Respiration & Homeostasis

RESPIRATION * The release of energy from food * All living cells need energy to carry out M R S G R E N, contraction of muscles, build up of larger molecules (e.g. proteins), maintains steady body temperature (homeostasis) * Aerobic: * needs oxygen * only occurs when a certain amount of oxygen is available * C6H12O6 + 6O2 6CO2 + 6H2O + Energy * releases large amount of energy (2900 KJ) * Anaerobic: * without oxygen * [glucose lactic acid] C6H12O6 2C3H6O3 * releases small amount of energy (120 KJ) * poisonous waste (lactic acid) removed to produce joined with O2, H2O + CO2

BREATHING * Inhalation: taking air in lungs * muscles contract – diaphragm, intercostal muscles * volume increases * outside of lungs: high atmospheric pressure; inside lungs: low pressure * air flows into the lungs because of the difference in pressure * Inhalation: taking air out of lungs * muscles relax – diaphragm, intercostal muscles contract – internal intercostal muscles * volume decreases * outside of lungs: low pressure; inside lungs: high pressure * air flows out of the lungs because of the difference in pressure * GASES EXCHANGED INHALED EXHALED * Carbon Dioxide: 0.04% 4% * Nitrogen: 79% 79% * Oxygen: 21% 16% * Water: Variable High * Temperature: Variable High * Alveoli are the site of gas exchange. Adaptations: * large surface area * good supply of oxygen and blood (surrounded by capillaries) for rapid diffusion of gas * thin walls * moist lining for dissolving gases

HOMEOSTASIS

* the maintenance of a constant internal environment in the body * Conditions that are kept the same: 1. Body Temperature 2. pH 7.4 (Blood) 3. water content 4. oxygen 5. glucose concentration * thermoregulation: maintaining a constant temperature (370C) * enzymes work best at 370C * temperature is monitored by hypothalamus (thermoregulatory centre) as the blood passes * BODY TEMPERATURE RISES: 6. hairs lie flat: less air trapped (less insulation) more heat is lost from the skin 7. sweat is produced: water in swear evaporates taking away heat from the skin 8. vasodilation: blood vessels near the surface of the skin dilate to increase blood flow from the capillaries so more heat is lost * BODY TEMPERATURE FALLS: 9. hairs stand up on end: air is trapped for body insulation 10. less/ no sweat is produced 11. vasoconstriction: blood vessels near surface of skin constrict to decrease blood flow to capillaries so less heat is lost 12. shivering: muscles produce heat by respiration