GCSE Biology -
Homeostasis, Excre
& Hormones
Pearson Edexcel IGCSE
, Biology GCSE –Homeostasis, Excreti
Contents
q Homeostasis and Excretion –
q Urinary System and the Kidney Structure –
q Deamination-Maintaining Nitrogen Balance –
q The Nephron –
q Kidney Functions –
q Parts of the Kidney –
q Hormones –
q Role od ADH-Osmoregulation –
q Endocrine & Exocrine System –
q Role of Insulin-Control of Blood Sugar –
q Regulating Blood Sugar & Diabetes –
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, Biology GCSE –Homeostasis, Excreti
Homeostasis and Excretion Excretion is the process by which waste produ
cell metabolism are removed from the body.
→ Our body has to control many tings Excretion is not faeces, that is undigest
such as our blood pressure,
breathing, blinking, temperature. Excretory organs in plants would includ
leaves which remove CO2 .
Homeostasis means “steady state” and
that refers to keeping the conditions
In animals our kidneys get rid of urea, a
inside the body as constant as possible.
water and salt/sodium ions. The lungs a
of CO2 like the leaves. Our skin is also a
The things included in homeostasis would be: helps get rid of salt and water via swea
Temperature control {thermoregulation}
This is controlled to maintain the temperature at which Negative feedback
the body’s enzymes work best, which is usually 37°C. Homeostatic control is
Blood Sugar Control {Role of Insulin} achieved using negative
This is controlled to provide cells with a constant supply feedback mechanisms:
of glucose for respiration. It is controlled by the release if the level of something rises,
and storage of glucose. control systems reduce it
Body Water Content {Role of ADH} again
This is controlled to protect cells by stopping too much if the level of something falls,
water from entering or leaving them. Water content is control systems raise it again
controlled by water loss from: skin, lungs and kidneys