Homeostasis

• The pancreas is an organ that produces digestive enzymes, which are released into the small intestine to break down food molecules.
• What is the need for communication systems within organisms?

  Because when there are changes to the internal and external environment, an organism needs to respond in order to keep the internal conditions constant.
• What is the definition of homeostasis?

  Regulation of internal and external conditions of a cell or organism to maintain the optimum conditions for function in response to a internal or external change.
• What is the mechanism of homeostasis?

  The receptor recieves the stimulus and relays the information to the effectors via the coordination system.The effectors receive the information and bring about a response
• What is cell signalling?

  the sending and recieving of signals between cells that are close to each other or cells that are at a great distance from each other. A receptor receives a stimulus and converts the stimulus into a signal that is transmitted to an effector. A response is brought about within the receptor.
• What is thermoregulation?

  The control of core body temperature.
• What are endotherms?

  Organisms(warm-blooded)that have physiological mechanisms to regulate internal body temperature.
• What are ectotherms?

  Organisms(cold-blooded) that rely on behavioural adaptations to control their internal body temperature by absorbing heat from their surroundings.
• How is vasodilation a cooling mechanism in endotherms?

  It allows more blood to flow into the skin capillaries.Therefore more heat can be lost at the body’s surface
• How is sweating a cooling mechanism in endotherms?

  Sweat glands secrete sweat. The evaporation of sweat requires heat energy.
• What are some warming mechanisms in endotherms?

  Vasoconstriction; less heat is lost at the body’s surface. Boosting metabolic rate; most metabolic processes are exothermic so they release heat. Shivering; this is powered by metabolic processes that release heat, which warms the blood and raises the core body temperature. Standing up of hairs; trapped air around the the hairs act as an insulator.
• What is thermoregulation an example of?

  Negative feedback because if the temperature is too high or low then physiological mechanisms bring the internal body temperature back to optimum
• How does thermoregulation work in ectotherms?

  They move to shaded areas or areas with water to cool down. But to warm up they bask in sunlight or on warm surfaces.Therefore they require more energy to maintain the body temperature.
• What is vasodilation and vasoconstriction caused by?

  Caused by the contracting and relaxing of muscles in the walls of arterioles. This controls the volume of blood in capillaries
• What is the role of the hypothalamus in endotherms?

  It receives signals from peripheral receptors and brings about physiological responses depending on the external temperature.
• What is the role of the hypothalamus in regulation of blood temperature?

  Initiates homeostatic responses when the temperature of the blood flowing through it is too high or too low.
• What is excretion and why is it important in homeostasis?

  A process that involves the removal of toxic waste products ( from metabolic reactions) and unwanted substances. It is important in maintaining metabolism.
• What is the effect of CO2 left to accumulate in the body?

  Can lower the pH of cells, causing them to become damaged.
• What is the effect of leaving urea to accumulate in the body?

  Urea easily diffuses into cells, decreasing their water potential and therefore they absorb more water by osmosis causing them to burst eventually.
• What is the effect of leaving uric acid to accumulate in the body?

  Can build up in joints causing a very painful form of arthritis
• What is the effect of leaving ammonia to accumulate in the body?

  Can increase the pH of the cytoplasm of cells
• What is the effect of bile pigments accumulating in the body?

  Can cause the yellowing of the skin( jaundice)