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Endo/Repro: Week 1 > Downing: Pineal, Thyroid and Parathyroid > Flashcards

Downing: Pineal, Thyroid and Parathyroid Flashcards

1
Q

When is the pineal gland the largest?

A

first decade of life

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2
Q

Describe the gross structure of the pineal gland.

A

Cone shaped

Attached by a STALK to the roof of the 3rd ventricle

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3
Q

What composes 95% of cells in the pineal gland?

A

pinealocytes

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4
Q

What do pinealocytes produce?

A

melatonin

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5
Q

What are the supporting elements in the pineal gland?

A

glial cells (astrocytes)

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6
Q

What happens to the pineal gland as you get older?

A

Brain sand!

concretions of hydroxyapetite and Ca that increase w/ age (good tumor markers)

*displacement from midline is evidence of cerebral tumor

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7
Q

What is the nerve supply to the pineal galnd?

A

Sympathetic (Epi) that END on pinealocytes

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8
Q

What are the functions of the pineal gland

A

produces melatonin

  1. low light periods
  2. suppresses gonadotrophin secretion via hypo inhibition
  3. retards gonadal growth and fxn
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9
Q

What may be associated w/ SAD?

A

pineal gland

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10
Q

What is the embryological growth of the thyroid gland?

A 
downgrowth at FLOOR of pharynx (pouches I and II)>
vascular mesenchyme separates diverticulum into follicles>
ultimobranchial body (pouch IV) fuses with downgrowth from pharynx (primordium)>
which brings in C cells
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11
Q

What is the origin of C cells?

A

NCC

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12
Q

What makes up the follicles of the thyroid?

A

simple low cuboidal cells

contain colloid

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13
Q

Where do you store the precursor to T4 and T3?

A

colloid

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14
Q

Wha synthesizes thyroid hormones?

A

follicular cells

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15
Q

What surrounds all off the thyroid follicles?

A

fenestrated capillaries providing RICH vascularization

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16
Q

A normal/resting follicular cells have what characteristics?

A

Makes small amt of thyroid hormone

Low cuboidal
few mito, small golgi
some RER in base of cells

17
Q

What are the characteristics of a TSH stimulated follicle (active)?

A 
TSH from the pars distalis>
columnar
cells increase in representation
lipid droplets
PAS + colloid
apical lysozymes
18
Q

What is the origin of parafollicular cells?

A

NCC

19
Q

What synthesizes calcitonin (high Ca)?

A

parafollicular cells

SLOWS down the activity of osteclasts–> decreased Ca

20
Q

How does calcitonin lower Ca?

A

inhibits bone resorption
decreases osteoclast motility/numbers
promotes excretion of Ca and PO4 from the kidneys

21
Q

What is the only gland that stores large quantities of product extracellularly?

A

Thyroid

Stores in colloid (3 mo supply)

22
Q

Where is thyroglobulin composed of?

A

glycoprotein

3% are tyrosyl residues that are available for iodination

23
Q

How is iodine taken up?

A

Basal portion of follicular cells have an active iodide transport>
concentates>
oxidation to iodine at cell surface via TPO

24
Q

What gets iodated in thyroglobulin?

A

tyrosyl residues

EXTRACELLULARLY

25
Q

What occurs to the follicle with TSH stimulation?

A

follicle cell height increases
gland hypertrophy
accellerated follicle metabolism

26
Q

Describe the pincocytosis of thyroglobulin.

A

fusion w/ lysosomes>
thyroglobulin proteolysis>
formation and release of T3 and T4>
diffusion to capillaries

27
Q

What is the embryological origin of hte parathyroid gland?

A

pouches III and IV

28
Q

What are the principles cell types in the parathyroid gland?

A

chief cells*

oxyphil cells

29
Q

What are the most numerous cells in the PTG?

A

chief cells

eosinophilic cytoplasm

30
Q

How do hte resting and active forms of chief cells differ?

A

resting: sparse RER, abundant glycogen
active: increased RER, glycogen depleting, many vesicles

31
Q

What do chief cells secrete?

A

PTH

32
Q

What does PTH do?

A

increased blood Ca

-increases osteoclast numbers

33
Q

How do oxyphil cells compare to chief cells?

A

large
dark staining nuclei w/ eosinophilic cytoplasm

fxn unknown

Endo/Repro: Week 1 (10 decks)

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