSTEM Sympathetic System Parasympathetic System INTERNAL ORGANS The autonomic nervous system connects hypothalamus and medula oblongata to internal organs ; heart, small intestine, pancreas, ovary, testes etc. Symphatetic system prepares body for emergency situations; increase the heartbeat and Parasymphatetic system bring back body condition to normal condition; decrease heartbeat to a relaxed state The autonomic nervous system consists of symphatetic and parasymphatetic systems Heartbeat : Fast Heartbeat: Normal

  35. My body and neurons From a-ffe-rent neu-rone Sym-pa-the-tic nerves Pre-pare for e-mer-gency To e-ffe-rent spi-nal cord This was ne-ver the way I planned Not my in-ten-tion I was so brave, touched the pan From e-ffe-rent neu-rone To run, to scream or to fight To the quad-ri-ceps mu-scle Don’t know it was hot In-crease a-bi-li-ty In-vo-lun-ta-ry act Ion it’s ref-lex ac-tion Mu-scle con-tracts Leg kicks for-ward When I’m OK When I feel safe Pro-du-ce im-pulse Sen-so-ry re-cep-tors Main-tain pos-ture and ba-lance I walk and no wo-rry Dec-rease ev-rything Pa-ra-sym-pa-the-tic will Bout each step Im-pulse is trasn-mi-tted A-long a-ffe-rent neu-rone To nor-mal Sent to the spi-nal cord Then goes to in-ter-neu-rone To e-ffec-tor Au-to-no-mic ner-vous sys-tem To e-ffe-rent Helps in-vo-lun-ta-ry ac-tion I pull my hand and say ouch! Neu-rones and spi-nal cord Four of them Co-nnectd to glands and heart mu-scle Smooth mu-scle in-ter-nal Or-gan like the small in-tes-tine One more in-vo-lun-ta-ry name It’s knee jerk reflex Stri-king pa-te-llar li-ga-ment With ru-bber ha-mmer Quad-ri-ceps ten-don streched Put out stretch re-cep-tors Tri-ge-rring nerve im-pulse Trans-mi-ssion starts

  36. DISEASES OF THE NERVOUS SYSTEM As a person ages, brain mass and the number of synaptic contacts decreases. The brain capacity to send and receive nerve impulses decreases The brain ability to process information diminishes Reflex time increases ALZHEIMER’S DISEASE PARKINSON’S DISEASE

  37. PARKINSON’S DISEASE Symptoms : -trembling of hands, arms, legs, jaws -stiffness of the arms, legs and trunk -slowness of movement -poor balance and coordination Also called : Paralysis agitans / Shaking Palsy A progressive disorder of the CNS Affects nerve cells or neurons, in a part of the brain that controls movement Neurones that make a chemical called dopamine die or do not work properly As sympoms get worse, people may have trouble walking, talking or doing simple tasks. Dopamine normally sends signals that help coordinate movements Begins around age 60 No cure for Parkinson’s Disease

  38. ALZHEIMER’S DISEASE Loss of reasoning and the ability to care for oneself Causes : Genetic factors(hereditary), enviromental factors (stress), ageing process Symptoms : -confused -forgetful -lose their sense of direction when even when travelling in familiar place Minds will continue to deteriorate, patients may lose the ability to read, write, eat, walk and talk

  39. THE ENDOCRINE SYSTEM Consists of a number of glands that secretes hormones How do hormones work? Chemical substance produce by endocrine glands, released directly into interstitial fluid or blood to be delivered to targeted cells Hormones bind to specific receptor molecule on the surface of the cell membrane of target cells Then, the hormone causes the cell to respond in a specific manner

  40. THE NEED FOR THE ENDOCRINE SYSTEM Maintain homeostasis Complement the nervous system Work together with nervous system Work alone You see a ghost, receptors in eyes generate impulses, impulses sent to the brain, scream and run. At the same time, adrenaline is produced to increase heartbeat. Heart beats fast to deliver oxygenated blood to muscle. When dehydrated Nervous system stimulate or inhibit the release of hormones The Blood osmotic pressure increases -Menstrual Cycle -Development of secondary sexual characteristic Neurones in the hypothalamus are stimulated Cells in the pituitary gland are activated Hormones promote and inhibit the generation of nerve impulses ADH is sent to kidneys Pituitary gland releases ADH Blood osmptic pressure decreases Kidneys retain more water

  41. DIFFERENCES BETWEEN THE ENDOCRINE SYSTEM AND THE NERVOUS SYSTEM ENDOCRINE SYSTEM NERVOUS SYSTEM Convey message rapidly via nerve impulses Convey message more slowly via hormones Carry information between specific locations Carry information from one source to many destinations List 4 differences NOW!! Effects are short and quick Effects are long lasting and linger Regulate certain activities Regulate wide range of activities

  42. THE HUMAN ENDOCRINE SYSTEM Testes T Hypothalamus Hypothalamus Pituitary Gland Ovary Thyroid Gland Label the diagram Pituitary Gland Adrenal Gland Pancreas Pancreas Adrenal Gland U Ovary Thyroid Gland Testes V

  43. REGULATION OF HORMONE SECRETION Endocrine gland If less stimulated? Stimulated H O R M O N E Concentration in blood : Secretion of hormones need to be regulated to prevent over production or under production. How it is regulated ? How many ways? Increase Decrease

  44. REGULATION OF HORMONE SECRETION Thyroid-Releasing Hormone TRH Hypothalamic Inhibiting Hormone Hypothalamic Releasing Hormone Inhibits the secretion of hormones in anterior pituitary TSH Stimulates the secretion of hormones in anterior pituitary Thyroid gland Thyroxine 1. Regulated by other hormones

  45. REGULATION OF HORMONE SECRETION Blood Glucose levels rises after eating Pancrease secretes insulin Glucose  Glycogen Blood Glucose level return to normal Pancreas Blood Glucose levels decreases ; fasting Pancreas secretes Glucagon Glycogen  Glucose Blood Glucose levels rises to normal 2. Regulated by the level of certain substances in the body

  46. REGULATION OF HORMONE SECRETION Posterior pituitary contains axons and synaptic terminals of the neurosecretary cells that originate in the hypothalamus Hypothalamus receives nerve impulses about the condition of the internal environment Hypothalamus Hypothalamus acts on endocrine system by controlling the pituitary gland-the master EG: secretes several hormones that control other endocrine glands The cell bodies of the neurosecretory cells are in the hypothalamus Posterior Pituitary Nerve impulses from hypothalamus sent to posterior pituitary trigger the release of hormones; ADH and oxytocin 3. Regulated by signals from the nervous system

  47. THE INVOLVEMENT OF THE NERVOUS SYSTEM AND THE ENDOCRINE SYSTEM IN A FIGHT AND FLIGHT SITUATION When you are chased by a dog Called to the principal’s room Nerve Impulses Adrenaline Noradrenaline

  48. Adrenaline Noradrenaline Increase Heartbeat Breathing rate Blood Pressure Blood Glucose Level Metabolic Action

  49. HORMONAL IMBALANCES AND RELATED DISEASES Undersecretion Oversecretion Symptoms/Disease Growth hormone Growth hormone Dwarfism Gigantism Acromegaly Slows bone growth Abnormal increase in the length of bones In adult : bones, hands, feet, cheeks and jaws thicken and other tissues enlarge The organs fail to grow and the body proportion is childlike The person grows abnormally tall

  50. HORMONAL IMBALANCES AND RELATED DISEASES Undersecretion Oversecretion Symptoms/Disease Thyroxine Iodine Myxedema Cretinism Goitre During childhood causing severe mental retardation In adulthood causing slow heart rate, low body temperature, high sensitivity to cold, general lethargy and a tendency to gain weight easily Thyroid gland grow and enlarge to two or three times its size