Communication, Homeostatis and Excretion

• What is homeostasis defined as?

  The maintenance of a stable internal environment
• Why do organisms need to respond to environmental changes?

  To coordinate activities of different organs
• What systems do organisms use to maintain internal conditions?

  Control and communication systems
• Why is homeostasis critically important for organisms?

  It maintains optimal conditions for enzyme action
• What are three key factors that need to be controlled in homeostasis?

  Temperature, pH, blood glucose concentration
• What is cell signaling?

  The communication process governing cell activities
• How does cell signaling benefit multicellular organisms?

  It coordinates body functions and responses
• What is the role of sensory receptors in a control system?

  They communicate with the coordination center
• What system is used for rapid responses to stimuli?

  The nervous system
• How does the hormonal system differ from the nervous system?

  It is slower but allows longer-term responses
• What principle do homeostatic control systems use?


  Negative feedback

  
• What happens after negative feedback restores a system?

  Sensory receptors detect and relay information

  
• What do negative feedback loops help maintain?

  A normal range or balance within an organism
• What do receptors detect in a negative feedback loop?

  Deviations from the normal range

  
• How many corrective mechanisms are usually in a negative feedback loop?

  Two corrective mechanisms
• What is the role of the nervous system in corrective mechanisms?

  It may be involved in the response
• What happens to the level of correction as a factor approaches normal value?

  The level of correction reduces
• What do positive feedback loops do to the original stimulus?

  They enhance the effect of the original stimulus
• What is vasoconstriction?


  Contraction of muscles in arterioles
• How does increasing metabolic rate help with low body temperature?

  It provides warmth to the body
• What is the purpose of shivering?

  To release heat energy and warm blood
• What is egestion?

  The removal of undigested food
• Why is excretion important?

  To remove toxic metabolic waste products
• What is the excretory product of carbon dioxide?

  CO2
• What happens if carbon dioxide builds up in the body?

  It can create acidic conditions
• What is the excretory organ for nitrogenous waste?

  Kidneys
• What is the reason for excreting nitrogenous waste?

  To alter pH and remove toxicity
• What is the excretory organ for water?

  Kidneys
• What is the role of bile pigments?

  Formed from breakdown of hemoglobin
• What is one function of the liver?

  Cholesterol synthesis
• What does the hepatic artery supply to the liver?

  Oxygenated blood from the heart
• What is the role of the hepatic portal vein?

  It carries deoxygenated blood from digestion

  
• What does the hepatic vein do?

  Blood leaves the liver

  
• What is the function of bile ducts?

  Transport bile from liver to gall bladder

  
• What are hepatocytes?

  Liver cells
• What do sinusoids connect in the liver?

  The hepatic artery and hepatic portal vein

  
• What is one function of hepatocytes?

  Producing bile
• What do Kupffer cells do?


  Remove bacteria and foreign particles
• What is the role of the intralobular vein?

  Connects to the hepatic vein
• What is deamination?

  The removal of an amino group from amino acids