Co-ordination and response

• What is homeostasis?


  The control or regulation of the internal conditions of a cell or organism
• Why is homeostasis important?


  It maintains optimal conditions for enzyme action and cell function
• Name physiological factors controlled by homeostasis in mammals.


  Body temperature, metabolic waste, blood pH, glucose concentration, water potential, respiratory gases.
• What are the two communication systems in mammals for homeostasis?

  The nervous system and the endocrine system.
• How is body temperature controlled in humans?

  The thermoregulatory centre in the brain monitors blood temperature and coordinates responses.
• How is water loss controlled in humans?


  The kidneys control urine production to regulate water reabsorption.
• What role does ADH (antidiuretic hormone) play in water regulation?


  It controls the amount of water reabsorbed by the kidneys.
• What are the four components required for a co-ordinated response?


  Stimulus, receptor, coordination centre, effector.
• What are tropisms?


  Directional growth responses of plants to stimuli like light and gravity.
• What is phototropism and geotropism?


  Phototropism is growth towards light; geotropism is growth towards gravity.
• What is auxin's role in plant growth?


  Auxin stimulates cell elongation, causing plants to grow towards light.
• How does the nervous system transmit information?


  Through electrical impulses along neurones.
• How do hormones transmit information in the body?

  Hormones are released into the blood and affect target organs.
• What are the two main parts of the nervous system?


  The central nervous system (CNS) and the peripheral nervous system (PNS).
• What occurs at a synapse?


  Neurotransmitters are released to transmit signals between neurones.
• What is a reflex arc?


  The pathway of a reflex response, including sensory, relay, and motor neurones.
• Describe the pain-withdrawal reflex.


  A stimulus (e.g., stepping on a pin) is detected, sending signals through sensory neurones to the spinal cord, activating motor neurones to pull away.
• Compare the speed of the nervous system to the endocrine system.


  Nervous system responses are fast; endocrine responses are slower and longer-lasting.
• What happens to neurotransmitters after signal transmission?


  They are destroyed to prevent continued stimulation of the next neurone.
• Explain the function of sensory neurones.


  Sensory neurones detect stimuli and transmit electrical impulses to the CNS for processing.
• What is the role of relay neurones?


  Relay neurones transmit impulses within the CNS, connecting sensory neurones to motor neurones.
• What do motor neurones do?


  Motor neurones carry impulses away from the CNS to effectors (muscles or glands) to trigger a response.
• How do hormones affect target organs?


  Hormones bind to specific receptors on target organs, altering their activity to bring about a physiological change.
• What is the significance of synaptic clefts?


  • Synaptic clefts prevent direct electrical transmission between neurones, requiring a chemical signaling process for communication.
• What happens to neurotransmitters after they have transmitted a signal?


  Neurotransmitters are destroyed or reabsorbed to prevent continuous stimulation of the postsynaptic neurone.
• How does the nervous system ensure the direction of impulse travel?


  Impulses only travel in one direction across synapses, preventing confusion in the nervous system.
• What are plant growth regulators?


  Plant growth regulators, such as auxins, are chemicals that control various aspects of plant growth and development.
• Describe the role of the brain in maintaining homeostasis.


  The brain processes information from receptors and coordinates appropriate responses to maintain internal balance.
• Why is rapid response important in reflex actions?


  Rapid responses minimize potential damage to the body and enhance survival by allowing immediate reactions to harmful stimuli.