Module 5

• What is the definition of homeostasis?

  The maintenance of a constant internal environment via physiological control systems
• What are the physiological control systems involved in homeostasis?

  • Maintaining body temperature
  • Maintaining blood pH
  • Maintaining blood glucose concentration
  • Maintaining blood water potential
• What type of feedback loop is most commonly associated with homeostasis?

  Negative feedback loop
• What happens in a negative feedback loop?

  A deviation from set limits is detected and mechanisms are put in place to return to those limits
• What is an example of a negative feedback loop in the body?

  Regulating body temperature
• What is positive feedback and when is it commonly observed?

  Positive feedback increases the deviation from set limits and is rare, such as during childbirth
• How does the hormone oxytocin function in positive feedback during childbirth?

  It is released in response to pressure on the cervix, causing more contractions
• Why is thermoregulation important for the body?

  To ensure enzyme-controlled reactions occur at optimal rates
• What happens if body temperature is too low?

  There won't be enough kinetic energy for enzyme-controlled reactions
• What happens if body temperature is too high?

  Enzymes will denature and reactions will stop
• How do ectotherms and endotherms regulate their body temperature?

  • Ectotherms: Regulate temperature through behavior (e.g., basking)
  • Endotherms: Use physiological mechanisms (e.g., sweating, shivering)
• Which animals are typically ectotherms?

  Fish, amphibians, reptiles, and invertebrates
• Why do ectotherms in aquatic environments have less need for temperature regulation?

  Water has a high specific heat capacity, acting as a temperature buffer
• What behavioral adaptations do terrestrial ectotherms exhibit to regulate temperature?

  They bask on hot rocks to absorb heat
• How do endotherms regulate their internal body temperature?

  Using the nervous system and various physiological mechanisms
• What role do peripheral receptors play in thermoregulation?

  They detect changes in external temperature and send impulses to the brain
• What is the role of the hypothalamus in thermoregulation?

  It coordinates impulses from peripheral receptors and triggers responses
• What physiological response occurs when the body is hot?

  Vasodilation occurs to increase heat radiation
• What physiological response occurs when the body is cold?

  Vasoconstriction occurs to reduce heat loss
• What is shivering and how does it help in thermoregulation?

  Shivering is the contraction and relaxation of skeletal muscles that generates heat
• What adaptations do animals with fur or feathers have for temperature regulation?

  They can raise or lower their fur/feathers to trap or release air for insulation
• How do humans modify their behavior to regulate temperature?

  By moving to the shade or removing clothing when hot
• What is excretion in the context of homeostasis?

  The removal of waste products that can become toxic if not eliminated
• What are the key waste products that need to be excreted?

  • Carbon dioxide (from respiration)
  • Nitrogenous waste (e.g., urea)
• What is the waste product from respiration?

  Carbon dioxide
• How is urea produced in the body?

  From the breakdown of excess amino acids in the liver
• What happens to excess amino acids in the diet?

  They are broken down in the liver
• What is the role of the liver in detoxification?

  The liver neutralizes and breaks down unwanted chemicals
• What is the function of hepatocytes?

  They produce bile and perform various metabolic functions
• What are the main functions of the liver?

  • Production of bile
  • Detoxification of chemicals
  • Storage of glycogen
  • Breakdown of toxins
• What is the structure of the liver made up of?

  Functional units called lobules
• How does blood flow through the liver?

  Blood enters through the hepatic artery and hepatic portal vein, mixing in sinusoids
• What are sinusoids in the liver?

  Spaces surrounding hepatocytes where blood mixes
• What is the role of Kupffer cells in the liver?

  They help destroy pathogens that enter the liver
• How is bile produced and transported in the liver?

  Bile is produced by hepatocytes and secreted into canaliculi, then drains into the bile duct
• What happens to excess glucose in the liver?

  It is absorbed and converted to glycogen in response to insulin
• What is the ornithine cycle?

  It is the process of converting ammonia to urea in the liver
• Why must ammonia be converted to urea?

  Ammonia is highly toxic and must be converted to a less toxic form
• What is the role of the kidneys in excretion?

  They excrete urea and regulate water potential of the blood
• What is the structure of the kidney?


  It consists of the cortex, medulla, and pelvis