cells, each type produces a particular hormone. Alpha cells produce glucagon. Beta
cells produce insulin, a hormone essential to the body's metabolism.
a. Glucagon. Glucagon is frequently called the hyperglycemic factor.
Glucagon causes glycogenolysis (the conversion of glycogen into glucose) and tends to
prevent hypoglycemia. Glucagon is released when blood glucose levels drop, thus,
glucagon tends to raise the level of sugar in the blood.
b. Insulin. Insulin's principal effect is to increase the cells' permeability to
glucose. When the glucose enters the cells, it is metabolized to produce energy.
Insulin also increases glycogenesis in the liver, thus, it increases glycogen stored there.
A hyposecretion of insulin is known as diabetes mellitus. There are essentially two
types of diabetes, juvenile diabetes and maturity-onset diabetes. Juvenile diabetes
develops early in life, usually about the time of puberty, and is frequently associated
with ketoacidosis. This form of diabetes is treated with insulin therapy. Maturity-onset
diabetes frequently does not appear until middle age. Maturity-onset diabetes is usually
milder than juvenile diabetes. Furthermore, maturity-onset diabetes is sometimes
managed by the administrating of oral hypoglycemics and by controlling the patient's
weight and diet. The lack of insulin decreases the amount of glucose that enters the
cells of the body and increases the amount of glucose present in the person's blood
(hyperglycemia). Hyperglycemia causes sugar to spill over into the urine. This results
in glycosuria and polyuria (due to the osmotic effect of the glucose). The lack of
glucose entering the cells causes gluconeogenesis and fat catabolism. This result in
wasting of the cells and ketoacidosis. Ketoacidosis leads to coma and death.
Uncontrolled diabetes mellitus may be accompanied by hyperglycemia, glycosuria,
polyuria, polydipsia (excessive thirst leading to increased water intake), ketoacidosis,
wasting coma, and death. A person who has diabetes mellitus may be required to take
insulin to treat the lack of insulin present in the body. If a person must take insulin, it is
likely that this individual must take insulin for the remainder of his or her life.
Remember, insulin taken by the diabetic does not cure diabetes. In the opposite
fashion, an overdose of insulin may cause hypoglycemia, depression of the central
nervous system, and death. One possible treatment of this condition is an injection of
glucagon. Remember, when injected, glucagon causes glycogenesis that results in an
elevated level of blood sugar.
6-12. THE GONADS
Both the male and female sexes have gonads. The female and male cells, or
gametes, are produced by the reproductive glands or gonads. In the male, the gonads
are the two testes. In the female, the gonads are the two ovaries. In addition to these
primary sex glands, there are a number of accessory organs. In the male, these
accessory organs are the vas deferens, seminal vesicles, prostate gland, and the penis.
In the female, the accessory organs are the fallopian tubes (oviducts), uterus, vagina,
and mammary glands. For a review of the human reproductive system, review Lesson
6 in MD0806, Pharmacology III.