The Great Communicator Chapter 11 The Great Communicator

Functions of the Endocrine System The endocrine system is composed of ductless glands that secrete chemical messengers called hormones into the bloodstream. Endo- means within. -crine means to secrete or separate.

Functions of the Endocrine System Hormones enter the bloodstream and are carried throughout the body to affect a variety of tissues and organs.

Structures of the Endocrine System The glands of the normal endocrine system: one pituitary gland one thyroid gland four parathyroid glands two adrenal glands one pancreas one thymus one pineal gland two gonads 4

The Pituitary Gland The pituitary gland is located at the base of the brain just below the hypothalamus. The hypothalamus secretes releasing and inhibiting factors that affect the release of substances from the pituitary gland. The combining form for the pituitary gland is pituit/o. The pituitary gland has two lobes: anterior and posterior.

The Pituitary Gland The hypothalamus also produces antidiuretic hormone and oxytocin, which are released from the posterior pituitary gland.

The Anterior Pituitary Gland Secretions of the anterior pituitary gland: thyroid stimulating hormone (TSH) adrenocorticotropic hormone (ACTH) follicle-stimulating hormone (FSH) luteinizing hormone (LH) interstitial cell-stimulating hormone (ICSH) prolactin growth hormone (GH) melanocyte-stimulating hormone (MSH) 7

The Posterior Pituitary Gland Secretions of the posterior pituitary gland: antidiuretic hormone (ADH) Oxytocin Note: These hormones are produced in the hypothalamus, but stored and released by the posterior pituitary gland. 8

The Thyroid Gland The thyroid gland is a butterfly-shaped gland that secretes the following: triiodothyronine (T3) thyroxine (T4) calcitonin The combining forms for the thyroid gland are thyr/o and thyroid/o.

The Parathyroid Glands The parathyroid glands are usually four glands located on the surface of the thyroid gland. The parathyroid glands secrete parathormone. The combining form for the parathyroid glands is parathyroid/o.

The Adrenal Glands The adrenal glands are two glands located cranial to each kidney; they consist of a cortex and a medulla. Ad- means toward. Ren/o means kidney. The adrenal cortex secretes mineralocorticoids, glucocorticoids, and androgens. The adrenal medulla secretes epinephrine and norepinephrine. The combining forms for the adrenal glands are adren/o and adrenal/o.

The Pancreas The pancreas is a gland located near the proximal duodenum that has exocrine and endocrine functions. The endocrine functions of the pancreas maintain blood glucose levels. The pancreas secretes insulin and glucagon. The combining form for the pancreas is pancreat/o.

The Thymus The thymus is a gland predominant in young animals located near midline in the cranioventral portion of the thoracic cavity. The thymus secretes thymosin. The combining form for the thymus is thym/o.

The Pineal Gland The pineal gland is located near midline in the central portion of the brain and functions in maintaining circadian rhythm. The thymus secretes melatonin. The combining form for the pineal gland is pineal/o.

The Gonads The gonads are glands that produce gametes (sex cells). The gonads are the ovaries in females and the testes in males. The combining form for the gonads is gonad/o.

The Ovaries The ovaries are the female gonads. Secretions of the ovaries: estrogen progesterone The ovaries are covered in more detail in the chapter on reproduction. 16

The Testes The testes are the male gonads. Secretion of the testes: testosterone The testes are covered in more detail in the chapter on reproduction. 17

Medical Terms for the Endocrine System Additional terms for endocrine system tests, pathology, and procedures can be found in the text. Review CourseMate to make sure you understand these terms.