NATS 1675 LN 15

What are the 3 functions of endocrine hormones?

1. Major roles in coordinating & managing the activities of cells in the body.

2. Responsible for the sequential changes of growth, development, and maturation

3. Involved in homeostasis (oxytocin regulates labour contractions)

What is a hormone?

Hormones are signalling molecules secreted from the endocrine glands that travel through the bloodstream to regulate bodily functions (growth, development and maturation) by acting upon target cells.

What are target cells?

Target cells are any cell with receptors for a specific hormone. Once bonded to the receptor it alters its behaviour and reacts.

What are endocrine hormones?

Endocrine hormones are synthesized and produced by endocrine glands, endocrine cell and neurosecretory cells. They are released into interstitial fluid and diffused into the bloodstream.

What are the two main classes of endocrine hormones?

Steroid hormones and Non-steroid hormones

Steroid hormones

• Lipid soluble

• Testosterones, estrogen’s, progesterone, cortisol

• Backbone of 4 carbon rings

Non-steroid hormones

• Not lipid soluble

• Peptides (oxytocin), amines (melatonin, epinephrine), and proteins (FSH, LH, etc.).

How is the effect of a steroid hormone produced?

The hormone ends to a hormone-receptor complex which triggers “gene activity” in DNA resulting in the formation of a protein that carries out the cell’s response to the hormones signal.

How is the effect of a non-steroid hormone produced?

The non-steroid hormone binds to the outer portion of the receptor, triggers formation of the secondary messenger which activates the cyclic amp which activates other molecules/responses until the final response (inhibit/activate protein) is achieved.

What are the neurosecretory cells?

Neurosecretory cells are neurons. They make hormones in their cell body and these hormones move along the axon leaving through the axon endings.

Describe the pituitary gland.

• connected to the hypothalamus by a stalk-like infundibulum

• consists of an anterior and posterior lobe each secreting diff hormones

Posterior pituitary gland

The posterior pituitary is made of nervous tissue, neurosecretory cells extend into it and it stores 2 hormones (AHD/Vasopressin and Oxytocin).

Anterior pituitary gland

The anterior pituitary is made of granular tissue and it makes/secretes other hormones.

What are the 3 groups of hormones from the pituitary gland that are important to sex and reproduction.

The three groups of hormones from the pituitary glands that are important to sex and reproduction are oxytocin (posterior), prolactin (anterior), and gonadotropins (anterior).

Which 3 categories of steroid hormones are produced by the gonads?

The three categories of steroid hormones produced by the gonads are testosterone, estrogen and progestins (progesterone’s).

What purpose does oxytocin serve to sexual development and reproduction?

Stimulates contraction of the uterus & mammary glands

Secretion regulated by nervous system

What purpose does prolactin serve to sexual development and reproduction?

Stimulates milk production & secretion

Secretion regulated by hypothalamic hormones

What purpose does the gonadotropin FSH serve to sexual development and reproduction?

• Stimulates production of sperm & ovary

• Secretion regulated by hypothalamic hormones

What purpose does the gonadotropin LH serve to sexual development and reproduction?

• Stimulates the ovaries & testes – various effects 

• Secretion regulated by hypothalamic hormones

What is the adrenal cortex?

• Each adrenal cortex consists of 2 parts; the adrenal cortex (inner portion) and adrenal medulla (outer portion)

• Adrenal hormones: cortisol, epinephrine, norepinephrine, and corticosteroids (i.e., glucocorticoids, mineralocorticoids, androgens), etc.

`What is the role of the gonads?

• Produce testosterone, estrogen and progesterone

• Affect growth and development

• Regulate reproductive cycles and sexual behaviour

What is estrogens role in the ovaries?

• Support maturation of eggs

• Stimulate uterine lining growth

• Promote development & maintenance of female sex characteristics

• Secretion regulated by FSH & LH

What is progesterone’s role in the ovaries?

• Promotes uterine lining growth

• Secretion regulated by FSH & LH