Fisiologia do Sistema Endócrino

Hormônios foliculares da Tireóide

Profa Cristina Maria Henrique PintoProfa. Dra. Associada III do Depto. Ciências Fisiológicas

CCB-UFSC

ESQUEMAS PARA FACILITAR O ESTUDO E O ACOMPANHAMENTO DE MINHAS AULAS

Porém, lembre-se que nada substitui a leitura de um bom livro-texto, como os abaixo recomendados:

“Fisiologia” Costanzo, 2011, 4ª Ed. (Ed. Elsevier)“Fundamentos de Fisiologia”, Berne et al, 2006, 4ª Ed.(Ed.

Elsevier)“Berne & Levy: Fisiologia” Koeppen & Stanton, 2009, 6ª Ed.

(Ed. Elsevier)“Fisiologia” Berne et al., 2004, 5ª Ed. (Ed. Elsevier)

“Tratado de Fisiologia Médica” Hall, J. E., 2011, 12ª Ed. (Ed. Elsevier)

“Fisiologia” Aires, M. M., 2012, 4ª Ed. (Ed. Guanabara Koogan/GEN)

AS FIGURAS AQUI UTILIZADAS FORAM RETIRADAS DE WEBSITES E, QUANDO POSSÍVEL, SÃO SEGUIDAS PELO

ENDEREÇO NA INTERNET. 

PRESERVE O DIREITO AUTORAL CITANDO A FONTE.

extraído, enquanto disponível, de: http://www.pathguy.com/lectures/thyroid.htm#intro

This is the normal appearance of the thyroid gland on the anterior trachea of the neck. The thyroid gland has a right lobe and a left lobe connected by a narrow isthmus. The normal weight of the thyroid is 10 to 30 grams. It cannot easily be palpated on physical examination.

This gland is located in the lower part of the neck, below the Adam's apple. The gland wraps around the windpipe (trachea) and has a shape that is similar to a butterfly - formed by two wings (lobes) and attached by a middle part (isthmus).

Características da glândula tireóide

A practical guide to clinical medicine, UCSD School of Medicine : http://medicine.ucsd.edu/clinicalmed/head.htm

http://www.healthopedia.com/pictures/site-of-thyroid-scan.html

Willians, 2004

Características da glândula tireóide

HISTOLOGIA DA TIREÓIDE

http://biology.clc.uc.edu/fankhauser/Labs/Anatomy_&_Physiology/A&P202/Endocrine_System/Endocrine_Histology.htm

extraído, enquanto disponível, de: http://www.biosbcc.net/barron/physiology/endo/thyr.htm

Os hormônios foliculares tireoideanos:

Características Síntese Armazenamento Secreção Circulação sistêmica

Tiroxina (t4)

Os Hormônios foliculares tireoideanos

Triiodotironina (t3)

extraído, enquanto disponível, de: http://smid.blueprint.org/smidblast_browse.php?gi=586092

extraído, enquanto disponível, de: http://www.colorado.edu/epob/epob1220lynch/18endo2.html

Triiodotironina (T3) e Tiroxina (T4)

Os Hormônios foliculares tireoideanos

Síntese, armazenamento e secreção dos hormônios tireoideanos

“Human Physiology”, Fox, 2004, 8th ed.

Síntese, armazenamento e secreção dos hormônios tireoideanos

Dietary iodine Daily intake (µg)

Dairy products 52

Grains 78

Meat 31

Mixed dishes 26

Vegetables 20

Desserts 20

Eggs 10

Iodized salt 380

Other iodine sources (µg)

Vitamin/mineral prep (per tablet) 150

Amiodarone (per tablet) 75,000

Povidone iodine (per mL) 10,000

Ipodate (per capsule) 308,000

extraído, enquanto disponível, de: http://www.thyroidmanager.org/Chapter15/15-frame.htm

Table 2-1. Some common sources of iodine in adults USA (1,2)Fontes dietéticas de Iodo

Overall schema of thyroid hormone effects. The upper portion represents intracellular actions resulting from T3 binding to its nuclear receptor (TR), which is linked to thyroid regulatory elements (TREs) in target DNA molecules. The lower portion catalogs all the various whole body effects of thyroid hormone that sustain increased oxygen consumption and permit disposal of the excess CO2, heat, and metabolic products. Levy et al., 2006

Efeitos metabólicos dos hormônios foliculares tireoideanos

Os hormônios foliculares tireoideanos:

Transporte Modo de ação Ações fisiológicas Regulação da secreção

extraído, enquanto disponível, de: http://connection.lww.com/products/braun-carie/PreviewChapters.asp

Regulação da secreção dos

hormônios tireoideanos

Regulação da secreção dos hormônios tireoideanos

extraído, enquanto disponível, de: http://www.colorado.edu/eeb/web_resources/thyroid/ Veja online: http://biologyinmotion.com/thyroid/

Regulação da secreção dos hormônios tireoideanos

extraído, enquanto disponível, de: http://www.colorado.edu/eeb/web_resources/thyroid/ Veja online: http://biologyinmotion.com/thyroid/

extraído, enquanto disponível, de: http://www.biosbcc.net/barron/physiology/endo/thyr.htm

Regulação da secreção dos hormônios tireoideanos

extraído, enquanto disponível, de: http://www.biosbcc.net/barron/physiology/endo/thyr.htm

Regulação da secreção dos hormônios tireoideanos

http://www.colorado.edu/epob/academics/web_resources/thyroid/thyrost1.gif

Regulação da secreção dos hormônios tireoideanos

extraído, enquanto disponível, de: http://www.colorado.edu/eeb/web_resources/thyroid/ Veja online: http://biologyinmotion.com/thyroid/

Como a deficiência de Iodo na dieta resulta em bócio

endêmico (hipotireoidismo com hipertrofia da tireóide)

“Human Physiology”, Fox, 2004, 8th ed.

http://www.colorado.edu/epob/academics/web_resources/thyroid/thyrost1.gif

O Bócio endêmico/hipotireoidismo pode ser evitado, incluindo-se pequenas quantidades de Iodo na dieta, por exemplo, no sal de cozinha

extraído, enquanto disponível, de: http://www.colorado.edu/eeb/web_resources/thyroid/ Veja online: http://biologyinmotion.com/thyroid/

A importância dos hormônios tireoideanos

no desenvolvimento ósseo

HT NA REMODELAGEM ÓSSEA NA VIDA ADULTA

Efeitos diretos do T3: proliferação e diferenciação dos

osteoblastos

Efeitos indiretos do T3: diferenciação dos

osteoclastos por sinalização dos osteoblastos

Process of bone remodeling. Signals carried by canalicular and syncytial routes from interior osteocytes, and endocrine signals to resting osteoblasts and lining cells generate local paracrine cytokine signals to nearby osteoclasts and osteoclast precursors. Osteoclasts also recruit their own precursors by paracrine signals. The osteoclasts resorb an area of mineralized bone, and local macrophages complete the clean-up of dissolved elements. The process then reverses to formation as osteoblast precursors are recruited to the site and differentiate into active osteoblasts. These lay down new organic matrix and mineralize it. Thus, new bone replaces the previously resorbed mature bone. Levy et al., 2006

A, A normal 6-year-old child (left) and a congenitally hypothyroid 17-year-old child (right) from the same village in an area of endemic cretinism. Note especially the short stature, obesity, malformed legs, and dull expression of the mentally retarded hypothyroid child. Other features are a prominent abdomen, a flat broad nose, a hypoplastic mandible, dry scaly skin, delayed puberty, and muscle weakness. Hand x-ray films of a 13-year-old normal child (B) and a 13-year-old hypothyroid child (C). Note that the hypothyroid child has a marked delay in development of the small bones of the hands, in growth centers at either end of the fingers, and in the growth center of the distal end of the radius. Berne et al., 2004

HIPOTIREOIDISMO E A FORMAÇÃO ÓSSEA

Disfunções de secreção de hormônios da Tireóide

Função acima do normal – Hipertireoidismodisfunções orgânicas: do metabolismo

basal, da freq. cardíaca e da freq. respiratória; do peso corporal e

intolerância ao calorDisfunções psíquicas: ansiedade, paranóia, fobias, labilidade emocional e hipercinesia.Função abaixo do normal – Hipotireoidismo

disfunções orgânicas: do metabolismo basal, do peso corporal e intolerância ao

frio

Sobre os Hormônios Tireoideanos:- Estimulam a maioria das funções

metabólicas e o consumo de oxigênio.- Uns dos responsáveis pelo crescimento e

desenvolvimento corporal e cerebral. 

Receptores para Horm. Tireoideano na cél-alvo:

- Membros dos receptores esteróides.- T3 liga-se mais avidamente ao receptor que

T4.

- Estimulam a atividade RNA-transcricional.- Aumentam a atividade Na+ - K+ ATPásica.

Excesso de H. Tireoideanos em adultos:- Aumenta o consumo de oxigênio.

- Aumenta a produção de calor.- Aumenta o consumo de reserva energética.

- Geralmente causa perda de peso.- Causa perda de cálcio ósseo.

- Causa fraqueza muscular esquelética.

Deficiência de Hormônios Tireoideanos:

- Afeta o desenvolvimento do SNC (cretinismo).

- Retarda o crescimento da criança.- Retarda o fechamento das epífises ósseas.- Lentifica a função mental (retardo mental).

- Lentifica a mobilização energética.- Pode levar ao coma e morte.

Sobre os hormônios tireoideanos

Congenital Hypothyroid:Congenital hypothyroidism is a relatively common disorder which is screened for at birth. Thyroid hormone is necessary for brain development in the first two years of life. If it is not present in adequate amounts during this period of time, permanent brain damage will occur. As thyroid hormone is necessary for linear growth, severe growth retardation occurs if it is absent during childhood. If treatment is started while the epiphyses are open and undamaged, growth will resume. In addition to the above problems, these patients may have all the other signs and symptoms of hypothyroidism.

Congenital Hypothyroid: Typical History                        

A 44 yr. old man who has always been cared for by his mother is presented. He is severely retarded and cannot communicate. He is only 40” tall, his epiphyses are still open, although severely damaged. He has very thick, dry skin. His tongue is thick, and he has a saddle nose. He still has his primary teeth; the secondary teeth have not erupted.

Alguns exemplos de distúrbios da secreção tireoideanaCretinismo

Veja mais em: http://arbl.cvmbs.colostate.edu/hbooks/pathphys/endocrine/thyroid/thyroid_preg.html

Myxedematous endemic cretinism in the Democratic Republic of Congo. Four inhabitants aged 15-20 years : a normal male and three females with severe longstanding hypothyroidism with dwarfism, retarded sexual development, puffy features, dry skin and hair and severe mental retardation. mixedema: edema com acúmulo de mucopolissarídeos/glicosaminoglicanas pois a tiroxina diminui a síntese dos ácidos hialurônico e condroitino- sulfúrico

extraído, enquanto disponível, de: http://www.thyroidmanager.org/Chapter20/20-frame.htm http://members.tripod.com/~Histology_2/conj_ic.htm

Alguns exemplos de distúrbios da secreção tireoideanacretinismo

Hypothyroidism during fetal development can lead to cretinism. This results as thyroid hormones are responsible for the development of the nervous system. Sufferers have mental impairment and often suffer from dwarfism as their linear growth is affected. The patient in the image below is suffering from cretinism.

http://cal.man.ac.uk/student_projects/2002/MNBY9APB/THETHYrOIDCLINICAL.htm

Male from Ecuador about 40 years old, deaf/mute, unable to stand or walk. Use of the hands was strikingly spared, despite proximal upper-extremity spasticity. From DeLong et al (107).http://www.thyroidmanager.org/Chapter20/20-frame.htm

Alguns exemplos de distúrbios da secreção tireoideanaCretinismo

Three women of the Himalayas with stage II goiters.

extraído, enquanto disponível, de: http://www.thyroidmanager.org/Chapter20/20-frame.htm

Hipotireoidismo secundário:

Deficiência de iodo na dieta (na criança pode provocar o cretinismo)

Hipertrofia da tireóide no bócio endêmico

Alguns exemplos de distúrbios da secreção tireoideana

Primary Hypothyroid: Typical History43 y/o patient with the chief complaint of "decreased energy." She complains of fatigue, inability to finish tasks, sleeping more, yet always being tired. She has also noticed a decreased cold tolerance, constipation, and dryness of the skin. She comments that she is always cold, even in the summer. She has a positive family history for thyroid problems, but does not know the details

Primary hypothyroidism occurs when disease of the thyroid gland prevents it from producing adequate amounts of thyroid hormone. Symptoms may vary from mild to severe and from nonspecific to very specific. In general, all metabolic processes slow down. Patients are often fatigued, and may also have depression, decreased intellectual function, and, rarely, overt psychosis (...).

Alguns exemplos de distúrbios da secreção tireoideana

http://www.pathguy.com/lectures/thyroid.htm

Hipotireoidismo no adulto(exemplo de mixedema)

Quer saber mais sobre Fisiopatologia da Tireóide?

Veja em:

http://www.thyroidmanager.org

Thyroid Disease Manager offers an up-to-date analysis of thyrotoxicosis, hypothyroidism, thyroid nodules and cancer, thyroiditis, and all aspects of human thyroid disease and thyroid physiology. It

provides physicians, researchers, and trainees (as well as patients) around the world with an authoritative, current, complete, objective, free, and down-loadable source on the thyroid.

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