Organs of the
Endocrine System
and Related Hormones
Hypothalamus
1.
2.
Collects information from the body. Integrates the nervous
system and Endocrine system responses to maintain
homeostasis.
Hormones: Hypothalamic Releasing Hormone and Hypothalamic
Non-releasing Hormone  stimulate or inhibit the pituitary
gland.
Pituitary
Two parts: Anterior Pituitary and Posterior Pituitary
2. Can act directly on target tissue or stimulate other endocrine glands.
3. Hormones Anterior Pituitary:
a. Tropic Hormones, stimulate other endocrine glands.
i. Adrenocorticotropin (ACTH)  Stimulates the adrenal cortex to
release steroid hormones.
ii. Thyroid-stimulating hormone (TSH)  acts on the thyroid to
stimulates the release of two thyroid hormones thyroxine(T4)
and triiodothyronine (T3).
1.
Anterior pituitary: Tropins continued
Follicle-stimulating hormone (FSH)  stimulates the
production of estrogen and eggs in women, and
production of sperm in men.
ii. Luteinizing hormone (LH) acts on ovaries to produce
progesterone an estrogen in women. Also signals the
release of eggs. In men stimulates the interstitial cells in
the testes to produce testosterone.
i.
Anterior pituitary: Other Hormones
Stores and releases hormones from the hypothalamus.
b. Growth hormone (GH)  acts directly on body tissues.
Responsible for the growth and development of the body.
Also important in the breakdown of fats and proteins into
useable energy, during exercise.
c. Prolactin  stimulates the growth of the mammary glands
and milk production in a nursing mother.
a.
https://www.youtube.com/watch?v=2ALEMLZKnfA
Posterior Pituitary
1.
Hormones of the Posterior Pituitary, the posterior pituitary
stores rather than produces hormones:
a. Antidiuretic hormone  targets the kidneys, decreases urine
output, increasing fluid volume in the body.
i. Secreted when plasma volume (the liquid portion of the
blood) gets low due to dehydration or profuse sweating.
ii. Subject to humoral control.
iii.Also plays a role in controlling blood pressure.
b. Oxytocin  secreted by pregnant women during labor and
continues to be secreted for as long as the woman is nursing.
Thyroid
1.
2.
Located near the larynx, controls metabolism.
Hormones of the Thyroid:
a. Thyroid hormone: Thyroxine (T4) and Triiodothryonine (T3)
Responsible for controlling energy metabolism and heat production
of the body.
b.
Calcitonin  when calcium levels in the blood rise, calcitonin is
released to facilitate uptake of calcium by the bones. It also reduces
absorption of calcium by the kidneys and intestines.
a.
Subject to humoral control
b.
Produced mostly during childhood.
Parathyroid
Two pairs of glands located on the posterior of the thyroid.
2. Hormone: Parathyroid hormone (PTH)  secreted in response to
low blood calcium.
a. Stimulates the breakdown of bone tissues, which releases
calcium into the blood.
b. Increases absorption of calcium in the intestines with the aid
of vitamin D
c. Stimulates reabsorption of calcium from the kidneys.
1.
Thymus and Pineal Gland

Thymus
Both an endocrine gland and a lymphatic organ. It grows smaller with
age. Inhibited by cortisol production.
2. Hormone: Thymosin  essential for the development of white blood
cells. Which plays an important role in the body’s immune system.
1.

Pineal Gland
Small gland located in the brain and contains the epithalamus.
2. Hormone: Melatonin  produced when the body is exposed to
darkness, causes sleepiness.
1.
Adrenal Glands: Adrenal medulla
A pair of glands that sit on top of the kidneys.
2. Two parts: the adrenal cortex and the adrenal medulla.
a. The adrenal cortex functions as a gland
b. The adrenal medulla is part of the nervous system.
3. Hormones of the Adrenal Medulla: epinephrine (adrenalin) and
norepinephrine  stimulated into production by the
sympathetic nervous system, during physical and emotional
stress. Increased breathing, heart rate, blood pressure. Change in
blood flow to redistribute resources to the muscles.
1.
Adrenal Cortex
1.
Hormones of the Adrenal Cortex, stimulated through hormonal
control by the anterior pituitary:
a. Mineralocorticoids, regulate sodium:
i. Aldosterone  stimulate the reabsorption of sodium and
water by the kidneys and the elimination of potassium.
Major role in regulating blood pressure and blood
electrolyte concentrations.
b. Glucocorticoids, regulate sugar:
i. Cortisone and Cortisol  converts fats and amino acids
into glucose. This insures the brain and nervous system
always has a constant supply of glucose.
c. Sex Hormones:
i. Estrogen and Androgens, primarily testosterone 
released in small amounts but steadily throughout life.
Pancreas
1.
Regulates blood sugar levels in the blood.
a. Hormones:
i. Insulin  causes the body’s cells to take up glucose for
energy use which reduces blood glucose. Stimulates the
liver to convert excess glucose into glycogen.
ii. Glucagon  increases blood glucose by stimulating the
liver to begin braking down glycogen into glucose.
Gonads
1.
2.
Sex glands, testes in men, ovaries in women.
Hormones:
a. Testosterone  produced by the testes, responsible for
sperm production, development of the male reproductive
system and the emergence of male secondary sexual
characteristics during puberty.
b. Estrogen and progesterone  development of the female
reproductive glands and secondary sexual characteristics.
Regulates the menstrual cycle and promotes breast
development.
Other Hormones
1.
Some hormones are actually produced by the tissues rather than
endocrine glands.
a. Erythropoietin  released by the kidneys, stimulates red
blood cell production.
b. Prostaglandins  released by fatty tissue, regulates smooth
muscle cells, and activates the inflammatory response.
c. Leptin released by adipose tissue, fatty tissue, reduces
appetite and increases energy production.