unit 2: the continuation of life

Unit 2: The Continuation of LifeChapter 24: Regulating Mechanisms*Mrs Smith Ch24 regulating Mechanisms*Higher Human Biology

Mrs Smith Ch24 regulating Mechanisms

*Mrs Smith Ch24 regulating Mechanisms*

Learning IntentionsTo know how the heart rate is regulated.

Success Criteria

Outline the principle of negative feedbackExplain how heart rate is controlled with reference to the role of hormonal and nervous system


Human Internal EnvironmentA humans internal environment is the millions of body cells and the tissue fluid that bathes them.For a healthy body, all body parts must work together keeping the internal environment within tolerable limits. e.g. Human body must be maintained at 37C to provide optimum conditions for enzyme controlled reactionsThe features of the internal environment are controlled by homeostasis.**Mrs Smith Ch24 regulating Mechanisms


Homeostasis**Mrs Smith Ch24 regulating MechanismsHOMEOSTASIS is the maintenance of the bodys internal environment within certain tolerable limits despite changes in the bodys external environment (or changes in the bodys rate of activity).


The value of HomeostasisHomeostasis is of survival value because it maintains the bodys internal environment at a relatively steady optimum state.

If the body is exposed to extremely adverse conditions (e.g. freezing temperatures or absolutely no water) homeostasis will eventually break down, which in extreme cases can be fatal. **Mrs Smith Ch24 regulating Mechanisms


Image source: www.hw.ac.uk 8. Negative Feedback ControlWhen a factor affecting the bodys internal environment deviates from its norm (or set-point) the body responds to correct the change. **Mrs Smith Ch24 regulating Mechanisms


Image source: www.hw.ac.uk 8. Negative Feedback ControlReceptors detect change and send messages to effectors.The change in the factor is detected by receptors.These send out nerve or hormonal messages which are received by effectors.The effectors then bring about certain responses which counteract the original deviation from the norm and return it to a set point.This corrective homeostatic mechanism is called NEGATIVE FEEDBACK CONTROL.It provides the stable environmental conditions needed by the bodys community of living cells to function efficiently and survive.**Mrs Smith Ch24 regulating Mechanisms


9. Control of Heart Rate: PacemakerAlthough the heartbeat is initiated by the pacemaker tissue also known as a Sino-atrial node (SAN). However, heart rate is not set at a fixed pace. Heart rate can be altered by nervous and hormonal activity both of which exert control over rate (though not initiation) of heartbeat.**Mrs Smith Ch24 regulating Mechanisms


The Nervous SystemImage source: www.drstandley.com The nervous system is a network of specialised cells that communicate information about an individuals surroundings and itself.

It processes this information and causes reactions in other parts of the body. **Mrs Smith Ch24 regulating Mechanisms


Control of Heart rate.The Autonomic Nervous SystemThe autonomic nervous system (ANS) controls involuntary responses to stimuli by the body. Autonomic nerves serve heart musclesmooth muscleGlandsall internal organs.

The ANS acts on these various effectors to maintain:homeostasis within the body (parasympathetic branch)response to stress the "fight or flight" response (sympathetic branch)

**Mrs Smith Ch24 regulating Mechanisms


Parasympathetic v Sympathetichomeostasisresponse to stress**Mrs Smith Ch24 regulating Mechanisms


The Autonomic Nervous System: The Vagus NervePeople have two vagus nerves, one for each side, running roughly parallel from the medulla in the brain to the bowels.The vagus nerve is the longest nerve in the body, and one of the most important. It sends commands to, and takes information from many important organs including the heart and lungs.



The heart is part of the autonomic nervous system. It has branches of 2 parts of the autonomic nervous system. These 2 pathways have opposite effects on heart rate (are antagonistic). Heart rate is regulated by control centres within the medulla of the brain. Control of Heart Rate: Autonomic nervous control**Mrs Smith Ch24 regulating Mechanisms


Control of Heart Rate: Autonomic nervous controlThe sympathetic cardiac nerves carry nerve impulses from the cardio-accelerator centre of the brain to the heart. The cardio-inhibitor centre sends nerve impulses via the parasympathetic vagus nerve. Image source: http://courses.scholar.hw.ac.uk **Mrs Smith Ch24 regulating Mechanisms


Two antagonistic pathwaysThe sympathetic and parasympathetic pathways are antagonistic to one another. i.e. They have an opposite effect on heart rate.An increase in the number of nerve impulses conducted to the to the pacemaker by the sympathetic nerve causes an increase in heart rate.An increase in the number of nerve impulses conducted to the to the pacemaker by the parasympathetic nerve causes a decrease in heart rate.**Mrs Smith Ch24 regulating Mechanisms


B. Control of Heart Rate: Hormonal ControlThe adrenal glands produce the hormone adrenaline, which also affects heart rate. Sympathetic nervous system causes the adrenal glands to release adrenalineAt pacemaker: adrenaline causes an increase in the rate of cardiac impulsesIncrease in heart rateDuring exercise or stress.**Mrs Smith Ch24 regulating Mechanisms



Learning IntentionsTo know how the heart rate is regulated and the effects of exercise on the cardiovascular and respiratory systems.

Success Criteria

Analyse graphs showing distribution of blood to tissues at rest and during exerciseCalculate cardiac output under different conditions


Control of the Heart. C. ExerciseBreathing rate & depth increases to increase ventilation this promotes O2 uptake and CO2 removalView the Scholar animation: http://courses.scholar.hw.ac.uk/vle/scholar/session.controller?action=viewContent&contentGUID=92be7024-6e80-a2da-455b-e306b499a29a Vigorous exercise can cause huge changes of the bodys internal environment. The metabolic rate increases in the muscles that are working hard. need more oxygen need more glucose produce more CO2. The body adjusts to meet these demands and returns to normal a.s.a.p



*Carbon dioxide as the stimulusExperiments show (see Torrance p188) high levels of CO2 acts as the stimulus to trigger an increase in breathing rate. The graph below shows the results!Only the abnormal air type 2 is found to cause breathing rate to increase sharply. It is concluded that it is the high level of CO2 in the abnormal air that acts as a stimulus triggering increased rate of breathing.*Mrs Smith Ch24 regulating Mechanisms


Carbon dioxide as the stimulus, ContFurther experiments showDepth of breathing also increases in response to inhalation of air rich in CO2. , In a person under going strenuous exercise it is the increased level of CO2 in the bloodstream that acts as the main stimulus for bringing about an increase in rate and depth of breathing.

*Mrs Smith Ch24 regulating Mechanisms*Oxygen as a stimulusIt is worth noting that experiments also show that severe lack of oxygen will eventually also cause an increased rate and depth of breathing.


Chemoreceptor's in the carotid arteries and aorta are sensitive to the concentrations of CO2 in the bloodstream. A rise in CO2 levels during vigorous exercise causes these sensory cells to send an increased number of nerve impulses to the respiratory control centre in the medulla.*Mrs Smith Ch24 regulating Mechanisms*The effect of Exercise on the Respiratory System: Homeostatic control: Part 1


This region of the brain responds by sending a greater number of nerve impulses to the intercostal muscles and diaphragm. The subsequent increased activity of these structures brings about an increase in rate and depth of breathing.Excess CO2 is removed and the internal environment is kept within tolerable limits.*Mrs Smith Ch24 regulating Mechanisms*The effect of Exercise on the Respiratory System: Homeostatic control: Part 2!


SUMMARY: The effect of Exercise on the Respiratory System: Homeostatic controlChemoreceptors in cartoid arteries & aorta detect CO2 concentrationMore nerve impulses sent to respiratory control centre in medullaMore nerve impulses sent to intercostal muscles and diaphragmBreathing rate & depth increases causing a return to normal CO2 concentrationAn example of negative feedback control**Mrs Smith Ch24 regulating Mechanisms


B. Effect of exercise on cardiovascular systemHeart rate (pulse) = number of cardiac cycles per minStroke volume = volume of blood expelled by each ventricle on contraction Cardiac output = volume of blood pumped out of a ventricle per minThe stronger the contraction the higher the stroke volumeAll of these increase with exercise and even more with strenuous exerciseCardiac output

Heart rate Stroke volume=XTo convert ml to litres**Mrs Smith Ch24 regulating Mechanisms


Task!!!*Mrs Smith Ch24 regulating Mechanisms*


Try this calculation! These figures actually show the effect of exercise on cardiac output for the average adult human!**Mrs Smith Ch24 regulating Mechanisms


Effect of exercise on cardiovascular systemThe cardio-accelerator centre in the medulla sends impulses via the sympathetic nerves in the heart making it beat more often and powerfully.This increase in both heart rate and stroke volume brings about the increase the total cardiac input needed to boost delivery of oxygenated blood to respiring tissues and to return deoxygenated blood to the lungs.During very strenuous exercise, the cardiac output of an average person can increase by X5. This is mainly due to the increased heart rate.

Mrs Smith Ch24 regulating Mechanisms**


All parts of the body require an adequate supply of blood to function efficiently. But the demands by each part are not constant.At rest the vegetative functions (digestion, urine production etc.) are promoted.When the body undergoes strenuous activity much blood is diverted to the skeletal muscles (for extra O2 and glucose).*Mrs Smith Ch24 regulating Mechanisms*Control of local distribution of blood


Control of local distribution of bloodDuring exerciseChemoreceptors detect CO2 concentrationNerve impulses sent to cardio-accelerator centre in medullaNerve impulses sent to arterioles in abdominal organs cause muscles in arteriole wall to contract to restrict blood flowNerve impulses sent to arterioles in working muscles causing arteriole wall to relax to increase blood flowAn example of negative feedback control**Mrs Smith Ch24 regulating Mechanisms


Distribution of blood to tissues during exercise

During exercise blood flow to various parts of the body changes. **Mrs Smith Ch24 regulating Mechanisms

TissueChange due to exerciseReasonHeartIncreaseto meet its demand for more glucose and oxygen BrainNoneBasic energy demands of cells not affectedKidneysDecreasekidney processes can be postponed until the exercise is finished SkinIncreaseallow the heat produced in muscles to be radiated from the surface of the skin Intestines & liverDecreaseprocesses of digestion and absorption can be postponed until the exercise is finished Skeletal musclesIncreaseto meet their demands for more glucose and oxygen


Task: Torrance-TYK pg192 Qu 1-3**Mrs Smith Ch24 regulating Mechanisms



Learning IntentionsTo know how the heart rate is regulated and the effects of exercise on the cardiovascular and respiratory systems. To know how blood sugar levels and body temperature are regulated..

Success Criteria

Explain how blood sugar level is controlled by the hormones insulin, glucagon and adrenalin.Analyse glucose tolerance curves of normal and diabetic subjects


Regulation of Blood Glucose ConcentrationBlood sugar level must be kept within a certain range to provide the energy needed by cells for:Synthesis of DNA, proteins and other complex molecules. Active uptake of ions. Muscle contraction.Image source: library.tedankara.k12.tr Cells are therefore constantly using up the blood sugar.To ensure a regular supply regardless of food consumed the body uses homeostasis!**Mrs Smith Ch24 regulating Mechanisms


Liver as a storehouseAbout 100g of glucose is stored as GLYCOGEN in the liver. Glucose can be added or removed from this reservoir if stored carbohydrate depending on supply and demand.*Mrs Smith Ch24 regulating Mechanisms*


Control of blood sugar: Insulin and glucagonInsulin and glucagon are two hormones that control how much glucose (sugar) is in the blood These hormones are made in the pancreas.Your pancreas contains small groups of cells called the islets (or islands) of Langerhans.



PancreasWhen you eat a meal, the amount of sugar in your blood rises. The cells in your pancreas react by making more insulin.When your blood sugar levels are low, the cells in your pancreas react by making more glucagon.**Mrs Smith Ch24 regulating Mechanisms


What does insulin do?After digestion, glucose enters your bloodstream.The Islets of Langerhans in the pancreas detects an increase in blood sugar level.These cells produce the hormone insulin, which is then transported to the liver in the bloodstream.Insulin activates an enzyme to catalyse the reaction glucose glycogen

This decreases the blood sugar level.Glycogen, a long chain carbohydrate, is stored in the liver until it is needed e.g. when you are sleeping**Mrs Smith Ch24 regulating Mechanisms


What does glucagon do?Glucagon stops your blood glucose level from dropping too low. When you exercise, your body uses the glucose in your blood to power your muscles. Your pancreas senses that you're using up your glucose supply. As your blood glucose level drops, your pancreas stops making insulin and your pancreas makes glucagon Glucagon activates an enzyme in your liver which catalyses the following reaction Glycogen GlucoseThese activities push up the amount of glucose in your blood. **Mrs Smith Ch24 regulating Mechanisms


Control of blood sugar**Mrs Smith Ch24 regulating Mechanisms


Task, can you place the boxes into the appropriate places in the table below!*Mrs Smith Ch24 regulating Mechanisms*


Watch this*Mrs Smith Ch24 regulating Mechanisms*


Adrenaline Stress ResponseThe adrenal glands produce the hormone adrenaline in an emergency when the body needs a quick supply of glucose (for fight or flight)Adrenaline is secreted by the adrenal gland and inhibits the secretion of insulin and promotes the breakdown of glycogen to glucose, overriding the normal homeostatic control. Image source: www.rch.org.au When the crisis is over the normal homeostatic control then returns the blood sugar level to its norm. **Mrs Smith Ch24 regulating Mechanisms


Alternative HomeostasisAll factors controlled by homeostasis can be represented by a standard diagram. When a factor deviates from the norm and is returned to normal it often overshoots the mark, which triggers the reverse set of corrective mechanisms. So factors in a state of dynamic equilibrium are constantly wavering on either side of the norm. This is usually represented by 2 linked circuits. **Mrs Smith Ch24 regulating Mechanisms


DiabetesDiabetics suffering from Diabetes mellitus can not produce enough (if any) insulin which causes their blood sugar level to get too high. Because of this the kidneys can not reabsorb all of the glucose from the glomerular filtrate and so glucose is excreted in the urine. Image source:Diabetes used to be fatal but can now be treated with a carefully controlled diet or insulin injections.**Mrs Smith Ch24 regulating Mechanisms


Glucose Tolerance TestGlucose tolerance is the capacity of the blood to deal with the glucose we eat. It depends on the bodys ability to produce enough insulin. A known mass of glucose is drunk. Then the level of glucose in the blood is monitored & graphed to give a glucose tolerance curve. **Mrs Smith Ch24 regulating Mechanisms


Glucose Tolerance CurvesSevere diabetic insulin injections and carefully controlled diet needed Mild diabetic condition controlled by diet Not diabetic - Insulin production normal Glucose level remains highDelayed responseGlucose level returns to normal quickly **Mrs Smith Ch24 regulating Mechanisms


Watch this!!!**http://www.bbc.co.uk/learningzone/clips/the-effect-of-high-sugar-intake-on-blood-sugar-levels/5371.htmlMrs Smith Ch24 regulating Mechanisms



Learning IntentionsTo know how the heart rate is regulated and the effects of exercise on the cardiovascular and respiratory systems. To know how blood sugar levels and body temperature are regulated.

Success Criteria

Explain how temperature is controlled with reference to;The role of the hypothalamusNerve communication between the hypothalamus and effectorsInvoluntary and voluntary responsesChanges in ability to control body temperature with age


Control of Body TemperatureCore body temperature must remain at 37oCCareful control of the blood supply to the skin can do this by reducing blood flow to the colder extremities in cool conditions.



Regulation of Body TemperatureAnother example of homeostasis is the bodys regulation of body temperature.

The hypothalamus (the bodys temp-monitoring centre)monitors body temperature in two ways:It contains central thermoreceptors which are sensitive to temperature changes in the blood, allowing detection of the bodys core temperature.It acts as a thermostat by detecting nerve impulses from thermoreceptors in the skin (this conveys info about the surface temp of the body).**Mrs Smith Ch24 regulating Mechanisms


The hypothalamus sends nerve impulses to the effectors allowing the body to correct overcooling or overheating by:Production of sweat.Control of body hairs.Vasodilation or Vasoconstriction of blood flow in the skinImage source: www.pg.com Regulation of Body Temperature**Mrs Smith Ch24 regulating Mechanisms


Role of the SkinImage source: images.encarta.msn.com The skin plays a leading role in temperature regulation. In response to nerve impulses from the hypothalamus the skin can act as both a receptor and an effector.

Role of the SkinThe skin helps to correct overheating of the body byIncreasing the rate of sweating.VasodilationThe skin help to correct overcooling of the body byDecreasing the sweat of sweating.VasoconstrictionContraction of erector muscles

Correcting and heat loss and gain 1 & 3 . Sweating - Why sweat?1. When we sweat, heat energy from the body causes water from sweat to evaporate which cools the body. 3. When we are cold sweating in inhibited to conserve heat.Sweat glands dampen the skin. This loses heat by causing evaporation of the sweat

Sweating under pressure!**Mrs Smith Ch24 regulating MechanismsSweating caused by heatSweating caused by muscular contraction


FYI: Nine Sweaty FactsHumans are the most prolific sweaters in the entire animal kingdomSweating is accomplished through specialized sweat glandsThese glands are found in the dermis and epidermis, distributed all over the body, except for the margins of the limbs, sex organs, and ear drumsThey average between 150 and 340 glands/cm2 of skin for a total of between 2,000,000 and 5,000,000 Add them all together and you get a hole the size of your mouthThe sweat glands are innervated by the sympathetic nervous systemWhen a rise in core temperature is detected by the hypothalamus, impulses to the sympathetic system cause an increase in sweat outputThe sweat gland consists of a deep coiled portion and a duct that opens on the skinThe duct aids in the re-absorption of electrolytes, mainly sodium and chloride, in the sweat so that the fluid discharged onto the skin has had the electrolyte concentration reduced by a factor of about 20



View the animation: Scholar Unit 2, Figure 6.10: Vasodilation and vasoconstriction http://courses.scholar.hw.ac.uk/vle/scholar/session.controller?action=viewContent&back=search&contentGUID=8062401e-bfa9-4231-9508-4b6df971a8b6 2. Correct overheating: VasodilatationWhen we get too hot arterioles leading to the skin become dilated, which allows lots of blood to flow near the skins surface and a loss of heat from the blood by radiation.FYI: Red skin indicates vasodilatation, Alcohol increases this hence rosy cheeks after a few tipples!

When we are cold arterioles leading to the skin become constricted, which reduces the flow of blood to the skins surface so only a little heat is lost from the blood by radiation.4. Correct overcooling: Vasoconstriction

5: Preventing overcooling: Contraction of erector musclesIn a cold environment we need to reduce heat loss. This system is more efficient in furry animals than in humans. Nerve impulses from the hypothalamus cause the erector muscles in our skin contract causing the hair (or feathers in birds) to rise up. This increases the layer of insulating air trapped by them so keeps the body warm. erector muscles relaxederector muscles contractedhairs erect

Hair muscleContraction of this muscle makes the hair stand on end, trapping more insulating air.hairSurface of skin**Mrs Smith Ch24 regulating Mechanisms


**Summary: Body Temperature

Activity: Complete the table using the given terms*Mrs Smith Ch24 regulating Mechanisms*


ANSWERS: *Mrs Smith Ch24 regulating Mechanisms*


Quick Quiz*Mrs Smith Ch24 regulating Mechanisms*


Answers*Mrs Smith Ch24 regulating Mechanisms*


Investigating response to sudden heat lossIf one hand is plunged into icy water the temperature of that hand will drop, as will the temperature of the other hand (this is measured with a device called a THERMISTOR this can take a measurement every 30 seconds) . It is therefore concluded when heat is lost from one extremity, there is a compensatory reduction in temperature that occurs in the matching extremity. This helps to conserve the temperature of the bodys core so that the bodys core temperature will stay the same. Extremities vary in temperature much more than the bodys core.

Role of other effectors in temperature regulationThese other effectors help temperature regulation by generating heat when it is needed: Shivering by skeletal muscles: muscle contractions which generate heat energy, helping return temperature to normal Liver:high metabolic activity produces heat and helps to maintain body temperatureHormones: increase metabolic rate release of adrenaline during sudden exposure to cold temperatures release of thyroxin

Voluntary Responses for temperature regulation.Temperature regulation mechanisms controlled by the hypothalamus are subconscious and involuntary.

When body temperature drops (or rises) nerve impulses pass the information to the thinking part of the brain (the cerebrum), which makes the person feel cold (or hot) and react. However body temperature is also controlled by voluntary responses e.g.

Coping with heat and coldFactors Affecting Thermal AcclimationAgeBoth infants and elderly have lessened ability to acclimatize to heat or coldBody size and shapeThe surface area to weight ratio will affect the level of acclimatization attainableBody compositionSubcutaneous adipose deposits (fat) insulate the core and make it more difficult to dissipate heat in hot or easier to retain heat in the cold**Mrs Smith Ch24 regulating Mechanisms


Involuntary responsesThe mechanisms of temperature regulation discussed thus far have all been involuntary responses, which are controlled at a subconscious level by the hypothalamus.*Mrs Smith Ch24 regulating Mechanisms*


Voluntary ResponsesWhen body temperature drops (or rises) nerve impulses pass the information to the thinking part of the brain (the cerebrum), which makes the person feel cold (or hot) and react. However body temperature is also controlled by voluntary responses e.g.

Watch this*Mrs Smith Ch24 regulating Mechanisms*



Learning IntentionsTo know how body temperature is regulated.

Success Criteria

Discuss Hypothermia in infancy & old age


Temperature regulation in infantsThe exposed area of a small animal relative to its volume is greater than that of a larger animal of similar shape. So the relative surface area of a baby is greater than an adults. So a baby would suffer more heat loss than an adult. Babys involuntary responses to decrease in temperature: vasoconstriction of skins blood vessels increase in metabolic rate in brown fat (adipose) tissue (more supplied with blood vessels than white fat) Brown fat deposits are found in newborns and hibernating mammals, and can produce heat to warm the body.

HypothermiaHypothermia is caused when the bodys core temperature drops to a dangerously low temperature.

Critical TemperatureThe lower critical temperature is the external temperature (~27oC) when a naked adults body can only just manage to maintain normal body temperature. As babies have a larger surface area they are more susceptible to the effects of cold temperature and have a higher critical temperature adults. If a newborn baby is exposed to cold temperatures, it will use up its limited food reserves to keep the body warm and once these are used up its core body temperature will drop. Any temperature below this needs heat energy to be generated by metabolism to keep the body at 37oC.

Hypothermia in BabiesTemperatures that are uncomfortably cold, but tolerable, for adults can cause hypothermia or even death in babies because their bodys temperature regulation mechanisms are not fully developed. Their temperature regulation mechanisms are even less developed. Small size, so larger relative surface area to loose heat. Higher critical temperature & burn food reserves at higher temperatures than normal. Small food reserves which run out quickly.Pre-term (premature) babies are even more susceptible to hypothermia because:

Hypothermia in the ElderlyThe elderly are more susceptible to hypothermia because: Their temperature regulation mechanisms are less efficient Blood vessels fail to undergo vasoconstriction when exposed to cold temperatures Fail to shiver when cold

They have a slower rate of metabolism so dont generate heat needed to keep body warmThey are less active so dont generate heat through movementBody temperature drops when you sit for long periods in a cold room

Breakdown of homeostasisHomeostasis only works in certain limits!!If exposed to an extreme environmental condition for a long time the negative feedback control breaks down. For example, the elderly often fail to realise the signs of hypothermia so dont take corrective action (e.g. turning up the heating). If their homeostatic temperature control has broken down their body cant recover on its own. They become hypothermic and need urgent medical attention.

Task: Torrance-TYK pg199 Qu 1-3**Mrs Smith Ch24 regulating Mechanisms


Task: Torrance AYK pg199/202 Qus 1-6**Mrs Smith Ch24 regulating Mechanisms


Essay style Questions ScholarGive an account of hormonal control of the regulation of blood sugar levels. *Mrs Smith Ch24 regulating Mechanisms*


ANSWER: Give an account of hormonal control of the regulation of blood sugar levels. (10)

*Each numbered point is worth 1 mark. The information in brackets is not a required part of the

Correct facts (8 marks) Insulin is secreted by the pancreas/islets of Langerhans when blood glucose/sugar levels are high Insulin controls/causes the conversion of blood glucose/sugar into glycogen (not 'converts') Glycogen is stored in the liver When blood glucose/sugar levels return to normal, insulin production decreases Glucagon is secreted by the pancreas/islets of Langerhans when blood glucose/sugar levels are low Glucagon controls/causes the conversion of glycogen to glucose (not 'converts') When blood glucose/sugar levels return to normal, glucagon production decreases This type of control is known as negative feedback control (mark if given for either insulin or glucagon, but not both) In emergency situations, (the hormone) adrenaline is secreted by the adrenal glands Adrenaline overrides the action of insulin Once the emergency is over, adrenaline levels return to normal and the homeostatic control (by insulin and glucagon) is regained

Coherence (1 mark) One mark is given if at least 5 relevant points provided.Relevance (1 mark) It causes glycogen to be (rapidly) converted to glucose (not 'converts') One mark is deducted if a detailed explanation of negative feedback control is given.

SQA Past Paper 2012Qu 2b. Describe involuntary mechanisms of temperature control. (10).*Mrs Smith Ch24 regulating Mechanisms*


SQA Past Paper 2008Give an account of temperature regulation in cold conditions under thefollowing headings:(i) voluntary responses (3) (ii) involuntary responses (5)(iii) hypothermia (2)*Mrs Smith Ch24 regulating Mechanisms*


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unit 2: the continuation of life

Documents

mechanismsmrs smith

nervous systemmrs smith

bodys rate of activity

control of heart rate

bodys external environment

human body

body parts

healthy body