Important Glands of the Endocrine System

Key Definitions Endocrine Gland: An organ in an animal’s body that makes a substance for release (in this case a hormone) into the bloodstream. Hormone: a chemical regulator that is made in one part of the body but acts on another part of the body.

Pituitary Gland (hypophysis) Located at the base of the brain connected under the hypothalamus, the pituitary gland is about the size of a pea.

Pituitary Gland (hypophysis) The pituitary gland secretes hormones that help maintain homeostasis. It can release special hormones called tropic hormones which stimulate other endocrine glands to secrete hormones. It is divided into two parts, the posterior (back) and anterior (front) pituitary.

Anterior Pituitary (adenohypophysis) With encouraging from the hypothalamus, the anterior pituitary releases many peptide hormones responsible for reproduction, growth and dealing with stress.

Anterior Pituitary (adenohypophysis) Hormones released from the anterior pituitary on its own include: Human Growth Hormone (hGH) Follicle-Stimulating Hormone (FSH) Luteinizing Hormone (LH) Thyroid Stimulating Hormone (TSH) Prolactin (PRL) Adrenocorticotropic Hormone (ACTH)

Anterior Pituitary (adenohypophysis) Hormones released from the anterior pituitary with urging from the hypothalamus include: Gonatropin-releasing Hormone (GnRH) Anti-diuretic Hormone (ADH) Somatostatin (SS)

Posterior Pituitary (Neurohypophysis) Unlike the anterior pituitary, the posterior pituitary is not so much a gland, but more of a series of nerve cells. It stores hormones produced in the hypothalamus, like ADH and oxytocin

Hypothalamus About the size of an almond, the hypothalamus is the link between the nervous system and the endocrine system through its control on the pituitary gland.

Hypothalamus Its main role in terms of the endocrine system, is to secrete releasing factor hormones that travel to the pituitary and stimulate/inhibit the release of pituitary hormones. This is where the brain’s thirst, hunger, anger, fatigue and body temperature centers are located as well.

Pineal Gland The pineal gland is a small pinecone shaped gland located between the two hemispheres of the brain. It is responsible for producing the hormone melatonin which controls sleep/wake patterns and seasonal functioning.

Thyroid Gland One of the largest glands in the body, the thyroid gland controls how quickly the body burns energy, how fast it makes protein and how sensitive the body is to other hormones.

Thyroid Gland The three main hormones produced by the thyroid gland are: Thyroxine (T4) Triiodothyronine (T3) Both used to regulate metabolism Calcitonin Used to control calcium levels

Parathyroid Glands The parathyroid glands are small endocrine glands found in the neck and are closely associated with the thyroid. They release the parathyroid hormone (PTH) Their main role is to control calcium levels in the body so that muscle flexion and nervous control are maintained.

Thymus Gland The thymus gland is located just above the heart and posterior to the sternum. It is very important in the maturation of T cells (infection fighting cells) for the immune system. It is the link between the endocrine system and the immune system.

Adrenal Glands (Suprarenal glands) They sit atop the kidneys. Their primary responsibility is to regulate the body’s stress level. The main hormones involved in stress regulation produced here are the protein hormones adrenalin and noradrenalin. Fight or flight response.

Pancreas The pancreas is an important gland for both digestion and blood sugar maintenance. The hormones important to blood sugar maintenance include insulin and glucagon.

Gonads (Testes and Ovaries) Important body parts as they make gametes, the sex cells of the body. They also are glands that produce the male and female sex hormones, testosterone (male) and estrogen (female). Their hormones are under the control of the hypothalamus and anterior pituitary.

Homework p. 377 #1 and #3