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The Glands and Hormones of the Endocrine System Chapter 9.1 McGraw-Hill Ryerson Biology 12 (2011) ENDOCRINE SYSTEM • Series of glands that produce hormones to help maintain homeostasis. • Hormones: Chemical regulators that affect other parts of the body. – – – Insulin Growth Hormone Gastrin Hormones • Some glands produce one hormone, some produce many kinds and even other chemicals. • Hormones must be produced and travel through the blood to a target cell or organ. • Levels of hormones vary throughout the day. • Difference between hormone and neurotransmitter – Hormone travels through blood stream to reach another cell – Neurotransmitter travels across synapse to neighbouring cell Coordination • The nervous system and the endocrine system work together to allow the body to function. • Nervous System --> SHORT TERM corrections • Endocrine System --> LONG TERM stability HORMONES • Two types of hormones: – Steroid hormones: made from cholesterol, complex ring structures, fat soluble • Sex hormones, cortisol – Protein hormones: amino acid chains • Insulin, growth hormone • To be susceptible to the effects of a hormone, a cell must have a specific receptor. Mechanism of Action: Steroid Hormones 1. hormones diffuse out of blood stream and into the target cells 2. combine with receptor molecules in cytoplasm Mechanism of Action: Steroid Hormones 3. hormonereceptor complex diffuses into nucleus 4. attaches to chromosomes and activates a gene, initiating transcription and protein synthesis. Mechanism of Action: Protein Hormones 1. 2. hormones diffuse out of blood stream attach to receptors on the cell membranes of target cells Mechanism of Action: Protein Hormones 3. the receptorhormone complex activates the production of enzyme that converts ATP into cyclic AMP (cAMP) 4. cAMP is a messenger that activates various enzymes inside the cell to begin their normal functions. PITUITARY GLAND • This is known as the master gland because it controls a lot of other endocrine glands. • A small sac connected to the hypothalamus. • Pituitary gland stores hormones while the hypothalamus stimulates it to release them. PITUITARY GLAND • The pituitary gland has two lobes: – – The posterior lobe stores and releases hormones produced by the hypothalamus (ex. ADH, oxytocin) The anterior lobe produces and stores its own hormones (ex. TSH, prolactin) Homework • Pg 395 #2, 5, 8, 10
