The Endocrine System

The Endocrine System is The 2nd great communication system. Behavior and personality are tied to the ebb and flow of hormones in the body. It is made up of a number of glands that pour chemicals (hormones) directly into the bloodsteam. These chemicals are carried throughout the body, where they affect internal activities and behavior. They are chemically related to neurotransmitters, and like transmitters, hormones activate cells in the body. To respond, the cells must have receptor sites for the hormone.

Hormones affect us in a number of ways:

- Hormone output from the adrenal glands rises during stressful situations.

- Androgens ("male" hormones) are related to the sex drive in both males and females.

- Hormones secreted during times of high emotion intensify memory formation.

- At least some of the emotional turmoil of adolescence is due to elevated hormone levels

- Different hormones predominate when you are angry, rather than fearful.

Additional Effects Hormones have on the Body and Behavior:
1. Pituitary = a small, grape-sized structure hanging from the base of the brain. It regulates growth. During childhood, it secretes a hormone that speeds body development. [Acromegaly = Secretion of too much hormone late in the growth period causes the arms, hands, feet, and facial bones to become enlarged--distorts appearance.] The pituitary regulates the functioning of other glands (especially the thyroid, adrenal glands, and ovaries or testes). These glands in turn regulate such bodily processes as reproduction, metabloism, and responses to stress. In women, the pituitary also controls the production of milk during pregnancy. It is often called the "master gland' because of its many effects. However - it has its master. The pituitary is directed by the hypothalamus, which lies above it in the brain. Thus, the hypothalamus affects glands throughout the body.

2. Thyroid gland = is found in the neck, on each side of the windpipe. It regulates metabolism--the rate at which energy is produced and expended in the body. As a consequence, it can have a sizeable effect on the personality.

Hyperthyroidism

Hypothyroidism = underactive thyroid. Causes inactivity, sleepiness, slowness, and overweight in adults. In infancy it limits development of the nervous system and can cause severe mental retardation.

NOTE: When you are frightened or angry, a number of important actions take place in your body to prepare it for action: Your heart rate and blood pressure are raised; stored sugar is released into the bloodstream for quick energy; the muscles tense and receive more blood; and the blood is prepared to clot more quickly in case of injury. These changes are brought about by the autonomic nervous system (ANS)--specifically, the sympathetic branch of the ANS causes the hormones adrenaline and noradrenaline to be released by the adrenal glands (the same substances also act as neurotransmitters).

3. Adrenal Glands = Located just under the back of the rib cage, atop the kidneys--the Sympathetic (or emergency) branch of the Autonomic System cause these hormones to be released. They activate and act as neurotransmitters.

Adrenal medulla

Adrenal cortex = outer "bark" of the adrenal glands, produces a second set of hormones called

corticoids

Virilism = Caused by oversecretion of adrenal sex hormones = woman grows a beard or man's voice becomes so low it is difficult to understand.

Premature puberty = Oversecretion in children, resulting in full sexual development [the 5-year-old Peruvian child who gave birth to a son].

[Notes from: Coon, Dennis. Introduction to Psychology, Exploration and Application. St. Paul: West Publishing Company, 1989.]

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