Lesson 11: The Endocrine System Chapter 2: Structures of the Endocrine System

parathyroid glands

are four small glands with the sole purpose of secreting parathyroid hormone to regulate the body's calcium level. Though located near each other, the parathyroid glands are unrelated to the thyroid gland.

thyroid gland

is a butterfly-shaped gland located in front of the trachea in the neck. It is comprised of two halves, known as lobes, attached by a band of thyroid tissue called the isthmus

pineal gland

Located near the center of the brain, is a very small organ shaped like a pinecone secretes a single hormone: melatonin.

thymus gland

located behind the sternum and between the lungs, secretes thymosin, an instrumental hormone in the production and maturation of T-lymphocytes, or T cells

cortisol

Helps regulate metabolism and also has anti-inflammatory action

aldosterone

Keeps the electrolyte balance within normal limits

androgens

Releases small amounts of male and female sex hormones

epinephrine (adrenline)

helps you deal with physical and emotional stress

norepinephrine

Works with epinephrine in responding to stress

adrenal glands

sit on top of the kidneys. Their name directly relates to their location -ad, which means "in the direction of" and renal, which means "pertaining to the kidneys."

pituitary gland

often dubbed the endocrine system's "master gland" because its hormones send signals to other endocrine glands to stimulate or inhibit their own hormone production, consists of an anterior lobe and a posterior lobe.

Adrenocorticotropic hormone (ACTH)

Stimulates the adrenal glands to produce hormones

Follicle-stimulating hormone (FSH)

Ensures normal functioning of the ovaries and testes

Growth hormone (GH)

Aids the growth of healthy bone and muscle mass

Luteinizing hormone (LH)

Works with FSH to ensure normal functioning of the ovaries and testes

Prolactin

Stimulates production of breast milk after childbirth

Thyroid-stimulating hormone (TSH)

Stimulates the thyroid gland to produce hormones

Melanocyte-stimulating hormone (MSH)

Increases the production of melanin, causing darkening of the skin pigmentation

Antidiuretic hormone (ADH)

Helps control blood pressure by prompting the kidneys to reduce the amount of water excreted

Oxytocin

Stimulates contraction of the uterus during childbirth and stimulates breast milk production

hypothalamus

is a region of the brain that controls an immense number of bodily functions, including:

• Heart rate and blood pressure

• Body temperature

• Fluid and electrolyte balance, thirst

• Appetite and weight

• Glandular secretions of the stomach and intestines

• Sleep-wake cycle

• Sex drive

pancreas

belongs to both the endocrine and digestive systems, with most of its cells (more than 90%) working on the digestive side. However, it performs the vital duty of producing hormones, most notably insulin, to maintain the balance of blood glucose (sugar) and salt in the body. Without this balance, your body is susceptible to serious complications, such as diabetes.

Insulin

Moves glucose from the blood into the cells for energy. This drops blood glucose levels.

Glucagon

Works in the opposite way of insulin by stimulating the cells to release glucose. This raises blood glucose levels.

gamete

is a reproductive cell: the ovum (egg) in a female and sperm in a male

overies

produce and release two groups of sex hormones: progesterone and estrogen. Progesterone and estrogen are necessary to prepare the uterus for pregnancy, and the hypothalamus triggers their release.

testes

secrete testosterone, which is necessary for proper physical development in boys. During puberty, testosterone is involved in the development of male secondary sex characteristics, including the maturation of male sex organs, growth of facial and body hair, lowering of the voice, and increase in height and muscle mass.