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Histology - Exam 4 > Endocrine - Part 2 > Flashcards

Endocrine - Part 2 Flashcards

1
Q

describe covering of pineal gland

A
  • pia matter

- no blood brain barrier

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2
Q

what divides the pineal gland into lobules?

A

CT septa (trabeculae) that extend from the capsule

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3
Q

what type of cells make up the pineal gland?

A
  • pinealocytes

- glial cells (interstitial cells)

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4
Q

what is the major product of pinealocytes and what is it’s function?

A

melatonin - for regulation of sleep cycle

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5
Q

describe pinealocytes

A
  • slightly basophilic
  • irregular lobulated nuclei
  • distinct nucleoli
  • silver stain: long tortuous branches
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6
Q

what is corpora arenacea?

A

brain sand - seen in PINEAL gland

  • calcium phosphate or calcium carbonate granules
  • irregular shaped, often lammelar dark spots
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7
Q

innervation of pineal gland

A

post ganglionic sympathetic nervs that arise in the superior cervical ganglion

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8
Q

what environmental factor affects pineal gland function?

A

external lighting - signals from retinal neurons relayed to pineal gland inhibit secretion of melatonin

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9
Q

what can pineal gland tumors cause?

A

may restrict CSF flow through aqueduct of Sylvius -> cause hydrocephalus

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10
Q

derivation of the thyroid gland

A

from the cephalic portion of the alimentary canal endoderm

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11
Q

thyroid gland: description, cells, blood/lymph

A
  • 2 lobes connected by isthmus
  • lobes made of follicles filled with colloid
  • principal cells
  • parafollicular/C cells
  • extensive blood/lymph capillary network surrounding follicles
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12
Q

describe lining of follicles

A

simple cuboidal epithelium:

  • inactive portions: almost squamous
  • active portions: more columnar
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13
Q

what do principal cells secrete?

A

T3 and T4

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14
Q

what type of vesicles may principal cells have?

A

colloidal reabsorption droplets

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15
Q

describe colloid

A
  • acidophilic
  • glycoprotein thyroglobulin
  • inactive storage form of thyroid hormones
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16
Q

what kind of endothelium do the capillaries in the thyroid gland have?

A

fenestrated

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17
Q

function of parafollicular/C cells

A

secrete calcitonin

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18
Q

describe C cells

A
  • somewhat larger than follicular cells
  • have numerous 100-180 nm granules
  • stain poorly in humans (white or clear)
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19
Q

function of calcitonin

A
  • suppresses bone resorption by inhibiting osteoclast activity
  • humans: minor role in regulating blood [calcium]
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20
Q

what stimulates calcitonin secretion?

A

elevated blood calcium levels

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21
Q

what suppresses calcitonin secretion?

A

when [calcium] falls below normal

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22
Q

what is more important than calcitonin for regulating blood [calcium]?

A

PTH

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23
Q

describe where thyroglobulin (THY) production, modification, and secretion

A

synthesized in rER
glycosylated in rER and golgi
vesicles release contents in lumen of follicle

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24
Q

describe the transport/processing of iodide in the thyroid gland

A
  • actively transported into cytosol across basal plasma membrane
  • oxidized in cytoplasm
  • enters colloid, where it iodinates Tyr residues on thyroglobulin
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25
Q

TSH: where does it come from, what does it bind, then what happens

A
  • released from anterior pituitary
  • binds TSH receptors on follicular cells
  • cells then endocytose colloid which combines with lysosomes
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26
Q

how are iodinated residues released from thyroid gland?

A

cleaved from THY, T3, T4 -> released into cytosol, then at plasma membrane

27
Q

what are the functions of thyroid hormones? (5)

A
  • stimulate transcription of many genes
  • cause general increase in cellular metabolism
  • stimulate carb metabolism
  • decrease synthesis of cholesterol, phospholipids, TGs
  • increase synthesis of FA’s
28
Q

what can excessive production of thyroid hormones lead to?

A
  • weight loss
  • increased heart rate, respiration, appetite
  • muscle tremors
  • tiredness
  • frequent or excessive menstrual bleeding
29
Q

what does iodine deficiency cause?

A

decreased T3, T4 -> production -> increased TSH -> leads to follicular hyperplasia (goiter)

30
Q

what does T3 stand for?

A

triiodothyronine

31
Q

what does T4 stand for?

A

thyroxine

32
Q

what is hyperthyroidism?

A

graves disease:

-thyroid hyperfunction due to immunologic dysfunction that produces a circulating Ig that has effects similar to TSH

33
Q

what is Hashimoto’s disease?

A

autoimmune destruction of thyroid resulting in hypothyroidism

  • thyroid peroxidase Abs formed
  • thyroid infiltrated with lymphocytes and plasma cells that may organize into germinal centers
34
Q

which gender gets thyroid cancer more often?

A

females 3-4x more

35
Q

what is myxedema? when can you get this?

A

localized skin disorder - swelling

-present in hypothyroidism

36
Q

describe the parathyroid glands

A
  • 4 small glands behind thyroid gland

- each w/i a CT capsule w/ septa

37
Q

what are the two main cell types in parathyroid glands?

A
  • chief/principal cells

- oxyphil cells

38
Q

describe chief/principal cells of parathyroid

A

have irregular granules that contain parathyroid hormone (PTH)

39
Q

function of PTH

A
  • increases calcium in blood by stimulating the number and activity of osteoclasts (calcified bone matrix resorbed and calcium released)
  • increased resorption of calcium and excretion of phosphate from kidney distal convoluted tubules
  • increased intestinal absorption of calcium by stimulating vitamin D synthesis, which then stimulates synthesis of Ca binding protein in intestine
40
Q

describe oxyphil cells of parathyroid

A
  • larger than chief cells
  • stain intensely w/ eosin (lots of mitochondria)
  • appear after puberty
41
Q

function of oxyphil cells of parathyroid

A

unclear - potentially transitional chief cells

42
Q

what are the causes/distribution of causes for hyperparathyroidism?

A
  • adenoma (80%)
  • carcinoma (1-2%)
  • hyperplasia (15%)
43
Q

what happens in hyperparathyroidism?

A
  • blood Ca high, PO4 low

- may get bone cysts (osteitis fibrosa cystica)

44
Q

symptoms of osteitis fibrosa cystica

A
  • rubbery deformed bones
  • kidney stones
  • pancreatitis
  • peptic ulcers
  • HTN
45
Q

what happens in hypoparathyroidism?

A

blood Ca low, PO4 high

  • tetany
  • muscle cramps
  • exaggerated tendon reflexes
  • jaw locks
46
Q

describe layers of adrenal gland

A

2 concentric layers:

  • cortex
  • medulla
47
Q

derivations of cortex and medulla of adrenal gland

A

cortex: from mesoderm
medulla: from neural crest

48
Q

what does the adrenal gland medulla consist of?

A

cells arranged in cords or clumps supported by a reticular fiber network
-may also see sympathetic ganglionic nerve cells

49
Q

describe chromaffin cells

A
  • adrenal medullary parenchymal cells

- have numerous secretory granules containing epinephrine or norepinephrine

50
Q

how can you differentiate b/w epinephrine or norepinephrine secreting chromaffin cells?

A

cells secreting epinephrine have smaller granules

51
Q

what are the adrenal gland cortex zones

A
  • zona glomerulosa
  • zona fasciculata
  • zona reticularis
52
Q

secretions of zona glomerulosa cells

A

secrete mineralocorticoids (aldosterone)

53
Q

what stimulates the synthesis of aldosterone?

A

angiotensin II and ACTH

54
Q

secretions of zona fasciculata cells

A

secrete glucocorticoids (corticol, corticosterone)

55
Q

describe capillaries of zona fasciculata

A

sinusoidal capillaries arranged longitudinally b/w columns of parenchymal cells in adrenal gland

56
Q

secretions of zona reticularis cells

A

secrete gonadocorticoids (DHEA, androstenedione)

57
Q

pheochromocytomas

A
  • adrenal medulla tumor

- causes hyperglycemia and transient elevations in blood pressure

58
Q

what is the most common adrenal tumor in adults?

A

pheochromocytomas

59
Q

neuroblastomas

A
  • common tumor in children

- does not affect blood pressure

60
Q

Cushing’s syndrome

A

excess secretion of cortisol:

  • moon face
  • high blood sugar
  • diabetes mellitus
  • amenorrhea (no period)
  • hirsutism (hair everywhere)
  • acne
  • emotionally labile
61
Q

Conn’s syndrome

A

excess production of aldosterone

  • excess water retention
  • HTN
  • hypokalemia
62
Q

Addison’s disease

A

adrenocortical insufficiency

  • weakness
  • nausea
  • weight loss
  • elevated ACTH levels (causes hyperpigmentation)
63
Q

Waterhouse-Friderichsen syndrome

A

acute cortical destruction

  • meningococcal sepsis
  • endotoxic shock

Histology - Exam 4 (5 decks)

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