Fundamentals of Anatomy and Physiology

282 Chapter 12

Hypothalamus

Brain^
Skull

Anterior lobe

of pituitary

Posterior lobe

of pituitary

Releasing
hormones
Releasing
hormones^
Hormones

Posterior lobe

Capillaries

Hormones^
Anterior lobe

(^) Gonadotropic Thyroid- (^) Growth
Prolactin^ hormones stimulating^ ACTH^ hormone
hormone^
Milk (^) Gonads Thyroid Adrenal (^) Growth
production gland cortex (^)
(^)
(^) ®
Learning
Cengage ©
Figure 12- 1 The relationship of the hypothalamus of the brain with the anterior lobe of the pituitary gland.
The Classification of Hormones
Hormones can be classified into three general chemical
categories. The simplest group includes hormones that are
modified amino acids. Examples are the hormones secreted
by the adrenal medulla: epinephrine and norepinephrine,
and the hormones secreted by the
posterior pituitary gland: oxytocin and vasopressin. The
second category is the protein hormones: insulin from the
pancreatic islets and the gonad-stimulating hormones and
growth hormone from the anterior pituitary gland. The third
category of hormones is the steroid hormones, which are
lipids. Examples are cortisol from the adrenal cortex and
estrogen and testosterone produced by the gonads.