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43 Cards in this Set
- Front
- Back
What are the organs considered to be part of the classical endocrine system?
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-hypothalamus
-pituitary gland -thyroid gland -parathyroid glands -thymus -adrenal glands -pancreas -ovaries (female) -testis (male) |
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What are hormones?
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-they are biochemical substances that exert a physiological effect
-they are messengers secreted into blood or body fluids to target organ/cell |
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What are the four ways that hormones work?
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-exocrine
-paracrine -endocrine -autocrine |
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How do exocrine hormones work?
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secreted externally or into a duct, affect distant targets
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How do paracrine hormones work?
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secreted by one cell, acts on an adjacent cell in the same tissue. affects cells of a different type.
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How do endocrine glands work?
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secreted internally
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How do autocrine hormones work?
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factor acts on the same cell (itself), a cell of the same type.
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What is the HPT Axis?
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hypothalamic-pituitary-target organ
-to control protein synthesis is to control cell metabolism, intra/intercellular transport, F&E balance, growth & development, reproduction. |
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For a hormone to have an action it must first interact with a what?
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receptor
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What is receptor up-regulation?
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when there is a low hormone concentration it causes the cell to increase the number & sensitivity of receptors
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What is receptor down-regulation?
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when there is a high hormone concentration is causes the cell to decrease the number & sensitivity of receptors
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What are the characteristics of water soluble hormones?
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large, high molecular weight molecules that cannot readily pass through the cell membrane.
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How do water soluble hormones interact with the cell?
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they activate the receptors on the plasma membrane (PM)
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What are the characteristics of lipid soluble hormones?
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-bound to plasma proteins
-fat soluble -freely dissolve through lipid bi-layer of the PM -steroids |
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How do most lipid‐soluble hormones regulate protein synthesis?
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at the level of RNA transcription
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Describe negative feedback.
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-most common method of hormonal control
-rising level of hormone will feed back to the source glad to shut down further production |
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Describe positive feedback.
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-a mechanism in which hormone stimulates the production of more hormone until a physiologic action occurs (ie. menstrual cycle & male ejaculation)
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Why do hormones go bad?
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-failure of feedback mechanism
-hyporesponsiveness -hyposecretion -hypersecretion -target cell may fail to respond |
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What is primary gland failure?
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-gland fails
-inadequate hormone produced -blood level of gland secreted hormone is too low -tropic hormones are high |
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What would tropic vs. peripheral hormone levels be with primary gland failure?
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-tropic hormones are high
-peripheral hormones are low |
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What is secondary gland failure?
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-hypothalamus/pituitary fails to stimulate tropic hormone
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What would tropic vs. peripheral hormone levels be with secondary gland failure?
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-tropic hormones are low
-peripheral hormones are low |
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Growth hormone equals what?
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somatotropin
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What does GH do physiologically?
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stimulates nutrient metabolism & tissue growth
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What is GH target organ?
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liver
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What does the thyroid gland secrete?
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-T3 (3 atoms of iodine)
-T4 (4 atoms of iodine) -structurally they are similar but T4 is more potent |
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What is the function of thyroid hormone?
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-stimulation of energy production
-stimulation of the heart & inotropic/chronotropic -promotion of growth & development of the brain & other nervous system components and the development of skeletal mm. |
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How does the HP Axis apply to the thyroid?
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-hypothalamus
-TRH (releasing hormone) -anterior pituitary -TSH -thyroid gland -T3, T4, thyroglobulin |
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What is necessary for T3/T4 production?
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iodine
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What hormone is secreted from zona glomerulosa?
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aldosterone
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What hormones are secreted from zona fasicularis?
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glucocorticoid = cortisol
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What hormone is secreted from zona retucularis?
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adrenal androgen
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What are the three zones/layers of the adrenal cortex?
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-zona glomerulosa
-zona fascularis -zona retucularis |
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Reminder: What is secreted from the adrenal medulla?
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epinepherine
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What is important to remember about glucocorticoids and mineralocorticoids?
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glucocorticoids can sometimes fill the receptor of a mineralcorticoid. they are basically a "good enough" fit for each other.
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What are the physiologic effects of cortisol?
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-anti-inflammatory: inhibits activity of phospholipase A2, thus reducing LT, PG production
*decreased capillary permeability of WBC *decreases immune system function -metabolic effects *raises blood glucose for immediate use *glucogenesis from AA's *increased appetite |
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What are the main functions of cortisol?
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-increase blood sugar
-suppress the immune system -aid in fat, protein & carbohydrate metabolism |
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How do the adrenal glands fit into the HP Axis?
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-hypothalamus is stimulated (stress, infection, pain, sleep, trauma)
-hypothalamus releases corticotropin-releasing hormone (CRH) -CRH acts on the anterior pituitary -ACTH is released and acts on adrenal cortex -adrenal cortex releases cortisol -cortisol acts on target organ(s) |
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Why is cortisol secretion critical for survival?
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-it is critical to balance stress in the body.
-without cortisol the body will not balance to homeostasis during stressors. -cortisol helps protect from damaging effects of stress by suppressing inflammation/immunity |
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How many parathyroid glands are there?
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four
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What do the parathyroid glands do?
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-regulate Ca++
-parathyroid hormone (PTH) acts on bones & renal tubules to cause increase in Ca++ levels |
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What is the function of PTH?
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-increase osteoclast activity
-increase release of Ca++ from bone matrix to ECF -increase renal Ca++ reabsorption -activates vitamin D |
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What is the function of calcitonin?
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it is the antagonist of PTH (does the opposite)
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