B9

• Aerobic respiration requires oxygen and its an exothermic reaction. It transfer energy to the environment : Glucose + oxygen = carbon dioxide + water
• In living cells most aerobic respiration take place in mitochondria
• The structure of these organelles allow respiration to take place because it has a folded inner membrane which provide a large surface area for enzymes to work
• Cytoplasm - is where enzymes are made and where anaerobic respiration occurs
• Nucleus holds the genetic code for enzymes needed for respiration cell membrane allows the reactants for respiration into the cell and products out of the cell
• Energy released from respiration are used for :

  Building molecules

  muscle contractions

  keeping body warm

  plants moving mineral ions from soil to root hairs using active transport
• when you exercise your muscles need more energy so that they can contract
• When you exercise your muscles need more energy so that they can contract

  The heart rate increase and the blood vessels supplying the muscles dilate. This allows more blood containing oxygen and glucose to reach the muscles
• Your breathing rate and the depth of each breath also increase. This allows a greater uptake of oxygen and release of carbon dioxide

  Muscle store glucose as glycogen. This can be converted back to glucose for use during exercise
• When your muscles cannot get enough for aerobic respiration they start to respire anaerobically.

  In anaerobic respiration the glucose is not completely broken down and lactic acid is produced
• Less energy is transferred from the glucose in anaerobic respiration

  One cause of muscle fatigue is the build up of lactic acid creating oxygen debt. Blood flowing through muscles removes lactic acid
• Lactic acid + oxygen = carbon dioxide + water
• 5 key functions of the liver : storing glycogen , breaking down lactic acid, producing bile to neutralise stomach acid and emulsify lipids , producing urea from excess protein, breaking down toxins
• Metabolism is the sum of all chemical reactions that take place in a cell or in a body
• Homeostasis maintain optimal conditions for enzyme actions and cell function
• They require a constant temperature and ph as well as a constant supply of dissolved food and water

  In order to do this the body requires control system that constantly monitor and adjust the compositions of blood and tissue
• In the human body temperature water content and sugar all need to be controlled
• ALL control systems in body have cells called receptors which detects stimuli. There is always a coordination centre such as brain, spiral cord or pancreas) that receive and processes information from the receptors.
• There are effectors which bring about responses which restore optimum levels
• Function of nervous system - enables human to react quickly to their surroundings and to coordinate their behaviour
• Stimulus -- receptor --- sensor neurone --coordinator --- motor neurone ---- effector --- response
• Reflex actions are automatic and rapid

  Reflex actions do not involve the conscious part of the brain

  Reflex actions help you to avoid danger or harm. They control your basic body functions breathing and moving food through the digestive system so you don't have to thin about them
• A gap between 2 neurones

  Electrical impulses travel along

  Neurone to synapse

  chemicals are released into gap

  The chemicals diffuse across the gap

  The chemicals trigger a new electrical impulse down the next neurone
• Cerebral cortex - memory , consciousness , language and intelligence

  Cerebellum - coordination of muscle activity

  Medulla - unconscious actions
• Hypothalamus - involved in control of body temperature

  Pituitary gland - produces many hormones which control and coordinate body systems
• Scientists have been able to map out the regions of the brain to particular functions by :

  Studying patients with brain damage

  Electrically stimulating different parts of the brain

  Using magnetic resonance imaging scanning techniques to monitor brain activity after surgery
• Problems with brain - drugs do not always pass through the membranes surrounding the brain

  Surgery is difficult because the function of each area of brain is not fully understood.