Psychology2016

66 CHAPTER 2

regulates metabolism (how fast the body burns its available energy). As related to

growth, the thyroid plays a crucial role in body and brain development.

PANCREAS The pancreas controls the level of blood sugar in the body by secreting

insulin and glucagon. If the pancreas secretes too little insulin, it results in diabetes. If it

secretes too much insulin, it results in hypoglycemia, or low blood sugar, which causes a

person to feel hungry all the time and often become overweight as a result. to

Learning Objective 9.6.

THE GONADS The gonads are the sex glands, including the ovaries in the female

and the testes in the male. They secrete hormones that regulate sexual behavior and

reproduction. They do not control all sexual behavior, though. In a very real sense,

the brain itself is the master of the sexual system—human sexual behavior is not con-

trolled totally by instincts and the actions of the glands as in some parts of the animal

world, but it is also affected by psychological factors such as attractiveness. to

Learning Objective 10.1.

THE ADRENAL GLANDS Everyone has two adrenal glands, one on top of each kid-

ney. The origin of the name is simple enough; renal comes from a Latin word meaning

“kidney” and ad is Latin for “to,” so adrenal means “to or on the kidney.” Each adrenal

gland is actually divided into two sections, the adrenal medulla and the adrenal cortex. It

is the adrenal medulla that releases epinephrine and norepinephrine when people are

under stress and aids in sympathetic arousal.

The adrenal cortex produces more than 30 different hormones called corticoids

(also called steroids) that regulate salt intake, help initiate* and control stress reactions,

and also provide a source of sex hormones in addition to those provided by the gonads.

One of the most important of these adrenal hormones is cortisol, released when the

body experiences stress, both physical stress (such as illness, surgery, or extreme heat

or cold) and psychological stress (such as an emotional upset). Cortisol is important

in the release of glucose into the bloodstream during stress, providing energy for the

brain itself, and the release of fatty acids from the fat cells that provide the muscles

with energy.

adrenal glands
endocrine glands located on top of
each kidney that secrete over 30 dif-
ferent hormones to deal with stress,
regulate salt intake, and provide a
secondary source of sex hormones
affecting the sexual changes that
occur during adolescence.

testes
the male gonads or sex glands.

gonads
sex glands; secrete hormones that reg-
ulate sexual development and behav-
ior as well as reproduction.

pancreas
endocrine gland; controls the levels
of sugar in the Dlood.

ovaries
the female gonads or sex glands.

*initiate: begin or start.

Concept Map LO. 2.6, 2.7

InteractiveDistant Connections: The Endocrine Glands

glands are organs in the body that secrete chemicals; some affect functioning of

the body but not behavior; others have widespread influence on the body and behavior

endocrine glands secrete chemicals called hormones into

bloodstream; affect behavior and emotions by influencing

the activity of the brain and by controlling muscles and

organs such as the heart, pancreas, and sex organs

pituitary gland

pineal gland

thyroid gland

pancreas

gonads

adrenal glands

Reset

When the pancreas does not excrete enough
insulin, the result is diabetes. A person with
diabetes must keep a close watch on blood
sugar levels. Some people test more than once
a day while others are able to test only a few
times a week. Devices such as the one in use
here make it much easier—and far less painful—
to test blood sugar levels than in years past.