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Homeostasis
Homeostasis
● Homeostasis is the maintenance of a constant internal environment
...
○ Is the regulation of conditions in the body such as temperature,
water content, and carbon dioxide levels
...
-Blood sugar level
● Controlled to provide cells with a constant supply of glucose for
respiration
...
-Water content
● Controlled to protect cells by stopping too much water from 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
-Negative feedback
● Homeostatic control is achieved using negative feedback mechanisms:
○ If the level of something rises, control system reduces it again
○ If the level of something falls, the control system raises it again
...
○ If you become too hot or too cold, there are ways in which your
body temperature can be controlled
...
○ They lie flat when we are warm and rise when we are cold
● The hairs trap a layer of air above the skin
○ Which helps to insulate the skin against heat loss
...
○ It receives information from temperature sensitive receptors in
the skin and circulatory system
● The hypothalamus responds to this information by sending nerve
impulses to effectors to maintain body temperature
...
■ This raises the skin hairs, and traps a layer of air next to
the skin
Skin hairs lie flat when we are hot and stand upright when we are cold
● Negative feedback mechanisms control body temperature
...
● It's important that the concentration of glucose in the blood is
maintained at a constant level
...
● The pancreas isn't secreting enough insulin
...
■ The extra insulin causes the liver to convert glucose into
glycogen which reduces the blood glucose level
...
-Diagnosis
● Blood glucose test
● Clinistix (Enzymes causes dye to change color when glucose
in urine)
present
-Type 1 diabetes
● Type 1 diabetes is caused by the lack of insulin
...
○ Their levels of physical activity and their diet affect the amount
of insulin needed
...
-Type 2 diabetes
● Type 2 diabetes is caused by a person's body becoming resistant to
insulin