Form 5 biology notes chapter 3 - Coordination


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Form 5 biology notes chapter 3 - Coordination

  1. 1. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 1ExternalenvironmentSoundSmellTasteTemperaturePressureLightTouchInternalenvironmentBloodpressureBodytemperatureSugar level inbloodpH level inbloodIn HumanHelp to surviveEnsure the metabolicactivities are carried outat optimal environmentIn AnimalProtect themselves fromchanges in externalenvironmentSensitive to presence offemale animal by the malefor reproductionHelp to move to find foodfrom one place to anotherIn PlantEnable plant to movetoward sunlightEnables plants to absorbwater and mineral salt.FORM 5 BIOLOGY NOTESCHAPTER 3 : RESPONSE AND COORDINATIONBy: Tn. Hj. Mohd Hafiz Bin Mohd Salleh3.1. Response and CoordinationDefinition: Stimulus - A change in external or internal environment in the body which can be detected by the body’ssystem. (plural : stimuli) Response - An action of the body, either consciously or unconsciously towards a certain stimulus. Receptor - A group of cells in the body specialised to detect the changes in the external or internalenvironment in the body. Coordination - The control of different parts of organs and systems that makes them working togethereffectively and efficiently.Changes in External and Internal Environment Faced by an Organism:Necessity for Living Organisms to Respond To Stimuli:
  2. 2. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 2Pathway in Detecting And Responding To ChangesPathway Information Due To External StimuliPathway Information Due To Internal Stimuli
  3. 3. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 33.2. Role of Human Nervous systemHuman being must MONITOR and MAINTAIN constant internal environment as well as monitor and responds toexternal environmentDefinition: NERVOUS SYSTEM is the system that monitors, maintain and responds to environment. (External @ Internal)Role of nervous system:1. The nervous system collects information about the changes in internal and external environment.2. The nervous system transmits information about the changes in internal and external environment via theneurons to the processing centre.3. The nervous system process, integrates and interprets the information received.4. The nervous system coordinates the body activities and brings about appropriate response.Organisation of nervous system
  4. 4. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 4PERIPHERAL NERVOUS SYSTEM Cranial nerves - Send nerve impulse to and from the brain.- Smell, vision, hearing, movement of eyeball and movement of head and shoulder. Spinal nerves - Send nerves to and from the spinal cord.- Contain sensory neurons and motor neurons.Structure and Function of Brain1. The brain consists of three main parts :a) Cerebrumb) Cerebellumc) Brain Stem (Medula Oblongota)1. Below the centre of the cerebrum is the thalamus,hypothalamus and pituitary gland.2. The brain is made up of nerve cells called neurones.3. The outer part of the brain consists of the grey matter[cerebral cortex] ( which contains the cell body of theneurone ) and the inner part consists of the whitematter ( which contains the fibres of the neurone ).Cerebrum1. The cerebrum is the largest and most complex part of thebrain.2. It is divided into two halves called the cerebral hemispheres.3. The left hemisphere controls the movements on the rightside of the body.4. The right hemisphere controls the movements on the leftside of the body.5. The cerebral hemisphere is divided into regions containingspecialised groups of nerve cells responsible for sensory,motor and association functions.6. The interrelationship between these three areas enables thecerebrum to control and coordinate all voluntary activities of the body, including highly-developedfunctions such as memory, reasoning, learning and speech.7. Cerebrum control: Learning, Memorising , Speech, Mathematical skill, Imagination, reasoning, Planning,Touch, Taste, Temperature, Movement, Sight, Hearing, Memory retrieval .Hypothalamus1. Located on the ventral region of the cerebrum.2. Pituitary gland is located at the end of the hypothalamus.3. Hypothalamus has the richest blood supply in the brain.4. It acts as a major coordinating centre for regulating: sleep, hunger,thirst, body temperature, water balance and blood pressure.5. For example, it detects changes in blood temperature and osmoticpressure. If there are any changes, it will initiate nerve impulses to
  5. 5. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 5the effectors to produce homeostatic responses required for regulation of the body temperature and theosmotic blood pressure.6. Thus, hypothalamus helps to regulate body temperature and osmotic blood pressure through the pituitarygland.7. Hypothalamus also control centre of the endocrine system.Thalamus1. Located on the region of cerebrum , above the hypothalamus2. The thalamus is responsible for sorting the incoming and outgoinginformation in the cerebral cortex.3. It also integrates the information from the sensory receptors to thecerebrum by enhancing certain signals and blocking others.4. Thalamus is also the integration centre for sensory impulses such assight and hearing to the various sensory areas of the cerebrum.Pituitary gland1. The pituitary gland secretes hormones that influence other glands and body functions.2. The hypothalamus controls the release of several hormones from the pituitary gland and thereby serves asan important link between the nervous and endocrine systems.Cerebellum1. The cerebellum is located below the cerebrum near the top ofthe spinal cord. It has a folded surface. The cerebellum has twohemispheres.2. Functions of cerebellum :a) Coordinates the contraction of musclesb) Controls the posture and balance of the body.Medula oblangota1. Located in front of the cerebellum.2. Medulla oblongata links the brain to the spinal cord.3. Functions of medulla oblongata :a) Controls and regulates involuntary actions such asthe rate of heartbeat, peristalsis, blood pressure,breathing and the variation in the size of bloodvessels during vasodilatation or vasoconstriction.b) Centre for certain reflex actions such as vomiting,coughing, sneezing and swallowing.
  6. 6. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 6Structure and Function of Spinal Cord1. Spinal cord linked between the brain and the peripheral nervoussystem.2. It consists of grey matter in middle and white matter.3. Spinal nerves arise from the spinal cord and spinal nerve has adorsal root which contains the afferent neuron and ventral rootwhich contains the efferent neuron.4. Spinal cord control reflex action.5. The spinal nerves emerge from the spinal cord through twoshort branches or roots.a. The dorsal root contains the axons of the afferentneurones which conduct nerve impulses from thesensory receptors to the spinal cord.b. The cell bodies of the afferent neurones areclustered in the dorsal root ganglion.c. The ventral root contains the axons of the efferentneurones which conduct nerve impulses away fromthe spinal cord to the effectors.d. The dorsal and ventral roots join to form a spinalnerve.Structure of a neuron1. The cells that carry information through the nervous system are called neurons.2. The message that a neuron carries is in the form of electrical signal called a nerve impulse.3. A neuron contain:a. A large cell body contain nucleus.b. Dendrites are the threadlike extension from the cell body.c. Axon is the long fibre from the cell body. It carry impulse away from the cell body.d. Axon terminals are the branches of the axon.e. Synaptic knobs is the swelling end of the axon terminals.f. Axon is surrounded by an insulating membrane known as myelin sheath.g. Myelin sheath has many gaps called node of Ranvier. It allows an impulse moves by jumping from onenode to the next and increase the speed.
  7. 7. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 7Type of neuronsi. Sensory neurones ( afferent neurones ) Has a long dendrites and short axon. The cell body is located in the ganglion of the dorsal root of the spinal cord. Transmit nerve impulses from receptors or sensory organs to the central nervous system (CNS).ii. Interneurones Found within the brain and spinal cord. Has a short dendrites and short axon. The cell body is located in the grey matter ofthe CNS. Connects one neurone to another neuroneand frequently connects a sensory neuroneto a motor neurone.iii. Motor neurones ( efferent neurones ) Transmit nerve impulses from the central nervous system to the motor organs or effectors, usuallymuscles or glands to produce response. Have a short dendrites and long axons. The cell body is located in the grey matter of the spinal cord.Axons of many neurons are surrounded by Schwann cells. A large number of Schwann cells cover the axonseveral times, forming a myelin sheath .These myelin sheaths contain lecithin, a type of phospholipids, which is anelectrical insulator. Its Enable fast transmission of impulses in the neuron. Nodes of Ranvier are region of theaxon not covered by myelin sheaths
  8. 8. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 8Transmission of Information along the NeuronStructure and function of synapse1. Neurons are not directly connected. Thereis a gap between two neurons. This narrowgap is called synapse.2. Synapse is formed between the axonterminals of a neuron with the dendrite ofanother neuron.3. The terminal dendrites of axons containsynaptic knobs.4. These knobs contain numerousmitochondria and synaptic vesicles whichfilled with neurotransmitters.5. Examples of neurotransmitters areacetylcholine , noradrenaline , serotoninand dopamine
  9. 9. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 9Transmission of chemical signals across the synapse
  10. 10. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 10Types of Coordinated responseThere are two types of coordinated response:1. Voluntary action2. Involuntary actionVoluntary action1. Voluntary action is a conscious action and is controlled by the cerebrum of the brain.2. Voluntary action occurs according to the will of an individual.1. It involves the process of integration and interpretation of information to produce a response according tothe will.2. Voluntary action involves the sensory organs, the cerebrum and the effectors (muscles or glands).Involuntary action1. Involuntary action is an automatic action that is not controlled by the will of an individual.2. Involuntary action is controlled by the medulla oblongata.3. It occurs in the body without any conscious control.4. Examples of involuntary actions in the body are peristalsis, heartbeat and breathing.5. The stimuli received by the receptors are internal stimuli.6. The nerve impulses generated are sent to the medulla oblongata to be integrated and interpreted.7. The effectors which produce the response are smooth muscles, cardiac muscles and glands.The differences between voluntary action and involuntary action.Aspect compared Voluntary action Involuntary actionType of action Occurs according to the will of anindividual.Does not occur according to the will of anindividual. It is an automatic action.Integrating centre Cerebrum Medulla oblongataStimulus Involves external stimuli Involves internal stimuliReceptor Sensory organ Specialised internal receptorsTransmission ofimpulseImpulses transmit from the brain to theskeletal musclesImpulses transmit from medullaoblongata to smooth muscles, cardiacmuscles and glands.Effector andresponseThe effector (skeletal muscles)produces a voluntary action. Forexample, kicking a ball.The effectors (smooth muscles ofinternal organs, cardiac muscles of theheart and glands) produce involuntaryresponses such as heartbeat andperistalsis.
  11. 11. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 11Reflex Action1. Reflex action is an involuntary action that occurs automatically and spontaneously without conscious controltowards a stimulus.2. Reflex action is controlled by the spinal cord and does not involve the cerebrum.3. It acts as a protection against injuries and dangerous situations, as well as an adaptation to any changes in theenvironment.4. Examples of reflex action are :a) Knee jerkb) Withdrawal of the hand from a hot objectc) Blinking of the eyesd) Changes in the size of pupil in the eyee) Balancing the body to prevent from slippingReflex Arc1. Reflex arc is the pathway that a nerve impulse travels from the receptor to the effectors in a reflex action.2. A reflex arc consists of the receptor, afferent neuron, and interneuron in the spinal cord, efferent neuron andeffectors.3. The process of a reflex arc :1. The receptor detects a stimulus and triggers the afferent neuron to send out nerve impulses2. The nerve impulses are carried by the afferent neuron to the spinal cord3. From the spinal cord, the nerve impulses travel along the efferent neuron to the effectors withoutpassing through the brain.4. The effector receives the information and produces an automatic response towards the stimulus.Knee jerk
  12. 12. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 12Withdrawal of the hand from a sharp object
  13. 13. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 13Involuntary action which involves smooth muscles, cardiac muscles or gland1. The autonomic nervous system Control involuntary action involving the glands, the cardiac muscles of the heart and the smoothmuscles of the internal organs such as the intestines. Connects the medulla oblongata and hypothalamus with the internal organs and regulates the internalbody processes that require no conscious effort. Since the information for involuntary actions does not involve the cerebral cortex of the cerebrum, noperception is generated. Therefore, we are not aware of the responses.2. This means the autonomic nervous system permits vital functions such as the heartbeats and blood circulationto continue even during states of unconsciousness such as sleeping or fainting when voluntary actions haveceased.3. The autonomic nervous system can be divided into The sympathetic division1. Prepares the body for stressful situations or an emergency, in which the responses areassociated with ‘fight or flight’.2. Increases the pulse rate, blood pressure, and breathing rate.3. Slows down the digestive system so that more blood is available to carry oxygen to the vitalorgans such as the brain, heart and muscles. The parasympathetic division1. Prepares the body during ordinary situations or brings on the responses associated with arelaxed state.2. Decreases the pulse rate, blood pressure, and breathing rate.3. Stimulates the digestive system to continue breaking down food.Diseases Related to the Nervous System1. Alzheimer’s disease A neurodegenerative disease characterised by progressive cognitive deterioration, such as loss ofintellectual ability and memory. The diseases are associated with the shrinkage of the brain tissue and the changes in the neurotransmittersystem such as lack of acetylcholine in the brain.2. Parkinson’s disease A disease of the nervous system that affects the part of the brain which controls the actions of the muscles. The muscles become weak and stiff, causing tremors and jerkiness in movement. This is due to the reduced level of a neurotransmitter called dopamine in the brain. In some cases, it iscaused by the hardening of cerebral arteries. This disease cannot be inherited. Symptoms of Parkinson’s disease are :o Slow movement due to stiffness and tremoro Jerkinesso Weak muscleso Muscles stiffness and crampso Impaired balance and coordination.
  14. 14. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 143.3. Role of Hormones in Humans1. Endocrine system is a system controls the body’s activities by releasing chemicals called hormones.2. Hormones are specific chemical messenger molecules in the bloodstream that can regulate the activities of organsand tissues. It synthesized by a group of specialized endocrine glands.The differences between the endocrine system and the nervous systemThe nervous system The endocrine systemControls voluntary and involuntary actions Controls involuntary actionsConveys electrical signals (nerve impulses) Conveys chemical signals (hormones)Messages are conducted via neuron Messages are conveyed via the bloodstreamMessages are conveyed rapidly Messages are conveyed slowlyMessages are carried between specific locations Messages are carried from the source to variousdestinationsThe responses or effects are temporary The responses or effects are long-lastingRole of Endocrine system1. Endocrine system is made up of ductless glands that produce and secrete hormones.2. The endocrine system regulates various physiological processes which are not directly regulated by the nervoussystem such as :a. Growthb. Reproductionc. Metabolismd. Menstrual cyclee. Development of secondary sexual characteristics3. Endocrine system and the nervous system work together to regulate the balance of the internal environmentthrough the process called homeostasis.4. Endocrine system complements the nervous system in carrying out various body process.
  15. 15. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 15Endocrine Glands and HormonesHormones can be divided into three main categories:i. Reproductioni. Follicle stimulating hormone ( FSH )ii. Luteinising hormone ( LH )iii. Estrogeniv. Progesteronev. Androgenii. Growthi. Growth hormoneii. Thyroid-stimulating hormone ( TSH )iii. Thyroxineiii. Homeostasisi. Insulinii. Glucagoniii. Antidiuretic hormoneiv. AdrenalineHypothalamusHypothalamicreleasing hormonesStimulate the secretion of the anteriorpituitary hormonesHypothalamicinhibiting hormonesSuppress the secretion of the anteriorpituitary hormonesAnterior pituitary gland (master gland)Growth Hormone(GH)Stimulates growth, protein synthesis andfat metabolismProlactin (PRL) Stimulates milk synthesis and secretionfrom the mammary glandsThyroid-stimulatinghormone ( TSH )Stimulates the thyroid gland to releasethyroxineAdrenocorticotrophichormone ( ACTH )Stimulates the adrenal cortex to releasehormonesFollicle-stimulatinghormone ( FSH )Stimulates the development of thefollicles in the ovaries in femalesLuteinising hormone( LH )Stimulates ovulation , development ofcorpus luteum and secretion of oestrogenand progesterone in femalesStimulates the secretion of testosteronein males.Posterior pituitary glandAntidiuretic hormone(ADH)Stimulates water reabsorption by therenal tubules in the kidneysOxytocin Stimulates the contractions of the uterinemuscles during childbirth; and stimulateslactation (the release of milk from themammary glands in females)
  16. 16. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 16Thyroid glandThyroxine Increases the metabolic rates of most body cellsIncreases body temperatureRegulates growth and developmentThymus glandThymosin Stimulates the formation of T-cells which help defend the body from pathogens.Adrenal cortexAldosterone Increases the reabsorption of mineral salts in the kidneysAdrenaline andnoradrenalineIncreases the levels of sugar and fatty acids in the bloodIncreases heart activity, and the rate and depth of breathingIncreases the metabolic rate and constrict some blood vesselsPancreas glandInsulin Decreases blood glucose levels and promotes the conversion of glucose to glycogenGlucagon Increases blood glucose levels and promotes the conversion of glycogen to glucoseOvaryOestrogen Stimulates the development of the female secondary sexual characteristics and maturationof the ova.Promotes the repair of the uterine liningProgesterone Stimulates the development of the uterine lining and the formation f the placentaInhibits ovulationTestisAndrogen(testosterone)Stimulates the development of male secondary sexual characteristics and spermatogenesisSecretion of hormones regulated by another hormone1. The release of thyroxine is regulated by the thyroid-stimulating hormone ( TSH ).2. A high level of thyroxine inhibits the release of TSH and stops the release of additional thyroxine.3. A low level of thyroxine stimulates the secretion of TSH which then stimulates the thyroid gland to secretethyroxine.
  17. 17. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 17Secretion of hormones regulated by levels of certain substances1. Certain hormones are regulated by the level of specific substances in the blood.2. After a meal, the blood glucose level rises and will promote the release of insulin into the blood stream by thepancreas.3. Insulin will cause cells to take up glucose and also cause liver and skeletal muscle cells to form the glycogen.4. If the glucose level in the blood falls, further insulin production is inhbited.5. Glucagons are released to break down the glycogen into glucose. Then the glucose is released into the blood tomaintain glucose level.6. Glucagon production is inhibited when the level of glucose rises.7. Insulin is an example of hormone and glucose is an example of specific substances.Secretion of hormones regulated by nervous system1. When faced with stimuli that are threatening, dangerous or exciting, our body goes through a series of changesthat prepares us to either fight or to flee.2. The fight-or-flight strategy is a safety measure that prepares the bodyto respond to the situation.3. The fight or flight response involves a coordinated effort of both the nervous and the endocrine systems.A. The nervous system in the fight or flight response1. When a threatening stimulus is received, the hypothalamus activates the nervous system (the sympatheticnervous system) to send impulses to the adrenal medulla to release adrenaline (and noradrenaline) into thebloodstream.2. Adrenaline is called the "fight or flight" hormone or the "stress hormone" because it prepares the body foraction.3. Adrenaline causes:i. more glycogen to be converted into glucose in the liverii. increased metabolic rateiii. deeper and rapid breathingiv. a faster heartbeat and a raised blood pressurev. blood to be diverted from the surface areas of the body and the gut to the musclesB. The endocrine system in the fight or flight response1. At the same time, the hypothalamus stimulates the anterior pituitary gland to secrete the adrenocorticotrophichormone (ACTH) to activate the adrenal-cortical system.
  18. 18. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 182. ACTH moves through the bloodstream to the adrenal cortex, where it activates the secretion of corticoidhormones (approximately 30 different hormones) which will prepare the body to deal with the stress.( raisesblood glucose level by stimulating the conversion of lipids and protein to glucose )3. The corticoid hormones are slow-acting and have lasting effects. In fight and flight situation, The heart contracts more vigorously to pump a larger amount of oxygen andglucoseto the brain and skeletal muscles.o The brain needs to be highly alert to mobilise the various parts of the body into immediate action.o The skeletal muscles become more energised and enable a person to fight off an attacker or fleeimmediately from danger. When a person is in a stressful situation, the nervous and endocrine system both work together to bring aboutimmediate responses to cope with the imminent threat. Once these mechanisms successfully counteract the danger, the bodily changes that occurred return to normal.Hormonal imbalances and related diseasesEndocrine gland Hormone Function Effects of hormonal imbalanceThyroid Thyroxine• containsiodine• important ingrowth Speeds up cell metabolic rate Stimulates normalphysical growth andmental development Thyroxine deficiency causes :a) Cretinism in children (severe mentalretardation )b) myxedema in adults (sluggishness ofmetabolism, swelling of subcutaneoustissue, disrupted mental and sexualactivities)
  19. 19. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 19 Excessive thyroxine causes:a) a high metabolic rateb) an increased rate of heartbeatc) hyperactivity andd) goitre in the neck and the eyeballsprotrude.Adrenal cortex(producescorticoidhormones)Cortisol Raises blood glucose levelby stimulating theconversion of lipids andprotein to glucose.Are produced in responseto stress.Cortisol deficiency causes Addison disease weight loss, weak muscles, fatigue, low blood pressure darkening of the skinExcessive cortisol causes Cushings Syndrome gains weight, weak muscles, fatigue, poor skin healing OsteoporosisAdrenal cortex(producescorticoidhormones)Aldosterone Regulate blood osmoticpressure by reabsorbingNa+ and excreting K+ in thekidneys to retain water.Aldosterone deficiency decreases Na+ andincreases K+ ,more water is excreted andblood pressure dropsExcessive aldosterone increases Na+, decreasesK+ , body retains excess water and bloodpressure increasesAdrenal medulla Adrenaline Prepares the body forstressful situations by: raising respiration andheartbeat rates increasing blood flowto muscles and brain contracting epidermalarteries and divertingblood to major musclegroups (face turnspale) Stimulates theconversion of glycogento glucose.Excessive adrenaline: raises blood pressure raises the blood glucose level causes glucose to be present in the urinePosteriorpituitary glandAntidiuretichormone (ADH)Stimulates the kidney toreabsorb water andproduce less urine. An inability of the posterior pituitary tosecrete ADH can result in a disorder knownas diabetes insipidus. As a result , the person excretes a largeamount of urine. People with diabetes insipidus are thirstyall the time. They often want to drinkliquids frequently. Because so much water is lost in the urine,the person may die of dehydration ifdeprived of water for even a day.
  20. 20. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 20Pancreas Insulin(is secreted bythe -cells)Lowers blood glucose levelby stimulating glucose storage asglycogen (in muscle andliver), fats (in adiposetissue) and protein oxidation of glucose incell respiration Insulin deficiency causes:a) elevated blood glucose levelsb) glucose to be excreted in the urine(diabetes mellitus)c) body becomes thin and weak Excessive insulin causesa) low blood glucose levels weakness,light-headedness, heart beat becomesrapid and irregularGlucagon(is secreted bythe -cells)Raises blood glucose levelby stimulating theconversion of glycogen toglucose Glucagon deficiency makes a person weakand lacking energy Excessive glucagon causes a person to beover active3.4. Homeostasis in Humans(Homeostasis : the regulation of the physical and chemical factors in the internal environment to maintain aconstant internal environment)Necessity to maintain internal environment at optimal conditionsa) Constant internal condition for the survival of organisms.b) Monitoring changes in the external and internal environments and adjusting the change through a negativefeedback mechanism.Changes in Blood Osmotic Pressure to Urine Output1. Water content of blood determines the blood osmotic pressure.2. Osmotic pressure of blood increase when water loses from body through urinating or sweating.a. So blood plasma becomes hypertonic to the blood cell.b. The content of water in the body need to regulate through homeostasis to maintain the optimal level.c. More water is reabsorbed into the blood by the kidneys.d. Amount of urine eliminated will decrease.3. When osmotic pressure in blood is low, it is because high water content in the blood.a. Less water is reabsorbed into the bloodstream.b. Excess water from the kidneys is eliminated as urine. This will increase the volume of urine.Structure of Kidney1. The kidneys filter blood and form urine which exits the bodythrough thei. ureters,ii. urinary bladder andiii. urethra.2. Urine is a fluid which consists ofi. water,ii. urea andiii. other dissolved wastes, andiv. some excess nutrients.
  21. 21. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 213. The human kidney has two distinct regionsi. an outer light-red region called the renal cortexii. an inner dark-red region called the renal medulla4. The renal artery supplies oxygenated blood and nutrientsto the kidney while the renal vein carries away filteredblood to the body.5. Each human kidney consists of about one millionnephrons.NEPHRON1. The functional unit of a kidney is the nephron.2. Each human kidney consists of about one millionnephrons.3. A nephron consists of three major parts:a) the glomerulus and its associated blood vesselsb) the Bowmans capsulec) a long, narrow tube called the renal tubule4. The renal tubule is made up of the5. proximal convoluted tubule6. loop of Henle7. Distal convoluted tubule8. The distal convoluted tubules of several nephrons join toa common collecting duct.9. The Bowmans capsule and both convoluted tubules liewithin the renal cortex, whereas the loop of Henleextends into the renal medulla.10. Within the kidney, each nephron is supplied with blood byan afferent arteriole which is a branch of the renal artery.11. Each afferent arteriole divides further into a tangledcapillary network called the glomerulus.12. The capillaries of the glomerulus reunite to form an efferent arteriole.13. Each efferent arteriole divides to form a network of blood capillaries surrounding the kidney tubules.14. These capillaries are called peritubular capillaries or the capillary network which eventually join together intothe renal vein.The structure of Bowman’s capsule1. The Bowmans capsule is made up of two layers of cells thatsurround the glomerulus.2. The space between the two layers of cells is called the capsularspace.3. The cells that make up the inner wall of the Bowmans capsuleare called podocytes.4. The podocytes adhere closely to the endothelial cells of theglomerulus.
  22. 22. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 22Formation of Urine1. The formation of urine involves three main processes :a) Ultrafiltrationb) Reabsorptionc) SecretionUltrafiltration process (Bowman’s capsule and glomerulus)1. Blood enters the glomerulus through the afferent arteriole andleaves through the efferent arteriole.2. The blood pressure in the afferent arteriole is high because it isderived from the renal artery which branches from the aorta. Thediameter of the efferent arteriole is also smaller than the afferentarteriole. As a result, there is a high resistance in the blood flow.This produces a high hydrostatic blood pressure in theglomerulus.3. The high hydrostatic pressure in the blood of the glomerulus causes most of the constituents of the plasma tobe filtered out of the glomerulus (through the thin capillary walls with pores) into the cavity of the Bowmanscapsule.4. The process where all the constituents of blood plasma are filtered under high hydrostatic pressure into theBowmans capsule is known as ultrafiltration.5. The fluid filtered into the Bowmans capsule is called glomerular filtrate.6. The filtrate in the Bowmans capsule consists of all the constituents of the blood plasma in the afferentarteriole except (which are too large to pass through the capillary walls of the glomerulus) erythrocytes, leucocytes, platelets and plasma proteins7. The glomerular filtrate consists of mainly dissolved small molecules such as inorganic ions, especially sodium ions, glucose, amino acids and urea.Reabsorption process1. From the Bowmans capsule, the glomerular filtrate flows into the uriniferous tubule.2. The reabsorption process occurs along the whole uriniferous tubule. Essential solutes and water in the filtrateare reabsorbed into the blood capillaries that surround the tubule.3. At the proximal convoluted tubule :i. About 75% - 80% of water is reabsorbed back into the blood capillaries by osmosis. This occurs becausethe glomerular filtrate is hypotonic to the blood plasma.ii. All glucose, amino acids and some mineral ions like sodium ions ( Na+) and chloride ions ( Cl-) in thetubule are reabsorbed into the bloodstream by active transport.
  23. 23. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 234. At the loop of Henle :i. About 15% of water is reabsorbed throughosmosis on the descending limb which ispermeable to water but not to other solutes.ii. Sodium ions and chloride ions are activelytransported out of the filtrate on theascending limb which is less permeable towater.5. At the distal convoluted tubule and the collectingduct:i. The amount of water and inorganic ions (salts)that will be reabsorbed from the filtratedepends on the bodys needs and is controlledby the endocrine system.ii. The rate of reabsorption of water and salts is affected by the quantity of water and salts consumed. It iscontrolled by hormones as the walls of the distal convoluted tubule and the collecting duct are morepermeable to water if antidiuretic hormone (ADH) is present and more permeable to salts ifaldosterone hormone is present.iii. Urea is not reabsorbed throughout the nephron and is excreted in the urine.6. The remaining filtrate in the tubule which is channelled into the pelvis of the kidney is called urine.i. If plenty of water from the filtrate is reabsorbed in the distal convoluted tubule and the collecting duct,then the amount of urine produced is little and concentrated (hypertonic urine).ii. However, if less water is reabsorbed from the filtrate, a larger amount of diluted urine is produced(hypotonic urine).7. Urine consists ofi. 96% water,ii. 2.5% nitrogenous waste products such as urea, uric acid and creatinine,iii. 1.5% inorganic ions andiv. traces of bile pigments.8. Urine is carried by the ureter from the kidney to the urinary bladder to be stored temporarily and excretedthrough the urethra
  24. 24. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 24Secretion1. Secretion is the process where unwanted substances like urea, uric acid, ammonia, drugs, alcohol, excess saltsand water in the blood are actively transported from the capillaries surrounding the nephron into the kidneytubule (especially at the distal convoluted tubule).2. This process helps to remove the toxic and unwanted substances from the bloodstream.3. Secretion process also helps to regulate the pH level of the blood. For example, when the blood is too acidic,the hydrogen ions, H+, are secreted into the filtrate whereas if the blood is too alkaline, the hydrogencarbonate ions, HCO-are secreted into the filtrate.4. Secretion plays an important role in adjusting the urine composition as it passes through the kidney tubule.Osmoregulation1. Osmoregulation is the process of regulating the blood osmotic pressure by regulating the water content andthe concentration of salts in the body.2. Osmoregulation is an example of homeostasis which is brought about by the negative feedback system.3. The negative feedback system is a corrective mechanism to restore the deviated osmotic pressure in the bloodto its normal level.4. The kidneys carry out osmoregulation by coordinating the rate of reabsorption of water and salts (especiallysodium and chloride ions) during the formation of urine.5. The amount of water and salts in the blood will determine the osmotic pressure of the blood.6. Reabsorption of water is controlled by the antidiuretic hormone (ADH) which is released by the posteriorpituitary gland.7. Reabsorption of salts is controlled by the aldosterone hormone which is produced by the adrenal cortex gland.The Mechanism of Osmoregulation(A) When the blood osmotic pressure is high1. The high osmotic pressure is detected by the osmoreceptors in the hypothalamus.2. The posterior pituitary gland is stimulated to release the antidiuretic hormone (ADH).3. The blood osmotic pressure is raised when water is lost excessively through sweating or after a salty mealwhere a large amount of salt is consumed.4. The adrenal gland is less stimulated and thus less aldosterone hormone is released.5. Antidiuretic hormone increases the permeability of the walls of the distal convoluted tubule and the collectingduct towards water.6. Hence, more water and less salt are reabsorbed from the tubules into the blood capillaries.7. This lowers the blood osmotic pressure to its optimum level. As a result, a small amount of concentrated urineis produced.( B ) When the blood osmotic pressure is low1. The blood osmotic pressure is lowered when an excessive amount of water is consumed.2. The low osmotic pressure in the blood is detected by the osmoreceptors in the hypothalamus.3. The adrenal gland is stimulated to release the aldosterone hormone.4. The pituitary gland is less stimulated and the release of ADH is greatly reduced.5. The aldosterone hormone causes the walls of the distal convoluted tubule and the collecting duct to becomemore permeable to salts and less permeable to water.6. Hence, more salt and less water are reabsorbed from the tubules into the blood capillaries.7. This increases the blood osmotic pressure to its optimum level.8. As a result, a large amount of diluted urine is produced.
  25. 25. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 25Consequences of Impaired Kidney Function1. For patients with impaired kidney function, the kidney cannot removethe excess water, mineral salt or urea. Hence, these substances remainin the blood.2. Kidneys that are damaged by disease or injury fail to carry outultrafiltration at the glomerulus, thus unable to regulate the bloodosmotic pressure, filter the blood and remove the unwanted wasteproducts. These problems can be overcome through haemodialysis.3. Haemodialysis is treatment takes about six hours, and most dialysispatients require three treatments per week.4. During haemodialysis, blood from the artery is passed through themachine which contains a dialyser (also called an artificial kidney).5. The dialyser has two sections separated by a semi-permeablemembrane.6. Blood passes on one side of the membrane and the dialysis solutionpasses on the other.7. Blood passes on one side of the membrane and the dialysis solutionpasses on the other.8. The concentration gradient between the blood and the dialysissolution is such that the excess salts and waste molecules such asurea can diffuse through the membrane from the blood into thedialysis solution while blood cells and plasma proteins remain within the blood.9. Glucose and other required substances that diffuse out of the blood may also be restored by the dialysissolution.10. The blood is then returned to the body.11. Another treatment for impaired kidney functions is the transplant of a healthy kidney from a donor to thepatient. However, there is a risk that the recipients body may reject the transplanted organ. Medicines to counteract organ rejection are used by the patients and this has greatly increased thenumber of successful kidney transplants. In kidney transplant, a new kidney is placed inside the lower abdomen. The artery and the vein of thenew kidney are connected to the aorta and vena cava. The damaged kidneys are left in place unlessthey are causing infection or high blood pressure.Regulation of blood sugar level1. The normal blood glucose concentration in humans is about 75 -110 mg of glucose in 100 cm3of blood.2. This level of glucose is regulated by the negative feedback mechanism controlled by hormones.3. Two organs are involved:i. Pancreas Small clusters of cells called islets of Langerhans consist of alpha cells ( cells) and beta cells (cells). The  cells secrete glucagon while the  cells secrete the insulin directly into the blood.ii. Liver The main target organ of insulin and glucagon is the liver. Hence, the hormones are quicklycarried in the blood from the pancreas by the hepatic portal vein to the liver where thehormones act.
  26. 26. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 264. Insulin converts the excess glucose in the blood to glycogen which is stored as granules in the cytoplasm of theliver cells and the muscle cells. The conversion of glucose to glycogen lowers the blood glucose concentrationto its optimum level.5. In liver cells, the excess glucose in the blood will be converted to lipids. Meanwhile, the cells will also use up theglucose in respiration.6. Glucagon converts the stored glycogen in the liver (and muscles) to glucose. The glucose then diffuse out of theliver cells into the blood. Glucagon also increases the conversion of glucose from amino acids and fatty acids inthe liver cells. This increases the blood glucose concentration to its optimum level.Regulation of blood glucose concentrationThe regulation of body temperature ( Thermoregulation )1. The human body temperature is regulated homeostatically so that it is always maintained at a constanttemperature of about 37°C despite the changes in the environmental temperature.2. This temperature is the optimum temperature for the reactions of enzymes in the body.3. If the body temperature is above 40°C, enzymes will be denatured. If the body temperature is too low, theenzyme reactions are slowed down.4. The skin plays an important role in thermoregulation. This is because the skin can regulate the heat gain andheat loss from the body to maintain a constant body temperature.5. Receptors which detect the changes in temperature are called thermoreceptors.6. In the skin, the thermoreceptors detect the changes in the environmental temperature while thermoreceptorsin the hypothalamus detect the changes in the temperature of the blood flowing near this region.
  27. 27. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 277. Thermoreceptors detect the stimulus and are stimulated. Then, nerve impulses are transmitted along theafferent nerve to the hypothalamus.8. The hypothalamus acts as the thermoregulatory centre (coordination centre) which transmits nerve impulsesto various effectors such as the sweat glands, hair erector muscles, skeletal muscles and endocrine glands.These effectors produce corrective responses by negative feedback mechanism to return the bodytemperature to the normal level.9. Thermoregulatory effector response is accomplished 完成 through the changes in metabolic heat productionand physical heat loss regulation.The action of the effectors in regulating the body temperatureBy physical method ( involving skin to regulate heat loss )Action of effectors In a warm environment In a cold environment1. Action of sweatglandsThe sweat glands are stimulated toproduce sweat. Excess body heat is lost throughsweating. This gives a cooling effectto the body.The sweat glands are not stimulated andthus no sweat is produced. Heat loss isreduced.2. Action of bloodcapillaries in skinVasodilation process Vasodilation occurs. Blood capillariesdilate and increase their diameter.Thus, more blood flows near the bodysurface. Excess heat in the body is lost throughconduction and radiation to theenvironmentVasoconstriction process Vasoconstriction occurs. Bloodcapillaries constrict and decrease theirdiameter. Thus, less blood flows nearthe body surface. Most blood is diverted further fromthe body surface. Hence, heat lossthrough conduction and radiation isreduced.3. Action of hairerector musclesRelaxation of hair erector muscles Hair erector muscles relax, causingthe hair to lie flat. Only a thin layer of air is trappedbetween the hairs. Heat loss throughconduction and radiation is increased.Contraction of hair erector muscles Hair erector muscles are stimulated tocontract, causing the hairs to bepulled and erect. A thick layer of air is trapped betweenthe hairs. The thick trapped air is apoor conductor of heat. Thus, lessheat is lost through conduction andradiation.
  28. 28. Chapter 3 : Response and Coordination Notes and exercises form 5 Biology – Tn Hj Mohd Hafiz ( 3: Response and Coordination ©MHMS 28Negative feedback mechanisms in human thermoregulation