Endocrine 3 THYROID and PARATHYROID.Key

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Endocrine Glands Prof Menna Abdel-Dayem THYROID GLAND Thyroid Gland Large endocrine gland in the front of the neck formed of 2 lobes connected by an isthmus. Thyroid Gland I. STROMA: ● Capsule: Outer false capsule of pretracheal fascia. Inner true capsule: C.T. cells & fibers, firmly adherent to the gland. ● Trabeculae ● Reticular framework Thyroid Gland II. PARENCHYMA: A. Thyroid Follicles: B. Interfollicular Tissue: A. Thyroid Follicles - The structural & functional units of the gland. - Rounded or oval in shape, surrounded by fenestrated blood capillaries. Lined with cubical epithelium, resting on thin basement membrane & surrounding a lumen filled with acidophilic colloid material (iodinated glycoprotein). Lined with 2 types of cells: 1. Follicular cells (98%) (endodermal): • LM: cuboidal cells with basophilic cytoplasm & central rounded nuclei. In hyperthyroidism, the cells become columnar & in hypothyroidism, the cells become flat squamous cells. 1. Follicular cells • EM: The apex of cells show short microvilli & adjacent cells joined by tight junctions. Have mitochondria, rER, supranuclear Golgi apparatus, ribosomes apical secretory vesicles & lysosomes. Function: secrete thyroid hormones (T3 & T4) under control of TSH. 2. Parafollicular cells C cells 2% Larger cells with paler cytoplasm, so called clear cells (stained with Ag). Present between the basement membrane and follicular cells. Do not reach the lumen of the follicle. 2. Parafollicular cells EM: have mitochondria, rER, Golgi apparatus & basal secretory granules. Function: secrete thyrocalcitonin (belong to APUD cells) →↓↓ blood calcium. B. Interfollicular Tissue: In-between thyroid follicles. ● Reticular C.T. ● Interfollicular cells (tangentially cut follicles), ● Occasional C-cells ● fenestrated blood capillaries. Parathyroid Gland Parathyroid Gland Parathyroid Gland I. STROMA: ● Capsule ● Trabeculae ● Reticular framework II. PARENCHYMA: Cells arranged in anastomosing cords separated by fenestrated capillaries. Two types of cells: chief cells and oxyphil cells. Parathyroid Gland (a) Chief (principal) cells (b) Oxyphil cells More numerous & small Less numerous but larger. No. ↑↑ with age. Polygonal cells with central Oval or rounded cells with eccentric rounded nuclei nuclei Have basophilic cytoplasm & Deeply acidophilic cytoplasm & vesicular nucleus dark nucleus Fine secretory granules Acidophilic granules Parathyroid Gland (a) Chief (principal) cells (b) Oxyphil cells EM: rich in mitochondria, rER, EM: mitochondria Golgi apparatus & secretory granules Function: secrete parathyroid Function not yet known hormone (parathormone) →↑↑ blood calcium .

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Thyroid Gland Parathyroid Glands
Human Physiology Course Thyroid Gland Parathyroid Glands Assoc. Prof. Mária Pallayová, MD, PhD [email protected] Department of Human Physiology, UPJŠ LF April 13, 2020 (10th week – Summer Semester 2019/2020) Hormones and Functions Thyroid gland Parathyroids Thymus Adrenal glands Endocrine pancreas Ovaries, Testes Pineal Pituitary Hypothalamus-Pituitary Axis GIT, adipose tissue, brain, heart, kidney, ... Hormones and Functions Thyroid gland Parathyroids Thymus Adrenal glands Endocrine pancreas Ovaries, Testes Pineal Pituitary Hypothalamus-Pituitary Axis GIT, adipose tissue, brain, heart, kidney, ... Lecture Outline Functional anatomy of the thyroid gland Synthesis, secretion, and metabolism of the thyroid hormones The mechanism of thyroid action Role of the thyroid hormones in development, growth, and metabolism Thyroid hormone deficiency and excess in adults Physiology of the parathyroids Functional Anatomy of the Thyroid Gland two lobes + isthmus (just below the cricoid cartilage) attached to the trachea by connective tissue A normal THGL in a healthy adult weighs about 15-20 g. Functional Anatomy of the Thyroid Gland arterial blood supply: from a superior and an inferior thyroid a., which arise from the external carotid and subclavian a., respectively. venous blood supply: a series of thyroid veins drain into the ext. jugular and innominate vv. ( a rich blood supply to the thyroid gland w/ a higher rate of blood flow per gram than even that of the kidneys). innervation: adrenergic innervation from the cervical ganglia; cholinergic innervation from the n. vagus (regulation of vasomotor function to increase the delivery of TSH, iodide, and metabolic substrates to the THGL). Functional Anatomy of the Thyroid Gland The colloid (a thick, gel-like substance) is a solution composed primarily of thyroglobulin (10-25% the high viscosity), a large protein that is a storage form of the thyroid hormones.
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The Fine Structure of the Parathyroid Gland*
The Fine Structure of the Parathyroid Gland* BY JERRY STEVEN TRIER, M.D. (From the Department of Anatomy, University of Washington School of Medicine, Seattle) PLATES 3 TO 10 (Received for publication, July 29, 1957) ABSTRACT The fine structure of the parathyroid of the macaque is described, and is cor- related with classical parathyroid cytology as seen in the light microscope. The two parenchymal cell types, the chief cells and the oxyphil cells, have been recognized in electron mierographs. The chief cells contain within their cyto- plasm mitochondria, endoplasmic reticulum, and Golgi bodies similar to those found in other endocrine tissues as well as frequent PAS-positive granules. The juxtanuclear body of the light microscopists is identified with stacks of parallel lamellar elements of the endoplasmic rcticulum of the ergastoplasmic or granular type. Oxyphll cells are characterized by juxtanuclear bodies and by numerous mito- chondria found throughout their cytoplasm. Puzzling lamellar whorls are described in the cytoplasm of some oxyphil cells. The endothelium of parathyroid capillaries is extremely thin in some areas and contains numerous fenestrations as well as an extensive system of vesicles. The possible significance of these structures is discussed. The connective tissue elements found in the perivascular spaces of macaque parathyroid are described. INTRODUCTION Other contributions to the present concepts con cerning the human parathyroid can be found in the It is the purpose of the present paper to report some observations on the fine structure of the reports of Bergstrand (7), Morgan (34), Pappen- parathyroid gland employing the electron micro- heimer and Wilens (45), Castleman and Mallory (10), and Gilmour (20).
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Endocrine Pathology Crines… Molecular Signaling Endocrine Pathology Endocrine Pathology
Endocrine Pathology Crines… Molecular signaling Autocrine Paracrine Endocrine Endocrine Pathology Endocrine Pathology Cell signaling system Too much hormone activity Surface receptors Too little hormone activity cAMP and tyrosine kinase system Autoimmune destruction Cytoplasmic receptors Inflammatory destruction Penetrate cell membrane Tumor or vascular destruction Gene activation -> transcription -> translation Space occupying lesions (tumors) Intranuclear receptors Malignant Gene activation -> transcription -> translation Benign 1 Endocrine Pathology Endocrine Pathology All parts of the endocrine system interconnect. All parts of the endocrine system interconnect Pituitary Pathology Too much Too little Especially space occupying lesions The Basics Pituitary Vascular Signaling proteins Anterior are release in hypothalmus. Comes from GI Travel by blood to Controlled by hypothalmus anterior pituitary Cause release of Posterior many activating Hormones orginate hormones further up. System of amplification 2 Pituitary Control Space Occupying Lesions Tumors Embryonic rests Squeeze gland out of existence. Generalized failure Visual field changes Visual Fields Loss of temporal fields. Nasal retina Damage to decusating optic nerve fibers 3 Acromegaly Pituitary Adenomas Rare Growth hormone excess after closing Make nothing or of epiphyses. Prolactin Periosteal bone ACTH, GH,TSH are very rare growth. More often end up with pituitary Diabetes failure. Prognathism Squeeze the daylights out of the
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Thyroid & Parathyroid Glands
THYROID & PARATHYROID GLANDS Objectives: ◧ Editing file • Describe the histological structure of ◧ thyroid & parathyroid glands. Important • Identify and correlate between the different ◧ Doctor notes / Extra endocrine cells in thyroid gland and their functions. • Describe the functional structure of the parathyroid cells. 438 Histology Team Endocrine Block THYROID GLAND STROMA 1- Capsule: dense irregular collagenous C.T. 2- Septa (Interlobular septa) 3- Reticular fibers: Thin C.T. composed mostly of reticular fibers with rich capillary plexus surrounds each thyroid follicle. PARENCHYMA Are the structural and functional units of the thyroid gland. 1- Simple cuboidal epithelium: 2- Colloid: central colloid-filled lumen. a- Follicular (principal) cells b- Parafollicular cells (C cells) (Clear cells) - Pale-stained cells (Clear Cells). (Polygonal/pyramidal cells) N.B. Each follicle is - Simple cuboidal cells. - Found singly or in clusters in between the follicular cells. - Round nucleus with prominent nucleoli. surrounded by thin - Their apices do not reach the lumen of the follicle. L/M: - Basophilic cytoplasm. basal lamina. - Are larger than follicular cells (2-3 times).(larger but less in number) - Apical surface reaches the lumen of the (Acidophilic) - Only 0.1% of the epithelial cells. thyroid follicle. - Have round nucleus - Mitochondria. - RER. (synthesis of thyroglobulin) - Supranuclear Golgi Complex. - Mitochondria. E/M: - Numerous apically-located lysosomes. - RER (moderate). - Numerous dispersed small vesicles - Well-developed Golgi. - The vesicles contain newly formed thyroglobulin. - Numerous apical short microvilli. Function: Synthesis of thyroid hormones (T4 & T3). Secrete calcitonin. 438 Histology Team - Endocrine Block 2 PARATHYROID GLAND They are 4 glands on the posterior of thyroid gland. STROMA 1- Capsule: Each gland has its Thin capsule.
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11 Hormonal Coordination Table 1 the Main Roles of Hormones Produced by the Different Endocrine Glands
B 11 Hormonal ■ B11 Hormonal coordination Table 1 The main roles of hormones produced by the different endocrine glands Endocrine gland Role of the hormones coordination Pituitary Controls growth in children Stimulates the thyroid gland to make thyroxine to control the rate of metabolism 11.1 Principles of hormonal control In women – stimulates the ovaries to produce and release eggs and make the female sex hormone oestrogen Learning objectives In Chapter B 10 you discovered how the nervous system acts to coordinate In men – stimulates the testes to make sperm and the male sex After this topic, you should know: and control your body, reacting in seconds to changes in your internal and hormone testosterone external environments. However, it is very important that your body acts as Thyroid Controls the metabolic rate of the body ● what a hormone is a coordinated whole, not just from minute to minute but from day to day Pancreas Controls the levels of glucose in the blood Figure 2 It isn’t just humans who need ● the main organs of the endocrine and year to year throughout your life. You have a second coordination and hormones – without the hormones from system Adrenal Prepares the body for stressful situations – ‘fight or flight’ response control system to help with this – the endocrine system. their thyroid glands, these tadpoles will ● the role of the pituitary gland. Ovaries Controls the development of the female secondary sexual characteristics and is involved in the menstrual cycle never become frogs The endocrine system Testes Controls the development of the male secondary sexual The endocrine system is made up of glands that secrete chemicals called characteristics and is involved in the production of sperm hormones directly into the bloodstream.
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Primary Hyperparathyroidism
Primary Hyperparathyroidism The parathyroid glands are 4 glands that reside within the thyroid glands: there are two parathyroid glands attached to each thyroid gland. The thyroid/parathyroid glands lie on either side of the trachea (wind pipe) about midway down the neck. The job of the parathyroid glands is to regulate calcium in the body. They secrete a hormone called parathyroid hormone (PTH), and this hormone draws calcium out of the bone where it is stored, as well as acting on the kidney and intestine to increase blood calcium. This is a normal process in response to fluctuations in blood calcium levels. The calcium in the blood is regulated by PTH (increases blood calcium) and calcitonin (a hormone secreted by the thyroid gland to decrease calcium) in order to keep it within a normal range. When the calcium gets too high or too low, symptoms arise. The most common symptoms of high calcium are increased thirst and urination. Other signs include: lethargy, weakness, diarrhea, inappetance, weight loss, tremors or stiffness. In about 50% of dogs with high calcium, urinary stones +/- urinary tract infection is present. Tumors (enlargement) of the parathyroid gland are typically not malignant, but they do over-secrete PTH. In 90% of cases only one of the four glands is enlarged. By one gland enlarging and over-secreting PTH, the three other glands typically shrink and temporarily stop functioning. Parathyroid tumors are suspected based on consistent blood work that shows elevated or normal PTH in the face of elevated calcium (the normal feedback mechanism would mean that when calcium is high, PTH is not needed and therefore is low).
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Parathyroid Disorders THOMAS C
Parathyroid Disorders THOMAS C. MICHELS, MD, MPH, Madigan Army Medical Center, Tacoma, Washington KEVIN M. KELLY, MD, MBA, Carl R. Darnall Army Community Hospital, Fort Hood, Texas Disorders of the parathyroid glands most commonly present with abnormalities of serum calcium. Patients with primary hyperparathyroidism, the most common cause of hypercalcemia in outpatients, are often asymptomatic or may have bone disease, nephrolithiasis, or neuromuscular symptoms. Patients with chronic kidney disease may develop secondary hyperparathyroidism with resultant chronic kidney disease-mineral and bone disorder. Hypo- parathyroidism most often occurs after neck surgery; it can also be caused by autoimmune destruction of the glands and other less common problems. Evaluation of patients with abnormal serum calcium levels includes a history and physical examination; repeat measurement of serum calcium level; and measurement of creatinine, magne- sium, vitamin D, and parathyroid hormone levels. The treatment for symptomatic primary hyperparathyroidism is parathyroidectomy. Management of asymptomatic primary hyperparathyroidism includes monitoring symptoms; serum calcium and creatinine levels; and bone mineral density. Patients with hypoparathyroidism require close monitoring and vitamin D (e.g., calcitriol) replacement. (Am Fam Physician. 2013;88(4):249-257. Copyright © 2013 American Academy of Family Physicians.) CME This clinical content he four parathyroid glands, located 84-amino acid peptide. PTH increases serum conforms to AAFP criteria posterior to the thyroid gland, reg- calcium levels through direct action on bone for continuing medical education (CME). See CME ulate calcium homeostasis through and the kidneys. It stimulates osteoclasts to Quiz on page 227. release of parathyroid hormone resorb bone and mobilize calcium into the T (PTH). Because most parathyroid disorders blood.
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Endocrine System with Special Reference to Thyroid Gland
Odisha Review December - 2012 Endocrine System With Special Reference to Thyroid Gland Soma Mishra Endocrine system consisting of a group of ductless glands viz. pituitary, thyroid, parathyroid, pineal, thymus, gonads, pancreas, adrenal etc. plays a very vital role in governing human behavior. Thyroid is one of the most important glands that control body’s metabolism and calcium level. It secretes iodothyronines that are (tri-iodo- thyronine, thyroxine) and calcitonin. Its secretion is mainly regulated by TRH (thyrotropin releasing hormone) and TSH (thyroid stimulating hormone). It helps in growth (physical, sexual, mental) – development- metamorphosis and calorigenesis- metabolism. The status of thyroid gland may be Euthyroid or Hypothyroid or Hyperthyroid. Hypothyroidism includes cretinism in children and myxoedema in adults. Common causes of hyperthyroid state are Grave’s disease, multinodular goiter, thyroiditis, etc. Any enlargement of thyroid gland, regardless of cause, is called goiter. Some common investigations for Introduction thyroid diseases are estimation of serum T3, T4 The endocrine system or hormonal system and TSH, cholesterol, radioiodine uptake, thyroid is a complex system composed of a group of imaging, etc. Common drug used in ductless glands known as endocrine glands that hypothyroidism is eltroxin, hyperthyroidism is pour their secretions i.e. hormones directly into carbimazole and iodine supplementation in goiter. blood for passage to different body organs known This paper presents a full picture of thyroid gland, as target organs in order to control their its functioning, disorders, and treatments which is functioning, metabolism, cell permeability, growth, very significant for human survival. differentiation and stress conditions. 54 December - 2012 Odisha Review The endocrine system includes the Diseases of the endocrine system result pituitary gland, thyroid gland, parathyroid glands, from too much or too little hormone secretion or adrenal gland, pancreas, ovaries and testes.
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Primary Hyperparathyroidism
Primary Hyperparathyroidism National Endocrine and Metabolic Diseases Information Service What is primary What are the parathyroid hyperparathyroidism? glands? Primary hyperparathyroidism is a disorder The parathyroid glands are four pea-sized U.S. Department of the parathyroid glands, also called glands located on or near the thyroid gland of Health and parathyroids. “Primary” means this disorder in the neck. Occasionally, a person is born Human Services originates in the parathyroid glands. In with one or more of the parathyroid glands primary hyperparathyroidism, one or more in another location. For example, a gland NATIONAL INSTITUTES of the parathyroid glands are overactive. may be embedded in the thyroid, in the OF HEALTH As a result, the gland releases too much thymus—an immune system organ located parathyroid hormone (PTH). The disorder in the chest—or elsewhere around this area. includes the problems that occur in the rest In most such cases, however, the parathyroid of the body as a result of too much PTH—for glands function normally. example, loss of calcium from bones. In the United States, about 100,000 people develop primary hyperparathyroidism each year.1 The disorder is diagnosed most often in people between age 50 and 60, and women are affected about three times as often as men.2 Secondary, or reactive, hyperparathyroidism can occur if a problem such as kidney failure causes the parathyroid glands to be overactive. Parathyroid glands Thyroid gland The parathyroid glands are located on or near the thyroid gland in the neck. 1Bilezikian JP. Primary hyperparathyroidism. In: DeGroot LJ, ed.; Arnold A, section editor.
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The Endocrine System
PowerPoint® Lecture Slides The Endocrine System: An Overview prepared by Leslie Hendon University of Alabama, Birmingham • A system of ductless glands • Secrete messenger molecules called hormones C H A P T E R 17 • Interacts closely with the nervous system Part 1 • Endocrinology The Endocrine • Study of hormones and endocrine glands System Copyright © 2011 Pearson Education, Inc. Copyright © 2011 Pearson Education, Inc. Endocrine Organs Location of the Major Endocrine Glands Pineal gland • Scattered throughout the body Hypothalamus Pituitary gland • Pure endocrine organs are the … Thyroid gland • Pituitary, pineal, thyroid, parathyroid, and adrenal Parathyroid glands glands (on dorsal aspect of thyroid gland) • Organs containing endocrine cells include: Thymus • Pancreas, thymus, gonads, and the hypothalamus Adrenal glands • Plus other organs secrete hormones (eg., kidney, stomach, intestine) Pancreas • Hypothalamus is a neuroendocrine organ • Produces hormones and has nervous functions Ovary (female) Endocrine cells are of epithelial origin • Testis (male) Copyright © 2011 Pearson Education, Inc. Copyright © 2011 Pearson Education, Inc. Figure 17.1 Hormones Control of Hormones Secretion • Classes of hormones • Amino acid–based hormones • Secretion triggered by three major types of • Steroids—derived from cholesterol stimuli: • Basic hormone action • Humoral—simplest of endocrine control mechanisms • Circulate throughout the body in blood vessels • Secretion in direct response to changing • Influences only specific tissues— those with ion or nutrient levels in the blood target cells that have receptor molecules for that hormone • Example: Parathyroid monitors calcium • A hormone can have different effects on • Responds to decline by secreting different target cells (depends on the hormone to reverse decline receptor) Copyright © 2011 Pearson Education, Inc. Copyright © 2011 Pearson Education, Inc.
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Endocrine System
Human Body Series Endocrine System Quiz Answer Key 1. List five functions of the endocrine system: Any five of the following: regulating mood, growth and development; tissue function; the fight or flight response; metabolism; blood glucose levels; sexual function and reproductive processes. 2. In general, the endocrine system is in charge of body processes that happen slowly, such as cell growth. Faster processes like breathing and body movement are controlled by the nervous system . 3. The brain contains these three glands: pituitary gland, hypothalamus , pineal gland (or pineal body) . 4. Hormones are chemical messengers that transfer information and instructions from one set of cells to another. 5. Once a hormone is secreted, it travels from the endocrine gland that produced it through the bloodstream to the cells designed to receive its message. These cells are called target cells . 6. The pancreas produces two important hormones, insulin and glucagon . 7. If the pancreas doesn’t produce enough insulin, the result is diabetes . 8. Parathyroid hormone controls the level of calcium in the blood. 9. The thyroid gland is involved in metabolism , the process by which the fuel in the food we eat is converted into cellular energy. 10. When hormone levels reach a certain normal amount in the blood, the endocrine system has a built-in turnoff process. It is called negative feedback system . 11. Endocrine glands release more than 20 major hormones directly into the bloodstream. 12. The pineal gland secretes melatonin . 13. If the pituitary glands release hormones that stimulate the gonads to produce sex hormones too early, some kids may experience precocious puberty and begin to go through puberty at a very young age.
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The Endocrine System Dr
The Endocrine System Dr. Ali Ebneshahidi Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Endocrine System . The endocrine system interacts with the nervous system to coordinate and integrate body activities by means of hormones . Endocrine tissues and organs secrete hormone into body fluids (mainly blood and lymph) directly using diffusion. Exocrine tissues, such as salivary glands, and sebaceous glands, secrete chemical substances through ducts into an open space. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Five major functions of hormones . a) Regulate metabolic processes (e.g. thyroid hormones). b) Control the rate of chemical reactions (e.g. growth hormone). c) Aid in the transport of substances across the cell membrane of target cells (e.g. insulin and glucagon). d) Regulate water and electrolyte balances (e.g. antidiurectic hormone, calcitonin, and aldosterone). e) Play a vital role in reproduction, growth and development (e.g. estrogens , progesterone, and testosterone). Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Major Endocrine Organs Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Chemistry of Hormones . Hormones are organic compounds secreted by endocrine glands, that have a potent effect in target cells Two types of hormones: . a) Protein hormones: made of amino acids joined by peptide bonds. fat – insoluble; as a result cannot diffuse across the membrane of target cells . most hormones belong to this group except hormones secreted by the gonads (testis and ovary) and the adrenal cortex. b) Steroid hormones: made of fatty acids using cholesterol as a functional group. Fat-soluble; as a result can diffuse into target cells .
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