Endocrine System Flashcards

1
Q

What do somatotrophs secrete?

A

Growth Hormone GH

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2
Q

What is percentage of somatotrophs in anterior pituitary?

A

50%

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3
Q

Describe somatotroph LM structure

A

Many granules, acidophilic

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4
Q

What does growth hormone target?

A

All tissues

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5
Q

What do lactotrophs/mammotrophs secrete?

A

Prolactin

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6
Q

What does lactotrophs target?

A

Mammary glands for milk production

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7
Q

What is percentage of lactotrophs in anterior pituitary?

A

20%

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8
Q

Describe lactotroph LM structure?

A

Few granules, acidophilic, secretory vesicles are large and ovoid

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9
Q

What does Corticotrophs secrete?

A

ACTH and lipoprotein

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10
Q

What does corticotrophs target?

A

Adrenal cortex

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11
Q

What is percentage of corticotrophs in anterior pituitary?

A

10%

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12
Q

Describe corticotrophs LM structure

A

ACTH granules are large and polygonal and arranged in clusters, basophilic

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13
Q

What do Gonadotrophs secrete?

A

FSH and LH

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14
Q

What is percentage of gonadotrophs in anterior pituitary?

A

20%

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15
Q

What do gonadotrophs target?

A

Gonads

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16
Q

Describe gonadotrophs LM structure

A

Abundant small secretion granules and distended rER, basophilic

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17
Q

What do thyrotrophs secrete?

A

TSH

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18
Q

What is percentage of thyrotrophs in anterior pituitary?

A

5%

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19
Q

What does thyrotrophs target?

A

Thyroid gland

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20
Q

Describe thyrotroph LM structure

A

Characteristic tapering of ends of cell, small round secretory granules, basophilic

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21
Q

What does supraoptic nucleus synthesize?

A

Vasopressin/ADH

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22
Q

What does vasopressin do?

A

Increases permeability of distal portions of nephron and causes rapid water reabsorption in collecting ducts

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23
Q

What does paraventricular nucleus synthesize?

A

Oxytocin

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24
Q

What does oxytocin do?

A

Induces contractions of myometrium of uterus, induces contractions of myoepithelial cells of mammary gland for milk ejection

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25
Q

Where are supraoptic and paraventricular nucleus located?

A

Hypothalamus, deliver hormones to posterior pituitary

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26
Q

What are 4 releasing hormones of anterior pituitary?

A

Thyroid releasing hormone TRH, gonadotropin releasing hormone GnRH, growth hormone releasing hormone GHRH, corticotropin releasing hormone CRH

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27
Q

What are two inhibitory hormones of anterior pituitary?

A

Somatostatin and dopamine

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28
Q

What does thyroid releasing hormone do?

A

Stimulates release of TSH

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29
Q

What does thyroid releasing hormone do?

A

Stimulates release of thyrotropin

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30
Q

What does gonadotropin releasing hormone do?

A

Stimulates release of FSH and LH

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31
Q

What does growth hormone releasing hormone do?

A

Stimulates release of GH

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32
Q

What does corticotropin releasing hormone do?

A

Stimulates synthesis of POMC, and release of B-lipotropic hormone B-LPH and corticotropin ACTH

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33
Q

What does somatostatin inhibit?

A

Release of somatostatin GH, and TSH

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34
Q

What does dopamine inhibit?

A

Release of prolactin

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35
Q

What are the two acidophilic chromophils of anterior pituitary?

A

Somatotrophs, Lactotrophs/Mammotrophs

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36
Q

What are the three basophilic chromophils of anterior pituitary?

A

Corticotrophs, Thyrotrophs, Gonadotrophs

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37
Q

What are chromophobes?

A

Cells that do not pick up stain, no secretory granules, stem cells and degranulated cells

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38
Q

Where does anterior pituitary develop from?

A

Ectoderm roof of mouth, called Rathkes pouch

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39
Q

Where does posterior pituitary develop from?

A

Hypothalamus part of the dicephalon

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40
Q

What does anterior pituitary (pars distalis) consist of structure wise?

A

Clumps and cords of endocrine cells, fenestrated capillaries, supporting reticular fibers

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41
Q

What is main controlling center of the autonomic nervous system?

A

Hypothalamus

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42
Q

What are the 5 major endocrine glands?

A

Pituitary, Pineal, parathyroid, thyroid, adrenal glands

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43
Q

What are the 3 chemical classifications of hormones?

A

Polypeptides/Peptides/Proteins
Steroids
Amino Acids and Catecholamines

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44
Q

What organs produce polypeptides and hormones?

A

Hypothalamus, pituitary, thyroid, parathyroid, pancreas

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45
Q

What organs produce cholesterol derived steroids?

A

Ovaries, testes, adrenal cortex

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46
Q

What organs produce amino acids?

A

Thyroid gland,
Catecholamines are produced by adrenal medulla

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47
Q

What is autocrine signaling?

A

Signals binds to same cell producing signal

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48
Q

What is juxtacrine signaling?

A

Signaling to neighboring cells through GAP junctions

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49
Q

What is paracrine signaling?

A

Signaling through diffusion into extracellular fluid to nearby cells

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50
Q

What is endocrine signaling?

A

Signaling through the blood circulatory system

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51
Q

What tissue is pituitary composed of?

A

Glandular epithelial tissue and neural tissue

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52
Q

What is Pars distalis?

A

Anterior lobe of pituitary, 75%

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53
Q

What is Pars intermedia?

A

Narrow band of tissue that lies between pars distalis and posterior pituitary

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54
Q

What is pars tuberalis?

A

Band of tissue around infundibulum stem

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55
Q

What does pars intermedia produce?

A

Endorphins, MSH Melanocyte Stimulating Hormone
Chromophobes
Small colloid filled cysts

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56
Q

Where are small colloid filled cysts in pars intermedia derived from?

A

Lumen of embryonic Rathkes pouch

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57
Q

What do corticotropes produce here and cleave differently to produce MSH and endorphins?

A

POMC

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58
Q

What are most cells in pars tuberalis?

A

Gonadotrophs

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59
Q

What rhythm is Pineal gland on?

A

Circadian rhythm

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60
Q

What kind of capsule covers pineal gland?

A

Vascularized connective tissue capsule of pia matter

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61
Q

What does the vascularized connective tissue covering do to lobes as it extends into gland?

A

Divides gland into variously sized lobules

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62
Q

What does LM show of pineal gland?

A

Two types of cells, and BRAIN SAND

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63
Q

What is Brain Sand?

A

Concentrations of calcium and magnesium salts

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64
Q

What is characteristic feature for pineal gland?

A

Brain Sand, formed by mineralization of extracellular protein deposits

65
Q

What are two cell types found in pineal gland?

A

Pinealocytes and interstitial cells

66
Q

What are pinealocytes in pineal gland?

A

Secretory cells, produce melatonin

67
Q

Describe structure of pinealocyte

A

Abundant, basophilic cytoplasm, euchromatic nuceli due to active synthesis, lipofuscin granules, secretory vesicles and mitochondria, long cytoplasmic process extending into vascularized septa

68
Q

What are pinealocytes connected by?

A

GAP junctions

69
Q

What enzyme does pinealocyte use to produce melatonin?

A

AANAT Arylalkylamine N-acetyltransferase

70
Q

What does AANAT do?

A

Represses melatonin production in daylight, only synthesized at night

71
Q

What is retinohypothalamic tract?

A

Tract that connects with sympathetic neural tracts traversing the pineal gland, detects daylight and darkness through retina and transmits information through this tract

72
Q

What is Seasonal Affective Disorder SAD?

A

Pineal gland plays role in emotional responses to altered daylight during winter

73
Q

What are interstitial cells of pineal gland?

A

Supporting cells, 5% of cells, modified astrocytes

74
Q

What is LM structure of interstitial pineal gland cells?

A

Elongated nuclei, heavily stain, stain positive for glial fibrillary acidic protein GFAP

75
Q

Where are interstitial cells of pineal gland found in epithelium?

A

Usually found in perivascular areas between groups of pinealocytes

76
Q

What is the band of tissue that connects the lobes of thyroid gland?

A

Isthmus

77
Q

What does the connective tissue capsule do for thyroid gland?

A

Sends trabeculae into glandular parenchyma and divides lobes into lobules

78
Q

What is the functional unit of the thyroid gland?

A

Thyroid follicle

79
Q

What are the three hormones that thyroid gland produces?

A

T3, T4, Calcitonin

80
Q

What is epithelium of thyroid follicle?

A

Simple cuboidal or low columnar

81
Q

What does thyroid follicle contain?

A

Thyroglobulin- Glycoprotein colloid

82
Q

What is colloid secreted by?

A

Follicular cells/Thyrocytes

83
Q

Where are parafollicular cells found?

A

Inside basal lamina of follicular epithelium or in isolated clusters between follicles

84
Q

Where are parafollicular cells derived from?

A

Ultimobranchial body of 4th pharyngeal pouch with neural crest contribution

85
Q

What does parafollicular cells secrete?

A

Calcitonin

86
Q

What does calcitonin act on?

A

Directly on osteoclast cells, inhibits activation of osteoclast activity

87
Q

Where do parafollicular cells secrete?

A

Straight into blood capillaries

88
Q

What are calcitonin secretions triggered by?

A

Elevated blood calcium levels

89
Q

Where are thyrocytes derived from?

A

Endoderm of floor of mouth

90
Q

What do thyrocytes secrete?

A

T3 and T4

91
Q

Where do thyrocytes secrete?

A

Directly into blood capillaries, no storage of hormones in colloid

92
Q

What are thyrocytes controlled by?

A

TSH from anterior pituitary

93
Q

What epithelium do active thyrocytes show?

A

Low columnar

94
Q

What epithelium do hypoactive thyrocytes show?

A

Simple squamous

95
Q

How are thyrocytes connected to each other?

A

Apical junctional complexes

96
Q

What does light coloration/haziness on cells next to colloid represent?

A

Exocrine secretion process

97
Q

What do thyrocytes show in apical region of cell?

A

Golgi, secretory granules, phagosomes and lysosomes, microvilli

98
Q

What do thyrocytes show in basal region of cell?

A

Rich in rER

99
Q

Where are parathyroid glands located?

A

In same capsule that covers lobes of thyroid

100
Q

Where are superior parathyroid glands derived from?

A

Endoderm 4th pharyngeal pouch

101
Q

Where are inferior parathyroid glands derived from?

A

Endoderm 3rd pharyngeal pouch

102
Q

What does parathyroid secrete?

A

Parathyroid Hormone PTH

103
Q

What does parathyroid hormone do?

A

Increases blood calcium levels by indirect stimulation of osteoclastic action and decreasing calcium excretion by kidneys

104
Q

How is PTH regulated?

A

By serum calcium levels through feedback mechanism

105
Q

What is parathyroid surrounded by?

A

Thin connective tissue capsule that divides into lobules

106
Q

What is parathyroid parenchyma rich in?

A

Rich network of fenestrated capillaries

107
Q

What happens with connective tissue component of parathyroid with increasing age?

A

Becomes more obvious, increased numbers of adipose tissue is deposited

108
Q

What two types of cells are present in parathyroid parenchyma?

A

Chief cells and oxyphil cells

109
Q

What are parathyroid chief cells/principal cells?

A

Most numerous, contain lipofuscin granules, acidophilic cytoplasm

110
Q

What do parathyroid chief cells/principal cells secrete?

A

Parathyroid hormone PTH

111
Q

What are parathyroid oxyphil cells?

A

No secretory role, acidophilic cytoplasm, occurs in clusters, mitochondria causes acidophilia

112
Q

What is the adrenal gland covered with?

A

Connective tissue capsule, thin trabeculae extend from the capsule into glandular parenchyma

113
Q

What does adrenal gland stroma consist of?

A

Reticular fibers for support and microvasculature

114
Q

What are two divisions of adrenal gland secretory parenchyma?

A

Yellow adrenal cortex, red brown adrenal medulla

115
Q

Where does adrenal cortex develop from?

A

Intermediate mesoderm

116
Q

Where does adrenal medulla develop from?

A

Neural crest

117
Q

What are the three layers in adrenal cortex?

A

Zona glomerulosa
Zona fasciculata
Zona reticularis

118
Q

What is zona glomerulosa in adrenal cortex?

A

Outer zone, 15% of cortex, glomerulus like arrangement of closely packed rounded arched cords of columnar cells with many capillaries

119
Q

What does zona glomerulosa in adrenal cortex secrete?

A

Aldosterone, major regulator of salt balance, stimulates sodium reabsorption in distal convoluted tubules

120
Q

What is aldosterone secretion stimulated by?

A

Angiotensin II and increases in plasma potassium concentration, weakly stimulated by ACTH

121
Q

What is zona fasciculata in adrenal cortex?

A

Middle zone, 80% of cortex, long cords of polyhedral cells, cells are filled with lipid droplets called spongiocytes, separated by fenestrated capillaries

122
Q

What does zona fasciculata in adrenal cortex secrete?

A

Glucocorticoid or cortisol, affects carbohydrate metabolism, induces fat mobilization and muscle proteolysis, and can also suppress many immune functions

123
Q

What is cortisol secretion stimulated by?

A

Controlled by ACTH

124
Q

What is unusual feature in zona fasciculata in adrenal cortex?

A

Shows unusual round mitochondria with tubular cristae, large numbers of anastomosing tubular elements and small vesicles of sER

125
Q

What is zona reticularis in adrenal cortex?

A

Inner zone, 5-7% of cortex, small cells in a network of irregular cords separated by wide sinusoidal capillaries, contain lipofuscin granules

126
Q

What does zona reticularis in adrenal cortex secrete?

A

Weak androgens, including DHEA that is converted to testosterone

127
Q

What is zona reticularis in adrenal cortex stimulated by?

A

Controlled by ACTH

128
Q

Describe structure of adrenal medulla

A

Pale staining polyhedral cells arranged in cords and supported by reticular fibers, separated by sinusoidal capillaries and parasympathetic ganglion cells

129
Q

What are cells in adrenal medulla called?

A

Chromaffin cells, considered modified sympathetic postganglionic neurons

130
Q

Where do chromaffin cells arise from?

A

Neural crest

131
Q

What are adrenal medulla electron dense granules?

A

Granules of catecholamines; epinephrine and norepinephrine

132
Q

What does adrenal medulla secrete more of, epi or norepi?

A

Epinephrine, 80% of secretions

133
Q

What is chromagranin?

A

Glandular storage complexes of proteins that store both catecholamines and calcium and ATP

134
Q

What are chromaffin cells innervated with?

A

Preganglionic sympathetic neurons, trigger catecholamine release during stress and emotional distress

135
Q

What does epinephrine do?

A

Increase heart rate, dialates bronchioles and arterioles of cardiac and skeletal muscles

136
Q

What does norepinephrine do?

A

Constricts vessels of digestive system and skin, increasing blood flow to heart, muscles, and brain

137
Q

What is the endocrine pancreas covered in?

A

Thin reticular capsule surrounds each islet, separating it from adjacent acinar tissue

138
Q

Where is endocrine pancreas derived from?

A

Endoderm

139
Q

What is the structure of cells of islets?

A

Polygonal or rounded cells, lightly stained compared to other acinar tissue, arranged in cords and separated by fenestrated capillaries, acidophilic and basophilic with fine cytoplasmic granules

140
Q

What are the minor cells of endocrine pancreas?

A

PP cells/Pancreatic peptide cells/F cells
Endochromaffin cells
Epsilon cells

141
Q

What are three major cells of endocrine panreas?

A

Alpha cells
Beta cells
Delta cells

142
Q

What are pancreatic alpha cells?

A

15% of cells, located within the islet on the periphery of beta cell clusters

143
Q

What do pancreatic alpha cells secrete?

A

Glucagon, increases blood glucose levels

144
Q

What are pancreatic beta cells?

A

60% of cells, GAP junctions between cells, synchronize oscillations in intracellular calcium during hormone secretion

145
Q

What does pancreatic beta cells consist of?

A

GAP junctions, juxtanuclear golgi, moderate rER, free ribosomes, few mitochondria, numerous distinctive membrane bound secretory vesicles derived from golgi

146
Q

What do pancreatic beta cells secrete?

A

Insulin, lowers blood glucose by promoting its entry into cells

147
Q

What is pancreatic beta cells electron dense crystalloid composed of?

A

Insulin-zinc complex, surrounded by pale matrix and enclosed in loose fitting membrane

148
Q

What are pancreatic delta cells?

A

5% of cells, scattered and less abundant, pale staining granules

149
Q

What do pancreatic delta cells secrete?

A

Somatostatin, inhibits glucagon and insulin secretion

150
Q

What type of secretion is pancreatic cells secretion?

A

Paracrine secretion

151
Q

What is ultrastructure of islet cells?

A

Consistent with role in synthesis and secretion of polypeptide hormones, attached by intercellular junctions, free surfaces are close to fenestrated capillaries

152
Q

What is predominant feature of pancreatic ultrastructure?

A

Many membrane bound secretory vesicles of various size and internal destiny

153
Q

What are pancreatic PP cells/pancreatic polypeptide cells/F cells?

A

Mostly in head of pancreas, stimulate gastric chief cells

154
Q

What do PP/F cells secrete?

A

Pancreatic polypeptide, inhibits bile secretion, inhibits pancreatic enzymes, inhibits somatostatin

155
Q

What are pancreatic endochromaffin cells?

A

Scattered in pancreatic acini and ducts, DNES system, act in paracrine manner

156
Q

What does pancreatic endochromaffin cells secrete?

A

Hormones affecting digestive system

157
Q

What are APUD cells?

A

DNES cells secreting serotonin or other amine derivatives demonstrating amine precursor uptake and decarboxylation and originate from neural crest

158
Q

What do pancreatic epsilon cells secrete?

A

Ghrelin, simulates appetite