Homeostasis

• What is homeostasis?

  Regulation of internal conditions in organisms
• Why is homeostasis important for enzymes?

  Enzymes require specific conditions to function
• What are the key controlled conditions in homeostasis?

  Body temperature, blood glucose, water and ion levels
• What happens if homeostasis fails?

  It can lead to illness or death
• What does the nervous system enable?

  Fast responses to environmental changes
• What are the two main parts of the nervous system?

  Central Nervous System and Peripheral Nervous System
• What is the function of the reflex arc?

  It provides an automatic response to stimuli
• What are the steps of the reflex arc?

  1. Stimulus detected by receptor
  2. Impulse travels along sensory neurone to CNS
  3. Signal passed to relay neurone in spinal cord
  4. Relay neurone transfers signal to motor neurone
  5. Motor neurone carries impulse to effector
  6. Effector responds (e.g., muscle contracts)
• Why are reflexes important?

  They protect the body from harm
• How does the endocrine system control homeostasis?

  Using hormones as chemical messengers
• What is a key feature of hormones?

  They travel through the bloodstream
• How do hormonal responses compare to nerve responses?

  Hormonal responses are slower but longer-lasting
• What are the major endocrine glands and their functions?

  • Pituitary Gland: Controls other glands, regulates water balance
  • Pancreas: Regulates blood glucose levels
  • Thyroid: Controls metabolism, growth, and development
  • Adrenal Glands: Prepares body for 'fight or flight'
  • Ovaries: Regulates menstrual cycle
  • Testes: Controls sperm production and male traits
• How does the pancreas control blood glucose levels after eating?

  It releases insulin to lower glucose levels
• What happens to blood glucose levels after eating?

  They decrease due to insulin action
• What is the process when blood glucose is low?

  1. Detected by pancreas
  2. Pancreas releases glucagon
  3. Glycogen converts back to glucose
  4. Glucose is released into blood
  5. Blood glucose levels increase
• What is Type 1 Diabetes?

  The pancreas does not produce insulin
• What is Type 2 Diabetes?

  Cells do not respond to insulin properly
• How do kidneys regulate water balance?

  By filtering blood and adjusting urine concentration
• What are the steps of kidney function?

  1. Ultrafiltration: Blood is filtered, removing waste
  2. Selective Reabsorption: Useful substances reabsorbed
  3. Excretion: Waste products form urine
• What does ADH do when water levels are low?

  It makes kidney tubules more permeable
• What happens when the body is too hot?

  Blood vessels vasodilate and sweat is produced
• What are the responses when the body is too cold?

  1. Blood vessels vasoconstrict to reduce heat loss
  2. Muscles shiver to generate heat
  3. Hairs stand up to trap warm air
• What are hormonal methods of contraception?

  The pill, injection, and implant
• What hormones control the menstrual cycle?

  • FSH: Stimulates egg maturation
  • Oestrogen: Thickens uterus lining, inhibits FSH
  • LH: Triggers ovulation
  • Progesterone: Maintains uterus lining, inhibits LH & FSH
• What are the functions of plant hormones?

  • Auxins: Control growth responses
  • Gibberellins: Promote seed germination and flowering
  • Ethene: Controls fruit ripening
• What is phototropism in plants?

  Growth towards light due to auxins
• What is gravitropism in plants?

  Roots grow downwards due to gravity
• What are the uses of plant hormones?

  • Auxins: Weed killers and rooting powders
  • Gibberellins: Promote fruit growth and seed germination
  • Ethene: Control fruit ripening