B5.4

• What is homeostasis?

  Maintenance of a constant internal environment
• What role do feedback systems play in homeostasis?

  They help maintain body temperature
• What are the systems involved in maintaining body temperature?

  • Shivering
  • Sweating
  • Vasodilation
  • Vasoconstriction
  • Pilorelaxation
  • Piloerection
• How does shivering help regulate body temperature?

  It generates heat through muscle activity
• What is the function of sweating in temperature regulation?

  It cools the body by evaporating heat
• What happens during vasodilation?

  Blood vessels dilate, increasing heat loss
• What is the effect of vasoconstriction on heat loss?

  It reduces heat loss from the body
• What does pilorelaxation do to body hair?

  It relaxes hair, reducing heat retention
• What is the role of piloerection in temperature regulation?

  It raises hair to trap more heat
• Where does unfiltered blood enter in the nephron?

  Bowman's capsule via the glomerulus
• What small molecules are filtered out in the nephron?

  Glucose, urea, water, and mineral ions
• What happens to larger molecules during filtration in the nephron?

  They remain in the bloodstream
• What is selective reabsorption in the nephron?

  Reabsorption of substances back into the blood
• Where does selective reabsorption primarily occur?

  In the proximal convoluted tubule
• How are minerals reabsorbed in the nephron?

  Through active transport in the distal tubule
• What happens to water in the loop of Henle?

  Some water is reabsorbed into the blood
• What happens to excess water in the nephron?

  It is flushed out as urine
• How does filtered blood exit the nephron?

  Via the renal vein
• What is the structure of the nephron designed for?

  Efficient diffusion with capillaries
• What is the role of ADH in the nephron?

  It increases permeability of the collecting duct
• What happens when dilute blood is detected by the hypothalamus?

  ADH production is stopped by the pituitary gland
• What is the effect of stopping ADH production?

  Kidney tubules become less permeable
• What occurs when concentrated blood is detected?

  ADH is produced, increasing permeability
• What is produced when kidney tubules are more permeable?

  More concentrated urine is produced