Homeostasis

homeostasis = controlling internal conditions

Waste products that need to be removed:

• Carbon Dioxide (CO2)
  • produced by respiration 
  • released by the lung
• Urea
  • produced in the liver, the breakdown of amino acids
  • removed by kidneys and stored in bladder

Internal conditions that are controlled:

• water content
• ion content
• temperature
• blood sugar levels

Water and Ion content

Water and Ions enter the body when you eat and drink

If the water or ion content is wrong then your cells can become damaged

The kidneys control the water content

Sweating helps cool the body

Water is lost when it is hot, so you would have to drink more frequently to replace this loss

Maintenance of body temperature

Enzymes work best at 37*C

Metabolism of cells releases heat warming the animals body

Metabolism most efficent when internal temperature is maintained when the external temperature changes

Temperature monitered and controlled

• body temperatured is mointered & controlled by the thermoregulatory centre in the brain
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• the centres receptors are sensitive to the blood temperature
• temperature receptors in the skin send impluses to the centre giving information

• contains sweat glands
• network of capillaries just under the surface

core temperature too high?

• blood vessels dilate (get wider)
  • more blood flows through the capillaries & more heat loss from skin
• Sweat glands sweat more
  • cools the body as it evaporates

core temperature too low?

• blood vessels constrict (get narrower)
  • reduces flow of blood through capillaries & reduces heat loss
• shivering muscles
  • contraction needs respiration, which releases some energy as heat

• blood glucose concentration of the body is monitored and controlled by the pancreas
•  
• insulin is produced in the pancreas
• insulin allows glucose to move from the blood to the cells

• Food Eaten
• Carbohydrates digested into glucose
• Glucose absorbed into blood
• Blood glucose levels rise
• Detected by the pancreas
• Insulin released into blood
• Insulin reaches the liver
• Glucose converted into glycogen
• Glycogen stored
• Blood glucose levels return to normal

Diabetes is a disease in which a person's pancreas does not produce enough insulin. So after a meal, the blood glucose concentration may rise to a very high level. And the results could be fatal if  not controlled.

Discovery

• Banting and Best two scientists in 1920 investigated for a cure
• Tested on dogs by looking at their pancreas

Treating

• by careful diet and injections of insulin
• 
•  
• Insulin was taken from cows and pigs but now its produced using micro organisms that have been genetically engineered to contain the human insulin gene
• Pancreas transplants can also be a treatment but not always successful