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Block 3; Week 6 Michelle > HISTO > Flashcards

HISTO Flashcards

1
Q

Does a hormone have to be released into blood?

A

No, it could be released into ECF or Lymph.

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2
Q

What are the 3 categories of hormones?

A
  1. Steroid Hormones (including thyroid hormone)
  2. Protein Hormones
  3. Amino acid analog
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3
Q

What types of receptors do steroid hormones use?

A

Often intracellular receptors b/c they can diffuse thru plasma membranes…then they change the rate of gene transcription
Some bind to cell surface receptors & achieve their desired response that way…
Note: they are lipid soluble

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4
Q

What types of receptors do protein & amino acid analog hormones use?

A

bind to receptors on the cell membrane
use second messengers & ions
Note: they are water soluble

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5
Q

What is the state of most hormones circulating in the blood?

A

most are bound to protein carriers & are inactive

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6
Q

T/F Most hormones circulating in the blood are in over-supply.

A

True.

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7
Q

What are the 4 types of secretion?

A

autocrine
paracrine
endocrine
synaptic

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8
Q

What does DNES stand for?

A

diffuse neuro endocrine system

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9
Q

With endocrine secretions…the targets are usu____.

A

remote

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10
Q

Which structure is the hallmark of the endocrine pancreas? How many cell types are found here? Which are the most important?

A 
Islets of Langerhans
6-9 cell types
Most important:
Alpha cells
Beta cells
Delta cells
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11
Q

Which cells in the islet of langerhans are peripheral & the largest? What do they secrete?

A

Alpha cells

glucagon

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12
Q

Which cells in the islet of Langerhans are most numerous? What do they secrete?

A

Beta Cells

Insulin

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13
Q

What do delta cells secrete?

A

somatostatin

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14
Q

What is the blood supply to the pancreatic acini? How about the islets of Langerhans?

A

Pancreatic Acini: Acinar Vascular System

Islets of Langerhans: Insuloacinar Portal System

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15
Q

What type of portal system is found @ the islet? Which organ is this similar to?

A

Venous portal system

similar to the liver

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16
Q

What is the alternative to the venous portal system? Which organ is this similar to?

A

Arterial Portal System

found in kidney

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17
Q

What separates the 2 halves of the hypothalamus?

A

the 3rd ventricle

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18
Q

What are the following limits of the hypothalamus? Rostrally? Caudally? Laterally? Dorsolaterally?

A

Rostrally: optic chiasma (sorta the front)
Caudally: mamillary bodies (sorta low)
Laterally: optic tracts
Dorsolaterally: thalamus

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19
Q

How many hormones does the pituitary gland synthesize? How many of the hormones do they release?

A

Synthesize 7

Release 9

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20
Q

What is the embryological origin of the adenohypophysis? The neurohypophysis?

A

Adenohypophysis: oral ectoderm
Neurohypophysis: neural ectoderm

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21
Q

Rathke’s pouch is associated w/ which hypophysis?

A

The adenohypophysis.

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22
Q

What are the 3 main structures of the adenohypophysis?

A

Pars tuberalis: this wraps around the stalk coming off of the hypothalamus
Pars distalis: this is the main part of the anterior pituitary
Pars Intermedia: separates the pars distalis from the pars nervosa

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23
Q

What are the 2 main structures of the neurohypophysis?

A

Infundibulum: the thing growing down from the brain, the stalk
Pars Nervosa: the bulk of the posterior pituitary

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24
Q

What is the basic structure of the adenohypophysis?

A

epithelial cells surrounded by extensive sinusoids

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25
Q

What are the 4 cell types of the adenohypophysis identified by histology stains?

A
  1. acidophils
  2. basophils
  3. chromophobes
  4. folliculostellate cells
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26
Q

What are the 5 cell types of the adenohypophysis identified by immunocytochemistry?

A
  1. Acidophils
    - somatotrophs
    - mammotrophs
  2. Basophils
    - corticotrophs
    - thyrotrophs
    - gonadotrophs
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27
Q

What do folliculostellate cells make up? What do these cells look like?

A

the framework or stroma of the adenohypophysis

they look like fibroblasts

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28
Q

What are chromophobes really?

A

degranulated acidophils or basophils

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29
Q

What color are acidophils? What color are basophils?

A

Acidophils: red
Basophils: blue

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30
Q

How is MSH formed in the adenohypophysis?

A

it is a cleavage by-product when ACTH is being made by corticotrophs, a type of basophil.

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31
Q

What do somatotrophs release? Which cell type is this?

A

GH

Acidophil

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32
Q

What do mammotrophs release? What cell type is this?

A

prolactin

Acidophil

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33
Q

What do corticotrophs release? What cell type is this?

A

ACTH (MSH by by-product)

Basophil

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34
Q

What do thyrotrophs release? What cell type is this?

A

TSH

basophil

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35
Q

What do gonadotrophs release? What cell type is this?

A

FSH & LH

basophil

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36
Q

What is one of the hallmarks of the adenohypophysis?

A

an extensive sinusoidal system

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37
Q

T/F The adenohypophysis & neurohypophysis both enjoy a direct blood supply.

A

False. The adenohypophysis does not.

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38
Q

Describe the hypothalamohypophyseal portal system.

A

Superior hypophysial artery supplies the primary capillary plexus found in the infundibulum.
The portal veins of the anterior pituitary carry that to the secondary capillary plexus of the pars distalis
It is then drained by a hypophyseal vein
**this carries blood & releasing factors from the hypothalamus to the anterior pituitary.

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39
Q

T/F The neurohypophysis is not an endocrine gland.

A

True. It is a storage site.

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40
Q

Describe the hypothalamoneurohypophyseal tract.

A

made up of unmyelinated axons & nerve endings of hypothalamic neurosecretory neurons
swelling at the ends of these axons called Herring bodies–>this is where oxytocin & vasopressin are stored for release

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41
Q

Describe the path of the oxytocin & vasopressin from synthesis to release.

A

Oxytocin is synthesized in paraventricular nuclei.
Vasopressin is synthesized in supraoptic nuclei (synthesized w/ neurophysin).
These hormones are transported along the axons. They are carried w/ the protein neurophysin. They are released from the Herring bodies/axon terminals. the hormones enter the fenestrated capillaries of the pars nervosa formed by the inferior hypophysial artery.

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42
Q

Pituicytes are found in the neurohypophysis. What is their role?

A

they are supporting cells, glial-like, they help in the release of oxytocin & vasopressin

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43
Q

What special protein do pituicytes possess that astrocytes also possess?

A

intermediate filament protein: glial fibrillary acidic protein

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44
Q

What is the first endocrine gland to appear in embryonic development?

A

thyroid gland

45
Q

What is the structure of the thyroid gland?

A

CT capsule extending into the gland to form septa
follicles are the structural unit
possesses follicular cells & parafollicular cells (C cells)

46
Q

Describe in detail the structure of the follicle.

A

outer lining of epithelium (follicular cells)
lumen of colloid (iodinated thyroglobulin)
lumen enclosed by a basal lamina

47
Q

What is the embryonic origin of follicular cells? What stimulates them? What are they responsible for producing?

A

endoderm
TSH stimulates them
produce thyoglobulin & release T4/T3

48
Q

What is the embryonic origin of parafollicular cells? What do they produce?

A

neural crest cells
aka C cells
produce calcitonin

49
Q

What are the effects of the calcitonin released by C cells?

A

target osteoclasts, inhibiting them
decrease Ca++ levels in the blood
peak effect 1 hour later

50
Q

When does the fetal thyroid start working?

A

@ 14 weeks

51
Q

One iodinated thyroglobulin makes how many molecules of thyroid hormone?

A

4 thyroid hormone molecules!

52
Q

What are 2 clinically significant things that can inhibit the iodination of thyroglobulin?

A

thiourea

MMI: methyl mercaptoimidazole

53
Q

What is something that can inhibit NIS, the iodide pump on follicles?

A

perchlorate, a competitive anion

54
Q

What location does the iodination of thyroglobulin occur in?

A

the follicular lumen!

55
Q

What are the 3 phases of thyroid cells/follicular cells?

A

Synthesis Stage: tall follicular cells
thyroglobulin is being produced
Resting stage: short follicular cells
Uptake Stage: tall follicular cells processes extend into the lumen to take up thyroglobulin & produce thyroid hormones for release

56
Q

Where are parafollicular cells located?

A

in b/w follicles, in clusters

57
Q

What cells are included in parafollicular cells?

A

enteroendocrine cells, APUD cells

58
Q

What do parafollicular cells do to osteoclasts?

A

decrease osteoclast ruffling
reduce osteoclast numbers
promote excretion of Ca++ from kidneys & the excretion of phosphate from kidneys

59
Q

How can C cells be distinguished from surrounding follicular cells?

A

they have a pale cytoplasm

Can also use immunocytochemistry or electron microscopy for more detail.

60
Q

What are the 4 mini organs on the back of the thyroid gland? What is their embryological origin?

A

parathyroid glands

mesoderm

61
Q

What are the 2 main cell types of the parathyroid gland? Which of them is acidophilic? Which is larger in size?

A

Chief Cells

Oxyphil Cells–acidophilic, larger

62
Q

What is the fcn of principal or chief cells? What is the function of oxyphils?

A

Chief Cells: release of PTH

Oxyphil Cells: fcn unknown

63
Q

Although we don’t know anything about their function, what do we know about oxyphil cells?

A 
have many mitochondria
larger than chief cells
appear at puberty & increase w/ age
acidophilic
paler cytoplasm on stain
64
Q

What prompts the release of PTH from chief cells in the parathyroid gland?

A

decrease in calcium blood levels
increase in cAMP
release of PTH

65
Q

How is PTH made in chief cells?

A

PreproPTH synthesized in RER
Modified to ProPTH
packaged in Golgi in secretory vesicles of PTH

66
Q

What are the effects of PTH release?

A

peak effect after several hours
increase in calcium levels
binds to receptors on osteoblasts releasing osteoclast stimulating factor

67
Q

In 2 words, what is the fcn of osteoclasts?

A

bone resorption

68
Q

Where is the origin of the precursor of the osteoclast?

A

in the bone marrow

precursor in common w/ monocytes

69
Q

What do osteoclasts look like?

A

large
multinucleated (up to 50 nuclei)
motile
acidophilic cytoplasm

70
Q

Osteoclasts’ home is ________ a place for ___ _____.

A

Howship’s lacunae: a shallow depression

regions of bone resorption

71
Q

In the microenvironment of the osteoclast…which enzyme is missing? Where is it found?

A

collagenase

Found as procollagenase in the bone matrix, produced by osteoblasts

72
Q

Where is the microenvironment of the osteoclast found?

A

in b/w the bone matrix & peripheral clear zone of the osteoclast

73
Q

What is the embryological origin of the medulla of the adrenal gland?

A

neural crest cells

74
Q

What’s the deal w/ ectopic sites of the adrenal gland?

A

some of the adrenal medulla is sometimes found in ectopic sites vascularly. Keep in mind that they are derived from neural crest cells & they like to migrate!

75
Q

What is the embryological origin of the adrenal cortex? What 2 things control its secretions? What is its structure? What are its 3 zones?

A 
mesoderm
ACTH & the kidney
cords of cells separated by sinusoids
out--In
Zona Glomerulosa
Zona Fasciculata
Zona Reticularis
76
Q

What are some arterial blood sources found in the adrenal cortex?

A

subcapsular arterial plexus
medullary artery
capillaries

77
Q

What types of hormones does the adrenal cortex produce? How are they produced? What are the 3 categories?

A 
Steroid Hormones:
Mineralcorticoids
Glucocorticoids
Androgens
**synthesized from cholesterol on an LDL frame
78
Q

Describe the blood supply of the adrenal medulla.

A

suprarenal vein & other blood vessels

large vascular sinusoids

79
Q

What types of hormones are released by the adrenal medulla? Which hormone is mainly released? What stimulates its release?

A

Catecholamines
Epinephrine (80%)
Norepinephrine (20%)
sympathetic stimulation

80
Q

Describe the sympathetic stimulation of the adrenal medulla.

A

innervated by preganglionic sympathetic fibers
via thoracic splanchnic nerves
these nerves pass thru the celiac plexus

81
Q

The zona glomerulosa is the zone of the adrenal cortex nearest the capsule. Which hormones does it secrete? What controls it? What is another special fcn that it has?

A

Mineralcorticoids
Main Hormone: Aldosterone
Controllers: RAAS & ACTH
Regenerative Zone of the adrenal cortex

82
Q

Which layer is the zone fasciculata in the adrenal cortex? Which hormones does it secrete? What is it controlled by?

A

Middle zone
Glucorticoids: mainly corticosterone, cortisol
Controllers: ACTH

83
Q

Describe the structure of the zone fasciculata & the specific structure of the cells found there.

A

thick middle zone
parallel cords of cells separated by sinusoids
large cells with lipid droplets

84
Q

Dr. Highi told a story about the dangers of getting a cortisol shot. What is it?

A

It can shut down the production of cortisol in your zone fasciculata cells for 2-4 months. Shouldn’t be used long-term.

85
Q

Where is the zone reticularis located in the adrenal cortex? Which hormones does it secrete? What controls its secretions? What is another special feature of it?

A

Innermost layer, closest to the medulla
Secretes weak androgenic steroids
Controlled by ACTH
Special Feature: contains lipofuscin granules

86
Q

What is the role of chromaffin cells in the adrenal medulla?

A

they act as the postganglionic sympathetic neurons
secrete epinephrine & norepinephrine
store opioid peptides

87
Q

What keeps chromaffin cells from growing axons?

A

the glucocorticoids released from the adrenal cortex suppress axonal growth

88
Q

80% of the secretions from the chromaffin cells are epinephrine. What are the effects of this?

A

an increase in heart rate & cardiac output

no change in BP

89
Q

20% of the secretions from the chromaffin cells re norepinephrine. What are the effects of this?

A

increase in BP thru vasoconstriction

90
Q

Describe the blood supply to the cortex of the adrenal gland.

A

capsular arteries

form sinusoids that drain into the medulla

91
Q

Describe the blood supply to the medulla of the adrenal gland.

A

from the cortical sinusoids that drain into the medulla.

directly from capsular arterioles

92
Q

Why is the blood supply to the medulla so important?

A

required for the synthesis of epinephrine & for the inhibition of axonal growth

93
Q

What is another name for chromaffin cells?

A

normal medulla cells OR pheochromocytes

94
Q

What’s the deal w/ pheochromocytomas in ectopic sites?

A

so sometimes they can run w/ vasculature…in ectopic sites (paraganglia)…and then if a vessel is moved in abdominal surgery…it will start secreting epinephrine & the vitals will go off the charts.

95
Q

How do the chromaffin cells convert norepinephrine to epinephrine?

A

with an enzyme called PNMT: phenylethanolamine N-methyltransferase
this is activated by the cortisol that is transported via the bloodstream from the adrenal cortex

96
Q

Which blood vessels supply the cortical plexus?

A

superior & middle adrenal arteries

97
Q

The cortical plexus eventually flows into the fenestrated cortical capillaries. Where are these found?

A

in the zona reticularis

98
Q

The fenestrated cortical capillaries eventually form the ____ ______ _____.

A

medullary venous sinuses

99
Q

Aside from the cortical capillaries, what else supplies the medullary venous sinuses?

A

the medullary artery

100
Q

Describe the path of the medullary artery in the adrenal gland.

A

Begins as inferior adrenal artery
enters the cortex w/o branching & goes to the medulla
in the medulla it branches & w/ the cortical capillaries forms the medullary venous sinuses

101
Q

Where is the pineal gland found? Why is this helpful for radiology?

A

found in b/w the 2 hemispheres

helpful for radiology b/c if it were deviated, indicative of increased CSF or brain tumor

102
Q

What is the embryological origin of the pineal gland? What are its 2 cell types? What covers it?

A

neuroectoderm
pinealocytes
neuroglial cells
**leptomeningeal covering

103
Q

There are CT septa in the pineal gland. How did this come to be?

A

meninges enveloped the pineal gland & invaded it.

104
Q

Neuroglial cells are the supporting interstitial cells of the pineal gland. What is the role of pinealocytes?

A

they secrete melatonin during the night & serotonin during the day

105
Q

How do the melatonin levels change during someone’s lifetime?

A

they are high before puberty & they decline with the onset of puberty…

106
Q

Another feature of the pineal gland is the presence of brain sand. What is this? How does it change during a person’s lifetime?

A

these are calcifications in the pineal gland also known as corpora arenacea

107
Q

In the pineal gland, what surrounds the clusters of pinealocytes? What surrounds the blood vessels supplying the pineal gland?

A

Glial-like interstitial cells surround the clusters of pinealocytes. Processes of pinealocytes surround the blood vessels.

108
Q

What is the nervous supply of the pineal gland?

A

postganglionic sympathetic nerve fibers from the superior cervical ganglion

Block 3; Week 6 Michelle (5 decks)

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