FORM 5CHAPTER 3COORDINATION AND RESPONSE

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COORDINATION AND RESPONSEAn organism experiences changes in its internal and external environments all the timeThe changes which cause responses in the body are called stimuliThere are two types of stimuli:a)internalb)external4. Mammals detect stimuli through highly specialised sensory cell called receptor.5. Effectors in the body carry out the responses to stimuli

COORDINATION AND RESPONSEWhen the stimuli are detected and eventually resort in an appropriate response, it is called coordinationThe roles of coordination and response are carried out by two different coordinating systems, namely the nervous system and the endocrine system

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The main component and pathway involved in detecting and responding to changes in the external environmentputeri5578*

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The main component and pathway involved in detecting and responding to changes in the internal environmentputeri5578*

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THE ROLE OF HUMAN NERVOUS SYSTEMOrganisation of the nervous systemThe human nervous system consist of a giant network of nerve cells or neurones, and nerve tissues which convey information between the sensory receptors, the organs and effectors.It is divided into main subsystem:a) central nervous system (CNS), consist of brain and spinal cordb) peripheral nervous system (PNS), consist of cranial nerves and spinal nerves. *

Human nervous system*

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Cerebrum Divided into two halves called the cerebral hemispheres (left and right)It is responsible for many mental abilitiesCerebellumCoordinating centre for body movementsEvaluates the information and relays the need for coordinated movements back to the cerebrumThen sends appropriate commands to the muscle

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Medulla oblongataRegulates the internal body processes that do not requires conscious effort, that is, automatic functions such as the heart beat and breathing.Reflex centre for vomiting, coughing, sneezing, hiccupping and swallowing.

HypothalamusImportant role in homeostatic regulation.Control centre of the endocrine system *

Pituitary glandSecretes hormones that influence other glands and body functionControls the release of several hormones from the pituitary gland and thereby serve as important link between the nervous and endocrine system.

ThalamusResponsible for sorting the incoming and outgoing information in the cerebral cortexIntegrates the information from the sensory receptor to the cerebrum by enhancing certain signals blocking others.puteri5578*

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The spinal cord and its functionContain within the vertebral columnIt is consist of white matter and grey mattera) in cross section, grey matter looks like a butterfly or the letter Hb) consist mainly of cell bodies of neuronesc) surrounded by white matterd) the white matter comprises myelin-coated axons of neurones that extend the whole length of the spinal cord

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A cross section of the spinal cord showing the white matter and the grey matterputeri5578*

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The neuronesThe nervous system is made up of millions of nerve cells called neuronesNeurones transmit nerve impulses to other nerve cells, glands or musclesputeri5578*

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Types of neuronesNeurones afferent (sensory)Carry sensory information from receptor cell to the brain and spinal cord.puteri5578*

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Types of neuronesNeurones efferentcarry information from the brain or spinal cord to the effectors, that is the muscle or gland cells

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Types of neuronesInterneuronesconvey nerve impulses between the various parts of the brain and spinal cord, transmit nerve impulses between afferent and efferent

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The transmission of information across synapsesSynapse is the site where two neurons, or a neuron and a effector cell communicate.The transmission of information across a synapse involve the conversion of electrical signals in the form of neurotransmitterThe function of synapses include controlling and integrating the nerve impulses transmitted by the stimulated receptorsputeri5578*

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Voluntary action and involuntary actionThe PNS has two main functionIt transmits signal to the CNS for processingIt transmits responses from the CNS to the rest of the bodyVoluntary actions such as walking and talking are under conscious controlInvoluntary actions that involve skeletal muscle allows immediate action that does not require conscious effortputeri5578*

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For example, if a finger touch a hot stove, the reaction is to pull the finger immediately without having to think about itIn such circumstance when the responses to stimuli are involuntary, they are called reflexes.The nerve pathway involved in a reflex action is called a reflex arcThe effectors involved in involuntary action are smooth muscle and cardiac muscleputeri5578*

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Diseases of the nervous systemParkinsons diseaseIs a progressive disorder of a CNS that typically affect victims around the age of 60 years onwards.Parkinsons disease affect muscular movements, causing tremors or trembling of the arms, jaws legs and facePatients also have difficulty in maintaining normal postures and experience impaired balance and coordinationputeri5578*

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Alzheimer's diseaseAlzheimer's disease is a neurological disorder which affect victims around the age of 60yearsonwards, causes the loss of reasoning and the ability to care for oneself.Individual of Alzheimer's disease often become confuse, forgetful, and lose their way although they are in place which are familiar to them.As their mind continue to deteriorate, patients may lose the ability to read, write, eat, walk and talk. the cause of this disease still unknown, but the factors such as genetic, environmental or the aging process itself can lead to Alzheimer's disease

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The role of hormone in humanEndocrine system consists of a number of glands that secrete hormones.Hormones are the chemical messenger produce by the endocrine glands.Although the hormones travel in the blood of the body, they affect and influence only the specific target cell.Once the hormone binds to its target cell, the hormone cause the cell to respond in the specific manner.

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puteri5578*The transport of hormones to target cells

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The need for the endocrine systemThe endocrine system and nervous system play important roles in maintaining homeostasis. Both this system often works together.puteri5578*

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puteri5578*The endocrine systemcontrols involuntary actionsConveys chemical signal (hormones)Messages are conveyed via the bloodstreamMessage are conveyed slowlyMessages are carried from the source to the various destinationThe response or effects are long-lastingThe nervous systemControl voluntary and involuntary actionsConveys electrical signalsMessages are conducted via neurones.Messages are conveyed rapidlyMessages are carried between specific locationsThe responses or effect are temporary

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Regulation of hormones secretionThe pituitary gland is regarded as the master endocrine gland because it secrete several hormones that control other endocrine glandPituitary gland itself controlled by the hypothalamus.Pituitary gland consist of two parts:a)posterior pituitaryb)anterior pituitaryThe posterior pituitary contains the axons and synaptic terminals of the neurosecretory cells that originate in the hypothalamus

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puteri5578*The role of the hypothalamus in regulating the secretion of hormones from the pituitary glandHypothalamusAnterior pituitaryAnterior pituitaryADHoxytocinKidney tubulesSmooth muscle in the uterusAdrenal cortexThyroid Ovaries, testesBones, tissuesMammary glands

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ADH and axytocin are synthesised in the neurosecretory cells of the hypothalamus but secrete by the posterior pituitaryThe hypothalamus controls the hormone secretion of the anterior pituitary gland and therefore, affect the secretion of many other endocrine glands indirectly.The anterior pituitary controls the secretions of hormones from the thyroid gland, the adrenal gland and gonad. All of which are also endocrine glands.

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HOMEOSTASIS IN HUMANHomeostasis is the maintenance of a relatively constant internal environment.Physical factor such as body temperature and blood pressure while chemical factor are sugar level and osmotic pressure such as partial of carbon dioxide and oxygenThe excretory systemPlays an important role in homeostasisThe primary organs of the excretory system are the kidneys.puteri5578*

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Function of the kidneysHelps to regulates the water and salt balance in the body by excreting more or less salt, and increasing the in take or loss of water.Regulate the osmotic pressure and ionic levels in the bloodExcrete waste products.Regulate the blood pHWaste products excreted by the kidneys are substances that are not useful to the body such as waste products from the metabolic reaction (urea, creatinine and uric acid) and foreign substances in the diet (drugs or toxins)puteri5578*

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The human kidneyThe kidneys filter the blood and form the urine which is exits the body through the ureters, urinary bladder and urethra.Urine consists of water, urea and other dissolved waste, and some excess nutrients.Human kidney has two distinct region:Renal cortexRenal medullaputeri5578*

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The nephronThe functional unit of the kidney is the nephron.The human kidney consists of about 1 million nephrons.A nephron consists of three major parts:GlomerulusBowmans capsuleRenal tubuleRenal tubule is made up of the:Proximal convoluted tubuleLoop of HenleDistal convoluted tubuleputeri5578*

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puteri5578*Nephron

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Nephron perform three basic process:UltrafiltrationReabsorptionSecretionUltrafiltrationWhen the blood enters the glomerulus, ultrafiltration take place when the high pressure forces fluid through the filtration membrane into the capsular space The fluid that enters into the capsular space is called the glomerular filtrateglomerular filtrate contain water, glucose, amino acid, urea, mineral salt and other small molecule. Some composition as blood plasma but not contain red blood cells and plasma proteinputeri5578*

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Ultrafiltration in bowmans capsuleputeri5578*

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ReabsorptionReabsorption take place when the substance moves across the renal tubule into the capillary network.In the proximal convoluted tubule, there are abundance of mitochondria to generate ATP for the process of active transport that used to reabsorb glucose and amino acid.Solute concentration in the capillary network is increase, so that water moves into the blood capillary by osmosisIn the loop of Henle, water, sodium and chloride ions are reabsorbed.puteri5578*

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At the distal convoluted tubule, more water, sodium and chloride ions are reabsorbed.B the time, the filtrate reaches the collecting duct, very little salt left and 99% of water has been reabsorbed into the bloodstream.Only 1% of water in the filtrate actually leaves the body as urine.Some urea diffuses out into the surrounding fluid and blood because of its small molecular size.Finally, about 45% of the original urea remain in the collecting duct to be excrete in the urine.

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SecretionNot everything is filtered, only 20% of the plasma leaves the blood vessels and enters the renal tubule. Hence there are waste product in the blood which were not filtered originally.Secretion is a process in which waste and excess substances that were not initially filtered are secreted into the renal tubule.Secretion take place in the renal tubules and collecting ducts but is especially active at the distal convoluted tubule.Secretion occurs by passive diffusion and active transport.puteri5578*

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REGULATION OF ADH PRODUCTION

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puteri5578*Notes about Kidney Dialysis:

The main stages that blood passes through during the dialysis process include:

Blood enters machine from body (under pressure from radial artery). Pump (some diagrams show a roller pump) controls pressure and flow rate. Anticoagulant added to prevent clotting. Blood passes through dialysis membrane (equivalent to kidney nephrons). Bubble Trap removes any gas bubbles from blood. Blood is filtered then returned to the patient's radial vein.

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Practising a healthy lifestyleDrugs can alter brain functions and the rates at which neurones release neurotransmittersThere are some types of drug and their effects on the body:puteri5578*

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StimulantsIncrease the activity of the central nervous systemCocaine, nicotine, amphetamines & caffeine increase the heart rate and alertnessHallucinations, LSD perceive things that do not exist

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DepressantsSlow down the activity of the central nervous systemAlcohol, barbiturates & heroin slow down the breathing rate &lower blood pressure

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Plants hormonesPlants hormones is a chemical substances which is produced by the plants and influences the growth and development of the plants. Examples auxins and ethylene AuxinsAuxins controlled the plants respond to stimuli by growing in a certain direction called tropism.Growth of shoots towards sunlight is called +ve phototropism and growth of shoots away from sunlight is called -ve phototropism.Auxins promotes the elongation of cells in the shootputeri5578*

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The growth movement of a plant is response to gravity is called geotropism.Auxins is used to:Increase the stem length by increasing the rate of cell divisionStimulate the growth of adventitious roots from the stemParthenocarpy, produce seedless fruitPromotes growth of plants cells. Delay fruit ripening and prevent fruit from falling off the plant before it is ripeputeri5578*

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EthyleneEthylene is a plant hormones which is synthesised during the ripening of fruits.The synthesis of ethylene occurs in fruits, leaves and stemsSpeedup the ripening of fruits by stimulating the production of cellulase that used to hydrolyses the cellulose in plants cells walls, making the fruits soft.Promotes the breakdown of complex carbohydrates into simple sugar. That is why a ripe fruit tastes sweeter than an unripe fruitputeri5578*

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THE ENDputeri5578*

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