Regulating Blood Sugar

• Exocrine functions of the pancreas → secretes pancreatic juice (enzymes, base, etc.) which have digestive functions in the sm. intestine.
• Endocrine functions → regulation of blood glucose → the endocrine cells (2% of the mass of the pancreas) are interspersed among the exocrine cells in clusters called the islets of Langerhans (think BIGA!):

· Alpha cells → produce Glucagon → ↑ blood sugar in the blood by converting glycogen into glucose, also break down fats and proteins to make glucose

· Beta cells → produce Insulin → ↓ blood sugar via increased permeability (uptake) of glucose into muscle and liver cells. In the liver, glucose is converted into glycogen.

· Therefore, these are antagonistic hormones.

Disorders:

Hyperglycemia: High blood sugar, causes thirst, frequent urination….

Hypoglycemia: Low blood sugar, causes nervousness, cold sweats, headaches, nausea

Diabetes: A disorder with symptoms relating to abnormal urine production.

Diabetes Mellitis = sugar urine

• This form of diabetes is due to improper sugar regulation in the blood caused by insulin problems, leads to excessive glucose in the blood.
• Causes increased glucose to pass into the nephron, very little of it is reabsorbed by the proximal tubule.
• More glucose in the filtrate leads to a higher osmotic potential so water tends to STAY in the nephron, resulting in a large volume of sugary urine being produced.
• Symptoms of thirst and increased appetite due to reduced glucose uptake

Type I Diabetes - usually diagnosed in children, caused by degredation of the beta cells that normally secrete insulin.

• patients require insulin injections (why is it not ingested like most medication?)
• insulin is produced using recombinant technology (recall the plasmid activity from the Molecular Genetics unit)

Type II Diabetes (~90% of diabetics)– insulin is produced normally or in lower amounts, the body cells develop resistance to insulin.

• treated with healthy diet, exercise, and oral drugs to stimulate insulin production or insulin binding

Gestational Diabetes (~2% of population)– a temporary condition that occurs rarely during pregnancy.

Diabetes Insipidus = without taste, very dilute urine

• This form of diabetes is due to inadequate ADH (antidiuretic hormone) activity.
• Without ADH, the distal tubule and collecting duct of the nephron do not reabsorb as much water, resulting in a very dilute urine.
• This form of diabetes HAS NOTHING TO DO WITH INSULIN OR GLUCAGON.

Textbook Practice

p.483-487#1-5, 7