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Staying in balance

Staying in balance. 4 May 2010. Lesson Objectives. All : To understand that the body works to maintain steady levels of temperature , water and carbon dioxide , and that this is essential to life.

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Staying in balance

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  1. Staying in balance 4 May 2010

  2. Lesson Objectives • All: To understand that the body works to maintain steady levels of temperature, water and carbon dioxide, and that this is essential to life. • Most: To understand that maintaining a constant internal environment involves balancing bodily inputs and outputs and is called homeostasis. • Some: To be able to apply knowledge that insulin controls blood sugar levels and that a lack of insulin causes diabetes.

  3. Staying in balance • Our body cells work best at normal body temperature. • Normal body temperature is 37 degrees C. • It can be dangerous to get too hot or too cold. • You can easily check your body temperature • using a heat-sensitive strip placed on your • forehead, or by using a thermometer. • Our body systems make sure that our water, • oxygen and carbon dioxide levels are kept • steady.

  4. Sweating • Increasing blood flow to nearer the surface of the skin • We can gain heat or warm ourselves up by: We can lose heat and cool ourselves down by: • Exercising • Shivering • Releasing energy from food • Less blood flow near to the surface of the skin

  5. What is homeostasis? Various body systems keep the levels of oxygen, carbon dioxide, water and temperature constant. Keeping a constant internal environment is called homeostasis. One way of achieving this is through sweating.

  6. Sweating • Sweat comes from sweat glands in her skin. • We wear deodorant and shower after exercise. This stops bacteria from living on the sweat and causing smells. • When you step out of the shower you feel cold. This is because the water uses heat from your skin to evaporate. • The more we sweat, the cooler we get.

  7. Dangers of high and low temperatures • There are some conditions that occur if we get too hot. These are: • Heat stroke • Dehydration • If these are left untreated she could die. • If you get too cold you could get hypothermia.

  8. The hypothalamus • A small gland in the brain, called the hypothalamus, helps to keep the body in balance when detecting when the blood is too hot or cold. • It then triggers mechanisms such as shivering or sweating. • It can also alter the size of the blood capillaries. • Vasoconstriction – When the body is too cold, blood capillaries constrict, so less blood flows through, reducing heat loss. • Vasodilation – When the body is too hot, they dilate so more blood flows nearer the surface increasing heat loss.

  9. PLENARY • Name 3 things that the body has to keep steady (3) • State normal body temperature (1) • Name the process that maintains a constant internal environment in the body (1) • Name the conditions if the body temperature goes too high or too low (2) • Describe how sweating works (2) • Describe vasodilation (3) • What monitors and controls body temperature? (1)

  10. G = 1-2 F = 3-4 E = 5 D = 6-7 C = 8-9 B = 10-11 A = 12 A* = 13 Answers • Levels of water & carbon dioxide & temperature • 37°C • Homeostasis • Too high – heatstroke & dehydration Too low – hypothermia • Sweating evaporates from the skin; taking heat with it • Where blood vessels dilate/get wider; blood flow increases; bringing more blood/heat to the surface • The brain/hypothalamus

  11. Hormones • When you are diabetic, your pancreas does not produce enough insulin. • Insulin is a hormone. • Hormones are made in glands. • They are carried in the blood to where they have their effect. • The part of the body the hormone effects is called the target organ. • Blood takes time to travel around the body, so the body reacts more slowly to hormones than nervous reactions.

  12. Our bodies also produce sex hormones. • A females ovaries produce the hormones oestrogen and progesterone. • A males testes produce testosterone.

  13. Diabetes • If your pancreas does not make enough insulin, you are diabetic. • Sometimes this can be controlled by eating a diet low in sugar. • Other diabetics have to inject insulin. • Insulin controls the levels of glucose in the blood.

  14. Task • Read ‘Evie is a teenager’ on page 39 of the student book. • List secondary sexual characteristics of males and females on your sheet. (D-C) • Read ‘Control of blood sugar levels’ and ‘Evie’s menstrual cycle’ on page 39 of the student book and then to answer questions 14–15. (B-A*)

  15. PLENARY • Name the main endocrine organs and the hormones they produce (6) • Describe the causes & treatment of diabetes (3) • What does insulin do? (1) • Give 1 secondary sexual characteristic of males & females (2) • What does oestrogen do? (1) • What does progesterone do? (1) • What does oestrogen & progesterone together do? (1)

  16. G = 1-2 F = 3-4 E = 5-6 D = 7-8 C = 9-10 B = 11-12 A = 13-14 A* = 14-5 Answers • Pancreas = Insulin Ovaries = Oestrogen & Progesterone Testes = Testosterone • Diabetes occurs when blood sugar levels get too high; can be treated by diet OR insulin • Controls blood sugar levels • Male = voice deepens; more muscular; hairy! Female = hips widen; breasts; periods • Oestrogen repairs uterus wall • Progesterone maintains the uterus wall • Oestrogen and progesterone together control ovulation

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