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ER Week 1 > Pineal, Thyroid and Parathyroid Histology > Flashcards

Pineal, Thyroid and Parathyroid Histology Flashcards

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1
Q

What is the pineal gland named for?

A

it’s haped like a pine cone

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2
Q

Where is the pineal gland attached?

A

by a stalk to the roof of the third ventricle

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3
Q

What is the capsule of the pineal gland made of?

A

pia mater

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4
Q

When during life is the pineal gland the largest?

A

first decade of life

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5
Q

Where does most of the innervation come from for the pineal gland?

A

postganglionic sympathetic nerve fibers from the superior cervical ganglion (release epinephrine)

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6
Q

What cells make up 95% of the pineal gland/

A

pinealocytes

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7
Q

What do pinealocytes produce?

A

melatonin production at night

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8
Q

What provide supportive role in the pineal gland/

A

glial cells most similar to astrocytes (can’t identify them on section tough)

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9
Q

The pineal gland sort of looks lobulated on histology. why?

A

you get fine CT septations formed by the pia mater

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10
Q

Over age, the pineal gland can accumulate what forming “braine sand” - copora arenacea?

A

hydroxyappatite and calcium

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11
Q

WHy is this brain sand helpful for radiological markers?

A

it helps the radiologist see the pineal gland and displacement of the pineal form midline is evidence of cerebral tumors

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12
Q

What does melatonin do?

A

suppresses gonadotrophins secretion via inhibition on the hypohtalamus

retards gonadal growth and function

possibly alters emotional responses to reduced day length during winter months (SAD)

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13
Q

How is the thyroid gland formed embriologically?

A

endodermal downgrowth at floor of pharynx (between pouches 1 and 2)

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14
Q

The vascular mesenchyme separates this diverticulum into what?

A

follicles

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15
Q

What bodies from pouch IV fuse with thyroid primordium?

A

ultimobranchial bodies

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16
Q

What cells are located in the ultimobranchial bodies and from what are they derived?

A

C cells (parafollicular cells) of neural crest origin

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17
Q

What connects the two lobes of the htyorid?

A

isthmus

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18
Q

True or false: thyroid has no capsule.

A

false - has a CT cpasule which is quite delicate

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19
Q

What kidn of capillaries surrund the follicles?

A

fenestrated

20
Q

What are some variables that will vary the appearache of the thyroid?

A

sex, nutrition, temperature, age, season, iodine content, etc.

21
Q

What cells make up the follicle? What cells are just outside the basement membrane?

A

follicular cells

parfollicular cells (C-cells)

22
Q

What do the C cells produce?

A

calcitonin

23
Q

In between all these cells is what? What’s stored there?

A

colloid

stores thyroglobulin, which is the precurosr for T3 and T4

24
Q

What kind of epithelium is in the follicles?

A

simple cuboidal epithelium

25
Q

An inactive (resting) follicular cell will have more or less mitochodnria?

A

less

and only small golgi

26
Q

What will be the organelle situation for the active follicular cells?

A

lots of mitochondira
enlarged golgi
increased rough ER
apical lysosomes to break down the colloid

27
Q

What will you see in the lipid droplets within the active follicular cells?

A

PAS-positive colloid (from resoprtion)

28
Q

What does calcitonin do?

A

lowers blood calcium by inhibiting bone resorption and decreases osteoclast motility and numbers

promotes excretion of caclium and phosphate from the kidneys

29
Q

How much thyroid hormone does the thyroid store?

A

probably a 3-month supply

30
Q

Where int he cell is thyroglobulin synthesized?

A

the endoplasmic reticulum

31
Q

What residues are available for iodination in the thyroglobulin?

A

tyrosine

32
Q

How is iodide taken up in the thyroid?

A

the basal portion of follicular cells have an active iodide transport pump

33
Q

What happens to the iodide? using thyroid peroxidase at the cell surface…

A

it’s oxidated to iodine

that iodine is then used to iodinate the tyrosine residues

34
Q

What enzyme does the iodination?

A

thyroid peroxidase again (TPO)

35
Q

What will happen to the follicular cells under TSK stimulation?

A
  1. follicle cell height increases
  2. gland hypertrophy
  3. accelerated follicular cell metabolism
36
Q

On to the Parathyroid gland….

A

1

37
Q

Where are the parathyroid glands located?

A

tehre are two pairs located on the posterio surface of each lateral lobe of the thyroid

38
Q

THey are derived from what pharnygeal structures?

A

puches III and IV

39
Q

Describe the parenchymal arragnement in the parathyroids?

A

anastomosing cords and groups of cells with poorly defined lobules made of fine CT

40
Q

WHat are the two main cell types in the parathyroid gland?

A

chief (principal) cells

Oxyphil cells

41
Q

Which are more numerous?

A

Chief

42
Q

Describe what the chief cells look like/

A

vesicular appearing nucleus

eosinophilic cytoplasm

43
Q

What hormone is produced by the chief cells?

A

parathyroid hormone

44
Q

What does parathyroid hormone do?

A

involve din regulation of calcium and phosphate levels - increases blood calcium by stimulating increased osteoclasts (by stimulating osteoblastst o produce osteoclast stimulating factor)

45
Q

Which are bigger - osyphil cells or chief cells?

A

oxyphil

46
Q

What is the function of the oxyphils?

A

we don’t know

47
Q

True or false: there is no fat in the parathyroids.

A

false

ER Week 1 (11 decks)

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