Thyroid Flashcards

1
Q

TRH from the hypothalamus stimulates ___ secretion from the anterior pituitary gland

(control of thyroid hormone secretion)

A

TSH

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2
Q

Thyroid hormone synthesis/secretion occurs within the thyroid gland in the presence of __

(control of thyroid hormone secretion)

A

TSH

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3
Q

Negative feedback causes the hypothalamus to stop or slow production of TRH which then causes the ___ pituitary to stop or slow release of TSH

A

anterior

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4
Q

thyroid hormones, think:

A

T3, T4

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5
Q

Anything that increases cellular energy demand causes an increase in __ production (e.g., Cold environment, hypoglycemia, high altitude, pregnancy
)

A

T3/T4

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6
Q

Lateral lobes (wings) on each side of the trachea projecting upward to just below the ___

Lobes connected by an ___ located anterior to the trachea

(thyroid location)

A

larynx

isthmus

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7
Q

Largest of pure endocrine glands

A

Thyroid gland

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8
Q

A thyroid has an ___ blood supply

A

extensive

fer all them hormones

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9
Q

___ are the functional units of the thyroid

A

Follicles

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10
Q

A follicle is a sphere with its wall consisting of __ cells

A

follicular

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11
Q

This inside of this unit is called the __

thyroid micro

A

colloid

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12
Q

___ cells reside in between follicles

A

Parafollicular

produce calcitonin but not considered a thyroid hormone

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13
Q

The inactive form of thyroid hormone

Much more abundant, but less potent

A

Tetraiodothyronine (Thyroxine, T4)

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14
Q

The active form of thyroid hormone

Much more potent, less abundant

A

Triiodothyronine (T3)

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15
Q

Made in small quantities by parafollicular cells, helps to regulate calcium levels of the blood

(not a “thyroid hormone” only made in the thyroid)

A

Calcitonin

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16
Q

Follicular cells pull ___ ions from the blood stream

17
Q

Follicular cells are also producing ____

A

thyroglobulin (TGB) (glycoprotein-carbon chain of many amino acids)

18
Q

produced in endoplasmic reticulum

Packaged in the Golgi apparatus

Released by exocytosis into the lumen (colloid)

A

thyroglobulin (TGB)

glycoprotein-carbon chain of many amino acids – tyrosine

19
Q

Iodide requires ___ to make iodine (the useable form for thyroid hormone synthesis)

____ oxidizes the iodide into iodine (I2)

A

oxidation

Perioxidase

20
Q

(Insuffienct ___ lead to thyroid issues)

A

tyrosine, iodine, or peroxidase

21
Q

(T3 and T4 are __ soluble)

22
Q

At this point there is now TGB and iodine (I2) roaming in the colloid

Simultaneously TGB and ___ begin to react with each other forming bonds (at the tyrosine portions of TGB)

“middle step”

23
Q

One iodine to one tyrosine

A

monoiodotyrosine (MIT)

24
Q

Two iodines to one tyrosine

A

diiodotyrosine (DIT)

25
These MIT and DIT molecules continue to form bonds to one another
MIT + DIT = T3 (3 iodine molecules) DIT + DIT = T4 (4 iodine molecules)
26
The colloid is then pulled back into the follicular cells by ___
pinocytosis This colloid contains the T3 and T4
27
Once back in the follicular cell, this colloid is engulfed by a lysosome which digests the TGB and cleaves off the ___
T3 and T4
28
This T3 and T4 is sent out of the cell, into the interstitial space, into the bloodstream
Because they are weak in terms of water solubility, more than 99% of both T3 and T4 are then bound to transport proteins (thyroxine-binding globulin; TBG) in the blood stream
29
This is the “glue” binding the MIT, DIT, T3, T4
TGB – Thyroglobulin
30
This is the transport protein found in the blood stream that carries the T3/T4 to their target cells after synthesis of them is complete
TBG Thyroxine Binding Globulin
31
Actions of Thyroid Hormones (T3/T4)
Increase basal metabolic rate (BMR) Stimulates synthesis of additional Na+/K+ pumps Helps to regulate the metabolism Can enhance actions of some catecholamines Works with hGH and insulin to accelerate body growth
32
BMR is the rate of oxygen consumption under normal conditions When increased, BMR causes metabolism of carbohydrates, proteins, and lipids (Actions of Thyroid Hormones (T3/T4))
Increase basal metabolic rate (BMR)
33
This causes increased ATP production and consumption by the constant turnover of the Na+ and K+ These reactions release heat as a byproduct This heat helps to raise and maintain the body temperature
Stimulates synthesis of additional Na+/K+ pumps
34
Stimulates protein synthesis Increases use of glucose and fatty acid for ATP production Increases lipolysis and enhances cholesterol excretion
Helps to regulate the metabolism
35
T3 and T4 upregulate ____ in the presence of these substances
beta adrenergic receptors The upregulation can explain why hyperthyroid patients experience increased heart rates, and blood pressure
36
____ of T3/T4 in fetal growth, infancy or childhood causes severe mental retardation and stunted bone growth
Deficiency