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Histology > Thyroid, Parathyroid and Adrenal Gland > Flashcards

Thyroid, Parathyroid and Adrenal Gland Flashcards

1
Q

Primary Endocrine Glands

A
  • Pineal
  • Pituitary
  • Thyroid
  • Parathyroid
  • Thymus
  • Adrenals
  • Islets of Langerhans
  • Ovaries
  • Testes
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2
Q

Secondary Endocrine Organs

A
  • Heart
  • Liver
  • kidneys
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3
Q

Effects of hypophyseal hormones on Target Organs

A

PIC

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4
Q

How many lobes does Throid Gland Have?

A

2

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5
Q

Thyroid Gland Development

A

The foramen cecum of the tongue marks where the thyroid diverticulum originates at week 4 and it is formed by week 7(PIC)

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6
Q

What is the functional and structural unit of the thyroid gland?

A

Thyroid Follicle

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7
Q

____ Is the only endocrine gland that stores the hormone it produces in large quantities extracellular in the colloid of the follicles

A

The Thyroid

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8
Q

Follicular Cells purpose

A

In charge of producing thryoid hormone- typical secretory cells that contain microvilli and RER

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9
Q

Parafollicular cells (C Cells) Produce…

A

Produce Calcitonin

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10
Q

Where do C Cells derive from and where can they be found?

A

Derived from NEURAL CREST CELLS and can be found within the FOLLICULAR EPITHELIUM or as clusters between follicles

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11
Q

Is Throid highly vascularized?

A

YES, commonly in secretion organs

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12
Q

T3

A

Triiodothyronine (thyroid hormones)–more active than T4

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13
Q

T4

A

Thyrozine (thyroid hormones)–Less Active than T3

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14
Q

T3 and T4

A
  • Produces, stored, absorbed, and secreted by FOLLICULAR CELLS
  • Increase basal metabolic rate (mitochondrial number, their cristae density and activity)-Cause OxPhos
  • Influence body growth and nervous system development at fetal state
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15
Q

Calcitonin

A
  • Produced and secreted by PARAFOLLICULAR (C CELLS)
  • Induced by increases in blood calcium levels
  • Lowers blood calcium by inhibiting bone resorption (osteoclasts)
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16
Q

What happens when blood has too much calcium in blood?

A

Osteoclasts destroy bone locally and adjust calcium availability

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17
Q

What is needed to produce T3 and T4

A

Follicular cells have IODIDE PUMPS (transporters) that concentrate iodide in the thyroid gland

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18
Q

Radioactive Iodine Scan

A

After injection of radioactive iodide, 40% is in thyroid gland within 10 MINS

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19
Q

First Step of Synthesis of Thyroid Hormones

A

Synthesis of THYROGLOBULIN (660 kDA) and secretion into the follicles

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20
Q

Second Step of Synthesis of Thyroid Hormones

A

Uptake of circulating iodide by follicular cells via Na/I symporter in their basolateral membrane

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21
Q

Third Step of Synthesis of Thyroid Hormones

A

Oxidation of iodine by THYROID PEROXIDASE and transport of oxidized iodine into the follicle cavity by PENDRIN, an anion transporter

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22
Q

Fourth Step of Synthesis of Thyroid Hormones

A

IODINATION OF TYROSINE residues of thyroglobulin by thyroid peroxidase generates T4, T3, fiiodotyrosine and monoiodotyrosine

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23
Q

Thyroid Feedback Loop- How Thyroid is regulated

A

By hypothalamus- which stimulates pituitary gland

  • Releasing TSH
  • T3 and T4 are released in bloodstream and goes to target cells
  • Negative Feedback loop tells hypothalamus to stop releasing hormones

PIC

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24
Q

Thyroid Hormone Secretion First step

A

upon stimulation by thyrotropin, follicular cells take up colloid by endocytosis

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25
Q

Thyroid Hormone Secretion second step

A

endocytic vesicles are digested by lysosomal enzymes

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26
Q

Thyroid Hormone Secretion third step

A

Proteases cleave the bonds between iodinated tyrosine residues and the thyroglobulin molecule

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27
Q

Thyroid Hormone Secretion fourth step

A

T4 and T3 are liberated to the cytoplasm and secreted basally into the blood

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28
Q

Thyroid Hormone Secretion fifth step

A

Di- and monoiodotyrosines are NOT secreted; their iodine is recycles after cleavage by iodine halogenase

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29
Q

Thyroid Hormone Secretion sixth step

A

T4 is most abundant (90%) but most hormone activity is attributed to T3

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30
Q

Throid Gland-Resorption Vesicles- The thyroglobulin (precursor of active hormones) in the colloid is taken back into the follicular cells via…

A

Pinocytosis

31
Q

Variation in Follicular Activity:

Hyperactive Follicle, Normal Follicle, Hypoactive Follicle

A

Hyperactive Follicle-Columnar type epithelial
Normal Follicle-Cuboidal Epithelium
Hypoactive Follicle- Very little colloid use- almost squamous epithelium

32
Q

Goiter (NEED TO KNOW??)

A

Thyroid gland disorder- referring noly to an enlarged thyroid (proliferation problem)

33
Q

Hyperthyroidism- Graves disease (NEED TO KNOW??)

A

involves autouimmune Ab which binds to the TSH receptor of the follicular cells.- Ab binding activates the receptor, thereby stimulating thyroid activity

34
Q

Cretinism (NEED TO KNOW??)

A

Congenital hypothyroidism leads to stunted growth and mental retardation without promt postnatal treament

35
Q

Parathyroid glands derive from…

A

Parapharyngeal puches

36
Q

Where can Parathyroid glands appear?

A

in the mediastinum, next to the thymus which derives from the same pouches

37
Q

Parathyroid glands are bounded by…

A

A connective tissue capsule that send branching septa towards the inside

38
Q

Chief (principle) cells produce Parathyroid hormone (PTH) which promotes…

A

Bone Reabsorption. The Function of OXYPHIL cells is unknown

39
Q

What are certain histological characteristics of adrenal cortex??

A

Cell cords

40
Q

Eosinophilia of oxyphil cells is attributable to…

A

The abundant mitochondria

41
Q

in the bone, which cells have PTH receptors?

A

Osteoblasts

42
Q

What promotes absorption of calcified bone matrix and the release of calcium to the blood?

A

PTH binding signals the secretion of osteoclast-stimulating factor, which increases the number and activity of osteoclasts

43
Q

Hyperparathyroidism (NEED TO KNOW??)

A

Pathological deposits of calcium in organs such as kidneys and arteries. Increased numbers of osteoclasts- multiple bone cavities- OSTEITIS FIBROSA CYSTICS

44
Q

Parathryoid Neoplasia

A

A functional tumor of the parathyroid gland will lead to excessive levels of PTH

45
Q

Hypoparathyroidism

A

Bones become dense and more mineralized. Spastic contractions of skeletal muscles plusgeneralizes convusions-TETANY

46
Q

Suprarenal (Adrenal Glands) loaction

A

Paired organs located near SUPERIOR poles of they kidneys.. Embedded in aipose tissue
-flat, half moon shape

47
Q

Cortex of Adrenal Cortex-Color, Location, Development

A

Yellowish, located in the periphery

Develops from the CELOMIC EPITHELIUM aka. mesothelium derived from MESODERM

48
Q

Medulla of Adrenal Cortex-Color, Location, Development

A

Red/brown- located centrally

Develops from NEURAL CREST CELLS derived from ECTODERM

49
Q

3 concentric layers of AC with not defined limits

A
  • Zona Glomerulosa-15% under the capsule
  • Zona Fasciculata-65% in the middle
  • Zona Reticularis-7% inside
50
Q

Adrenal Gland Vascularization

A

Dual Blood Supply:

  • Arterial Blood (via medullary arteries)
  • Venous Blood (via Cortical Veins)
51
Q

Zona Glomerulosa

A

Columnar or pyramidal cells that secrete ALDOSTERONE (minteralocorticoid) which acts to stimulate Na+ reabsoprtion in the distal convulated tubules of the kidney.

52
Q

What stimulates Aldosterone Secretion

A

Angiotensin II

53
Q

Zona Fasciculata

A

Typically arranged in cords
-Secrete predominantly HYDROCORTISONE (cortisol), and suppress the immune system and aid in fat protein and carbohydrate metabolism

54
Q

What is Cortisol

A

A glucocorticoid that functions to increase blood sugar levels through gluconeogensis

55
Q

Zona Reticulari

A

Smaller, arranged in irregular cords- secrete DHEA ( weak androgen) which is converted into testosterone somewhere else in body

56
Q

Endocrine control of AC

57
Q

Adrenal medullary cells are specialized…

A

Postganglion sympathetic neurons

58
Q

Adrenal Medulla

A

polyhedral parenchymal cells arranged in cords or clusters that secrete epinephrine (80%) and norepinephrine (20%) in response to sympathetic stimuoation. Also secrete ATP chromogranins

59
Q

Adrenal Medulla recieves a dual blood supply. Cortical arterioles, cappilarries and sinusoids first irrigate…

A

the cortex

60
Q

Adrenal Medulla recieves a dual blood supply. Medullary Arterioles pass directly though…

A

the cortex

61
Q

Adrenal Medulla Secretory

62
Q

Fetal suprarenal galnds are ___ than in adults

A

10-20x larger (relative to body weight). Secrete sulfate conjugates of androgens that are converted at the placenta into active androgens and estrogens and enter maternal ciculations

63
Q

Short Term stress response

A

heartbeat and blood pressure increase. Blood glucose level rises. muscles become energized

Involving Epinephrine and Norepinephrine

64
Q

Long term stress response

A

Glucotricoids- proteins and fat metabolsm instead of glucose breakdown. Reduction of inflammation; immune cells are SUPPRESSED

Mineralcorticoids: sodium ions and water are reabsorbed by kidney. Blood volume and pressure increase

(PPIC)

65
Q

Disorders of Adrenal Function (NEED TO KNOW??)

66
Q

Cushings Syndrome

A

Associated with excessive levels of glucocorticoid hormones

67
Q

Conns Syndrome

A

Hyperaldosteronism (PIC)

68
Q

Pheochromocytoma

A

Medullary tumors secrete large quantities of catecholamines, and cause hyperglycemia and elevation of blood pressure. (RARE but highly malignant)- Produce steroids

69
Q

The 2 thyroid gland are held together by

70
Q

At what week of development is the thyroid gland seen next to the Larnyx and not Foramen Cecum

71
Q

What week does the Thyroid Diverticulum begin to form by the tongue?

72
Q

What are thyroid gland follicles full of?

A

Colloid-Gelatin Substance

73
Q

What organ is the only endocrine gland that stores the hormone it produces in large quantities extracellularly in the colloid of the follicles

A

The Thyroid

74
Q

What part of the gland reacts with stress?

A

Cortical– becomes hyperactive

Histology (23 decks)

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