EX 2; Thyroid Gland Flashcards by Courtney Kast

What is the gross anatomy of the thyroid

2 lobes
located inferior to the larynx
one of the largest endocrine glands
4 cm long/wide
20 grams

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What is the vascularization of the thyroid gland

more capillaries per gram than the kidney

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The internal structure of the thyroid consists of what

hollow follicles formed by spheres of epithelial cells; follicles are filled with colloid, lots of protein

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The follicular cells of the thyroid regulate production of what

two iodine-containing hormones

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What is thyroid hormone synthesis stimulated by

TSH, which comes from the pituitary

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Iodide is transported into follicular cells and then does what

diffuses into the colloid

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Follicular cells also synthesize this, which is exocytosed into colloid

thyroglobulin; lots of tyrosine

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Iodidie oxidized by this and is linked to thryoglobulin; attaching iodide to tyrosine creating MITs and DITs

thyroid peroxidase

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The mono-iodo-tyrosine and di-iodo-tyrosie combine to form what

MIT + DIT = T3

DIT + DIT = T4

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The thyroid hormone stored in colloid is attached to thyroglobulin, why is this necessary

the protein backbone is not lipid soluble, so it traps the hormone

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What three additional actions does TSH stimulate

stimulates iodide uptake
protein synthesis
mitosis in follicular cells; hypertrophy and hyperplasia

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Thyroglobulin droplets are pinocyotsed into follicle cells and the droplets fuse with what and what occurs

lyosomes and T3 and T4 are released by lysosomal hydrolysis and diffuses into capillaries

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10% of secreted thyroid hormone is what variety

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80% of T4 is converted to T3 in which organs

liver and kidney (and certain target cells)

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Where are the receptors for thyroid hormone located and what are the different forms

they are in most cells of the body

α and β forms

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Expression of receptor isoforms differs in respect to what two things

stage of development (α first)
target tissue (regulate and stimulate cell metabolism)

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These two things combined regulate gene transcription

dimerized receptors + TH

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Thyroid hormone is used to stimulate what

metabolism

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thyroid hormone stimulates cellular metabolism by increasing the activity of what three things

Na/K-ATPase activity
increases substrate availability
produces heat

What does thyroid hormone do to the mitochondria

increases size and number

Insufficient TH during fetal development causes what condition

cretinism

True or False

diseases of the thyroid gland are the most common of endocrine diseases

True

How common is thyroid disease in women and in men

2-5% in women (childbearing years most common)
0.5% of men
twice as many people have thyroid disease than the number of people diagnosed

What is the primary cause of hypothyroidism

a primary defect in the thyroid gland

95% due to iodine deficiency

What are three consequences of an iodine deficiency

insufficient production of TH lack of negative feedback growth of goiter because hypertrophy or hyperplasia of follicular cells

Hypothyroid due to an iodine deficiency was primarily reversed due to what for additive

iodized salt

This is also known as Hashimoto's, which affects the enzymes synthesizing thyroid hormone

autoimmune thyroiditis

What two additional primary defects can lead to hypothyroidism

damage or destruction due to surgery/radiation, etc. | dysfunction associated with other illness

What is a second defect that can result in hypothyroid

problem in the pituitary; release or receptor issue

What are some mild symptoms of hypothyroid

cold sensitivity low metabolism weight gain

What are some moderate symptoms of hypothyroid

fatigue poor circulation GI/mental function is sluggish

What are some severs symptoms of hypothyroid

myxedema due to accumulation of glycosaminoglycans in the ECF

What are four primary defects that can cause hyperthyroid or thyrotoxicosis

thyroid tumor Graves disease thyroiditis thyrotoxicosis facitia

This is when antibodies to TSH receptor stimulate the gland, the feedback mechanism is disrupted, and is more common in women

Grave's disease

This is when too much thyroid hormone due to ingesting of endogenous thyroid hormone

thyrotoxicosis factitia

What are four symptoms of hyperthroid

abnormal levels of circulating hormone goiter metabolic and nervous system symptoms; upregulation ocular symptoms; fat pad behind eye is bulging

What are some options for treatment of hyperthyroid

surgically/radioactivity destroy the gland | anti-thyroid drugs

What are some dental problems associated with hypothyroid

abnormal response to drugs; increased sensitivity myxedema; extra CSF diminished cardiac and respiratory functions

What are some dental problems associated with hyperthyroid

early eruption of teeth must avoid catecholaminergic drugs; sensitive to epinephrine, sympathetic already on "high alert" thyroid storm salivary gland damage due to radiation treatments

Thyroid hormone up regulates these receptors

beta adrenergic

Upregulation of beta adrenergic receptors by thyroid hormone increases sensitivity to what

catecholamines

When the thyroid hormone up regulates beta adrenergic receptors, what does this due to the sympathetic system

involved with the sympathetic system; NE and E | increasing HR and dilating respiration

The thyroid hormones also regulate production of this

Thyroid hormone is important for this development

CNS development and function

Thyroid hormone regulates what in adults

normal neural responses in adults; hence why if you have limited TH in fetal development = cretinism