Thyroxine T 4 and Triiodothyronine T 3 Both T 3 and T 4 increase cellular

Thyroxine t 4 and triiodothyronine t 3 both t 3 and t

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Thyroxine (T 4 ) and Triiodothyronine (T 3 ) Both T 3 and T 4 increase cellular metabolism
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Hypothalamus releases TRH TRH Pituitary gland Anterior lobe Anterior lobe TSH Adenohypophysis releases TSH Normal T 3 and T 4 concentrations, normal body temperature HOMEOSTASIS Homeostasis Disturbed Decreased T 3 and T 4 concentrations in blood or low body temperature Homeostasis Restored Increased T 3 and T 4 concentrations in blood Thyroid gland Thyroid follicles release T 3 and T 4 Regulation of Thyroid Secretion 1.Decreased concentration of T 3 & T 4 2.Triggers release of TRH from the hypothalamus 3.TRH targets the adenohypophysis 4.Causes release of TSH 5.TSH targets the thyroid gland 6.Triggers release of T 3 and T 4 7.Normal levels of T 3 and T 4 are restored Thyrotropin- releasing hormone
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The Thyroid Gland C thyrocyte cell Thyroid follicle Cuboidal epithelium of follicle Thyroglobulin stored in colloid of follicle Follicles of the thyroid gland LM x 260 Capillary Capsule Follicle cavities C thyrocyte cell T thyrocyte cells Thyroid follicle Histological details of the thyroid gland showing thyroid follicles and both of the cell types in the follicular epithelium
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The C Thyrocytes (aka, parafollicular cells ) C Thyrocytes are parafollicular cells Produce calcitonin (CT) Regulates blood calcium ion levels by causing a reduction in the ion concentration Targets: Osteoclasts of bones: inhibits osteoclast activity, therefore calcium ions do not leave the bones to enter the blood Nephrons of kidneys: stimulates calcium ion excretion
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Left lobe of thyroid gland Parathyroid glands The location and size of the parathyroid glands on the posterior surface of the thyroid lobes The Parathyroid Glands Two major types of cells associated with the parathyroid glands: 1. Parathyroid cells (principal cells) 2. Oxyphil cells
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Thyroid follicles Blood vessel Connective tissue capsule of parathyroid gland Parathyroid and thyroid gland Parathyroid (principal) cells Oxyphil cells Parathyroid gland The histology of the parathyroid and thyroid glands A histological section showing parathyroid cells and oxyphil cells of the parathyroid gland c LM x 600 LM x 100 Parathyroid cells monitor blood calcium ion levels - Produce parathyroid hormone (PTH) when calcium is low > PTH increases blood calcium ion levels Oxyphil cells are thought to be immature or inactive parathyroid cells
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The Parathyroid Glands Release parathyroid hormone (PTH) Targets osteoclast cells and kidneys Causes osteoclast cells to remove calcium ions from bone Osteoclasts will put calcium ions into the blood thus increasing blood calcium ion levels Causes kidneys to reduce calcium ion excretion thus increasing blood calcium ion levels Causes kidneys to produce calcitriol Calcitriol promotes the small intestine to absorb calcium ions into the bloodstream, thus increasing blood calcium ion levels
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Homeostasis - Calcium
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KEY TO PITUITARY HORMONES Hypothalamus Pituitary Gland Thyroid Gland
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