B5 - Homeostasis and response

• What is homeostasis?

  The maintenance of a constant internal environment
• Why is homeostasis necessary for the body?

  It is needed for enzyme action and all cell functions
• What are the three main factors controlled by homeostasis in the human body?

  • Blood glucose concentration
  • Body temperature
  • Water levels
• What role do nervous and hormonal communication play in homeostasis?

  They are involved in the automatic control systems that detect changes and respond to them
• What are the components of control systems in homeostasis?

  • Receptors: detect stimuli
  • Coordination centres: process information (e.g., brain, spinal cord, pancreas)
  • Effectors: bring about responses to restore optimum conditions
• What are receptors in the context of homeostasis?

  Cells that detect stimuli (changes in the environment)
• What is the function of coordination centres in homeostasis?

  They process the information received from the receptors
• What are effectors in the homeostasis control system?

  Muscles or glands that bring about responses
• How does the nervous system allow us to react to our surroundings?

  It coordinates actions in response to stimuli
• What do receptor cells do in the nervous system?

  Convert a stimulus into an electrical impulse
• What is the pathway of an electrical impulse in the nervous system?

  It travels along sensory neurons to the CNS, then to motor neurons to effectors
• What are reflexes?

  Automatic responses that occur before you have time to think
• Why are reflexes important?

  They prevent the individual from getting hurt
• What is a reflex arc?

  1. A stimulus is detected by receptors
  2. Impulses are sent along a sensory neuron
  3. The impulse passes to a relay neuron in the CNS
  4. Impulses are sent along a motor neuron
  5. The impulse reaches an effector resulting in the appropriate response
• What are synapses?

  The gaps between two neurons
• What happens when an impulse reaches the end of the first neuron at a synapse?

  A chemical is released into the synapse
• How does the chemical released at a synapse affect the next neuron?

  It triggers the impulse to begin again in the next neuron
• What is reaction time?

  The time it takes to respond to a stimulus
• How can reaction time be measured?

  With the ruler drop test
• What is the brain made up of?

  Many connected neurons
• What does the cerebral cortex control?

  Consciousness, intelligence, memory, and language
• What is homeostasis?

  The maintenance of a constant internal environment
• Where is the cerebellum located?

  Towards the bottom/back of the brain
• What is the function of the medulla?

  Controls unconscious actions such as breathing and heart rate
• What is abstinence in the context of sexual health?

  Deliberately refraining from having sexual intercourse.
• Why is homeostasis important for the body?

  It is needed for enzyme action and all cell functions
• Why is investigating brain function difficult?

  • The brain is complex and delicate
  • It is easily damaged
  • Drugs cannot always reach the brain due to protective membranes
  • The functions of different brain parts are not fully understood
• What is accommodation in relation to vision?

  The process of changing the shape of the lens to focus on near or distant objects.
• How do neuroscientists map out brain regions?

  1. Studying patients with brain damage
  2. Electrically stimulating different parts of the brain
  3. Using MRI scanning techniques
• What are the three main factors controlled by homeostasis in the human body?

  • Blood glucose concentration
  • Body temperature
  • Water levels
• What does the retina do?

  It contains light-sensitive cells that send impulses to the brain to create an image
• What role do nervous and hormonal communication play in homeostasis?

  They are involved in the automatic control systems that detect changes and respond to them
• What role does adrenaline play in the body?

  It increases the heart rate and boosts blood delivery to the brain and muscles during 'fight or flight' response.
• What is the function of the optic nerve?

  It carries impulses from the retina to the brain
• What is antidiuretic hormone (ADH) responsible for?

  Increasing the reabsorption of water in the kidney tubules.
• What is the role of the sclera?

  It supports the structures inside the eye
• What does the cornea do?

  It allows light through and bends it to focus on the retina
• What are the components of control systems in homeostasis?

  1. Receptors - detect stimuli
  2. Coordination centres - process information
  3. Effectors - bring about responses
• What is the purpose of contraception?

  Methods used to prevent pregnancy.
• What are receptors in the context of homeostasis?

  Cells that detect stimuli (changes in the environment)