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Cards In This Set
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What does the endocrine system consist of?
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- glands that secrete chemicals (hormones) into the blood
- the hormones then travel throughout body to their target site to initate their effect |
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What are the major organs of the endocrine system?
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- hypothalamus
- pituitary gland - parathyroid glands (on dorsal aspect of thyroid gland) - thyroid gland - adrenal glands - pancreas - ovaries (female) - testes (male) |
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What is the function of the endocrine system?
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- maintenance of internal environment, adaptation to stress, control of growth and metabolism, and control of reproduction
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How does the endocrine system contrast with the nervous system?
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- actions are slower to take effect yet last longer and are more widespread throughout body
- it indirectly affects organs at a distance by secreting chemicals into body |
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What is a gland?
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- a group of specialized cells that synthesize, store, and release hormones into blood
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How do hormones work?
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- they are released into the blood stream and circulate throught body to target cells that have receptors for hormone
- either stimulates or inhibits activity of cell |
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What are the three catagories of hormones based on chemical makeup?
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- hormones derived from amino acid Tyrosine (thyroxine, triiodothyronine), secreted from thyroid gland
- hormones derived from proteins: calcitonin, parathyroid hormone, pituitary and pancreatic hormones, hormones from hypothalamus - steroid hormones: cortisol, aldosterone, estrogen, progesterone, testosterone - all derived from cholesterol |
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How are protein hormones carried in the blood? How do they act on target cells?
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- they circulate freely in blood but cannot diffuse through cell membrane (both because they are hydrophilic)
- receptors must be located on cell membrane of target cell |
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How are steroid and thyroid hormones carried in the blood? How do they act on target cells?
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- they require a protein carrier to circulate blood and they diffuse easily through cell membrane (both because they are hydrophobic)
- receptors are located inside target cells |
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How are hormones secreted into the blood?
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- in "pulses" by specific stimulus (neural or blood borne)
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Are they present in large or small concentrations in the blood after being secreted?
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- very small concentrations
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What is a receptor?
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- in or on a cell - it interacts with hormones in a particular way
- a specific hormone binds to a specific receptor - the interaction triggers a response in the cell |
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What is a receptor?
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- in or on a cell - it interacts with hormones in a particular way
- a specific hormone binds to a specific receptor - the interaction triggers a response in the cell |
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What is a receptor?
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- in or on a cell - it interacts with hormones in a particular way
- a specific hormone binds to a specific receptor - the interaction triggers a response in the cell |
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Explain receptors for hydrophobic hormones.
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- located in cytoplasm or nucleus
- hormone is released by carrier protein and then enters cell where it binds with its receptor - new hormone/receptor complex will the bind to the DNA within the nucleus to eventually alter various activities of cell (increase or decrease production of proteins) |
