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Download 29.6 The Endocrine System and Hormones
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29.6 The Endocrine System and Hormones KEY CONCEPT The endocrine system produces hormones that affect growth, development, and homeostasis. 29.6 The Endocrine System and Hormones Hormones influence a cell’s activities by entering the cell or binding to its membrane. • Glands are organs of the endocrine system. 29.6 The Endocrine System and Hormones • Hormones are chemical signals that influence cell’s activities. – produced by glands – travel through the circulatory system – affects cells with matching receptors target cell hormone bloodstream receptor not a target cell 29.6 The Endocrine System and Hormones • There are steroid hormones and nonsteroid hormones. – Steroid hormones enter the cell. – Nonsteroid hormones do not enter the cell. Steroid hormone Steroid hormone diffuses through the cell membrane Nonsteroid hormone binds to receptor on the cell membrane. Non-steroid hormone receptor Steroid hormone binds to a receptor within the cell. receptor nucleus The hormone and receptor enter the nucleus and bind to DNA DNA Steroid hormone causes DNA to make proteins. proteins Receptor stimulates a second messenger with in the cell. Second messenger starts a series of chemical reactions in the cytoplasm. Second messenger reactions activate enzymes. second messenger Chemical reactions activated enzymes 29.6 The Endocrine System and Hormones Endocrine glands secrete hormones that act throughout the body. • There are many glands located throughout the body. HYPOTHALAMUS PITUITARY THYROID THYMUS ADRENAL GLANDS PANCREAS FEMALE GONADS :OVARIES MALE GONADS : TESTES – Hormones travel through the bloodstream to cells with matching receptors. 29.6 The Endocrine System and Hormones The hypothalamus interacts with the nervous and endocrine systems. • The hypothalamus is a gland found in the brain. – a structure of both the nervous and endocrine systems – produces releasing hormones, sent to pituitary gland • The pituitary gland is found below the hypothalamus in the brain. – controls growth and water levels in blood – produces releasing hormones sent throughout the body 29.6 The Endocrine System and Hormones • Releasing hormones stimulate other glands to produce hormones. – allow glands to communicate with one another – are used in temperature regulation 29.6 The Endocrine System and Hormones Hormonal imbalances can cause severe illness. • Abnormal hormone levels affect homeostasis. • Hormonal imbalances might be treated with surgery or medicine. • Steroids, a pituitary tumor, or some prescription drugs can make the pituitary overactive and indirectly cause problems.
