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The endocrine system

Learn about the glands, hormones, and functions of the human endocrine system, including pituitary, thyroid, adrenal glands, and more.

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The endocrine system

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  1. The endocrine system

  2. Endocrine system • Is made up of glands that release hormonesinto the bloodstream to deliver messages throughout the body • Messages travel slower than the nervous system, but their affect can last for days

  3. Hormones • Are the chemicals that broadcast messages from the endocrine system • Are released from one part of the body and travel through the bloodstream to affect activities of cells in other parts of the body • Target cells are cells that have hormone receptors for a particular hormone • If there is no receptor for a certain hormone, then no affect will be seen

  4. Glands • Endocrine glands release their secretions into the blood stream • Exocrine glands, such as sweat, release their secretions directly onto their target location

  5. Control of endocrine system • Like most systems, the endocrine system is regulate by negative feedback mechanisms to maintain homeostasis

  6. Human endocrine glands • Pituitary gland • Hypothalamus gland • Thyroid gland • Parathyroid gland • Adrenal glands • Pancreas • Reproduction glands (gonads)

  7. Pituitary gland • Is a bean sized structure that dangles at the base of the skull • It is divided into two parts: the anterior and posterior portions • It secretes 9 hormones that directly regulate many body functions and controls the actions of several others endocrine glands

  8. Posterior pituitary hormones • Antidiuretic hormone (ADH)—stimulates he kidneys to reabsorb water • Oxytocin—stimulates contractions of uterus during childbirth; releases milk in nursing mothers

  9. Anterior Pituitary hormones • Follicle-Stimulating hormone (FSH)—stimulates production of mature eggs and sperm • Luteinizing hormone (LH)—stimulates ovaries and testes; prepare uterus for implantation of fertilized egg • Thyroid stimulating hormone (TSH)—stimulates the synthesis and release of thyroxine from the thyroid gland • Adreno-cortcotropic hormone (ACTH)—stimulates the release of some hormones from the adenal cortex

  10. Anterior pituitary hormones • Growth hormone (GH)—stimulates protein synthesis and growth in cells • Prolactin—stimulates milk production in nursing mothers • Melanocyte-stimulating hormone (MSH)—stimulates melanocytes of the skin, increasing their production of melanin

  11. Hypothalamus • Is the part of the brain above the pituitary gland • Controls secretions of the pituitary gland • Regulates when and how much hormones the pituitary gland secretes

  12. Thyroid gland • Is located at the base of the neck and wraps around the trachea • Has a major role in regulating the body’s metabolism • Releases thyroxine, the hormone which controls the metabolic activity of all cells in the body • Hyperthyroidism—causes nervousness, elevated body temperature, increased metabolic rate, weight loss, increased blood pressure • Hypothyriodism—may causes a goiter, and reverse symptoms of hyperthyroidism

  13. Parathyroid glands • Found on the back surface of the thyroid gland • Hormones from the parathyroid and thyroid act to maintain homeostasis of calcium levels in the blood • Parathyroid hormone (PTH)—increase calcium reabsorption in the kidneys and cause the digestive system to increase uptake of calcium as well

  14. Adrenal glands • Are pyramid like structures that sit on top of the kidneys • They release hormones that help the body prepare for and deal with stress • Releases many hormones (about 2 dozen) • Epinephrine and norepinephrineare released during times of stress to increase heart rate, blood pressure, blood flow to muscles, stimulate extra glucose into blood for instant energy, etc • We commonly call this adrenaline

  15. Pancreas • In additions to producing enzymes that break down food in the small intestine, the pancreas also makes hormones • Serves as both an endocrine and exocrine gland • Secretes both insulin and glucagon to help keep the level of glucose in the blood stable • Insulin—stimulates cells to remove sugars from the blood and store them as fat or glycogen • Glucagon—stimulates the liver to break down glycogen and to release sugars back into the blood • Diabetes results from improper functioning of these hormones

  16. Reproductive glands • The gonads serve 2 important functions • 1. the production of gametes • 2. the secretion of sex hormones

  17. Ovaries • The female gonads • Produce the female sex hormones of estrogen and progesterone • Estrogen—is responsible for development of eggs and the formation of the physical characteristics associated with the female body • Progesterone—prepares the uterus for the arrival of the developing embryo

  18. The testes • Male gonads • Produce testosterone • Is required for normal sperm production and the development of the physical characteristics of the male body

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