Endocrine System

• Pre-Movie:http://kidshealth.org/kid/closet/movies/how_the_body_works_interim.html

• Major structures:– Hypothalamus– Pituitary– Pancreas and many other endocrine glands

Endocrine System Key Functions

• Regulates body temperature, metabolism, development, and reproduction

• Maintains homeostasis

• Regulates other organ systems

Hormones

• Hormones – substances released by cells that regulate the activity of other cells in the body (chemical messengers of the endocrine system)

• Some of the functions of hormones include the following:1) regulating growth, development, behavior, and

reproduction2) coordinating the production, use, and storage of energy3) maintaining homeostasis (temperature regulation,

metabolism, excretion, water & salt balance)4) responding to stimuli from outside the body

Endocrine Glands and Tissues

• The human body makes more than 40 hormones, and the body must regulate the release of the hormones

• Endocrine glands – ductless organs that secrete hormones directly into either the bloodstream or the fluid around cells

• Several organs contain cells that secrete hormones– Brain– Stomach– Small intestine– Kidney– Liver– Heart

Hormones Act On Target Cells• Target cell – a specific cell that a hormone

binds to and acts on (carries the message to)» The binding of the hormone with its receptor signals the

target cell to change its activity

Nervous System Works With Endocrine System

• Nerve impulses alone can increase or decrease secretion of some hormones– Example: a baby nursing on a mother’s breast stimulates

the release of the hormone oxytocin, which in turn stimulates the release of milk from the mother’s mammary glands

• The endocrine system plays an important role in homeostasis; different hormones moving through the bloodstream affect specific target tissues and the amounts of various hormones must be maintained within a very narrow range.

Endocrine System Control• The hypothalamus

coordinates the activities of the nervous and endocrine systems & issues instructions (hormones) to the pituitary gland

• The pituitary gland secretes many hormones, including some that control endocrine glands elsewhere in the body

The thyroid gland makes and releases thyroid hormones, which regulate the body’s metabolic rate and promote normal growth of the brain, bones, and muscles during childhood. They also affect reproductive functions and maintain mental alertness in adults.

• Adrenal glands – endocrine organs located above each kidney; the adrenal medulla releases “fight-or-flight” hormones that prepare the body for action in emergencies (increase heart rate, blood pressure, blood glucose level, blood flow to the heart and lungs, etc.)

Pancreas

• The pancreas contains clusters of cells called islets of Langerhans that release hormones

• Insulin – a hormone that lowers blood glucose levels by promoting the accumulation of glycogen in the liver

Regulating Reproduction

• The ovaries and the testes secrete hormones that regulate reproduction, affecting the formation of gametes & controlling sexual behavior/cycles. The hormones also stimulate the development of secondary sex characteristics, such as breast size, hair growth, and muscle development.– Ovaries: secrete estrogens and progesterone– Testes: produce testosterone

Females: ovaries

Males: testes

Endocrine System Practice and Enrichment

• http://www.purposegames.com/game/2588• http://www.funtrivia.com/playquiz/quiz25283

71cf2a60.html• http://www.execulink.com/~ekimmel/drag_oa

/endo.htm• http://www.quia.com/jg/284670.html