Chapter 36 Thyroid. and Parathyroid Hormones Flashcards
Describe the structure of thyroid gland and thyroid follicle
Thyroid gland:
-located in the anterior neck, below the larynx close to the first part of the trachea
-two lobes on either side of the trachea
-Each lobe is divided into many small lobules that contain thyroid follicles
Thyroid follicle:
-Contain parafollicular cells (C cells)
-Follicle lumen(filled with colloid)
-follicular cells
-Blood vessels
Describe hormones produced in the thyroid gland (synthesis, storage and conversion)
It first transports iodide into the blood and then it produces thyroglobulin which then helps with the production of tyrosine and then transfers it into the blood which then in turn creates T4 and T3 with the help of MIT and DIT and after are all put into a colloid droplet and pushed out where T4 and T3 are secreted into the blood and MIT and DIT are pushed back into the loop
Describe the regulation of thyroid gland hormone secretion (by hypothalamus-pituitary hormones, negative feedback and metabolic signals)
Hypothalamus pituitary hormone regulation is done when:
Hypothalamus stimulates —> TRH which then stimulates—>Anterior pituitary which then stimulates—> TSH which then stimulates thyroid gland to produce thyroid hormones
When the T4 and T3 are too high it sends a negative feedback to Hypothalamus and Anterior pituitary to lower the TRH and TSH production and vice versa when its too low
Describe major biological effects of thyroid hormone
Growth and development
Metabolism
Cardiovascular
Iodine metabolisms
Describe the importance of calcium in physiological functions
- Blood clotting
- Muscle contraction
- Mineralization of bone and tooth
- Neurotransmission
Describe the regulation of calcium homeostasis by hormones and effect of these hormones on three major organs(bone , intestine , and kidney)
- Parathyroid gland
Bone: increase in bone resorption
Small intestine: no direct effect
Kidney:
-Increase in Ca2+ reabsorption
-Increase in production of vitamin D which stimulates absorption of calcium in the intestine - Vitamin D
Bone: Increase in Bone resorption
Small intestine: Increase in Calcium absorption
Kidney: Increase in reabsorption of calcium - Calcitonin
Bone : Decrease in bone resorption
Small intestine : no direct effect
Kidney: decrease in reabsorption of calcium
Describe the clinical feature and laboratory test for diagnosis of Hyperthyroidism
Clinical feature:
-Increased overall metabolism
-Tachycardia(increased heart rate)
-Palpitations
Lab test for diagnosis:
-To diagnose which one, you check their TSH levels if it is low its primary failure , but if it has high TSH levels it is secondary failure
Describe the cause and treatment of hyperthyroidism
CAUSE:
Graves disease(most common cause of hyperthyroidism)
-increased production of thyroid stimulating immunoglobulin
Treatment
Anti thyroid medications
-inhibition of thyroid hormone synthesis
-Inhibition of thyroid hormone synthesis and conversion of T4 to T3
Describe the clinical feature and laboratory test for diagnosis of Hypothyroidism
Clinical feature:
-Low overall metabolism
-Lower heart rate
Lab test for diagnosis:
-TO diagnose which one, you check their TSH levels if it is high its primary failure and if it is low its secondary failure
Describe the cause and treatment of hypothyroidism
Causes
1.Hashimoto’s Thyroiditis -Autoimmune disease
2.Iodide deficiency
Treatment
1. Thyroid hormone replacement therapy
2.Iodine supplementation (if the cause is insufficient dietary iodine)
Describe the difference between primary and secondary hyperthyroidism (including hormone levels)
Primary hyperthyroidism
-defects in thyroid gland itself
-Increase in T4&T3
-Decrease in TSH
Secondary Hyperthyroidism
-Defects in pituitary
-Increase in both T4&T3 and TSH
Describe the difference between primary and secondary hypothyroidism (including hormone levels)
Primary Hypothyroidism
-Defects in thyroid gland itself
-Decrease in T4&T3
-Increase in TSH
Secondary hypothyroidism
-Defects in pituitary
-Decrease in both T4&T3 and TSH
