1. Temperature Control Physical activity can increase metabolic activity, releasing energy This leads to increase in core body temperature Homeostasis Is maintenance of a stable internal environment So cells can function propperly Partly achieved by maintaining stable conditions within blood In blood conc of glucose, ions, CO2, must be kept within narrow limits Also water potential, ph and temperature regulated Each condition controlled has norm value/set point A homeostatic system requires: Receptors- detect change away from norm value Control mechanism- respond to info. Uses nervous system or hormones to switch effectors on/off Effectors- bring about response ie: muscles, bring condition back to norm value Negative feedback helps to keep internal environment constant Change in internal env. will trigger response, counteract change (opposite) eg: rise in body temp cause response that lower temp For negative feedback to occur must be norm value/set point Ie:core body temp: 37.5 C

2. Homeostatic response summarised receptors Control mechanism EffectorsOutput feedback 1) Input

3. Temperature control Thermoregulation is control of body temp This temp allows enzyme controlled reactions occur at reasonable rate Low temp  reactions slow High temp  enzyme denature Humans temp control by negative feedback receptors in hypothalamus detect change in blood temp Hypothalamus acts as thermostat returning temp to normal

5. Skin also helps control temp

9. Shivering is uncontrolled reaction of muscles Increases heat production Shivering transfers energy to muscle tissue  helps maintain body temp During exercise body temp increase Once hypothalamus detects stimulus chain of actions begin to bring body temp to norm

10. How energy is transferred to and from the body

11. Methods of energy transfer Radiation- energy radiated from one object to another through air/vacuum as electromagnetic radiation. Our bodies radiate energy and we’re warmed by energy radiated from sun. Conduction- energy loss through direct contact with objects. Eg: sitting on cold rock energy transferred from body to rock Convection- air lying next to skin will be warmed. Air expands and rises or moved away by air currents. Will be replaced by cooler air which is warmed by body Evaporation- energy needed to convert water liquid to vapour energy required to evaporate sweat cooling body. 37.5 c human core body temperature higher than surrounding so energy transferred to environment In very cold environment excessive cooling- core body temp falls Hypothalamus detects this increases metabolic rate and slows energy loss

12. Exercising too much Scientists discovered a U-shaped relationship between risk of infection and amount of exercise Higher infection rates due to: Increase exposure to pathogens Suppressed immunity with hard exercise

13. Effects of exercise on immunity Components of non-specific and specific immune system are affected by moderate and excessive exercise Moderate Exercise moderate exercise increase activity of natural killer cells Unlike B/T cells do not use specific antigen recognition but provide non-specific immunity against cells invaded by viruses etc.

14. During recovery after vigorous exercise number and activity of cells in immune system falls including:  natural killer cells  Phagocytes  B cells  T helper cells Decrease in helper T cells reduce amount of cytokines to activate lymphocytes Reduce quantity of antibody production Hence increase chance of infection and upper respiratory tract infections

15. How joints are damaged by exercise Repeated forces on joints such as knee lead to wear and tear. Many joint disorders associated with overuse Disorders typically associated with: pain, inflammation, restricted movement of joint Treatment usually rest, ice, compression, elevation (RICE) Anti-inflammatory pain killers Surgical repair

16. Keyhole surgery and prosthetic limbs can help injured/disabled to participate more fully in sport Surgical operations to repair damage used to be painful and recovery took a long time Large incisions had to be made causing lots of bleeding and pain Keyhole surgery can now repair damaged joints through small holes Keyhole surgery on joints is known as arthroscopy

17. Damage to the cruciate ligaments in knee can be tackled by key hole surgery Ligaments attach bone to bone Also help for movement and prevent joint becoming overstretched Posterior cruciate ligament prevents knee from bent too far Anterior cruciate ligament prevents knee from bent too far forwards These sudden damages can be caused by sports When cruciate ligament torn surgery carried out Small incision is made and camera and light source inserted Ligament can be repaired Recovery after keyhole surgery can be rapid

18. Prosthesis Prosthesis is artificial body part used by someone with disability to regain normal function Specialised prosthesis allow disabled athletes to be more physically active and perform at higher levels Prosthetics also used to replace damage joints due to wear and tear in sports Replacing knee joints successful use of prosthetics

19. Performance enhancing substances Use of drugs to enhance performance in sports known as doping Human growth hormone, insulin and erythropoietin (EPO) are on list for prohibited substances used by athletes Yet these peptide hormones produced by body naturally Other substance also banned is testosterone, body produces naturally, belongs to hormonal group: steroid humans

20. Hormones Hormones are chemical messengers released in blood from endocrine glands Unlike exocrine glands endocrine glands do not have ducts It is important cells that make hormones are not affected by hormones Therefore most hormones produced in an inactive form or packaged by Golgi apparatus Vesicles fuse with the cell surface membrane releasing contents by exocytosis

22. How hormones affect cells Each hormone affects specific target cells modifying their activity Each hormone bring about characteristic responses resulting in effects on enzymes Peptide bonds are protein chains cant pass through cell membranes easily as charged Instead they bind to receptor this activates another molecule called second messenger Peptide hormones are EPO, human growth and insulin

23. Steroid hormones formed from lipids and have complex ring structures They pass through cell membrane and bind directly to receptor molecule in cytoplasm Once activated characteristic response happens from its effect on transcription Hormone receptor complex functions as a transcription factor- switching enzyme synthesis on/off

24. How transcription factors work Transcription initiated by enzyme RNA polymerase and protein transcription factors binding to DNA Only when transcription inititiation complex formed and attached to DNA will transcription proceed

25. EPO peptide hormone produced by Kidneys Stimulates formation of new red blood cells If EPO level too high too many red blood cell leads to thrombosis and heart attacks If Athletes take EPO it enhances oxygen delivery to muscle tissue improving aerobic capacity due to more haemoglobin and red blood cells

26. Testosterone Produced in testes by male and adrenal glands in female and male Causes development of sexual organ in male Binds to androgen receptors and modify gene expression Will increase anabolic reactions such as protein synthesis in muscle cells which increases size and strength of muscle Athletes and body builders may use this to increase muscle development But testosterone is quickly broken down Chemical modification of testosterone  anabolic steroids such as nandrolone

27. Overuse of anabolic steroids  high blood pressure, liver damage, and kidney failure They can be detected in urine samples But because these substances occur naturally its difficult to set level to confidently state doping has been done Enhancing substance not banned is creatine  a nutrition supplement It is absorbed by body unchanged carried to blood tissues Creatine increase creatine phosphate levels CP benefit  improvement of performance, increase in muscle mass and strength But some side effects  high blood pressure, diarrhoea, muscle cramps

28. Should performance enhancing substance be banned? Some say it is unhealthy and against ethics of sport Bans help to protect health of athletes and ensure competitions are fair Some say it is ethically acceptable as athletes have right to decide themselves Some say there is already inequality in competition due to difference in time fro training and resources hence drug use acceptable