Thyroid Gland Anatomy Physiology Structure 2 main lobes

Thyroid Gland Anatomy & Physiology

Structure 2 main lobes § Right Lateral § Left Lateral Highly vascularized 50% of thyroid glands have a 3 rd lobe! • Pyramidal lobe WHY? ! Left Lateral Lobe Right Lateral Lobe Trachea

Cellular Make-Up • Follicles Produce & secrete hormones cavities lined with follicular cells surround colloid Composed of thyroglobulin Used to produce hormones

lls e C r a l • Extrafollicular cells u c i ll o f ra a P Cellular Make-Up Where are they?

Hormones How many does the thyroid produce? 2 from follicular cells § Thyroxine T 4 1 from extrafollicular cells § Calcitonin T 4 T 3 § Triiodothyronine T 3 3 TH Thyroid hormone CT

Thyroxine & Triiodothyronine • Regulate metabolism of carbohydrates, lipids, & proteins • Increase rate of protein synthesis • Stimulate breakdown and mobilization of lipids Also… TH production is controlled by thyroid stimulating hormone (TSH) from the pituitary. Needed for normal growth & development Determine basal metabolic rate (BMR) • How many calories are needed to maintain life

Hormone Production • What is necessary to produce T 3 & T 4? DIET • Where does it come from? Starts as iodide… Digestion Blood IODINE Iodide pump Thyroid Gland Converts & concentrates IODINE!

Hormone Production • Iodine + tyrosine = used to synthesize TH FROM What happens when TH levels in the blood get too low? The pituitary releases more TSH until levels normalize. Thyroglobulin in colloid Breakdown Follicular cells break apart compound TH released into bloodstream

Hormones