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Histology Lecture 3 > Endocrine part 2 - thyroid, parathyroid, pancreas, adrenal > Flashcards

Endocrine part 2 - thyroid, parathyroid, pancreas, adrenal Flashcards

1
Q

Where is the thyroid gland located?

A

anterior to tracheal rings 2-3

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2
Q

What separates the right and left lobes of the thyroid?

A

isthmus

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3
Q

What does each lobe of the thyroid gland consist of?

A

follicles filled with colloid

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4
Q

What are the characteristics of a thyroid follicle?

A
  • single layer of epithelium
  • cuboidal or columnar
  • central lumen of colloid
  • thyroglobulin
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5
Q

Follicular epithelium has receptors for __________________

A

thyroid stimulating hormone (TSH) from anterior pituitary

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6
Q

What does the thyroid epithelium control?

A

synthesis (exocrine) and secretion (endocrine) of thyroid hormones

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7
Q

What is the process of exocrine part of thyroid hormone synthesis?

A
  1. uptake amino acids and iodine
  2. thyroglobulin (TGB) synthesied on rough ER
  3. addition of idoine to tyrosine residues of TBG
  4. released into lumen via exocytosis
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8
Q

Thyroid hormones are stored extracellularly as _______

A

thyroglobulin (TGB)

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9
Q

What is the process of the endocrine part of thyroid hormone synthesis?

A
  1. endocytosis/digestion of colloid
  2. colloid droplets fuse with lysosomes
  3. digestive enzymes breakdown TGB releasing T3, T4, and iodine
  4. T3 and T4 diffuse through membrane into capillary
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10
Q

Which thyroid hormone is secreted more and which is more potent?

A

more T4 is secreted
T3 is 3-4x more potent

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11
Q

What are the functions of thyroid hormone?

A
  • stimulates basic metabolic rate
  • augments thermogenesis
  • augments glucose production
  • required for normal development of CNS
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12
Q

Where are parafollicular/ C cells found?

A

isolated clusters between follicles or within the follicular epithelium

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13
Q

What do parafollicular/ C cells produce?

A

calcitonin

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14
Q

What does calcitonin do?

A

decrease calcium concentration by inhibiting bone resorption

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15
Q

What does hypercalcemia do to calcitonin secretion?

A

stimulates calcitonin due to high blood levels of calcium

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16
Q

What are the symptoms of hyperthyroidism?

A

increased metabolic rate
weight loss
hyperactivity
heat intolerance

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17
Q

What is the disease associated with excessive production of TSH?

A

hyperthyroidism

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18
Q

What is the main symptoms of Grave’s disease?

A

exopthalamos (collagen deposition posterior to eyeball)

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19
Q

What causes hyperthyroidism?

A
  • excessive stimulation by adenophyophysis
  • loss of feedback control by thyroid gland (grave’s disease)
  • ingestion of T4
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20
Q

What causes grave’s disease?

A
  • autoimmune disorder that produces antibodies to the receptors for TSH on the follicular epithelium
  • antibodies bind to receptor and chronically stimulate it
  • results in too much circulating thyroid hormone
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21
Q

What are the symptoms of hypothyroidism?

A

low metabolic rate
feeling of being cold
weight gain
photophobia (thyroid associated eye disease)

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22
Q

What disease is caused by insufficient production of thyroid hormone?

A

hypothyroidism

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23
Q

What can cause hypothyroidism?

A
  • decreased iodine intake
  • loss of pituitary stimulation
  • post-therapeutic or destruction of thyroid by immune system
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24
Q

What is the treatment for hypothyroidism?

A

oral thyroid medication

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25
Q

Endemic goiter is caused by ________________________

A

iodine deficiency

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26
Q

How can goiter be avoided?

A

adding iodine to the diet

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27
Q

What are the two types of secretory cells in the parathyroid gland?

A

chief cells
oxyphil cells

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28
Q

What is the most abundant secretory cell in the parathyroid gland?

A

chief cell

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29
Q

What do the chief cell secrete in the parathyroid?

A

parathyroid hormone

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30
Q

Which parathyroid secretory cell contains a large number of mitochondria?

A

oxyphil cell

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31
Q

Parathyroid hormone is secreted by chief cells in response to _______________________________

A

low blood calcium level

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32
Q

Parathyroid hormone regulates calcium and phosphate how?

A

increasing blood Ca levels
decreasing phosphate levels

33
Q

______ acts on osteoblasts to promote osteoclast activity which increases calcium levels

A

PTH (parathyroid hormone)

34
Q

_____ acts on renal tubules to stimulate resorption of calcium

A

PTH (parathyroid hormone)

35
Q

Parathyroid hormone controls the rate of calcium uptake in the GI by regulating the production of ______________

A

vitamin D in kidneys

36
Q

What stimulates cells of intetinal mucosa to absorb calcium and synthesizes calbindin?

37
Q

What are the characteristics of hypoparathyroidism?

A
  • deficiency in secretion of PTH
  • blood calcium low
  • bone calcium not released
  • spontaneous depolarization of neurons and muscle fibers (tetany)
38
Q

What are the characteristics of hyperparathyroidism?

A
  • high blood calcium levels
  • bone loss (osteomalacia)
  • abnormal calcium deposition in arteries and kidneys
39
Q

Where are centroacinar cells found?

A

only in lumen of pancreatic acini

40
Q

Where are islets of langerhans?

A

embedded within exocrine tissue of pancreas

41
Q

How many islet of langerhans in a pancreas?

A

around 1 million

42
Q

What portal system is involved in the islets of langerhans?

A

insuloacinar portal system

43
Q

What is the pathway of blood through the islets of langerhans?

A

afferent arteriole -> fenestrated capillaries -> efferent capillaries

44
Q

Which capillaries in the islet of langerhans supply exocrine pancreatic acini?

A

efferent capillaries

45
Q

What are the three main cells in the islet of langerhans?

A

a-cells
B-cells
S-cells

46
Q

What are the characteristics of a-cells in the islet of langerhans?

A
  • 15-20%
  • secrete glucagon
  • increase blood glucose
  • stimulates glucogenesis and glycogenesis
47
Q

What are the characteristics of B-cells in the islet of langerhans?

A
  • 70%
  • secrete insulin
  • decrease blood glucose
  • stimulates intracellular glycogen synthesis
48
Q

What are the characteristics of S-cells in the islet of langerhans?

A
  • 5-10%
  • secrete somatostatin
  • inhibits both insulin and glucagon production
49
Q

What is diabetes mellitus?

A

insulin deficiency/abnormality

50
Q

What does type 1 diabetes cause?

A

decreased insulin production

51
Q

What does type 2 diabetes cause?

A

decrease number of insulin receptors or decrease in responsiveness

52
Q

What are the two main symptoms of diabetes mellitus?

A

hyperglycemia
glucosuria (glucose in urine)

53
Q

What hormone regulates the adrenal gland?

A

ACTH from the anterior pituitary

54
Q

Steroid hormones structurally related to ___________ precursor

A

cholesterol

55
Q

What are the three functional classes of adrenal hormones?

A

mineralocorticoids
glucocoricoids
sex hormones

56
Q

What are the characteristics of mineralocorticoids?

A

aldosterone
- control electrolyte and fluid balance
- regulate Na and K levels via Na pumps (in renal tubuels)
- regulates blood pressure via JGA

57
Q

What are the characteristics of glucocorticoids?

A

cortisol
- stimulates gluconeogenesis and glycogenolysis
- increases blood glucose
- increases metabolism of proteins, carbs, lipids

58
Q

What are the characteristics of sex hormones?

A

androgens
- small amount

59
Q

What are the three layers of the adrenal cortex?

A

zona glomerulosa (15%)
zona fasciculata (80%)
zone reticularis (5%)

60
Q

Which layer of the adrenal cortex secretes mineralocorticoids (aldosterone)?

A

zona glomerulosa

61
Q

Which layer of the adrenal cortex secretes glucocorticoids (cortisol)?

A

zona fasciculata

62
Q

Which layer of the adrenal cortex secretes small quanitities of androgens and glucocorticoids?

A

zona reticularis

63
Q

Which layer of the adrenal cortex contains spongiocytes?

A

zona fasciculata

64
Q

The zona glomerulosa produces aldosterone (mineralocorticoids) in response to what?

A

angiotension II
ACTH

65
Q

Which layer of the adrenal cortex is involved in electrolyte and water balance?

A

zona glomerulosa

66
Q

Which layer of the adrenal cortex have cells that contain lipid droplets in cytoplasm and have spongiocytes?

A

zona fasiculata

67
Q

What is the zona fasiculata involved in?

A
  • glucocorticoids
  • regulate CHO, protein, and fat
  • liver
  • catabolic effect in other tissues
  • suppress the immune system
68
Q

What are the characteristics of the zona reticularis?

A
  • cells arranged in irregular cords that frm an anastomosing network
69
Q

What disease has hypoadrenocorticism?

A

addison’s disease

70
Q

What disease has hyperadrenocorticism?

A

cushing’s disease

71
Q

What are the characteristics of hypoadrenocorticism (Addison’s disease)?

A
  • failure of adrenal cortex to produce hormone
  • atrophy of gland
  • decreased aldosterone
  • decreased cortisol
  • decreased blood glucose
72
Q

What are the characteristics of hyperadrenocorticism (Cushing’s disease)?

A

primary
- due to general adrenal hyperplasia or functional tumor
- excess cortisol secretion

secondary
- increased ATCH
- adrenal hyperplasia and excess cortisol secretion

73
Q

What cells are in the adrenal medulla?

A

chromaffin cells

74
Q

Chromaffin cells in the adrenal medulla secrete what?

A

epinephrine
nor-epinephrine

75
Q

What chromaffin cells in the adrenal medulla are regarded as?

A

modified sympathetic postganglionic neurons

76
Q

What are the characteristics of catecholemines?

A
  • secreted in response to intense emotional reactions
  • increase heart rate
  • dilates blood vessels to cardiac and skeletal m
  • bronchiole dilation
  • vasoconstriction of blood to GI tract, kidneys, skin
77
Q

What is pheochromocytoma?

A

benign tumor of the chromaffin cells

78
Q

What are the symptoms of pheochromocytoma?

A

elevated heart rate
elevated bp
palpitations
diaphoresis
anxiety
headaches
nausea

79
Q

What percent of pheochromocytoma are familial?

Histology Lecture 3 (10 decks)

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