13071970
Description
Flashcards by J yadonknow, updated more than 1 year ago
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Created by J yadonknow
about 6 years ago
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| Question | Answer |
| Bridge | Isthmus |
| Histology | Functional unit: Follicle Layer of simp cub. epi follicle cells around a colloid-filled lumen |
| Thyroid Hormones are | T4 thyroxine, T3 Trriodothyronine AA iodinated tyrosine hormones |
| What are they bound to and why? | Bound to Thyroxine-binding Globulin Or Albumin Prevents renal excretion |
| T1/2 | rT3 - 5 hours T3 - 1-3 Days T4 - 5-7 Days |
| TH synthesis (8) | 1. Thyroglobulin synth + secreted by follicle cells into colloid lumen. 2. I- trapped and A.T. into lumen. 3. I- [O] -> I2 by TPO 4. I2 attached to Tyr in colloid forming DIT/MIT 5. I-tyr linked to form T3/T4 6. Thyroglobulin endocytosed into follicle cells and combined with a lysosome. 7. Lysosomal Ez cleave T3/T4 from TG and hormone diffuses into circulation. 8. Bind to T-B G or Albumin |
| Major Advantage of Thyroid | Thyroid Gland can store TH in colloid Release when I2 is scarce |
| What conversion takes place in perinephral tissues? | T4->T3 |
| Principle action of TH | Metabolism - increases mobilisation of glucose/fat/protein. Calorigenic effect - 'c reg. + adaptation to cold environment. Growth + Development -synergy w/ GH |
| -FDBCK of TH | external conditions Hypothalamus A.P. TSH TG T3/T4 |
| What does TSH stimulate? (3) | Every aspect of thyroid functioning e.g: 1. Promote release of TH into blood. 2. Increased activity of Iodine pumps. 3. Iodination of tyrosine to increase production of TH's. |
| Hypothyroid causes | Underactive thyroid Iodine deficiency |
| Symptoms of hypothyroidism | met rate decreases, weight increases Low plasma T3/T4 High TSH and TRH |
| Hashimoto's Disease | Autoimmune AB attack: TSH R TPO Thyroglobulin Causes autodestruction of Follicles |
| Treatment for hypothyroidism | L-thyroxine |
| hyperthyroidism (4) | Excessive sweating bulging eyes ^ met. rate and O2 consumption ^HR |
| Graves Disease | Abnormal AB mimics TSH + TSH R, induces T3/T4 release |
| Treatment for hyperthyroidism | Surgical removal of thyroid gland Radiactive Iodine to selectively destroy most active thyroid glands Drugs that interfere w/ I- -> I2 conversion |
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