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12 Cards in this Set
- Front
- Back
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The second messenger system |
Uses chemical messengers (hormones) that are released into the blood. |
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Hormones control several major processes |
Reproduction Growth and development Mobilization of body defenses Maintenance of much of hormone homeostasis Regulation of metabolism |
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Hormone overview |
Hormones are produced by specialized cells Cells secrete hormones into extra cellular fluids Blood transfers hormones to target sites These hormones regulate the activity of other cells |
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Hormones are classified chemically as |
Amino acid based, which includes protein, peptides, amines. Steroids which are made from cholesterol. Prostaglandins which are made from highly active lipids. |
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Mechanisms of hormone action |
Hormones affect only certain tissues or organs. Target cells must have specific protein receptors. Hormone binding alters cellular activity. |
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Effects caused by hormones |
Changes in plasma membrane permeability or electrical state. Synthesis of proteins such as enzymes. Activation or inactivation of enzymes. Stimulation of mitosis. Promote of secretory activity. |
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2 mechanisms in which hormones act |
Direct gene activation Second messenger system |
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Direct gene activation (steroid hormone activation) |
Diffusion through the plasma membrane of target cells Enter the nucleus Bind to a specific protein within the nucleus Binds to specific sites on the cells dna. Activation of genes that results in synthesis of new protein. |
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Second messenger system (non steroid hormone) |
Hormone binds to a membrane receptor Hormone does not enter the cell Sets off a series of reactions that activates an enzyme Catalyzes a reaction that produces a second messenger molecule Oversees additional intracellular changes to response of the target cells to the hormone |
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Control of hormone release |
Hormone levels in the blood are mostly maintained by negative feedback A stimulus or low hormone levels in the blood triggers the release of more hormones Hormone release stole once an appropriate levels in the blood is reached |
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Hormonal stimuli of endocrine glands |
Most common stimuli Endocrine glands are activated by other hormones |
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Humoral stimuli of endocrine glands |
Changing blood levels or certain ions stimulate hormone release Humoral indicates various body fluids such as blood and bile Examples parathyroid hormone, calcitonin and insulin |
