Coordination and response

3.2 The role of human nervous systemRole of the nervous systemNS controls & coordinates the activities of human body by:Detecting changes (stimuli) by receptors inside (internal environment) & outside (external environment)Processing the received sensory information about these stimuli, and decides what to doInitiating responses to these stimuli (taking appropriate actions)Through detecting changes, processing of information and the taking of appropriate actions, the NS:Helps us think act consciouslyStores information & allows us to learn from past experiencesAdapts the body to changes in the environment (by reflex or involuntary actions) thus protecting it from harmControls and coordinates the activities of all other systems in the bodyOrganisation of the Nervous System

Brain and its function

CerebrumHypothalamusPituitary GlandMid BrainCerebellumMedulla oblongataSpinal CordFore BrainHind BrainMid BrainCerebrum

Cerebral Cortex

MOTOR AREA

Control voluntary movement

SENSORY AREAreceive & interpret sensations from the whole bodyASSOCIATION AREAlink motor areas with sensory regionFUNCTIONSContains millions of nerveCentre of intelligence, memory, language & consciousness

CEREBELLUMCerebellumLocated at the back and bottom of the brainHas folded surfaceReceives information from muscles, joints, tendons and the ears to maintain the posture and to balance the body

Receives information from muscles, joints, tendons and the ears to maintain the posture and to balance the bodyMEDULLA OBLONGATA

MEDULLA OBLONGATARelays information between the spinal cord & the brainControls the automatic reactions in the body Heartbeatbreathing constriction of blood vesselscontrol reflex centre for heart rate, blood pressure, peristalsis, vomiting, swallowing and sneezingHYPOTHALAMUS

Controls physical expression of emotions

Coordination centre for the autonomic nervous systemAssociated with homeostasis & control of hunger, thirst/ water balance, body temperature & the endocrine hormone systemRegulates the pituitary glandPITUITARY GLAND

THALAMUSThalamusProcesses all sensory impulses (except olfactory) before relaying them to the appropriate parts of the brain (cerebrum)

SPINAL CORD

A bundle of nerves that continues from the medulla oblongata of the brain to the pelvic girdleOccupies the neural canal of the vertebral columnSpinal CordHas 31 pairs of spinal nerves at intervals along its lengthCommunicates with the muscles and sensory organs below the head through efferent and afferent neurones respectively in the spinal nerves

Spinal Cord

Neurone

NeuronesThe basic unit of the nervous systemTransmits electrical impulses called nerve impulsesBasic structure:Cell bodyAxonDendrites

Type of neurone3 main types :Afferent or sensory neuroneEfferent neurone or motor neuroneInterneurone or intermediate neurone

Transmission of information along the neuroneMode of transmission along the neuroneA neurone:Transmits information in the form of electrical signalProduce an impulse which is like an electrical current passing along its length

Conduction of nerve impulses:Involves changes of charges on the inside and the outside of a neuroneInvolves ions of which the most important are sodium (Na+)and potassium (K+)

Synapse A gap across which a nerve impulse passes from an axon terminal to another neuroneRole:Transmits information from one cell to another (from nerve to nerve or from nerve to muscle)Causes nerve impulses to travel in one direction only

VOLUNTARY AND INVOLUNTARY ACTIONVoluntary actionInvolves thought and free willControlled by cerebrumVoluntary actions are learnedSlow response, as the cerebrum needs time to think before an action is carried outE.g. Raising your hand to answer a questionDecide to stand upTransmission of information in the voluntary action of raising an arm(a) Receptors:Eyes and ear(b) Sensory (afferent) neurons(c) Sensory areas of the cerebral cortex(d) Motor area of the cerebral cortex(e) Motor (efferent) neurones of the spinal nerve(f) Effector: arm muscle contracts to raise arm Involuntary action Does not involve thoughtNot under the control of the willControlled by Spinal cord, Hind-brainRole: to response quickly to avoid dangerRapidSame stimulus always result in the same responseE.g.:Knee jerkperistalsis

Disease of the nervous systemTypeSymptomsCauseParkinsons disease Shaking of hand at rest Weakness & stiffness of muscles Slowness of movement Poor balance Dopamine-producing neurones in brain break up Lack of dopamine (a neurotransmitter) in the brain which is important in movement controlTypeSymptomsCauseAlzheimers disease a.k.a getting senile cannot remember & behave abnormally patient begins to have problems speaking, understanding, reading, and writing Later becomes anxious & aggressive and wanders away from home loss of neurones in the areas of the brain for memory & other mental ability low levels of neurotransmitter