Endocrine System Flashcards
1
Q
What do somatotrophs secrete?
A
Growth Hormone GH
2
Q
What is percentage of somatotrophs in anterior pituitary?
A
50%
3
Q
Describe somatotroph LM structure
A
Many granules, acidophilic
4
Q
What does growth hormone target?
A
All tissues
5
Q
What do lactotrophs/mammotrophs secrete?
A
Prolactin
6
Q
What does lactotrophs target?
A
Mammary glands for milk production
7
Q
What is percentage of lactotrophs in anterior pituitary?
A
20%
8
Q
Describe lactotroph LM structure?
A
Few granules, acidophilic, secretory vesicles are large and ovoid
9
Q
What does Corticotrophs secrete?
A
ACTH and lipoprotein
10
Q
What does corticotrophs target?
A
Adrenal cortex
11
Q
What is percentage of corticotrophs in anterior pituitary?
A
10%
12
Q
Describe corticotrophs LM structure
A
ACTH granules are large and polygonal and arranged in clusters, basophilic
13
Q
What do Gonadotrophs secrete?
A
FSH and LH
14
Q
What is percentage of gonadotrophs in anterior pituitary?
A
20%
15
Q
What do gonadotrophs target?
A
Gonads
16
Q
Describe gonadotrophs LM structure
A
Abundant small secretion granules and distended rER, basophilic
17
Q
What do thyrotrophs secrete?
A
TSH
18
Q
What is percentage of thyrotrophs in anterior pituitary?
A
5%
19
Q
What does thyrotrophs target?
A
Thyroid gland
20
Q
Describe thyrotroph LM structure
A
Characteristic tapering of ends of cell, small round secretory granules, basophilic
21
Q
What does supraoptic nucleus synthesize?
A
Vasopressin/ADH
22
Q
What does vasopressin do?
A
Increases permeability of distal portions of nephron and causes rapid water reabsorption in collecting ducts
23
Q
What does paraventricular nucleus synthesize?
A
Oxytocin
24
Q
What does oxytocin do?
A
Induces contractions of myometrium of uterus, induces contractions of myoepithelial cells of mammary gland for milk ejection
25
Where are supraoptic and paraventricular nucleus located?
Hypothalamus, deliver hormones to posterior pituitary
26
What are 4 releasing hormones of anterior pituitary?
Thyroid releasing hormone TRH, gonadotropin releasing hormone GnRH, growth hormone releasing hormone GHRH, corticotropin releasing hormone CRH
27
What are two inhibitory hormones of anterior pituitary?
Somatostatin and dopamine
28
What does thyroid releasing hormone do?
Stimulates release of TSH
29
What does thyroid releasing hormone do?
Stimulates release of thyrotropin
30
What does gonadotropin releasing hormone do?
Stimulates release of FSH and LH
31
What does growth hormone releasing hormone do?
Stimulates release of GH
32
What does corticotropin releasing hormone do?
Stimulates synthesis of POMC, and release of B-lipotropic hormone B-LPH and corticotropin ACTH
33
What does somatostatin inhibit?
Release of somatostatin GH, and TSH
34
What does dopamine inhibit?
Release of prolactin
35
What are the two acidophilic chromophils of anterior pituitary?
Somatotrophs, Lactotrophs/Mammotrophs
36
What are the three basophilic chromophils of anterior pituitary?
Corticotrophs, Thyrotrophs, Gonadotrophs
37
What are chromophobes?
Cells that do not pick up stain, no secretory granules, stem cells and degranulated cells
38
Where does anterior pituitary develop from?
Ectoderm roof of mouth, called Rathkes pouch
39
Where does posterior pituitary develop from?
Hypothalamus part of the dicephalon
40
What does anterior pituitary (pars distalis) consist of structure wise?
Clumps and cords of endocrine cells, fenestrated capillaries, supporting reticular fibers
41
What is main controlling center of the autonomic nervous system?
Hypothalamus
42
What are the 5 major endocrine glands?
Pituitary, Pineal, parathyroid, thyroid, adrenal glands
43
What are the 3 chemical classifications of hormones?
Polypeptides/Peptides/Proteins
Steroids
Amino Acids and Catecholamines
44
What organs produce polypeptides and hormones?
Hypothalamus, pituitary, thyroid, parathyroid, pancreas
45
What organs produce cholesterol derived steroids?
Ovaries, testes, adrenal cortex
46
What organs produce amino acids?
Thyroid gland,
Catecholamines are produced by adrenal medulla
47
What is autocrine signaling?
Signals binds to same cell producing signal
48
What is juxtacrine signaling?
Signaling to neighboring cells through GAP junctions
49
What is paracrine signaling?
Signaling through diffusion into extracellular fluid to nearby cells
50
What is endocrine signaling?
Signaling through the blood circulatory system
51
What tissue is pituitary composed of?
Glandular epithelial tissue and neural tissue
52
What is Pars distalis?
Anterior lobe of pituitary, 75%
53
What is Pars intermedia?
Narrow band of tissue that lies between pars distalis and posterior pituitary
54
What is pars tuberalis?
Band of tissue around infundibulum stem
55
What does pars intermedia produce?
Endorphins, MSH Melanocyte Stimulating Hormone
Chromophobes
Small colloid filled cysts
56
Where are small colloid filled cysts in pars intermedia derived from?
Lumen of embryonic Rathkes pouch
57
What do corticotropes produce here and cleave differently to produce MSH and endorphins?
POMC
58
What are most cells in pars tuberalis?
Gonadotrophs
59
What rhythm is Pineal gland on?
Circadian rhythm
60
What kind of capsule covers pineal gland?
Vascularized connective tissue capsule of pia matter
61
What does the vascularized connective tissue covering do to lobes as it extends into gland?
Divides gland into variously sized lobules
62
What does LM show of pineal gland?
Two types of cells, and BRAIN SAND
63
What is Brain Sand?
Concentrations of calcium and magnesium salts
64
What is characteristic feature for pineal gland?
Brain Sand, formed by mineralization of extracellular protein deposits
65
What are two cell types found in pineal gland?
Pinealocytes and interstitial cells
66
What are pinealocytes in pineal gland?
Secretory cells, produce melatonin
67
Describe structure of pinealocyte
Abundant, basophilic cytoplasm, euchromatic nuceli due to active synthesis, lipofuscin granules, secretory vesicles and mitochondria, long cytoplasmic process extending into vascularized septa
68
What are pinealocytes connected by?
GAP junctions
69
What enzyme does pinealocyte use to produce melatonin?
AANAT Arylalkylamine N-acetyltransferase
70
What does AANAT do?
Represses melatonin production in daylight, only synthesized at night
71
What is retinohypothalamic tract?
Tract that connects with sympathetic neural tracts traversing the pineal gland, detects daylight and darkness through retina and transmits information through this tract
72
What is Seasonal Affective Disorder SAD?
Pineal gland plays role in emotional responses to altered daylight during winter
73
What are interstitial cells of pineal gland?
Supporting cells, 5% of cells, modified astrocytes
74
What is LM structure of interstitial pineal gland cells?
Elongated nuclei, heavily stain, stain positive for glial fibrillary acidic protein GFAP
75
Where are interstitial cells of pineal gland found in epithelium?
Usually found in perivascular areas between groups of pinealocytes
76
What is the band of tissue that connects the lobes of thyroid gland?
Isthmus
77
What does the connective tissue capsule do for thyroid gland?
Sends trabeculae into glandular parenchyma and divides lobes into lobules
78
What is the functional unit of the thyroid gland?
Thyroid follicle
79
What are the three hormones that thyroid gland produces?
T3, T4, Calcitonin
80
What is epithelium of thyroid follicle?
Simple cuboidal or low columnar
81
What does thyroid follicle contain?
Thyroglobulin- Glycoprotein colloid
82
What is colloid secreted by?
Follicular cells/Thyrocytes
83
Where are parafollicular cells found?
Inside basal lamina of follicular epithelium or in isolated clusters between follicles
84
Where are parafollicular cells derived from?
Ultimobranchial body of 4th pharyngeal pouch with neural crest contribution
85
What does parafollicular cells secrete?
Calcitonin
86
What does calcitonin act on?
Directly on osteoclast cells, inhibits activation of osteoclast activity
87
Where do parafollicular cells secrete?
Straight into blood capillaries
88
What are calcitonin secretions triggered by?
Elevated blood calcium levels
89
Where are thyrocytes derived from?
Endoderm of floor of mouth
90
What do thyrocytes secrete?
T3 and T4
91
Where do thyrocytes secrete?
Directly into blood capillaries, no storage of hormones in colloid
92
What are thyrocytes controlled by?
TSH from anterior pituitary
93
What epithelium do active thyrocytes show?
Low columnar
94
What epithelium do hypoactive thyrocytes show?
Simple squamous
95
How are thyrocytes connected to each other?
Apical junctional complexes
96
What does light coloration/haziness on cells next to colloid represent?
Exocrine secretion process
97
What do thyrocytes show in apical region of cell?
Golgi, secretory granules, phagosomes and lysosomes, microvilli
98
What do thyrocytes show in basal region of cell?
Rich in rER
99
Where are parathyroid glands located?
In same capsule that covers lobes of thyroid
100
Where are superior parathyroid glands derived from?
Endoderm 4th pharyngeal pouch
101
Where are inferior parathyroid glands derived from?
Endoderm 3rd pharyngeal pouch
102
What does parathyroid secrete?
Parathyroid Hormone PTH
103
What does parathyroid hormone do?
Increases blood calcium levels by indirect stimulation of osteoclastic action and decreasing calcium excretion by kidneys
104
How is PTH regulated?
By serum calcium levels through feedback mechanism
105
What is parathyroid surrounded by?
Thin connective tissue capsule that divides into lobules
106
What is parathyroid parenchyma rich in?
Rich network of fenestrated capillaries
107
What happens with connective tissue component of parathyroid with increasing age?
Becomes more obvious, increased numbers of adipose tissue is deposited
108
What two types of cells are present in parathyroid parenchyma?
Chief cells and oxyphil cells
109
What are parathyroid chief cells/principal cells?
Most numerous, contain lipofuscin granules, acidophilic cytoplasm
110
What do parathyroid chief cells/principal cells secrete?
Parathyroid hormone PTH
111
What are parathyroid oxyphil cells?
No secretory role, acidophilic cytoplasm, occurs in clusters, mitochondria causes acidophilia
112
What is the adrenal gland covered with?
Connective tissue capsule, thin trabeculae extend from the capsule into glandular parenchyma
113
What does adrenal gland stroma consist of?
Reticular fibers for support and microvasculature
114
What are two divisions of adrenal gland secretory parenchyma?
Yellow adrenal cortex, red brown adrenal medulla
115
Where does adrenal cortex develop from?
Intermediate mesoderm
116
Where does adrenal medulla develop from?
Neural crest
117
What are the three layers in adrenal cortex?
Zona glomerulosa
Zona fasciculata
Zona reticularis
118
What is zona glomerulosa in adrenal cortex?
Outer zone, 15% of cortex, glomerulus like arrangement of closely packed rounded arched cords of columnar cells with many capillaries
119
What does zona glomerulosa in adrenal cortex secrete?
Aldosterone, major regulator of salt balance, stimulates sodium reabsorption in distal convoluted tubules
120
What is aldosterone secretion stimulated by?
Angiotensin II and increases in plasma potassium concentration, weakly stimulated by ACTH
121
What is zona fasciculata in adrenal cortex?
Middle zone, 80% of cortex, long cords of polyhedral cells, cells are filled with lipid droplets called spongiocytes, separated by fenestrated capillaries
122
What does zona fasciculata in adrenal cortex secrete?
Glucocorticoid or cortisol, affects carbohydrate metabolism, induces fat mobilization and muscle proteolysis, and can also suppress many immune functions
123
What is cortisol secretion stimulated by?
Controlled by ACTH
124
What is unusual feature in zona fasciculata in adrenal cortex?
Shows unusual round mitochondria with tubular cristae, large numbers of anastomosing tubular elements and small vesicles of sER
125
What is zona reticularis in adrenal cortex?
Inner zone, 5-7% of cortex, small cells in a network of irregular cords separated by wide sinusoidal capillaries, contain lipofuscin granules
126
What does zona reticularis in adrenal cortex secrete?
Weak androgens, including DHEA that is converted to testosterone
127
What is zona reticularis in adrenal cortex stimulated by?
Controlled by ACTH
128
Describe structure of adrenal medulla
Pale staining polyhedral cells arranged in cords and supported by reticular fibers, separated by sinusoidal capillaries and parasympathetic ganglion cells
129
What are cells in adrenal medulla called?
Chromaffin cells, considered modified sympathetic postganglionic neurons
130
Where do chromaffin cells arise from?
Neural crest
131
What are adrenal medulla electron dense granules?
Granules of catecholamines; epinephrine and norepinephrine
132
What does adrenal medulla secrete more of, epi or norepi?
Epinephrine, 80% of secretions
133
What is chromagranin?
Glandular storage complexes of proteins that store both catecholamines and calcium and ATP
134
What are chromaffin cells innervated with?
Preganglionic sympathetic neurons, trigger catecholamine release during stress and emotional distress
135
What does epinephrine do?
Increase heart rate, dialates bronchioles and arterioles of cardiac and skeletal muscles
136
What does norepinephrine do?
Constricts vessels of digestive system and skin, increasing blood flow to heart, muscles, and brain
137
What is the endocrine pancreas covered in?
Thin reticular capsule surrounds each islet, separating it from adjacent acinar tissue
138
Where is endocrine pancreas derived from?
Endoderm
139
What is the structure of cells of islets?
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
What are the minor cells of endocrine pancreas?
PP cells/Pancreatic peptide cells/F cells
Endochromaffin cells
Epsilon cells
141
What are three major cells of endocrine panreas?
Alpha cells
Beta cells
Delta cells
142
What are pancreatic alpha cells?
15% of cells, located within the islet on the periphery of beta cell clusters
143
What do pancreatic alpha cells secrete?
Glucagon, increases blood glucose levels
144
What are pancreatic beta cells?
60% of cells, GAP junctions between cells, synchronize oscillations in intracellular calcium during hormone secretion
145
What does pancreatic beta cells consist of?
GAP junctions, juxtanuclear golgi, moderate rER, free ribosomes, few mitochondria, numerous distinctive membrane bound secretory vesicles derived from golgi
146
What do pancreatic beta cells secrete?
Insulin, lowers blood glucose by promoting its entry into cells
147
What is pancreatic beta cells electron dense crystalloid composed of?
Insulin-zinc complex, surrounded by pale matrix and enclosed in loose fitting membrane
148
What are pancreatic delta cells?
5% of cells, scattered and less abundant, pale staining granules
149
What do pancreatic delta cells secrete?
Somatostatin, inhibits glucagon and insulin secretion
150
What type of secretion is pancreatic cells secretion?
Paracrine secretion
151
What is ultrastructure of islet cells?
Consistent with role in synthesis and secretion of polypeptide hormones, attached by intercellular junctions, free surfaces are close to fenestrated capillaries
152
What is predominant feature of pancreatic ultrastructure?
Many membrane bound secretory vesicles of various size and internal destiny
153
What are pancreatic PP cells/pancreatic polypeptide cells/F cells?
Mostly in head of pancreas, stimulate gastric chief cells
154
What do PP/F cells secrete?
Pancreatic polypeptide, inhibits bile secretion, inhibits pancreatic enzymes, inhibits somatostatin
155
What are pancreatic endochromaffin cells?
Scattered in pancreatic acini and ducts, DNES system, act in paracrine manner
156
What does pancreatic endochromaffin cells secrete?
Hormones affecting digestive system
157
What are APUD cells?
DNES cells secreting serotonin or other amine derivatives demonstrating amine precursor uptake and decarboxylation and originate from neural crest
158
What do pancreatic epsilon cells secrete?
Ghrelin, simulates appetite
