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D1 Fall - Histology > 11/30: Pituitary and Pineal Histology > Flashcards

11/30: Pituitary and Pineal Histology Flashcards

1
Q

What does the endocrine system communicate via?

A

Chemical messengers (hormones)
Secretory products of endocrine cells

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2
Q

How does the endocrine system communicate?

A

By bloodstream to target tissue containing receptors

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3
Q

What are endocrine organs composed of?

A

Secretory cells of epitheial origin

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4
Q

What does the endocrine system lack?

A

Ducts

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5
Q

What does the endocrine system secrete?

A

Hormones into bloodstream

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6
Q

What does the endocrine system possess?

A

Rich blood supply with fenestrated capillary networks

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7
Q

What are fenestrated capillaries in the endocrine system function for?

A

Absorb and transport hormones

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8
Q

What is the duration of the endocrine system compared to nervous system?

A

Slower onset
longer duration than nervous control

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9
Q

What do endocrine organs integrate?

A

Function of physiological systems

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10
Q

What does the hypothalamus coordinate?

A

Endocrine functions of body

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11
Q

What does the hypothalamus act as?

A

Intermediate between autonomic nervous system and endocrine system

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12
Q

What do most endocrine glands form?

A

Discreet organs (anterior pituitary, pineal, thyroid and suprarenal (adrenal))

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13
Q

Where is endocrine and exocrine tissue intermixed?

A

Pancreas

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14
Q

What is the pituitary suspended by?

A

A stalk from hypothalamus

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15
Q

Where does the pituitary rest?

A

In sella turcica of the sphenoid bone, posterior to the two optic chiasm (CN II)

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16
Q

What are the two major divisions of the pituitary?

A
  1. Adenohypophysis (anteiror pituitary)
  2. Neurohypophysis (posterior pituitary)
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17
Q

What is the secretion of pituitary hormones controlled by?

A

Hypothalamus, w complex blood supply

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18
Q

What kind of portal system does the pituitary gland have and what does this allow for?

A

Hypophyseal portal system; communication with hypothalamus

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19
Q

What does the hypothalamus control secretion of? and how?

A

Anterior pituitary; hypothalamic regulating factors (hormones)

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20
Q

What do releasing factors of the hypothalamus stimulate?

A

Secretion

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21
Q

What do inhibitory factors of the hypothalamus inhibit?

A

Secretion

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22
Q

What does the portal system carry?

A

Neuroendocrine secretions from hypothalamus to cells in pars distalis

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23
Q

What kind of hormones have non-endocrine target organs?

A

Direct acting hormones
e.g. GH, ADH, MSH, oxytocin, prolactin

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24
Q

These hormones target organs in another endocrine gland

A

Trophic Hormones
e.g. TSH, ACTH, FSH, LH

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25
Q

What are examples of pituitary-dependent endocrine glands?

A

thyroid gland, adrenal cortex, and gonads

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26
Q

Functionally, anatomically, and embryologically, What is the pituitary divided into?

A

Anterior and posterior portions

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27
Q

The anterior pituitary gland contains what kind of tissue?

A

Glandular epithelial tissue

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28
Q

The posterior pituitary gland contains what kind of tissue?

A

Neural secretory tissue

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29
Q

What was the anterior pituitary once thought to be?

A

“master gland” - focal connection between nervous and endocrine system

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30
Q

Specialized glandular tissue in the anterior pituitary arises from the ectoderm of the oral cavity in the region of the pharynx called

A

Rathke’s pouch

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31
Q

What does the rathke’s pouch differentiate into?

A
  1. Pars Distalis
  2. Pars intermedia
  3. Pars tuberalis
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32
Q

What is the bulk of the anterior pituitary?

A

Pars distalis

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33
Q

What is the thin layer between anterior and posterior pituitary?

A

Pars intermedia

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34
Q

What hormones does the pars intermedia secrete?

A

MSH & ACTH

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35
Q

What does the pars intermedia frequently contain?

A

Cystic remnants of Rathke’s pouch

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36
Q

What is an extension of anterior pituitary?

A

Pars tuberalis

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37
Q

What does the pars tuberalis form?

A

Infundibulum (pituitary stalk)

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38
Q

What does the pars distalis secrete?

A

Bulk of pituitary hormones, including both direct acting and trophic hormones

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39
Q

What are examples of direct acting hormones?

A

GH and prolactin

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40
Q

What are examples of trophic hormones?

A

TSH, ACTH, FSH, LH

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41
Q

What are secretory cells of anterior pituitary traditionally classified as?

A

Chromophils (which stain)
Chromophobes (do not stain)

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42
Q

Cells are now classified by their…

A

Hormone content

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43
Q

What are cells of the pars distalis surrounded by?

A

Sinusoids that receive the secreted hormones

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44
Q

What are the two types of chromophils?

A

Acidophils - stain with acidic dye; pink on H&E
Basophils - stain with basic dye; pale blue to light purple on H&E

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45
Q

What are small cells, dont take up either dye, clear on H&E?

A

Chromophobes

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46
Q

What do chromophobes represent?

A

Inactive cells

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47
Q

What are examples of acidophils?

A

Somatotrophs - ~50% of cells
Mammotrophs - ~20% of cells

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48
Q

What do somatotrophs secrete?

A

Growth hormone (GH or somatotropin)

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49
Q

What do somatotrophs release?

A

GHRH

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50
Q

What do somatotrophs inhibit?

A

Somatostatin (GHIH)

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51
Q

What do somatotrophs stimulate?

A

Ghrelin (stomach enteroendocrine cells) coordinates food intake with GH secretion

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52
Q

What do mammotrophs secrete?

A

Prolactin (controls lactation)

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53
Q

What do mammotrophs release?

A

PRH

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54
Q

What do mammotrophs inhibit?

A

Dopamine

55
Q

What are examples of basophils?

A

Thyrotrophs - ~5% of cells
Gonadotrophs - ~5% of cells
Corticotrophs - ~20% of cells

56
Q

What do thyrotrophs secrete?

A

Thyroid stimulating hormones (thyrotropin)

57
Q

What do gonadotroph secrete?

A

Follicle stimulating hormone (FSH)
Leutinizing hormone (LH)

58
Q

What do corticotrophs secrete?

A

Adrenocorticotropic hormone
(ACTH)
Melanocyte-stimulating hormone (MSH)
endorphins

59
Q

What is excessive
production of growth hormone beginning in childhood?

A

Pituitary gigantism

60
Q

What is pituitary gigantism due to?

A

Loss of feedback control
of growth hormone secretion or to GH-secreting tumor in
pituitary (adenoma)

61
Q

What does pituitary gigantism effect?

A
  • Skeletal growth as well as
    internal organs
  • Significant problems with blood glucose management
62
Q

What is death from pituitary gigantism due to?

A

heart disease or diabetes
(complications)

63
Q

What is Excessive ADULT production of growth
hormone?

A

Acromegaly

64
Q

What does acromegaly result in?

A
  • Growth of face (prognathism), hands &
    feet
  • Increase in viscera
  • Overproduction of glucose leads to diabetes
65
Q

What is acromegaly due to?

A

loss of feedback control of growth hormone secretion or to GH-secreting tumor in pituitary

66
Q

What is treatment for acromegaly?

A

surgery, radiation, growth hormone receptor antagonist

67
Q

What is growth retardation resulting in abnormally short adult stature?

A

Pituitary dwarfism

68
Q

What is pituitary dwarfism caused by?

A

Insufficient growth hormone
or inadequate nutrition in early life

69
Q

Where can a pituitary dwarfism problem be located?

A

In hypothalamus or pituitary

70
Q

What is treatment for dwarfism?

A

Injections of GH

71
Q

What does prolactin stimulate?

A

Initiation and maintenanc eof milk production postpartum

72
Q

What is prolactin secretion mediated by?

A

Inhibition control mediated by dopamine

73
Q

What is prolactin secretion stimulated by?

A

PRH, but suckling during lactation is the primary stimulus

74
Q

How does prolactin work as birth control?

A

Prolactin inhibits the pulsatile secretion of GnRH which suppresses secretion of FSH & LH

75
Q

What can a pituitary macroadenoma tumor impinge?

A

optic chiasm producing visual field defects (classically: bitemporal hemianopsia)

76
Q

What can pituitary macroadenoma tumor erode?

A

Sella turcica

77
Q

What can a large tumor like a
pituitary macroadenoma produce?

A

Increased intracranial pressure (with headache nausea, and vomiting)

78
Q

What do corticotrophs produce?

A

Adrenocorticotropic hormone (ACTH) and lipotropic hormone (LPH)

79
Q

What does the ACTH stimulate hormone release by?

A

The adrenal (suprarenal) cortex

80
Q

What does LPH stimullate in some mamals?

A

Lipid mobilization; role in humans is unknown

81
Q

What do gonadotrophs produce?

A

follicle-stimulating hormone (FSH) and luteinizing hormone
(LH)

82
Q

What does FSH stimualte?

A

ovarian follicle development/estrogen secretion or production of androgen binding protein by Sertoli cells

83
Q

What does LH helps control and trigger?

A

menstrual cycle; release of
an egg

84
Q

What do thyrotrophs produce?

A

thyroid stimulating hormone (TSH) or thyrotropin

85
Q

What do thyrotrophs stimulate?

A

thyroid gland to synthesize, store & release thyroid hormones

86
Q

What do thyrotrophs release?

A

TRH

87
Q

What do thyrotrophs inhibit?

A

Negative feedback suppression by CNS based on amount of circulating thyroid hormones

88
Q

What are cells that DONT contain secretory granules?

A

Chromophobes - Undifferentiated (stem) cells
Folliculostellate cells

89
Q

What cells does the stroma support?

A

Chromophils

90
Q

What are cells with granules?

A

partially degranulated chromophils

91
Q

What has a secondary plexus in pars distalis?

A

Portal veins

92
Q

What are found in pars tuberalis?

A

Epithelial cells (gonadotrophs) arranged in cords and hypophyseal portal vessels

93
Q

Where are cords of basophilic cells and colloid-filled follicles found?

A

Pars intermedia

94
Q

What is synthesized in the pars intermedia?

A

MSH & ACTH

95
Q

What do alpha and beta melanocyte do?

A

Sitmulate hormone which stimulates melanin (pigment) production

96
Q

What do branches of specialized melanocytes called melanophotes have?

A

dramatic darkening of
the skin of fishes, amphibians, and reptiles as granules of melanin

97
Q

What makes up the posterior pituitary?

A

Pars nervosa and infundibulum/stalk

98
Q

What is a downgrowth of neural ectoderm of hypothalamus?

A

Neurohypophysis

99
Q

What does the stalk/stem of the infundibulum carry?

A

Axons from hypothalamus

100
Q

What does the infundibulum contain

A

Portal veins and primary capillary plexus (median eminence)

101
Q

Where are axon terminals found?

A

Pars nervosa

102
Q

Hormones are moved from hypothalamus via?

A

Hypothalamo-hypophyseal tract with neurophysin

103
Q

Where are unmyelinated axons found?

A

Infundibulum

104
Q

What are unmyelinated axons stored for and where?

A

Release in pars nervosa

105
Q

What does ADH (vasopressin) control?

A

Blood pressure by altering permeability of renal collecting tubules/ducts

106
Q

What does a decrease in production of ADH cause?

A

increase urine production (as in diabetes insipidus)

107
Q

What is ADH (vasopressin) synthesized by?

A

Neuron cell bodies in supraoptic nucleus of hypothalamus

108
Q

What does oxytocin promote?

A

smooth Mm contraction in uterus & breast (especially during labor & lactation)

109
Q

What is oxytocin synthesized by?

A

neuron cell bodies in paraventricular nucleus of hypothalamus

110
Q

Where do axons end?

A

Pars nervosa

111
Q

What do axon endings in the pars nervosa form?

A

large, fusiform swellings called Herring bodies

112
Q

What are herring bodies filled with?

A

Secretory product

113
Q

What is the pars nervosa surrounded by?

A

specialized glial-like cells called pituicytes

114
Q

What is the pituitary gland also known as?

A

Epiphysis cerebri or pineal body

115
Q

Where is the pineal gland found?

A

posterior extremity of the third ventricle

116
Q

What is the pineal gland attached by?

A

pineal stalk to the diencephalon

117
Q

What does the pineal gland communcate with?

A

Hypothalamus

118
Q

What does the pineal gland act as in lower vertebrates?

A

Photoreceptor

119
Q

What does the pineal gland translate?

A

light intensity & duration (photoperiod) into endocrine
activity—important in circadian rhythms & seasonal reproductive cycles

120
Q

What hormones does the pineal gland secrete?

A

Melatonin
Serotonin

121
Q

What does melatonin stimulate?

A

Melanophores, chromatophores (pigment-containing cells) -> change in color intensity

122
Q

What is a vasoconstrictor; neurotransmitter?

A

Serotonin

123
Q

What kind of effect does melatonin have in mammals?

A

Anti-gonadal effect, decrease in sex activity

124
Q

What does melatonin cause a decrease in?

A

GNRH form hypothalamus
Sex hormone secretion from gonads

125
Q

What is the pineal gland supplied by?

A

Postganglionic sympathetics from superior cervical ganglion

126
Q

What are the most common cell types, comprising 95% of all cells?

A

Pinealocytes

127
Q

What are neuroglial cells in the pineal gland?

A

support cells such as astrocytes, microglial cells

128
Q

What can also be seen in the pineal gland?

A

Corpora arenacea = brain sand, pineal sand

129
Q

What is corpora arenacea “brain sand”?

A

Calcified accretions of Ca & Mg
phosphate in aging individuals

130
Q

What is synthesis and secretion of melatonin affected by?

A

Light exposure to eyes
- concentrations of melatonin are low during the daylight hours, and increase to a peak during the dark

131
Q

What does melatonin help establish?

A

Body’s circadian rhythym
- duration of melatonin
secretion each day is directly
proportional to the length of
the night

132
Q

Where in the world is seasonala ffective disorder more prevalent?

A

latitudes north of 30°N or south of 30°S

133
Q

What are typical symptoms of seasonal affective disorder (SAD)?

A

depression, lack of energy, increased need for sleep, a craving for sweets and weight gain. Symptoms begin in the fall, peak in the winter and usually resolve in the spring

134
Q

Is SAD a subtype of major depressive episodes?

A

Yes - categorized in the DSM-IV

D1 Fall - Histology (20 decks)

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