15.1 The Principles Of Homeostasis Flashcards
What is homeostasis?
Why is important?
The maintenance of a constant internal environment despite external environmental changes.
It involves control systems that keep your internal environment roughly constant (within certain limits).
It is particularly important to maintain the right core body temperature. This is because temperature affects enzyme activity, and enzymes control the rate of metabolic reactions.
How does temperature affect the rate of metabolic reactions? Explain.
The rate of metabolic reactions increases when the temperature’s increased. More heat means more kinetic energy, so molecules move faster.
This makes substrate molecules substrate molecules more likely to collide with the enzyme’s active site.
But if temp gets too high, the reaction can stop. This rise in temp could make hydrogen bonds that hold the enzymes 3D shape break.
This causes the active site to change shape and therefore the substrate can no longer fit.
The enzyme is denatured.
If body temp is too low enzyme activity is reduced, slowing the rate of metabolic reactions.
The highest rate of enzyme activity happens at their optimum temp of 37°C.
Describe and explain negative feedback
Receptors detect when a level is too high or too low, and the information is communicated via the nervous system or the hormonal system to effectors.
The effectors respond to counteract the change - brining the level back to normal via the negative feedback mechanism
Negative feedback only works within certain limits though - if the change is too big then the effectors may not be able to counteract it (e..g hypothermia)
Describe and explain positive feedback
The positive feedback mechanism amplifies the change.
The effectors respond to further increase the level always from the normal level.
Positive feedback isn’t involved in homeostasis as it doesn’t keep internal environment constant. Positive feedback is useful to rapidly activate processes in the body (e.g. blood clotting process)
