5.1 - Communication and homeostasis Flashcards
What is negative feedback?
- A response that is opposite to the stimulus, returning conditions back to the optimum.
- Brought about by an effector
What is positive feedback?
- A response that increases the stimulus, taking conditions further away from the optimum
- For example child birth
What is the difference between endotherms and ectotherms?
- Endotherms generate their own heat by metabolic reactions
- Ectotherms rely on the environment to control their body temperature
What is an ectotherm? (Cold-blooded)
An organism that is unable to control its body temperature and is reliant on external sources of heat
What is an endotherm? (Warm-blooded)
An organism that controls its body temperature in a narrow range using physiological or behavioural adaptations
What is homeostasis?
Maintaining a relatively stable internal
environment/state within narrow limits even when the environment is changing
What factors need to be kept constant?
- Body temperature
- Blood PH
- Blood glucose
- Water potential, to ensure cells function properly
- Levels of: salt, O2 & CO2
- Blood pressure
- Blood volume
How do endotherms regulate their internal temperature?
Their body will be able to regulate the internal temperature
How do ectotherms regulate their internal temperature?
Ectotherms will rely on sitting in the sun (basking) or sitting in the shade
Why must internal temperature be maintained? (Enzymes)
- To ensure that enzymes have optimal temperature
- This is so they can work properly and not denature if too hot
- Or have a slower reaction rate due to colder temperatures
Why must internal temperature be maintained? (Aerobic respiration)
- Ectotherms may warm themselves up is so that they can undergo aerobic respiration
- This means they will be able to produce ATP needed for the active metabolic processes in the body, such as muscle contractions or active transport
How do endotherms regulate internal temperature?
- The thermoregulatory centre inside of the hypothalamus is used
- The thermoreceptors inside this centre will monitor the temperature of the blood and will send messages to parts of the body (Via the autonomic nervous system) to increase or decrease the body temperature depending upon what it is at the time
How is vasodilation used to regulate temperature?
- Vasodilation is when more blood flows closer to the skin in the capillaries
- The shunt vessel narrows and prevents the blood from flowing away from the surface of the skin, so the blood is redirected to the capillaries closer to the skin
- This means more heat is lost through radiation through the skin
- This causes body temperature to decrease
How is vasoconstriction used to regulate temperature?
- Vasoconstriction is when less blood flows closer to the skin in the capillaries and the blood goes through the shunt vessel further away from the skin instead
- This means less heat is lost through radiation through the skin
- This causes body temperature to increase
How do hair erector muscles work to regulate body temperature?
- The hair erector muscle contracts or relaxes to cause the hairs to stand on-end or lie flat
- If the hairs stand up it traps an insulating layer of air causing an increase in body temperature