1. B4 Homeostasis Route map Over the next 12 lessons you will study : Friday 21 October 2011 B4.1 Keeping the body constant B4.2 Negative feedback mechanisms B4.3 How do enzymes work B4.4 Factors affecting enzyme function End of module test B4.5 Getting hot, getting cold B4.6 Controlling your core temperature B4.7 Responses to changes in core temp B4.8 Osmosis and diffusion B4.9 Active transport in cells B4.10 Water homeostasis B4.11 Water homeostasis by ADH B4.12 When homeostasis goes wrong

3. B4.7 Extension questions: 1: Why would vasodilatation be likely to cool your core temperature ? 2: Why would vasoconstriction mean you lose less heat ? 3: Why do you think your fingers go white when you are cold ? 4: List 3 behaviours that you can do to remain warm in a cold environment and 3 behaviours you can do to remain cool in a warm environment ? 5: Explain why vasodilatation does not cool your core temperature when you are in a very hot environment above 37.0 o C Know this: a: Know how the body responds to an cooling and warming core body temperature. b: Know how changes in the blood flow to the skin help the body regulate its core temperature. Friday 21 October 2011 Introduction: The body is extremely good at changing it’s internal environment by such things as sweating and shivering. The way we behave can also have a real effect on our temperatures. For example if we are hot we can find shade or if we are cold we can have a hot drink. Another way the body controls heat is by changing the diameter of blood vessels. This is called vasoconstriction and vasodilation. Dilate means to enlarge and constrict means to get smaller. Because lots of heat is carried by our blood this can have a dramatic effect on heat loss or retention. Response to changes in core temp

6. Key concepts B4.7 c Look at the photograph and information and answer all the questions: Explain why when the tissue in your fingers or toes freeze this causes tissue damage leading to severe frostbite ? Explain why frostbite is much more likely on a cold windy day compared to a cold still day ? Frostbite occurs when tissues freeze. This condition happens when you are exposed to temperatures below the freezing point of skin and the body in an attempt to maintain its core body temperature begins to reduce the blood supply to the fingers and ties. This reduces the amount of heat and allows the fingers and toes to freeze. When cells freeze, they expand, rupture and cause tissue damage which can lead widespread tissue damage which may require digit amputation. Frostbite due to severe vasoconstriction

7. B4.7 Plenary Lesson summary: heat vasoconstrict vasodilate exercise Friday 21 October 2011 Many famous explorers have suffered from frostbite in their fingers. This is when fingers are permanently damaged due to the fact that they experienced such cold that the blood supply was cut off and the cells died due to lack of oxygen. How Science Works: Research into how small molecules, solutes an water enter and leave the cell. Look into osmosis, diffusion, facilitated and active transport. Preparing for the next lesson: If the body becomes to hot due to something such as __________ then the blood vessels will ____________ so that heat can be lost to the environment. If the body temperature starts to decrease due to a cold external environment then the blood vessels will ____________ to conserve _______ Decide whether the following statements are true or false : False True 3: Seeking shade or dressing up are behavioural responses to our environment ? False True 2: Vasodilatation and reduced blood flow to the skin helps preserve core temp ? False True 1: Hard, prolonged exercise causes the body to shiver ?

9. B4.8 Osmosis and diffusion Extension questions: 1: Give three examples of diffusion of a gas and diffusion of a solute in a solvent ? 2: Explain why tea gets stronger the longer you leave the teabag in for. 3: Why could respiration not take place if cell membranes were not permeable? 4: What does ‘partially permeable’ mean? 5: Name three chemicals that move into and out of cells. Know this: a: Know how solutes, water and small chemicals move in and out of the living cell. b: Know that diffusion is the random spreading out through a gas or liquid form an area of high to low concentration. Friday 21 October 2011 Introduction: Your cells need a constant supply of raw materials for chemical reactions such as respiration. Waste products are also formed and need to be moved out of the cell. This happens all the time and occurs due to two processes called osmosis and diffusion. In diffusion, molecules will move from an area of high concentration to low concentration until they are evenly spread. Osmosis is the movement of water from an area of high concentration to low concentration across a partially permeable membrane. All this can happen due to the way in which a cell membrane is structured.

10. B4.8 a Look at the photograph and information and answer all the questions: Diffusion refers to the process by which particles move and spread out as a result of their kinetic energy. If you sprayed a perfume in one corner of the room, the perfume particles will move randomly and begin to diffuse or spread out across the room. The rate of diffusion is affected by both the temperature and the size of the particles. Name three everyday examples where diffusion takes place ? You have two perfumes A and B. You spray both at the same time in the same corner. You stand at the opposite end and smell perfume A first, which perfume is made from the larger particles ? Explain why diffusion in liquid like water happens at a much slower rate when compared to diffusion in gases like air ? Diffusion in a gas Key concepts

11. Key concepts B4.8 b Look at the photograph and information and answer all the questions: Look at the four diagrams above and explain what happens to the sugar lump from picture one to four ? Explain why water is a good solvent and list three solutes that dissolve well in water ? Diffusion is the random spreading of particles form an area of high concentration to an area of low concentration. Liquids diffuse from solutions of higher concentration to solutions of lower concentration. In the example above, when the red dye is added it begins to diffuse and randomly spread out in all directions. Diffusion in liquids is slower when compared to diffusion in gases. Diffusion in liquids

12. B4.8 c Look at the photograph and information and answer all the questions: Diffusion, where particles spread out from an area of high concentration to an area of low concentration also happens in liquids. Think of tea particles spreading out through the tea bag into hot water. Diffusion rates are fastest when a large concentration difference exists. Diffusion rates also increase with rising temperature and decrease with increasing particle size. Explain why water needs to be boiling in order to make good cup of tea ? If you were PG Tips and wanted to make a tea bag that would make the ‘quickest cup of tea in the World...would you increase or decrease the size of the tea particles ? A stink bomb is let off in the corridor of your school, to reduce the spread of the smell why would you throw water over it ? Diffusion in a liquid Key concepts

13. Key concepts B4.8 d Look at the photograph and information and answer all the questions: How is osmosis a) similar and b) different to simple diffusion ? What happens to animals cells (e.g, red blood cells) if they are place in a) a strong salt solution and b pure distilled water ? Osmosis is the net movement of water across a selectively permeable membrane driven by a difference in solute concentrations on the two sides of the membrane, so water moves form an area of high concentration to an area of low concentration. A permeable membrane is one that allows unrestricted passage of water, but not solute molecules or ions . Osmosis (movement of water)

14. B4.8 Plenary Lesson summary: membranes oxygen urea gradient Friday 21 October 2011 Osmosis is important to plants. They gain water by osmosis through their roots. Water moves into plant cells by osmosis, making them turgid or stiff so they that able to hold the plant upright. If osmosis cease to occur the plant stem will lose turgidity and the plant will wilt and die. How Science Works: Research into how solutes and dissolved chemicals like sodium are transported across the membrane by active transport and facilitated transported. Preparing for the next lesson: Chemicals need to enter and leave cells and cell __________ have evolved to allow this to happen. Waste products such as _____ diffuse out of the cell along a concentration __________. Useful raw materials such as ___________ diffuse the other way. Decide whether the following statements are true or false : False True 3: Large molecules like white blood cells cannot diffuse across cell membranes ? False True 2: Diffusion can occur in both gases and liquids ? False True 1: Osmosis is the movement of water from an area of high to low concentration ?

16. B4.9 Extension questions: 1: What would happen to red blood cells if they were placed in freshwater ? 2: List two differences between active transport and diffusion ? 3: Name one chemical which is moved by active transport across a concentration gradient ? 4: Explain why cells sometimes need to use active transport ? 5: Why does a slug die if you put salt on its skin ? Know this: a: Know that some substances including ions an amino acids enter the cell against a concentration gradient. b: Know that the energy required for active transport comes from the very important molecule ATP. Friday 21 October 2011 Introduction: Processes such as osmosis and diffusion are called passive because they require no energy. This is because they involve substances going from areas of high concentration to low concentration. However sometimes substances must cross over the cell membrane from areas of low to high concentration. To do this requires energy and is called active transport. It also involves carrier molecules in the cell membrane which help the substances to move. Losing water to the environment is a big problem to land based animals and must be addressed by the kidneys controlling water balance. Freshwater animals have the opposite problem of gaining too much water. They need to pump water out of their bodies Active transport in cells

17. Key concepts B4.9 a Look at the photograph and information and answer all the questions: Name one chemical that is moved inside or outside of the cell by active transport ? Active transport is the process by which dissolved molecules move across a cell membrane from a lower to a higher concentration. In active transport, particles move against the concentration gradient - and therefore require an input of energy from the cell. Sometimes dissolved molecules are at a higher concentration inside the cell than outside, but, because the organism needs these molecules, they still have to be absorbed. Active transport Look at the three diagrams above and explain what is happening from picture one to three ?

18. Key concepts B4.9 b Look at the photograph and information and answer all the questions: How is facilitated transport different to a) simple diffusion and b) osmosis ? Facilitated diffusion is a process of passive transport not requiring cellular energy, facilitated by proteins located in the cell membrane of cells. Facilitated diffusion allows the passage of molecules like glucose or ions like calcium across. The facilitated diffusion may occur either across biological membranes or through aqueous compartments of an organism. Facilitated transport Look at the three diagrams above and explain what is happening from picture one to three ?

19. Key concepts B4.9 c Look at the photograph and information and answer all the questions: What happens to animal cells when placed in a) a hypotonic solution and b) hypertonic solution ? Explain what key organs help control and maintain the correct levels of water and dissolved ions like sodium ? Animal cells unlike plant cells have no cell wall. They are very fragile and animal cells like red blood cells can quickly lose of gain water through the cell membrane by a process called osmosis. If animals cells are placed in a hypotonic solution like pure distilled water or a hypertonic solution like a strong salt solution they will be damaged or even cease to function Animals cells in different solutions

20. B4.9 Plenary Lesson summary: conserving molecules cell diffusion Friday 21 October 2011 Plants and their tissues and cells have evolved to cope with water stress extremely well. Desert plants have thin spikes instead of leaves which reduce water loss. They also are able to store water for many months inside their stem. Plant cells also have very rigid cell walls which resist the effects of water moving in our out of the cell. How Science Works: Research into how humans regulate bodily water and how the kidneys filter some chemicals like urea and reabsorb some useful chemicals like ions and water depending on your body’s requirements . Preparing for the next lesson: Sometimes a cell needs to take in ____________ that are in higher concentration inside the _________ than outside. These molecules cannot move by ___________ alone. Some animals respond to water stress by ___________ water. Decide whether the following statements are true or false : False True 3: Our body’s are made up of 50% water ? False True 2: Animal cells are sensitive to osmotic stress and will rupture in distilled water ? False True 1: Active transport is a passive process requiring no cellular energy ?

22. B4.10 Water Homeostasis Extension questions: 1: List two way in which your body can a) gain water and b) lose water ? 2: Why does water lose increase on a hot summer’s day ? 3: The kidneys work like filters. Explain this statement ? 4: Explain why do we need to a) maintain the correct levels of water in tissues b) reabsorb glucose into the body and c) remove urea from the body ? 5: What happens to your urine if you drink lots of water ? Know this: a: Know how the body gains and loses water. b: Know how the kidneys excrete toxic chemical like urea and control levels of ions and water in the body. Friday 21 October 2011 Introduction: Correct water and ion balance in the body is crucial to survival. We gain water from behaviours such as drinking and eating whereas we lose water from urinating and sweating amongst others. The kidneys have a major role in how water levels are controlled by regulating the amount of urine the body produces. Kidneys also work to remove toxic compounds from your body. Urea is a toxic molecule formed from the break down of protein in the liver. The kidney removes urea from the blood and combines it with excess water and excess salts to form urine which can be sent to the bladder for excretion. Kidneys allow important molecules such as sugar to be reabsorbed back into your body for use.

23. Key concepts B4.10 a Look at the photograph and information and answer all the questions: Give three ways in which your body a) gains water and b) loses water ? List one chemical that is a) 100 % excreted by the kidney and b) one chemical that is 100% that is reabsorbed by the kidney ? The excretory system (kidneys) removes excess salts and water and dangerous chemicals like urea from our blood helping to maintain correct level of water and salt inside our tissue and blood. Urea made from the breakdown of excess proteins would kill us if the kidneys did not remove this toxic compound form the blood The kidney

24. B4.10 b Look at the photograph and information and answer all the questions: The kidney is made up of around a million small tubules like the one on the left called the nephron. It is here useful substances are reabsorbed back into the body like glucose and waste products like urea are collected and sent to the bladder. The kidney through the action of the neprhon also controls the amount of water and dissolved ions in the body at any one time. Explain how your urine changes if you compare its volume and colour on a) a hot summer’s day and b) a cold winter’s day ? Explain why finding a) protein or b) blood could be a sign of kidney damage ? The kidneys control the amount of a) salt and b) water. Why is this essential to help the body to maintain the correct levels of these chemicals in the body ? The nephron Key concepts

25. Key concepts B4.10 c Look at the photograph and information and answer all the questions: What other adaptations does a camel have to help it survive in a hot arid environment ? If you looked at the length of nephron for a kidney from a hippopotamus would their kidneys be similar to a camels of a fish and explain why ? You would expect the kidney of a camel to be very different to that of a fish. Camels live in arid dry areas with very little water. Their kidneys have long nephrons which are super efficient at reabsorbing water back into the blood therefore minimising water loss. Fish have very short nephrons. Why…well that’s quite simple, they live in water of course and have no need to conserve water. Different animals different kidneys Camel Fish Long nephron loop means more water re-absorption Short nephron loop means less water re-absorption

26. B4.10 Plenary Lesson summary: filtered urea blood filters Friday 21 October 2011 If both kidneys do not work then urea levels in the body would rise and the human body would become poisoned very quickly. The only solution is a kidney transplant or long term hospital treatment called dialysis, where a machine using semi-permeable membranes and the principles of osmosis will clean the patient’s blood. How Science Works: Research into how urine is formed, and how the hormone ADH (anti diuretic hormone) produced by the pituitary controls how much water is reabsorbed by the nephron. Preparing for the next lesson: Kidneys work like _________. Small molecules are ___________ out of the blood as it passes through the kidneys. These small molecules include water, dissolved ions like sodium, sugar and ______. Blood cells and large molecules such as proteins are too big so they stay in the ________. Decide whether the following statements are true or false : False True 3: Water is gained during cellular respiration and by drinking ? False True 2: Water can be lost by both sweating and exhaling air from your lungs? False True 1: Your kidneys help to control the body’s core temperature ?

28. B4.11 Water balance by ADH Extension questions: 1: Where is a) ADH produced and b) how does it travel form that place to the kidneys ? 2: What affect does ADH have on the human kidney? 3: Why can drinking too much alcohol cause you to become dehydrated ? 4: Ecstasy can lead to over hydration. Explain why? 5: What can you do to prevent dehydration? Know this: a: Know that some drugs including alcohol can alter the way the kidney regulate water level sin the body. b: Know that the pituitary gland produces and releases ADH which makes the nephron more permeable to water. Friday 21 October 2011 Introduction: The balance of water in your body depends on a large number of factors such as temperature of the day, activity of the person, how much water you have drunk and what types of food you have been eating. Drugs can also affect the amount of urine produced by interfering with the hormone ADH which regulates water reabsorption. Caffeine in tea and coffee causes a greater amount of dilute urine to be produced. Alcohol has the same effect but is stronger. The drug ecstasy has the opposite effect so that the body produces a small amount of concentrated urine. The pituitary gland in the brain controls the release of ADH.

29. B4.11 a Look at the photograph and information and answer all the questions: The control of water levels by the pituitary, ADH and the kidney sis a typical negative feedback system. Give one other example of negative feedback ? Look at the diagram opposite left, explain the role of the a) hypothalamus and b) the pituitary in maintaining correct water levels in the body ? Why is your urine more concentrated and dark when you wake up from a good nights sleep ? There has to be a balance between the amount of water taken in the diet and the amount lost by the body in sweating, evaporation, faeces and urine.. If there is too high a level of water in the blood because, for example, it is cold and you have not been losing any water through sweating, the hypothalamus sends a message to the pituitary and production of ADH will stop. The kidneys will not save as much water and the urine becomes dilute and of greater volume. Key concepts

30. Key concepts B4.11 b Look at the photograph and information and answer all the questions: Some drugs can affect the role of the kidneys in controlling correct water levels. These drugs include alcohol, caffeine and ecstasy. Both alcohol and caffeine reduce ADH levels increasing urine volumes which can lead to dehydration. Alcohol has a greater effect than caffine. Ecasty can reduce urine levels by increasing ADH levels which can lead to too much water in the body. This can be as dangerous as severe dehydration Drugs affecting how the kidney’s work Explain the effect of alcohol on urine production. Explain how ADH affects the reabsorption of water back into the body ? Ecstasy triggers the release of ADH. Explain the effect this will have on a) the kidney nephron and b) the amount of urine you produce ? Water loss: leads to dehydration Correct bodily hydration Water gain: leads to over hydration alcohol caffeine ecstasy

31. Key concepts B4.11 c Look at the photograph and information and answer all the questions: During a hot summer’s day if you measure ADH levels in the blood would they be high or low ? How else does the body gain or lose water ? ADH during water loss ADH response during water loss. ADH is produced and released into the blood and then travels to the nephron. The ADH then acts on the nephron tissue making it more permeable to water and helping the kidney better reabsorb water back into the blood. The actions of ADH on the kidney's nephron helps to restore water levels in the blood. Urine can be low in volume and yellow in colour

32. Key concepts B4.11 d Look at the photograph and information and answer all the questions: ADH during water gain There has to be a balance between the amount of water taken in the diet and the amount lost by the body in sweating, evaporation, faeces and urine.. If there is too high a level of water in the blood because, for example, it is cold and you have not been losing any water through sweating, the hypothalamus sends a message to the pituitary and production of ADH will stop. The kidneys will not save as much water and the urine becomes dilute and of greater volume. During a cold winters day if you measure ADH levels in the blood would they be high or low ? How else does the body gain or lose water ?

33. B4.11 Plenary Lesson summary: ADH large alcohol dilute Friday 21 October 2011 Water balance in athletes is crucial especially in endurance events such as marathon running. Drinking small amounts of water at frequent intervals can improve performance by up to 5% according to recent research done by top sports physiologists. How Science Works: Research into what happens if core body temperature becomes dangerous low (hypothermia) or dangerously high (hyperthermia). Preparing for the next lesson: Drugs such as ecstasy, caffeine and __________ all have an affect on the hormone ________ which acts on the kidneys to regulate the amount of water produced . ADH causes more water to be retained by the body leading to _________ amounts of __________ urine being formed. Decide whether the following statements are true or false : False True 3: Ecstasy can disrupt the body’s water balance leading to coma and death ? False True 2: Caffeine causes the body to become dehydrated ? False True 1: Drinking lots of alcohol results in becoming more concentrated ?

35. B4.12 When it all goes wrong Extension questions: 1: Give two different a) physiological and b) behavioural responses to a drop in core temperature and a rise in core temperature ? 2: Why are babies most at risk of hypothermia ? 3: Why might people not recognise that they have hypothermia ? 3: Why are athletes more likely to get heatstroke when training in the summer when compared to the winter months ? 5: How do you think you could treat someone with heat stroke? Know this: a: Know that spending long periods in cold wet conditions can lead to rapid heat loss and hypothermia. b: Know that spending long period of time in hot humid conditions or by doing heavy exercise can lead to rapid heat gain and hyperthermia Friday 21 October 2011 Introduction: Even though the body is very good at controlling it’s internal temperature, there are occasions when due to circumstances such as extreme climate or vigorous exercise our body’s cannot cope. When placed under such stresses humans can suffer from the symptoms of both heat stroke or hypothermia. Both conditions are treatable but if left untreated they can both cause death. Symptoms of hypothermia include shivering, confusion, drowsiness and loss of coordination. Symptoms of heat stroke include hot dry skin, stress and increased heart rate. First aiders at sports events such as the London Marathon are trained to spot the signs of both these conditions and know how to treat them quickly.

36. Key concepts B4.12 a Look at the photograph and information and answer all the questions: Explain why you at more at risk of hypothermia on a cold day when it is raining when compared to a cold dry day ? Give two responses to a drop in core body temperature ? Hypothermia is defined as a core body temperature below 35°C. The effects of hypothermia are proportional to the change in temperature, with metabolic rate reduced by 10% for every 1°C fall in temperature. The body also has a variety of methods to increase heat production. But at a certain low level, the body cannot continue heat production, and core body temperature drops quickly. From 98.6°F to 89.6°F, the body begins to shiver, blood vessels contract, and hormones generate heat. Hypothermia Cold, damp and pale skin is a typical sign of hypothermia. The skin may become very pale as blood vessels constrict in an attempt to reduce heat dissipation. Slow or slurred speech and shivering are also warning signs that a person is at risk from hypothermia

37. Key concepts B4.12 b Look at the photograph and information and answer all the questions: Hyperthermia is an elevated body temperature due to failed thermoregulation which start about about 39 o C. Hyperthermia occurs when the body produces or absorbs more heat than it can dissipate. When the elevated body temperatures are sufficiently high, hyperthermia is a medical emergency and requires immediate treatment to prevent disability or death. The most common causes are heat stroke and adverse reactions to drugs. Hyperthermia Hot, dry skin is a typical sign of hyperthermia. The skin may become red and hot as blood vessels dilate in an attempt to increase heat dissipation, sometimes leading to swollen lips. Nausea and sensitivity to light are also symptoms of people at risk form hyperthermia Explain why you at more at risk of hyperthermia on hot humid day when compared to a hot dry day ? Give two responses to a rise in core body temperature ?

38. Key concepts B4.12 c Look at the photograph and information and answer all the questions: Explain why ecstasy is a very dangerous drug to take for young people who then dance all night at a rave ? If young people still decide to take ecstasy then what advise would you give them ? Leah Betts story: Why did Leah Betts take Ecstasy ? Not even Leah's parents can answer that. In their heartbreaking letter, Paul and Janet Betts say, "Why our beautiful daughter felt she needed Ecstasy we will never know." Leah was not at a night club, or a rave when she took the single ecstasy pill. She was at home, with her parents, celebrating her 18 th birthday. One of the lessons to be learned from this tragedy is that there is no "safe and sound" advice about taking Ecstasy The Leah Betts story Ecstasy is an illegal drug which apart form damaging areas of the brain can affect the kidneys, liver and heart. About 10 to 5 young people die every year form taking this drug due to its affect on water balance and the kidneys

39. B4.12 Plenary Lesson summary: slurred brain temperature deaths Friday 21 October 2011 Drugs like ecstasy don’t only just affect water balance. They can also increase the body’s core temperature and lead to heat stroke. About 10 to 15 people die every year from taking ecstasy sometimes a single tablet and for the very first time. They are always aged between 18 and 25 and have no other medical conditions. How Science Works: Revise for an end of module test. Preparing for the next lesson: Symptoms of hypothermia include shivering, confusion and __________ speech. Temperatures over 43°C can cause shutdown of the body’s _____________ regulation centre in the ____________. It is estimated that hypothermia causes up to 30,000 __________ in the UK every year in the old and young. Decide whether the following statements are true or false : False True 3: Using a fan can reduce the core temperature of the body ? False True 2: A treatment for heatstroke is to give warm food ? False True 1: Athletes are likely to get heatstroke of they don’t re-hydrate properly ?