βš–οΈ Principles of homeostasis and negative feedback (AQA)


Introduction

Core Body temperature and Blood pH

Blood Glucose

Concentration

Negative Feedback

Positive Feedback


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Introduction

The internal environment of our bodies is constantly kept within strict limits. Take for example temperature. It must be a challenge keeping our fleshy selves at 37Β°C while the outside fluctuates wildly! Or how about blood glucose concentration? We’ve all heard of diabetes – if it goes too high our organs sustain damage, if it goes too low a coma may be induced or even death.

Welcome to homeostasis – the maintenance of physiological parameters within optimal range.

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Core Body temperature and Blood pH

Why, though, is it so important to keep a strict temperature and pH? From a physiological viewpoint, think of enzyme activity. Its sensitivity to both temperature and pH means that the only conditions of optimal function will be strictly defined. Lots of enzymes denature past 40Β°C and are inactivated below 35Β°C.

Similarly, extreme pH is detrimental to optimal enzyme function, so blood pH must be tightly regulated.

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Blood Glucose Concentration

The effects of suboptimal blood glucose concentration are twofold:

1. If it is too high, the very low water potential will result in water being drawn from cells. This is clearly cause for concern, since water is at the heart of so many reactions that take place within cells, and is in fact the solvent for all the contents of the cells themselves! A long term effect of hyperglycaemia is heart disease…