homeostasis basics

• What is homeostasis?

  regulation of the internal conditions of a cell or an organism to maintain optimum conditions for function in response to internal or external conditions
• What does homeostasis maintain the optimum conditions for?

  enzyme action and all cell functions
• In the human body what automatic control systems are controlled by homeostasis?

  blood glucose concentrations, water levels, body temperature
• What do all control systems include?

  cells called receptors which detect stimuli, coordination centres that receive and process information, effector muscles or glands that bring about a response to restore optimum levels
• What are examples of coordination centres?

  brain, spinal cord, pancreas
• What does the nervous system enable humans to do?

  react to their surroundings and coordinate their behaviour
• What is the path from the stimulus to the response?

  receptors detect stimulus. Receptors pass information on as electrical impulses through neurones to central nervous systems. CNS coordinates responses of effectors e.g. muscle contracting, glands secreting hormones
• neurone adaptations:

  have long fibre axon so they can carry messages up and down body over long distances. Axon insulated by fatty myelin sheath which increases speed of electrical impulses travelling along neurone. At the end of each neurone there are dendrons that branch into dendrites which receive incoming nerve impulses from other neurones
• Why are reflex actions important?

  automatic and rapid so don't involve conscious part of brain. Protects body from harm
• What is the synapse?

  gap between two neurones
• What happens to the electrical impulses as a synapse?

  electrical impulse transferred to chemical that can diffuse across synapse onto next neurone
• What is the cerebral cortex?

  highly folded outer layer of brain responsible for consciousness, intelligence, memory and language
• What Is the cerebellum?

  responsible for muscle coordination and balance
• What does the medulla do?

  controls unconscious activities e.g. breathing and heartbeat
• What are the difficulties of investigating brain function and treating brain damage and disease?

  brain is very delicate and complex so easy to damage, side effects might be created from brain surgery, physical damage could be caused to brain from surgery, brain is protected by skull so its difficult to access
• What is an MRI?

  tube machine that produces detailed image of brain structure . This can help scientists figure out which part of brain is active
• How can the brain be stimulated electrically?

  By pushing tiny electrode into tissue and giving it small amount of electricity. Buy seeing what stimulating different parts of the brain does it is possible to see what parts do
• What happens if the motor area In the brain is stimulated?

  muscle contraction and movement
• What does the brain contain?

  billions of interconnected neurones
• Why do scientists look at patient's brain who have received brain damage?

  scientists see which part of patient's brain has been damaged and then link part of brain to function