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29 Cards in this Set
- Front
- Back
How many lobes make up the thyroid gland? Where are they?
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2; on each side of the trachea in the anterior neck
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What makes up the folicle?
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cuboidal epithelial cells
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what shape is the folicle?
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circular
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what is the functional unit?
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the folicle
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Where is the thyroid hormone contained
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In the glycoprotein thyroglobin, in the colloid
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What happens to the epithelial cells when the gland is stimulated?
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they get a columnar shape
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What does the thyroid secret?
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Throxine (t4), triiodothyronine (t3)
reverse t3 |
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What is secreted the most?
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t4
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Which is the more biologically active form?
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T3, therefore t4 is converted into this form
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What is colloid?
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protein rich fluid that synthesizes/stores T3 and T4
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Name 3 places iodide is actively concentrated?
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thryroid, salivary, and gastroinstetrinal
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How many grams of iodide does the thyroid trap per day?
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70-80 micrograms
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What is Na+I- cotransport's fxn? where is it located?
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it traps iodide. in the basal lamina of the thyroid cells
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What is Na+I- cotransport's fxn? where is it located?
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it traps iodide. in the basal lamina of the thyroid cells
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Describe Iodide trapping and turn over?
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1. Iodide is trapped by Na+ I- cotransport
2. It moves across the apical cell and into the follecular lumen 3. It is oxidized to Iodine 4.It's incorportated to the tyrosine residuals in the thyrogobulin |
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synthesis of thyrogobulin ?
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synthesized in the ER of the follicle and packed by the golgi
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What does the Thryroglobulin do after it is synthesized?
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1.Thyroglobulin moves into the lumen
2. residual tyrosines are iodonized to MIT and DIT 3. The MITs and DITs couple to make t3 and t4 |
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How many months of hormones does thyroid store in the colloid of the follicle?
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2-3 months
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How many months of hormones does thyroid store in the colloid of the follicle?
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2-3 months
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Describe the secretion of the thyroid hormone
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1. Thyrogobulin is endocytosed into the thyroid cells
2. Lysosomal protease releases the thyroid hormone into circulations |
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What is the major binding protein of t3 and t4? Where is it synthesized?
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Thyroxine-binding globulin (t3 & t4). The liver.
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what are the fxns of th thyroxine-binding globulin?
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1. keeps a large circulating resivoir of t4
2. keeps it from being secreted in the urine |
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What happens to the iodinated tyrosine residues that were not incorporated into thyroid hormone?
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the thyroid gland recycles them
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What effects does TSH have on thyroid gland activity?
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1. growth proliferation of follicle cells
2.Iodide trapping 3.Proteolysis of the thyroglobin 4.Secretion of the thyroid hormone 5. Iodination of tyrosine to form thyroid hormone 6. Endocytosis of colloid 7. Synthesis of thyroglobulin |
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What regulates secretion of TRH/TSH
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1. Iodide availability
2. Calories 3. Exposure to cold 4. Drugs 5. Anxiety/stress 6. Negative feedback |
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What are the major effects of thyroid hormone
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fetal/child brain development
basal metabolic rate |
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What is an indication of hyperthyrodism?
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an elevated heart rate
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What happens to thy thyroid homrone once inside?
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1. Free t3 and T4 inter by energy requiring carrying processes
2. most of t4 converted to t3 by deionating enzymes 3. T3 binds to receptors on target cells 4. Proteins are made |
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What protiens do the thyroid hormone stimulate the synthesis of?
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Na+/K+ ATPase
Mitochondrial enzymes Enzyme that effect the BMR |