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Histology Test 4 > Endocrine System > Flashcards

Endocrine System Flashcards

1
Q

What parts make up the adenohypophysis?

A

pars distalis
pars tuberalis
pars intermedia

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2
Q

What parts make up the neurohypophysis

A

pars nervosa

infundibulum

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3
Q

What do hypothalmic nuclei produce?

A

peptide hormones that stimulate the anterior pituitary to produce: thyrotropin, gonadotropin, somatostatin, growth hormone, and corticotropin, and inhibit prolactin release

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4
Q

Where are the peptide hormones produced by hyopthalmic nuclei released?

A

primary capillary plexus of the infundibulum

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5
Q

What artery supplies the pars nervosa?

A

inferior hypophyseal artery

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6
Q

What does the superior hypophyseal artery supply?

A

median eminance

infundibulum

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7
Q

What drains venous blood from the capillary plexuses surrounding the pituitary gland?

A

hypophyseal portal veins

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8
Q

What 3 chromophobe subpopulations make up the majority of cells in the pars distalis?

A

undifferentiated nonsecretory cells (possibly stem cells)
degranulated chromophils
Follicular cells

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9
Q

What is the function of follicular cells in the pars distalis?

A

form a stromal network to support chromophil cells (and some phagocytic function)

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10
Q

What chromophiles would you find in the pars distalis, and which one is the largest?

A

acidophils (stain with eosin and orange G) and basophils (stain with basic dyes and PAS)
basophils are larger

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11
Q

What do acidophils secrete in general?

A

peptide hormones

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12
Q

What cells are acidophiles (in the pars distalis) and what do they secrete?

A

somatotrophs (growth hormone aka somatotropin)

mammotrophs (prolactin)

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13
Q

What controls somatotroph activity?

A

GH-releasing factor and GH-inhibiting factor (somatostatin)

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14
Q

What does prolactin do, and what controls the cells that release prolactin?

A

stimulates and maintains lactation

mammotrophs are under the control of thyrotropin-releasing factor (TRF) and prolactin-inhibiting factor (dopamine)

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15
Q

What cells are basophilic (in the pars distalis) and what do they secrete in general?

A

gonadotrophs
corticotrophs
thyrotrophs
secrete glycoprotein hormones

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16
Q

What do gonadotrophs secrete and what do these secretions do?

A

follicle-stimulating hormone (FSH)- stimulates development of ovarian follicles and stimulates Sertoli cells to produce androgen-binding protein

luteinizing hormone (LH)- stimulates steroidogenesis in ovarian follicles and c. luteum, and controls rate of testosterone synthesis by Leydig cells

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17
Q

What do corticotrophs secrete and what does it do?

A

adrenocorticotropin (ACTH)- stimulates growth and steroid synthesis in the zona fasciculata and zona reticularis of the adrenal glands

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18
Q

What do thyrotrophs secrete and what controls them?

A

thyrotropin (aka thyroid-stimulating hormone [TSH]). Under control of TRF

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19
Q

What would you find in the pars nervosa?

A

non-myelinated axonal processes and pituicytes (astrocyte-like glial cells)

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20
Q

What would you find inside of a pituicyte?

A

glial fibrillary acidic proteins and pigment granules

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21
Q

What is a Herring body?

A

a large dilation of an axon containing neurosecretory granules

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22
Q

What do hypothalamic neurons release?

A

oxytocin and antidiuretic hormone (vasopressing)

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23
Q

What type of neurons are the primary producers of oxytocin, and what does oxytocin do?

A

produced by para ventricular cells

stimulates milk ejection from mammary glands and uterine smooth muscle contraction during childbirth

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24
Q

What type of neurons primarily produce antidiuretic hormone (ADH) and what does it do?

A

supraoptic cells

stimulates water absorption by the renal medullary collecting ducts

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25
Q

What is neurophysin?

A

a carrier protein that complexes with neurohypophyseal hormones for transport down axons

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26
Q

What would you find in the pars intermedia?

A

basophil and chromophobe cells, and Rathke’s cysts

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27
Q

What is a Rathke’s cyst?

A

cuboidal epithelium lined cavity (remnant of Rathke’s pouch)

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28
Q

What would you find in the pars tuberalis?

A

lots of vasculature (especially veins of the hypophyseal portal system) and gonadotropes

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29
Q

What is acromegaly?

A

excessive growth hormone

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30
Q

What is a possible effect of prolactin secreting tumors?

A

infertility (lack of ovulation)

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31
Q

What is the most common cause of hypopituitarism in adults?

A

adenomas (pituitary tumors)

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32
Q

What is intrinsic pituitary destruction?

A

destruction of hormone-secreting cells of the anterior pituitary

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33
Q

What is caused by poor (pituitary) anterior lobe function?

A

failure of lactation
amenorrhea (lack of menstruation)
poor thyroid function
adrenal insufficiency

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34
Q

What is caused by poor (pituitary) posterior lobe function?

A

diabetes insipidus (impaired water absorption in distal renal tubuli)

35
Q

What covers the pineal gland?

A

pia mater

36
Q

Does the pineal gland have a blood-brain barrier?

A

No

37
Q

What cells make up the pineal gland?

A

pinealocytes and glial cells (insterstitial cells)

38
Q

What do pinealocytes produce and what does it do?

A

melatonin- regulates sleep cycle

39
Q

What distinguishing feature is sometimes seen in the pineal gland?

A

corpora arenacea (brain sand)- calcium phosphate or calcium carbonate granules

40
Q

What innervates the pineal gland?

A

postganglionic sympathetic nerves from the superior cervical ganglia

41
Q

What effects pineal gland function?

A

external lighting (signals from retinal neurons are relayed to pineal gland and inhibit secretion of melatonin)

42
Q

What can effect can pineal tumors have?

A

may restrict flow of CFS through the aqueduct of Sylvius and cause hydrocephalus (build up of fluid in skull that can lead to brain swelling)

43
Q

What is the embryonic origin of the thyroid gland?

A

cephalic portion of the alimentary canal endoderm

44
Q

Describe the macroscopic structure of the thyroid gland

A

2 lobes connected by an isthmus

45
Q

How are lobes in the thyroid gland structured?

A

made of follicles lined by simple cuboidal epithelium

46
Q

How do the cells lining thyroid follicles change with activity?

A

inactive look squamous, active look columnar

they’re really simple cuboidal

47
Q

What do thyroid principal cells secrete?

A

T3 and T4 (thyroid hormones)

48
Q

What is colloid?

A

acidophilic staining glycoprotein thyroglobulin (inactive storage form of thyroid hormones found in thyroid follicles)

49
Q

Where are parafollicular cells (C cells) found and what do they secrete?

A

found as part of follicular epithelium or as isolated clusters between thyroid follicles, and they secrete calcitonin

50
Q

What does calcitonin do?

A

inhibits osteoclast activity and suppresses bone resorption (calcitonin only has a minor role in regulating Ca levels)

51
Q

Where is thyroglobulin produced in the cell?

A

synthesized in rER, glycosylated in rER and Golgi, and transported to lumen of follicle by vesicles

52
Q

How does iodide interact with thyroglobulin?

A

iodide transported across basal plasma membrane, oxidized in cytoplasm, enters colloid, and iodinates tyrosine residues on thyroglobulin

53
Q

Describe the steps by which thyroid stimulating hormone (TSH) leads to the release of thyroid hormones

A

TSH released from anterior putitary, binds to TSH receptors of follicular cells, colloid is endocytosed and combines with lysosomes, iodinated residues are cleaved from thyroglobulin and T3 and T4 are released into cytosol and transported across basal plasma membrane

54
Q

What are the functions of thyroid hormones?

A

stimulate gene transcription
cause a general increase in cellular metabolism
stimulate carbohydrate metabolism
decrease synthesis of cholesterol, phospholipids, tryglycerides
increase FA synthesis

55
Q

What can excessive production of thyroid hormones cause?

A 
weight loss
increased heart rate, metabolism, respiration, and appetite
muscle tremors
tiredness
excessive menstrual bleeding
56
Q

What goiter and what causes it?

A

follicular hyperplasia, caused by insufficient iodine uptake (with leads to decreased T3 T4 and increased TSH production)

57
Q

What is Graves’ disease?

A

hyperthyroidism due to immunologic dysfunction that produces a circulating immunoglobulin which has effects similar to TSH

58
Q

What is Hashimoto’s disease?

A

autoimmune destruction of thyroid resulting in hypothyroidism (thyroid perooxidase autoantibodies produced and thyroid is infiltrated with lymphocytes and plasma cells)

59
Q

Is thyroid cancer more frequent in men or women

A

3-4 times more common in women

60
Q

What is myxedema?

A

localized skin swelling present in thyroid cancer and hypothyroidism

61
Q

What cell types are found in parathyroid glands?

A

chief (principal) cells and oxyphil cells

62
Q

Describe parathyroid chief cells…now…or else

A

contain irregular granules that contain parathyroid hormone (PTH)

63
Q

What does parathyroid hormone (PTH) do?

A

increases blood calcium

64
Q

By what mechanisms does PTH increase blood calcium?

A

stimulates osteoclast activity and number

increases resorbtion of Ca from kidney distal convoluted tubules and increases phosphate excretion

increases intestinal absorption of Ca from food by stimulating vit. D synthesis which stimulates synthesis of Ca binding protein in the intestine

65
Q

Describe parathyroid oxyphil cells

A

larger than chief cells, stain with eosin, large number of mitochondria, appear after puberty, function unclear (may be transitional chief cells)

66
Q

What causes hyperparathyroidism?

A

adenoma (80%), carcinoma (1-2%), hyperplasia (15%), (terrorists must be the other 3-4%… thanks Obama…)

67
Q

What are the symptoms of hyperparathyroidism?

A

increased blood Ca and low PO4
bone cysts
osteitis fibrosa cystica (causes rubbery deformed bones, kidney stones, pancreatitis, peptic ulcers, and hypertension)

68
Q

What are the symptoms of hypoparathyroidism?

A

decreased serum Ca and increased PO4, tetany (involuntary muscle contractions), muscle cramps, exaggerated tendon reflexes, jaw lock)

69
Q

What is the macroscopic structure of the adrenal (suprarenal) gland?

A

2 concentric layers: cortex and medulla

70
Q

What is the embryonic origin on the adrenal gland?

A

cortex from mesoderm, medulla from neural crest cells

71
Q

How is the adrenal medulla organized?

A

cells arranged in cords or clumps supported by a reticular fiber network

72
Q

Describe medullary parenchymal cells (chromaffin cells)

A

have secretory granules that contain epinephrine or norepinephrine (cells with epinephrine have smaller granules)

73
Q

Apart from chromaffin cells, what else would you find in the adrenal medulla?

A

sympathetic ganglionic nerves

74
Q

What are the layers of the adrenal cortex (from outside to inside)?

A

capsule, zona glomerulosa, zona fasciculata, and zona reticularis

75
Q

What is secreted in the adrenal zona glomerulosa?

A

cells secrete mineralcorticoids (aldosterone); stimulated by angiotensis II and ACTH

76
Q

What is secreted in the adrenal zona fasciculata?

A

cells secrete glucocorticoids (cortisol and corticosterone)

77
Q

Describe the vasculature of the adrenal zona fasciculata

A

sinusoidal capillaries arranged logitudinally between columns of parenchymal cells

78
Q

What is secreted in the adrenal zona reticularis?

A

cells secrete gonadocorticoids (DHEA, andostenedione)

79
Q

What is a pheochromocytoma?

A

adrenal medulla tumor- causes hyperglycemia and transient elevations in blood pressure (most common adrenal tumor in adults)

80
Q

What is a neuroblastoma?

A

adrenal tumor common in children; does not affect blood pressure like a pheochromocytoma

81
Q

What is Cushing’s syndrome?

A

excess secretion of cortisol; causes moon face, hyperglycemia, diabetes mellitus, amenorrhea (lack of menstruation), hirsutism (male-patterned hair growth in women), acne, and emotional lability

82
Q

What is Conn’s syndrome?

A

excessive aldosterone production; causes water retention, hypertension, and hypokalemia (low potassium)

83
Q

What is Addison’s disease?

A

adrenocortical insufficiency; causes weakness, nausea, weight loss, and elevated ACTH which causes hyperpigmentation

84
Q

What is Waterhouse-Friderichsen syndrome?

A

acute cortical destruction (bleeding into the adrenal gland); causes meniogococcal sepsis (endotoxic shock)

Histology Test 4 (2 decks)

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