1. Blood Glucose, insulin and glucagon
Homeostasis and negative feedback

2. Blood Glucose Carbohydrates in food
Glucose in digestive system
Must adhere to ‘Goldilocks’ principle
Too much is bad = hyperglycemia
Too little is bad = hypoglycemia
mg glucose per dL blood = ‘just right’
Glucose in blood
Glucose in cells
Cellular Metabolism
(aerobic + anaerobic)

3. Blood Glucose - Abnormal
Hypoglycemia
<60-65 mg/dL = hunger; shaky, light-headed; rapid heart rate
<40-50 mg/dL = loss of mental function, including confusion and/or erratic behavior; seizures; loss of consciousness
Hyperglycemia
>180 mg/dL
Immediate symptoms = increased thirst; headache; fatigue; frequent urination; blurred vision
Long term results = nerve damage; blood vessel damage; slow healing; loss of vision; cardiovascular disease

4. Blood Glucose - REgulation
Blood glucose levels maintained by hormones
Hormones = proteins made by endocrine glands
Hormones = proteins that effect specific cells away from site of hormone production

5. Pancreas and blood glucose
Pancreas is part of digestive system
Exocrine gland produces enzymes to digest proteins, carbohydrates and fats (pancreatic juice)
Pancreas is part of endocrine system
Endocrine (ductless) gland produces hormones insulin and glucagon from ‘Islets of Langerhans’ cells

6. Negative feedback and blood glucose
blood glucose = insulin production
Insulin = blood glucose Insulin responds to high glucose and causes it to decrease (‘negative feedback’)
blood glucose = glucagon production
glucagon = blood glucose
Glucagon responds to low glucose and causes it to increase (‘negative feedback’)

7. Glucagon and blood glucose
Blood glucose is low
Glucagon produced in alpha cells of pancreas
Glucagon effects liver + muscle cells that store glycogen
Cells breakdown glycogen to glucose
Glucose released to bloodstream + blood glucose increases
Glucagon production is stopped

8. Insulin and blood glucose
Blood glucose is high
Insulin produced in beta cells of pancreas
Insulin effects liver cells that store glycogen
Cells absorb glucose and create glycogen
Glucose removed from bloodstream + blood glucose decreases
Insulin production is stopped

9. Blood glucose and homeostasis

10. Problems with homeostasis – Insulin and diabetes
Diabetes is a breakdown in homeostasis that results in abnormal blood sugar levels
In U.S., 25.8 million people have diabetes (8.3% of total population)
18.8 million are diagnosed
7.0 million are undiagnosed
Care of diabetes and diabetes related conditions costs ~$150 billion each year
Two forms of diabetes – Type 1 and Type 2 – different cause/same effect

11. Problems with homeostasis – Insulin and diabetes
Type 1 Diabetes (~5% of all diabetes cases)
‘juvenile diabetes’
Cells that produce insulin are destroyed
No insulin = high blood glucose levels
No insulin = no stored glycogen
Type 2 Diabetes (~95% of all diabetes cases)
‘adult onset diabetes’
Cells in liver and muscle become insensitive to insulin (insulin resistance)
Insulin resistance = high blood glucose levels
Insulin resistance = no stored glycogen