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Table of Contents
Homeostasis
Blood sugar level
Body temperature
The body's water content
Osmoregulation
Controlling water content of the body
Ion (salts) content of the body
Thermoregulation
Controlling body temperature
Control mechanisms
Controlling temperature
Thermoregulation - Higher tier
Too hot
Too cold
Hormones
Hormones produced by glands and their target…

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Dormancy
Receptors and effectors
Receptors
Different receptors
Effectors
Neurones
Synapses
Reflex actions




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Homeostasis
Conditions in the body are controlled, to provide a constant internal environment. This
is called homeostasis. The conditions that must be controlled include body
temperature, water content, carbon dioxide level, and blood sugar level. Diabetes is a
condition where the body cannot effectively regulate the levels of blood sugar.…

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Osmoregulation


Controlling water content of the body
This is controlled to protect cells by avoiding too much water entering or leaving them.
Water content is controlled by water loss from:
the lungs when we exhale
the skin by sweating
the body, in urine produced by the kidneys

Ion (salts) content…

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air. Blood vessels can shrink down again - vasoconstriction. This reduces heat loss
through the skin once the body's temperature has returned to normal.

Muscles can also receive messages from the brain when you are cold. They respond by
shivering, which warms you up.

Controlling temperature

Too cold Too hot…

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Too cold
muscles contract rapidly and we shiver when we're cold. These contractions need
energy from respiration, and some of this is released as heat.
Vasoconstriction occurs - blood vessels leading to the skin capillaries become
narrower (constrict) letting less blood flow through the skin and conserving heat in the…

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too low insulin not secreted into the liver does not convert glucose into goes up
blood glycogen

Use the animation to make sure you understand how this works.



Glucagon ­ Higher tier
The pancreas releases another hormone, glucagon, when the blood sugar levels fall.
This causes the cells in the…

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Rising levels of obesity and type 2 diabetes are linked.

Obesity
As obesity is a risk factor for type 2 diabetes doctors are keen to monitor the situation.
Someone is considered obese is they have a body mass index (BMI) of more than 30.
BMI is calculated by:




Plant hormones…

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