29 6 The Endocrine System and Hormones KEY

29. 6 The Endocrine System and Hormones influence a cell’s activities by entering the

29. 6 The Endocrine System and Hormones • Hormones are chemical signals that influence

29. 6 The Endocrine System and Hormones • There are steroid hormones and nonsteroid

29. 6 The Endocrine System and Hormones Endocrine glands secrete hormones that act throughout

29. 6 The Endocrine System and Hormones The hypothalamus interacts with the nervous and

29. 6 The Endocrine System and Hormones • Releasing hormones stimulate other glands to

29. 6 The Endocrine System and Hormones Hormonal imbalances can cause severe illness. •

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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 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 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 Steroid hormone causes DNA to make 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.