• The maintenance of a constant internal environment.

What are the main factors that are controlled?

In I/GCSE Biology, Internal conditions which are controlled include:

• The water content of the body.
• The ion content of the body.
• Blood sugar levels

• In I/GCSE Biology, The process of water movement into or out of cells is called osmosis.
• We take in waterand salts by drinking.
• We lose water by breathing, sweating, and urine production by the kidneys.
• We lose ions by sweating and urinating.
• The major control of water and ions is by our kidneys.

• We take in sugar as carbohydrate in our food.
• We control blood sugar levels by releasing insulin (a hormone) from the pancreas.
• Our cells need a constant supply of blood sugar for energy.

• Temperature regulation.
• Enzymes work best at 37^OC.
• Above and below this by a few degrees, and our cellular reactions stop working.
• We control our body temperature using our skin, eg by sweating.

Contain salts (sodium and potassium ions), glucose and water.

Isotonic sports drinks

• The same concentration of ions as the body fluids
• Enables rapid uptake of glucose

Hypotonic sports drinks

• Lower concentration of ions than in body fluids.
• Enables rapid uptake of water by osmosis.

Hypertonic solutions – not in sports drinks

• Higher concentration of ions than in body fluids
• Water is drawn into the gut – this dehydrates you - not sensible in a sports drink!

That's the end of the topic!

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Drafted by Joey (Biology)

Reference:

https://getrevising.co.uk/resources/biology_revision_notes4