BIOLOGY: Homeostasis and Response

• What are the two main parts of the human nervous system?

  Central nervous system and peripheral nervous system

  
• What is the primary function of the nervous system?

  To react to surroundings and coordinate behavior
• How is information transmitted in the nervous system?

  As electrical impulses along neurones
• What is a bundle of neurones called?

  A nerve
• What are the adaptations of neurones?

  • Cell body contains nucleus and organelles
  • Axons and dendrites extend from the cell body
  • Some axons are over a metre long
  • Efficient information transfer reduces impulse transfer time
• What is the function of the myelin sheath?

  To insulate the axon and speed up impulses
• What is the role of the CNS?

  To coordinate responses of effectors
• What is the pathway through the nervous system?

  • Stimulus
  • Receptor
  • Coordinator (CNS)
  • Effector
  • Response
• What is a reflex response?

  An involuntary response not involving conscious brain
• What is the first step in a reflex arc?

  The stimulus is detected by a receptor

  
• What type of neurone carries impulses to the CNS?

  Sensory neurones
• What is the function of relay neurones?

  To connect sensory and motor neurones

  
• What type of neurone carries impulses to effectors?

  Motor neurones
• How can you identify the three types of neurones?

  • Sensory neurones: long, cell body in middle
  • Relay neurones: short, small cell body with many dendrites
  • Motor neurones: long, large cell body at one end

  
• What are synapses?

  Junctions where neurones do not touch
• What is the size of synaptic junctions?

  Around 10 nm
• How do neurotransmitters function at synapses?

  They diffuse across the synaptic cleft

  
• What happens to neurotransmitters after they bind to receptors?

  They are destroyed or recycled

  
• Why do synapses ensure one-way impulse travel?

  To avoid confusion in the nervous system
• Where do drugs like heroin act in the nervous system?

  At synapses affecting neurotransmitter receptors
• What is the slowest part of the reflex arc?

  Diffusion of neurotransmitters across the synaptic cleft

  
• What factors can affect reaction time?

  • Age
  • Stress
  • Use of drugs (e.g., caffeine)
  • Background noise
• What is homeostasis in biology?

  Regulation of internal conditions for function
• Why is homeostasis important for cells?

  It maintains optimal conditions for enzyme action
• How is homeostasis maintained in the body?

  Through involuntary control by the brain and spinal cord
• What are the components of automatic control systems in homeostasis?

  Receptors, coordination centres, effectors
• What role do receptors play in homeostasis?

  They detect stimuli in the environment
• What is the function of coordination centres in homeostasis?

  They process information from receptors
• What do effectors do in the homeostasis process?

  They bring about responses to restore levels
• What is the human endocrine system composed of?

  Glands that secrete hormones into the bloodstream

  
• How do hormones affect target cells?

  They produce effects when they reach target cells

  
• What is the role of the pituitary gland?

  It secretes hormones that stimulate other glands

  
• What hormone does the pancreas produce to regulate blood glucose?

  Insulin

  
• What does the thyroid gland produce?

  Thyroxine, which controls metabolic rate
• What hormone do adrenal glands produce?

  Adrenaline
• What hormone do ovaries produce?

  Oestrogen
• What hormone do testes produce?

  Testosterone
• How does the pancreas monitor blood glucose concentration?

  By producing insulin when glucose is high
• What happens when blood glucose levels are too high?

  The pancreas produces insulin to lower it

  
• What is Type 1 diabetes?

  A disorder where the pancreas produces insufficient insulin