the thyroid gland Flashcards
where is the thyroid gland located
located in the neck, lobes and isthmus
what does the thyroid gland have relations to
larynx trachea laryngeal nerves parathyroid glands
what does the thyroid gland consist of
2 lobes lateral to the trachea, isthmus, follicles follicle cells surrounding colloid, parafollicular cells (C cells) that produce calcitonin
the regulation of thyroid hormone secretion with the thyrotropin releasing hormone and the thyroid stimulating hormone.
what cells are thyroid follicles
simple columnar cuboidals the colloid contains rich thyroglobulin and rich vascularisation with parrafollicular cells
explain the steps of synthesis and secretion
1.iodide trapping takes place
2.there is synthesis of thyroglobulin
3. the oxidation of iodide
4.iodiniation of tyrosine
5.the coupling of T1 AND T2 CELLS
6.pinocytosis and the digestion of the colloid
7.secretion of thyroid hormones
8. transport in blood
what cells transport thyroid hormones
90% by t4 cells 10% by t3 cells
what are the affinitys of binding hormones
TBG thyroid binding globulin has the highest affinity
thyroid binding prealbumin intermediate affinity
albumin low infinity high capacity
actions of the thyroid hormone
the thyroid sends signals all through the body as all of the body has t3 and t4 receptors cells
1. thyroid hormones increase basil metabolic rate
2.due to bar increasing cellular metabolism of lipids carbohydrates and proteins increase
3.it stimulates the increase of sodium potassium pumps ATP pase
4.affects the growth and maturation of tissues, cell metabolism, heat production and oxygen consumption
what are the physiological effects of the thyroid hormone
- it increases oxygen consumption and heat production
2.positive chronotopic and inotropic effects on the heart
3.increases sensitivity to adrenergic affectors
increase in gut motility and bone turnover
4.increases hepatic glycogenolysis and glucogeneisis
what are ways hyperthyroidism can show in the body
1.thyrotoxicosis (graves disease)
toxic adenoma
toxic multinodular goitre
chronic thyroiditis
how does hypothyroidism show in the body
in the newborn
cretinism and lack of myelination
in children lack of growth and disproportionate
how can you see hypothyroidism in adults
muscle weakness, mental slowness, tired fatigued and cold with slow intestinal peristalsis and slow renal function,
what causes non toxic goitre
an iodine deficiency
causes of thyroid hormone resistance
mutation of the receptor and high levels of of both TSH and thyroid hormones
