II. Embryology

  1. Thyroid Gland develops from Tongue root (foramen cecum)
  2. Formed by 5th-6th week of development

III. Anatomy

  1. Images
    1. ThyroidAnterior.gif
  2. Normal Adult Thyroid weighs 20-25g
  3. Components
    1. Two Lateral lobes
    2. Isthmus centrally connects the lobes
  4. Near structures
    1. Recurrent laryngeal nerve
    2. Parathyroid Glands

IV. Physiology

  1. Stressors stimulate increased Thyroid function
    1. Puberty
    2. Pregnancy
    3. Physiologic stress
  2. Hypothalamus
    1. Thyrotropin Releasing Hormone (TRH) released
    2. TRH passes down pituitary stalk to pituitary
  3. Anterior Pituitary
    1. Thyroid Stimulating Hormone (TSH) released
    2. TSH passes into circulation to Thyroid
  4. Thyroid
    1. Iodine is absorbed from circulation
    2. Thyroxine (T4) released into circulation
    3. Triiodthyronine (T3) is also 20-30% produced in the Thyroid (remainder is peripheral conversion of T4)
  5. Peripheral Tissues
    1. Triiodothyronine (T3) produced from T4 deiodination
  6. Circulation
    1. Thyroid Binding Globulin (TBG) binds T4 and T3
      1. T4 is 99.96% protein bound in serum (<1% is Free T4, the active form)
      2. T3 is 99.7% protein bound in serum
    2. T4 and T3 stimulate all metabolic processes
      1. T3 is several times more potent than T4
  7. Effects of Thyroid hormone
    1. Peripheral tissue oxygen utilization and basal metabolic rate increased
    2. Positive chronotropic and ionotropic cardiovascular effects, with secondary increased Cardiac Output
    3. Decreases Systemic Vascular Resistance via arteriole dilation
    4. When Thyroid hormone is in excess (e.g. Thyroid Storm), high output Heart Failure may result
  8. Feedback Loop
    1. Increased T4 and T3 levels suppress TRH and TSH

V. References

  1. Mason, Herbert and Swadron in Herbert (2019) EM:Rap C3 3(11):1-10

Images: Related links to external sites (from Bing)

Related Studies

Ontology: Thyroid Diseases (C0040128)

Definition (MEDLINEPLUS)

Your thyroid is a butterfly-shaped gland in your neck, just above your collarbone. It is one of your endocrine glands, which make hormones. Thyroid hormones control the rate of many activities in your body. These include how fast you burn calories and how fast your heart beats. All of these activities are your body's metabolism.

If your thyroid gland is not active enough, it is called hypothyroidism. It can make you gain weight, feel fatigued, and have difficulty dealing with cold temperatures.

If your thyroid is too active, it makes more thyroid hormones than your body needs. That condition is called hyperthyroidism. Too much thyroid hormone can make you lose weight, speed up your heart rate, and make you very sensitive to heat.

There are many causes for both conditions. Treatment involves trying to reset your body's metabolism to a normal rate.

The thyroid gland can also develop cancer.

Dept. of Health and Human Services Office on Women's Health

Definition (NCI) A non-neoplastic or neoplastic disorder that affects the thyroid gland. Representative examples include hyperthyroidism, hypothyroidism, thyroiditis, follicular adenoma, and carcinoma.
Definition (CSP) condition in which there is a deviation from or interruption of the normal structure or function of the thyroid gland, which is a highly vascular endocrine gland that produces the thyroid hormones which are concerned in regulating the metabolic rate of the body.
Definition (MSH) Pathological processes involving the THYROID GLAND.
Concepts Disease or Syndrome (T047)
MSH D013959
ICD9 246.9, 240-246.99
ICD10 E00-E07.9 , E07.9, E00-E07
SnomedCT 14304000, 190311002, 190232008, 191036006, 154649009
LNC LA17778-4, LA15157-3
English Disease, Thyroid, Diseases, Thyroid, Thyroid Diseases, Unspecified disorder of thyroid, THYROID DISORDER, Disorders of thyroid gland, Thyroid disorder NOS, Disorder of thyroid, unspecified, THYROID DIS, Disease of thyroid gland, thyroid disorder, thyroid disorder (diagnosis), Thyroid gland disorders, Disorder thyroid, Disorder of thyroid NOS, Thyroid disorders, Thyroid Diseases [Disease/Finding], thyroid gland disease, thyroid gland diseases, abnormal thyroid, diseases of the thyroid gland, thyroid disease, thyroid diseases, thyroid gland disorder, thyroid disorders, thyroid abnormal, thyroid gland disorders, Disorders of thyroid gland (E00-E07), Thyroid disorder NOS (disorder), Thyroid gland--Diseases, Diseases of the thyroid gland, Thyroid Disease, Thyroid disease, Thyroid disorder, disease (or disorder); thyroid, thyroid; disorder, Disease of thyroid gland, NOS, Disorder of thyroid gland, NOS, Thyroid disorder, NOS, Disorder of thyroid gland, Disease of thyroid gland (disorder), Disorder of thyroid gland (disorder), Thyroid Disorders, Thyroid Gland Diseases, Thyroid Gland Disease, Thyroid Gland Disorders, Thyroid Gland Disorder, DISORDERS OF THYROID GLAND
Italian Patologia della tiroide, Patologie della ghiandola tiroidea, Disturbo della tiroide, Patologia della tiroide NAS, Disturbo non specificato della tiroide, Malattie tiroidee
Dutch schildklieraandoening NAO, aandoening schildklier, niet-gespecificeerde schildklieraandoening, aandoening; schildklier, schildklier; aandoening, Schildklieraandoening, niet gespecificeerd, schildklieraandoeningen, thyroïdaandoening, Schildklieraandoening, Schildklierziekte, Schildklierziekten, Ziekte, schildklier-
French Trouble de la thyroïde non précisé, Trouble thyroïdien SAI, TROUBLE THYROIDIEN, Trouble thyroïdien, Troubles de la glande thyroïde, Maladies thyroidiennes, Maladies de la thyroïde
German unspezifische Funktionsstoerung der Schilddruese, Erkrankungen der Schilddruese NNB, Erkrankung der Schilddruese, Krankheit der Schilddruese, nicht naeher bezeichnet, SCHILDDRUESENSTOERUNG, Erkrankungen der Schilddruese, Schilddruesenerkrankung, Schilddrüsenkrankheiten
Portuguese Doença da tiroideia NE, Afecção NE da tiroideia, Afecção da tiroideia, ALTERACAO TIROIDEIA, Doenças da Glândula Tireoide, Doenças da Tireoide, Anomalia da tireóide, Doenças da tiroideia
Spanish Trastorno no especificado del tiroides, Trastorno de tiroides NEOM, enfermedad de la glándula tiroides (trastorno), TIROIDES, TRASTORNO, trastorno tiroideo, SAI (trastorno), trastorno tiroideo, SAI, Enfermedades de la Glándula Tiroides, Enfermedades Tiroideas, trastorno tiroideo, Trastorno de tiroides, Trastornos de la glándula tiroides, trastorno de la glándula tiroides, trastorno de la glándula tiroides (trastorno), enfermedad de la glándula tiroides, Enfermedades de la Tiroides
Japanese 甲状腺障害, 甲状腺障害NOS, 詳細不明の甲状腺障害, コウジョウセンショウガイNOS, コウジョウセンショウガイ, ショウサイフメイノコウジョウセンショウガイ
Swedish Sköldkörtelsjukdomar
Finnish Kilpirauhasen sairaudet
Czech Porucha štítné žlázy, Porucha štítné žlázy NOS, Poruchy štítné žlázy, Blíže neurčená porucha štítné žlázy, thyreoidea - nemoci, nemoci tyreoidey, tyreoidea - nemoci, nemoci štítné žlázy
Korean 상세불명의 갑상샘의 장애
Polish Choroby tarczycy
Hungarian Pajzsmirigy nem meghatározott betegsége, Pajzsmirigy betegségek, Pajzsmirigy betegség k.m.n., Pajzsmirigy betegség
Norwegian Sykdommer i skjoldbruskkjertelen, Skjoldbruskkjertelsykdommer

Ontology: Thyroid Gland (C0040132)

Definition (FMA) Lobular organ the parenchyma of which consists of ductless, glandular follicles filled with colloid. Examples: thyroid gland proper, accessory thyroid gland, lingual thyroid gland.
Definition (MSHCZE) Žláza s vnitřní sekrecí tvořená dvěma laloky spojenými úzkým můstkem (isthmem). Je umístěna na krku v oblasti chrupavky štítné. Histologicky je patrná folikulární struktura; v centru folikulů je hlenovitá hmota a jsou zde shromažďovány prekurzory hormonů. Hormony štítné žlázy (thyroxin a trijodthyronin) obsahují jod, který je důležitý pro její funkci. Hormony mají význam pro látkovou výměnu a pro rozvoj mozku v dětství. Jejich tvorba je řízena z předního laloku hypofýzy TSH. Mimo to jsou ve štítné žláze buňky (C-buňky, parafolikulární) produkující hormon kalcitonin, který ovlivňuje hospodaření s vápníkem. Hlavní choroby t. jsou struma, záněty (tyroiditidy), poruchy funkce (hypertyreóza, hypotyreóza), karcinomy. (cit. Velký lékařský slovník online, 2012 http://lekarske.slovniky.cz/ )
Definition (UWDA) Lobular organ the parenchyma of which consists of ductless, glandular follicles filled with colloid. Examples: thyroid gland proper, accessory thyroid gland, lingual thyroid gland.
Definition (NCI_NCI-GLOSS) A gland located beneath the larynx (voice box) that makes thyroid hormone and calcitonin. The thyroid gland helps regulate growth and metabolism.
Definition (NCI) An endocrine gland located at the base of the neck that produces and secretes thyroxine and other hormones. Thyroxine is important for metabolic control.
Definition (NCI_CDISC) An endocrine gland located at the base of the neck that produces and secretes thyroxine and other hormones. Thyroxine is important for metabolic control. (NCI)
Definition (MSH) A highly vascularized endocrine gland consisting of two lobes joined by a thin band of tissue with one lobe on each side of the TRACHEA. It secretes THYROID HORMONES from the follicular cells and CALCITONIN from the parafollicular cells thereby regulating METABOLISM and CALCIUM level in blood, respectively.
Definition (CSP) endocrine gland normally situated in the lower part of the front of the neck; secretes, stores and releases the iodine dependent thyroid hormones thyroxine and triiodothyroine which play major endocrine roles in regulating metabolic rate; also secretes thyrocalcitonin.
Concepts Body Part, Organ, or Organ Component (T023)
MSH D013961
SnomedCT 69748006
LNC LP32941-4, LP7636-6, MTHU007792
English Gland, Thyroid, Glands, Thyroid, Thyroid Gland, Thyroid Glands, Thyroid, Thyroids, Glandula thyroidea, thyroid, thyroid glands, thyroids, thyroid gland, THYROID GLAND, Thyroid gland, Thyroid structure, Thyroid structure (body structure), Thyroid gland, NOS, Thyroid, NOS, Head and Neck, Thyroid
French Corps thyroïde, Glande thyroide, Thyroïde
Swedish Sköldkörtel
Czech štítná žláza, tyreoidea, glandula thyreoidea, thyreoidea
Finnish Kilpirauhanen
Japanese 甲状腺
Latvian Vairogdziedzeris
Polish Tarczyca, Gruczoł tarczowy
Norwegian Skjoldbruskkjertel, Glandula thyreoidea
Portuguese Glândula Tireoide, Tireoide, Glândula Tiroide, Tiroide
Spanish estructura de la glándula tiroides (estructura corporal), estructura de la glándula tiroides, glándula tiroides, Glándula Tiroides
German Glandula thyreoidea, Schilddrüse
Italian Tiroide
Dutch Glandula thyreoidea, Schildklier