18.4 & 18.5 Thyroid & Parathyroid Flashcards

1
Q

thyroid gland location

A

anterior surface of trachea, inferior to thyroid cartilage

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2
Q

isthmus

A

slender connection between two lobes of thyroid gland

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3
Q

thyroid follicles

Surround what?

A

hollow spheres lined by simple cuboidal epithelium.. surround follicle cavity.
-each follicle is surrounded by a network of capillaries

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4
Q

follicle cavity

A

holds colloid, fluid containing dissolved proteins

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5
Q

thyroglobulin

Secreted by?

A

globular protein secreted by follicle cells into the colloid

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6
Q

thyroid gland requires _____ for hormone synthesis

A

iodide

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7
Q

thyroid hormone synthesis

A

TSH-sensitive proteins transports iodide into cytoplasm. I- is converted to I+ by thyroid peroxidase at apical membrane surface. Iodide is attached to tyrosine portions of thyroglobulin. these are linked together to form hormones

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8
Q

thyroid peroxidase

A

converts I- to I+, and attaches iodide to tyrosine portions of thyroglobulin at apical membrane surface

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9
Q

thyroxine AKA, % of thyroid secretion?

A

tetraiodothyronine (T4)

-makes up 90% of all thyroid secretions

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10
Q

Thyroid-binding globulins (TBG)

A

transport proteins in the bloodstream that ~70% T3 and T4 attach to.

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11
Q

transthyretin

A

AKA thyroid-binding prealbumin (TBPA)… most of remaining T3 and T4 binds to this in circulation

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12
Q

thyroid hormones bind to receptors…where?

A

in cytoplasm (storage), on mitochondrial surfaces (increase ATP production), and in nucleus (activates genes involved in energy utilization)

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13
Q

calorigenic effect of thyroid hormones

A

cell consumes more energy and generates more heat due to an increased metabolic rate

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14
Q

observed effects of thyroid hormones.. Which hormone is most responsible?

A

strong, immediate, and short-lived increase in rate of cellular metabolism
-T3 is primarily resposible

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15
Q

minimum amount of iodine needed each day to maintain normal thyroid funtion

A

120-150 micrograms I-

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16
Q

C cells

Aka?

A

(clear cells) aka parafollicular cells

-produce the hormone calcitonin

17
Q

CT stimulation, effects, and target cells

A
  • stimulated by elevation of Ca2+ in blood
  • CT inhibits osteoclasts, slowing the rate of Ca2+ release from bone, and stimulates Ca2+ secretion by kidneys
  • stimulates bone growth & mineral deposition in children
  • targets bone and kidneys
18
Q

Four parathyroid glands are embedded in the ____ surface of thyroid gland

A

posterior

19
Q

parathyroid (chief) cells produce..

A

parathyroid hormone PTH

20
Q

two cell populations in parathyroid glands

A

parathyroid (chief) cells and oxyphils

21
Q

PTH stimulation, effects, and target cells

A
  • stimulated by low Ca2+ levels
  • mobillizes calcium from bone, enhances reabsorption of Ca2+ by kidneys, stimulates secretion of calcitrol by the kidneys (also enhances reabsorption)
  • targets bone and kidneys
22
Q

T3 & T4 stimulation, effects, and target cells

A
  • stimulated by TSH
  • increases energy utilization, oxygen consumption, growth, and development
  • targets most cells