Endocrine Histo Flashcards Preview

Histology Sem 3 > Endocrine Histo > Flashcards

Flashcards in Endocrine Histo Deck (118):
1

Regulates the activities of different cells, tissues, and orgrans

Hormones

2

Provides communication between different systems in the body and coordinates body growth and development, is similar to the nervous system

Endorcine system

3

Provides endocrine and neuroendocrine control of the other endocrine glands

Pituitary gland and hypothalamus

4

Pea-sized unpaired endocrine gland located at the base of the brain

Pituitary gland

5

Where does the pituitary gland sit?

Sella Turcica

6

Connects the pituitary gland to the hypothalamus

Infundibular stalk

7

Surrounds the pituitary gland and is formed of dense irregular connective tissue

Capsule

8

2 fundamental components of the pituitary gland

Adenohypophysis and Neuropophysis

9

How does the adenohypophysis develop?

Develops as an invagintation of the ectoderm of the oral cavity known as Rathke's pouch

10

How are the adenohypophysis cells organized?

Clumps and cords around fenestrated capillaries

11

Regions of the adenohypophysis

Pars distalis, pars intermedia, pars tuberalis

12

Bulk of the anterior lobe of the adenohypophysis

Pars distalis

13

Thin remnant of the wall of Rathke's pouch

Pars intermedia

14

Remnants of the Rathke's pouch

Rathke's cysts

15

Lines the pars intermedia

Cuboidal epithelium

16

Forms a collar or sheath around the infundibular stalk

Pars tuberalis

17

5 cells of adenohypophysis

Corticotropes, somatotropes, lactotropes, gonadotropes, thyrotropes

18

Basophils

Corticotropes, gonadotropes, thyrotropes

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Acidophils

Somatotropes, Lactotropes

20

What do somatotropes secrete?

Somatotropin, aka growth hormone

21

2 hormones that control the release of GH

GH releasing hormone (release) and somatostatin (inhibits)

22

Most abundant endocrine cells in the adenohypophysis

Somatotropes

23

What do lactoropes secrete?

Prolactin

24

Hormone that controls the production and release of prolaction

Inhibited by dopamine, thyrotropin releasing hormone stimulates

25

What do corticotropes produce?

Adrenocorticotropic hormone (ACTH)

26

What does ACTH act on?

The cells of the adrenal cortex

27

Controls the release of ACTH

Corticotropin-releasing hormone (CRH) released from the hypothalamus

28

2 main hormones secreted by gonadotropes

Follicle-stimulating hormone (FSH) and lutenizing hormone (LH)

29

Controls the secretion of the gonadotropes

Gonadotropin-releasing hormone released from the hypothalamus

30

What do thyrotropes produce?

Thyrotropic hormone (TSH)

31

Controls the release of TSH

TRH

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Part of the pituitary derived from nerve tissue

Neurohypophysis

33

Regions of the neurohypophysis

Pars nervosa, infundibulum

34

Glial cells in the neurohypophysis

Pituicytes

35

What is secreted into the pars nervosa by the hypothalamus?

Oxytocin and anitduiretic hormone

36

Large distended axon terminals of these neurons can sometimes be visualized as what?

Herring bodies

37

What does the superior hypophyseal artery supply?

Pars tuberalis, infundibulum, median eminence, pars distalis

38

Most prominent feature of the hypophyseal blood supply

Hypophyseal portal system

39

What does the superior hypophyseal artery form upon arrival to the pituitary?

Primary capillary plexus

40

Where does blood go after the primary capillary plexus?

Into the hypophyseal portal veins, into the secondary capillary plexus in the pars distalis

41

Within which plexus do the hormones for the bloodstream exit the pituitary?

Secondary capillary plexus

42

Blood supply to the pars nervosa

Inferior hypophyseal artery

43

Unpaired pine-cone-shaped midline organ of the brain

Pineal gland

44

Where is the pineal gland located?

Posterior end of the third ventricle of the brain, covered by cerebral hemispheres

45

What does the pineal gland develop out of?

Outgrowth from the dicephalon

46

What covers the pineal gland?

Pia mater forms the capsule, septa extends into the gland fron this capsule

47

What are aggregates of calcuim phosphates found with the pineal gland?

Corpora arenacea, aka brain sand

48

Principle cells of the pineal gland

Pinealocytes

49

What do the spaces between the clusters of the pineal gland contain?

Axons, pinealocyte cell processes, blood vessels, corpora arenacea

50

Describe pinealocytes on microscope

Large euchromatic nuclei with a prominent nucleolus

51

What do pinealocytes secrete?

Melatonin

52

How does the information about the light/dark cycles reach the pineal gland?

Retinothalamic tract, connecting the suprachiasmic nucleus with the sympathetic neural tracts

53

How is the synthesis/secretion of melatonin controlled?

Norepinephrine released by the sympathetic neurons

54

What is the activity of melatonin?

Inhibits the steroidogenic activity of the gonads

55

Supporting cells of the pineal gland

Glial cells (interstitial cells)

56

Describe the glial cells of the pineal gland

Nuclei are smaller and more heterochromatic

57

Divisions of the adrenal gland

Cortex(yellow peripheral layer) and medulla(central reddish-brown layer)

58

Embryological origin of the cortex

Mesenchyme, mesodermal in origin

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Embryological origin of the medulla

Neural crest cells, ectodermal in origin

60

Tissue of the capsule

Dense connective tissue with thin trabeculae into the parenchyma of the gland

61

Forms the majority of the adrenal gland

Cortex (90% of the gland)

62

Steriod-producing part of the gland

Cortex

63

What does the cortex produce?

Mineralocorticoids, glucocorticoids, some androgens

64

Characteristics of steriod-producing cells

Numerous lipid droplets, mitochondria with tubular cristae, abundant smooth ER

65

What do cortex cells do with steriod hormones?

Released immediately

66

Divisions of the adrenal cortex

Zona: glomerulosa, fasciculata, reticularis

67

Cell appearance of the zona glomerulosa

Closely packed cubodial/pyramidal cells, arranged into arched cords/curved columns, surrounded by numerous fenestrated sinusoidal capillaries

68

What do the cells of the zona glomerulosa secrete?

Mineralocorticoids

69

Purpose of mineralocorticoids

Regulate sodium and potassium honeostasis and water balance

70

Principle mineralocorticoid of the zona glomerulosa

Aldosterone (causes reabsorption of sodium)

71

Stimulates the zona glomerulosa to produce aldosterone

Angiotension II

72

Makes up the majority of the adrenal gland

Zona fasciculata

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Describe the zona fasciculata

Cells form one or two cell-thick straight cords that run at a right angle to the capsule and have fenestrated sinusoidal capillaries between them

74

Large secretory cells in the zona fasciculata

Spongiocytes

75

Secretion of the spongiocytes

Mostly glucocorticoids

76

Role of glucocorticoids

Increase metabolism of glocus and fatty acids, depress the immune and inflammatory responses

77

How do glucocorticoids depress the immune and inflammatory responses?

Suppress the production of interleukin-1 and IL-2 by lymphocytes and macrophages, also supress lymphoblast mitosis within lymph nodes

78

What controls glucocorticoid production?

ACTH produced by the corticotropes of the anterior pituitary lobe. Necessary for cell growth and increased blow flow thru the adrenal gland

79

Innermost layer of the cortex

Zona reticularis

80

Appearance of the zona reticularis

Relatively small cells arranged into irregular cords that anastomose to form a network, contain fewer lipid droplets and stain more intensely with eosin

81

Contants of zona reticularis cells

Lipofuscin granules

82

What do the cells of the zona reticularis secrete?

Androgens and glucocorticoids

83

Composition of the adrenal medulla

Polyhedral cells arranged into clumps or cords supported by reticular fibers, with an extensive network of fenestrated capillaries

84

Principle secreting cells of the adrenal medulla

Chromaffin cells

85

Where are chromaffin cells derived from?

Neural crest cells, so they are modified postsynaptic neurons that lack axons

86

What is unique about the granules of the chromaffin cells?

Accumulate and store hormones

87

How to differentiate between norepinephrine and epinephrine cells in chromaffin cells?

Epi cells are smaller and more abundant. NE cells have larger secretory granules

88

Innervation of chromaffin cells

Synaptic nerve fibers

89

Causes the degranulation of chromaffin cells

Release of acetylcholine from the synaptic terminals

90

How are the hormones of the chromaffin cells delivered to the body?

Via the bloodstream thru fenestrated capillaries

91

Modulate the activity of chromaffin cells and innervate blood vessels within the medulla

Ganglion cells

92

Irrigates the adrenal gland capsule

Capsular arteries

93

Blood supply within the cortex

Cortical arteries that branch and form a dense network of fenestrated cortical sinusoidal capillaries

94

Blood supply within the adrenal medulla

Medullary arteries that form a dense network of fenestrated medullary sinusoidal capillaries AND the cortical capillaires

95

Recieves blood from smaller blood vessels withing the medulla

Adrenimedullary collecting veins

96

Drains the blood from the adrenal gland

Central adrenomedullary vein (IVC on right side, left renal vein on left side)

97

Main structural unit of the thyroid gland

Thyroid follicle

98

Structure of a thyroid follicle

Spherical structure forms by a layer of simple cuboidal follicular epithelium surrounding a cyst-like central cavity

99

Contents of thyroid follicle

Colloid

100

2 types of cells of the follicular epithelium

Follicular and parafollicular cells

101

Principle endocrine cells of thyroid gland

Follicular cells

102

Origin of thyroid follicular cells

Endodermal

103

2 main hormones synthesized by follicular cells

Thyroxine (T4) and Triiodothyronine (T3)

104

Synthesized in RER of follicular cells and is secreted into the lumen of the follicle

Thyroglobulin

105

How is iodide used in follicular cells?

Actively transported from blood into cytoplasm, iodine is oxidized to iodine and released into the colloid

106

How are T4 and T3 stored in the follicular cells?

Linked to thyroglobulin molecule to remain stored in cell

107

How are T4 and T3 released?

TSH causes cells to take up thyroglobulin resobring the colloid, thyroglobulin is borken down by lysosomes, releasing T3:T4 (1:20) and diffuse into the blood

108

Main function of parafollicular cells

Synthesis of calcitonin

109

What does calcitonin do?

Lowers blood calcium levels by suppressing the resorptive activity of osteoclasts and promoting calcium deposition in bones by osteoblasts

110

Where are parafollicular cells derived from?

Neural crest

111

Small endocrine glands usually embedded with the thyroid

Parathyroid glands

112

Arrangement of parathyroid gland cells

Arranged into cords that follow the fenestrated capillaries

113

2 types of cells of the parathyroid gland

Parathyroid chief cells and oxyphil cells

114

What do parathyroid chief cells produce?

Parathormone (PTH)

115

How does parathormone work?

Increases the blood levels of calcium

116

Regulates PTH

Calcium blood levels

117

Where are parathyroid chief cells derived from?

Neural crest

118

Cell in parathyroid that has a large number of mitochondria in the cytoplams that stain intensely with acidic dyes

Oxyphil cells