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histology exam 3 > endocrine > Flashcards

endocrine Flashcards

1
Q

endocrine organs

A
  • ductless glands
  • usually secrete hormones into bloodstream via fenestrate capillaries
  • generally have systemic effects
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2
Q

systemic effects

A

endocrine cell releases hormone in blood capillary and then travels to distant target cells. hormone binds to its receptor on the distant target cells

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3
Q

Paracrine hormones

A

–localized effect

paracrine cell releases hormone, paracrine hormone binds to its receptor on a nearby target cell

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4
Q

autocrine hormones

A

–localized effect

autocrat cell releases hormone that binds to a receptor on its own cell

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5
Q

localized effects

A
  1. paracrine

2. autocrine

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6
Q

functions of hormones

A

regulation of:

  1. other endocrine organs (tropic hormones)
  2. metabolism and energy balance
  3. glandular secretions
  4. smooth and cardiac muscle contraction
  5. growth and development
  6. “flight or fight” responses and reproduction
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7
Q

which endocrine functions are augmented by the ANS?

A

regulation of:

  1. smooth and cardiac muscle
  2. regulation of glandular secretions
  3. “flight or fight” responses
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8
Q

in what “non-endocrine” organs is there endocrine tissue?

A
  1. EPO and renin secreting cells in kidney

2. enteroendocrine cells in gut, lung

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9
Q

types of hormones

A
  1. protein
  2. peptide
  3. lipid-derived
  4. monamine
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10
Q

protein hormones

A

bind to cell surface receptors, activate 2nd messengers, etc
exs:
1. prolactin
2. growth hormone

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11
Q

peptide hormones

A

bind to cell surface receptors, activate 2nd messengers, etc

exs:
1. ADH
2. oxytocin (9AA each)

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12
Q

lipid-derived hormones

A

diffuse through cell/nuclear membranes, bind to nuclear receptors to effect gene expression

  1. from cholesterol: steroid hormones (estrogen, glucocorticoids)
  2. from eicosinoids: prostaglandins
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13
Q

monamine hormones

A

derived from AA: phenylalanine, tyrosine, tryptophan, thyroxine, melatonin, catecholamines [adrenaline/noradrenaline]

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14
Q

pituitary gland

A

aka hypophysis (Gk, hypo, under, phyein to grow)

anterior and posterior lobes

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15
Q

posterior lobe of pituitary gland

A

aka neurohypophysis

  • pars nervosa
  • infundibulum
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16
Q

anterior lobe of pituitary gland

A

aka adenohypophysis

  • pars distalis
  • pars intermedia
  • pars tuberalis
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17
Q

pituitary development

A
  1. posterior lober–formed from neuroectoderm (from floor of 3rd ventricle)
  2. anterior lobe-grew from remnants of Rathke’s pouch and oropharnyx ectoderm
    - -gland surrounded by developing sphenoid bone
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18
Q

type of cells in pars distalis

A

anterior lobe of pituitary

  1. basophils
  2. chromophobes
  3. endothelial cells
  4. acidophils
  5. fenestrated capillary

2 classes of cells: acidophils and basophils

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19
Q

acidophils

A
  1. somatotropes (50%)- growth hormone

2. lactotropes/mammotropes (15%) -prolactin

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20
Q

growth hormone

A 
released by somatotrope (acidophil- class cell type) cells in anterior pituitary
-growth of muscle, cartilage, bone; liver, pancreas, immune system, etc. functions
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21
Q

prolactin

A 
released by lactotropes/mammotrope cells (acidophil class cell type) in anterior pituitary 
functions:
1. mammary gland development
2. milk production
3.modulates spermatogenesis
4. surfactant synthesis in fetal lung
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22
Q

basophils

A 
found in anterior pituitary
 tropic hormones: act on other endocrine organs 
cell types:
1. corticotropes (15%)
2. thryrotropes (5%)
3. gonadotropes (10%)
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23
Q

corticotropes

A

anterior pituitary-basophils

adrenocorticotropic hormone- ACTH
target: adrenal cortex, production of corticosteroids

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24
Q

thyrotropes

A

anterior pituitary-basophils

thyroid stimulating hormone- TSH
target: thyroid gland, production of thyroid hormones

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25
Q

gonadotropes

A

anterior pituitary-basophils

follicle stimulating hormone-FSH and luteinizing hormone-LH
target: female and male reproductive organs

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26
Q

chromophobes

A

found in anterior pituitary

  • degranulated acidophils/basophils?
  • stem cells?
  • folliculostellate cells?
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27
Q

folliculostellate cells structure

A

found in anterior pituitary

  • devoid of granules, occupy 10% of anterior pituitary
  • form cell clusters (“follicles”)
  • dendritic morphology
  • possess gap junctional connections to other FS cells and to acidophils/basophils/chromophobes
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28
Q

folliculostellate cells functions

A
  1. paracrine regulation
  2. neuro/immune regulation of inflammation
  3. stem cells?
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29
Q

pars intermedia

A
  • part of anterior lobe
  • between pars nervosa and pars distalis
  • consists mostly of basophils (corticotrophs)
  • synthesizes proopiomelanocortin (POMC) which is cleaned to form: MSH, B-endorphins, ACTH
  • contains colloid filled cysts/ remnants of rathke’s pouch (identification/differentiation from pars nervosa and pars distalis)
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30
Q

pituitary portal system

A

aka hypothalamic-hypophyseal portal system
in pars tuberalis

transports neurosecretory cells from hypothalamus to endocrine cells of anterior pituitary

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31
Q

hormones released from pituitary to rest of body/tissues

A
  1. TSH
  2. ACTH
  3. FSH AND LH
  4. Growth hormone (GH)
  5. Prolactin (PRL)
  6. Endorphins
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32
Q

hormones released from hypothalamus via pituitary portal system

A

negative feedback mechanisms usually control hypothalamic secretions (e.g. high TSH levels inhibits TRH release)

  1. TRH-thyrotropin releasing hormone
  2. CRH- corticotropin releasing hormone
  3. GnRH- gonadotropin releasing hormone
    GHRH- growth hormone releasing hormone
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33
Q

TSH

A

released from portal system and targets thyroid

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34
Q

ACTH

A

released from portal system and targets adrenal cortex

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35
Q

FSH and LH

A

released from portal system and targets testes or ovaries

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36
Q

growth hormone (GH)

A

released from portal system and targets entire body

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37
Q

prolactin (PRL)

A

released from portal system and targets mammary glands (in mammals)

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38
Q

endorphins

A

released from portal system and targets pain receptors in the brain

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39
Q

posterior lobe components

A

neurosecretory organ
2 components:
1. pars nervosa
2. infundibulum

40
Q

posterior lobe cell types

A
  1. pituicytes (glia)
    - -its cytoplasm surrounds axon terminals
  2. unmylinated axons
  3. capillaries
41
Q

pars nervosa

A

component of posterior lobe

storage and release of ADH and oxytocin

42
Q

neurosecretion of posterior pituitary

A
  • hormones are stored (herring bodies–bulb-like projections of axon terminal)
  • axons terminate near blood vessels
  • hormones (9AA each) are coupled to neurophysin I and II
  • calcium release stimulate exocytosis
43
Q

hormones released via neurosecretion in posterior pituitary

A
  1. oxytocin

2. ADH (Vasopressin)

44
Q

oxytocin

A

released from posterior pituitary

  1. smooth muscle contraction of uterus
  2. myoepithelial cell contraction (mammary gland)
  3. emotional (trust, calmness)
45
Q

ADH

A

(vasopressin)

  1. increases collecting duct permeability
  2. vasoconstrictor (minor role)

–absence/deficiency leads to central diabetes insipidus

46
Q

pineal gland: structure, cell types

A

-neuroendocrine gland-aka third eye
-contains calcifications
divided in lobules by CT
cell types:
1. pinealocyte–purple cells with clear purple nucleus
2. interstitial (glial) cells–dark purple-ovalish shape

47
Q

pinealocyte

A

in pineal gland

produces melatonin

48
Q

melatonin functions

A
  1. participate in circadian rhythms (sleep cycles)
  2. role in puberty??
  3. powerful antioxidant
49
Q

production of melatonin pathway

A

pathway active in darkness and inhibited by light

  • occurs in pinealocyte of pineal gland
    1. tryptophan enters
    2. conversion to 5-hydroxytryptophan
    3. serotonin+NAT
    4. N-acetylserotonin+HIOMT
    5. Melatonin

melatonin released from pinealocyte’s perivascular process into fenestrated capillary

50
Q

pineal gland calcifications

A

2 types of calcifications

  1. corpora arenacea (brain sand)
  2. myeloconia (brain dust)
51
Q

corpora arenacea structure/size, composition

A

aka brain sand
-mid-sagittal organ-deviation from center may be indicative of pathology –tumors

  • one type of calcifications in pineal gland
  • large mulberry-like concretions
  • hydroxyapatite, protein, glycoprotein
  • increases with age
52
Q

myeloconia:

shapes, structure/size, composition

A 
aka brain dust
one type of calcifications in pineal gland 
-small 10-20 um crystals
-100-300 micro crystals/mm3
-calcite (CaCO3), glycoprotein 
-similar to otoliths of inner ear

shapes: cubic, hexagonal, cylindrical

53
Q

pancreas

A 
islets of Langerhans 
beta cells
alpha cells 
delta cells
gamma cells
epsilon cells
54
Q

islets of Langerhans

A

in pancreas

  • circular areas of lighter purple/pink areas with cells
  • abundant supply of fenestrated capillaries
55
Q

islet hormones

A
  1. insulin
  2. glucagon
  3. somatostatin
  4. pancreatic polypeptide
  5. gherlin
56
Q

insulin

A

islet hormone

  • synthesized by beta-cells in islets
  • 51 AA dimer (a-chain/ b-chain)
  • released in responses to elevated blood glucose levels
  • promotes glucose absorption in muscle and adipose tissue
57
Q

glucagon

A

islet hormone

  • synthesized by alpha-cells in islets
  • 29AA polypeptide
  • released in response to low blood sugar
  • promotes glycogen conversion to glucose- gluconeogenesis
58
Q

somatostatin

A

islet hormone

  • synthesized by delta cells in islets
  • 14 or 28 AA
  • inhibitory actionsL pituitary, gastrointestinal hormones, endocrine and exocrine pancreas
59
Q

pancreatic polypeptide

A

islet hormone

  • synthesized by F-cells (gamma cells) in islets
  • released in response to hypoglycemia and food ingestion
  • regulated pancreas/GI functions
60
Q

gherlin

A

islet hormone

  • synthesized by epsilon cells in islets and GI cells
  • “hunger hormone” (increasing hunger, opposite of leptin)
61
Q

beta cells

A

islets

insulin producing

62
Q

alpha cells

A

islets

glucagon producing

63
Q

delta cells

A

islets

somatostatin

64
Q

gamma cells

A

islets
aka F cell
pancreatic polypeptide

65
Q

epsilon cells

A

islets

ghrelin

66
Q

thyroid gland cell types

A
  1. follicular cells

2. parafollicular cells

67
Q

thyroglobulin

A

-iodainated glycoprotein (lots of tyrosine residues)
-comprises the major colloid component of thyroid
-extracellular storage form of thyroid hormone precursor
also present:
1. thyroid peroxidase
2. Iodine (I)
3. iodide (I-) –ion

68
Q

T4

A

thyroxine

-stable, long .5 life–one week

69
Q

T3

A

triiodothyronine
aka thyroid hormone
-potent form

70
Q

goiter

A

iodine-deficiency goiter

  • -large/inflamed thyroid–can see in neck
  • -iodized salt has all but eradicated these goiters in most parts of the world
71
Q

goiter cycle

A

low thyroxine (hypothyroidism)–> increased TRH from hypothalamus–> increased TSH from pituitary–> hypertrophy and hyperplasia of thyroid cells and increased colloid–> return to low thyroxine (hypothyroidism)

72
Q

graves disease

A

autoantibodies against TSH receptor (resulting in excess activation)

  • hyperthyroidism
  • goiter develops from follicle cell hyperplasia
  • excess periorbital CT/fat deposition leads to exopthalamos (enlarged-staring eyes)
  • -periorbital fibroblasts express TSH receptors
73
Q

graves disease mechanism

A
  1. TSH and ABs compete and ABs stimulates TSH receptors

2. follicular cells in thyroid are then stimulated and T3/T4 produced and released, and follicle cell hyperplasia occurs

74
Q

parafollicular cells

A

clear cells

  • reside within basal lamina
  • neural crest-derived
  • stores and produces calcitonin
75
Q

calcitonin

A

-released and stored by parafollicular cells
- stimulated by high calcium
lowers blood calcium levels by
a. increases osteoblast activity
b. decreases osteoclast activity
c. decreases calcium absorption
-opposes parathyroid hormone

76
Q

calcitonin

A

-released and stored by parafollicular cells
- stimulated by high calcium
lowers blood calcium levels by
a. increases osteoblast activity
b. decreases osteoclast activity
c. decreases calcium absorption
-opposes parathyroid hormone

77
Q

parathyroid gland: cell types

A

4 parathyroid glands in the thyroid

  1. principal cell
  2. oxyphil cell
  3. chief cells
78
Q

chief cells

A

in parathyroid gland
-secretes parathyroid hormone (PTH)

smaller cells with large nucleus, little cytoplasm, lots of them

79
Q

oxyphil cells

A

in parathyroid gland
-appear at puberty
-unknown function
look like egg cells–larger pink cell with purple nucleus in middle

80
Q

Parathyroid hormone (PTH)

A
  • secreted by chief cells in parathyroid gland
  • 84 aa polypeptide
  • opposes (opposite of) action of calcitonin but only PTH is vital
  • functions:
    1. increases blood calcium
    a. increases osteoclast activity
    b. stimulates vitamin D activation in kidney
    c. vitamin D stimulates coliseum resorption in GI tract and kidney
81
Q

exotic thyroid

A

remnant of thyroglossal duct outside of thyroid (thyroid tissue growth somewhere else in throat/mouth area

82
Q

thyroglossal duct cyst

A

can see on neck–growth of cyst –fluid filled

83
Q

adrenal gland composition/strucutre/components

A

-CT capsule
-cortex/medulla
-3 layers in cortex:
1. zona glomerulosa
(outer most part-near capsule)
2. zona fascuculata
3. zona retutcularis (inner most part-near medulla)

  • cortex: steroid hormone synthesis
  • medulla:catecholamine synthesis
84
Q

steroid secreting cell features

A

released from adrenal cortex

-lipid, smooth ER, mitochondria with tubular cristae

85
Q

aldosterone

A

aka mineralocorticoid
released/made in zona glomerulosa of adrenal cortex
1. promotes Na resorption in kidney, increases b.p.
2. controlled primarily by angiotensin II-less so by K+ levels and ACTH

86
Q

zona glomerulosa features

A

outer most layer of cortex in adrenal gland

  • in picture–can see capsule wall
  • produces/makes aldosterone
87
Q

production of angiotensin 2 pathways

A
  1. angiotensinogen is released from liver when pt has decreased b.p., fluid volume and increase Beta-1 sympathetic
  2. increased renin from kidney makes angiotensin 1
  3. ACE plus angiotensin 1 make angiotensin 2
88
Q

angiotensin 2 effects

A
  1. increased vasoconstriction
  2. increased salt (NaCl) and water reabsorption in kidney
  3. makes aldosterone via adrenal cortex–which increases Na resorption in DCT of kidney

all three together, increase bp, fluid volume

89
Q

zona fasciculata:
cell type/shape
hormone produced?

A

middle layer of adrenal gland cortex

  • -cells with purple nucleus, lighter cytoplasm filled with dots
  • –elongated cords of cells
  • -large cells, extracted lipid droplets
  • -fenestrated capillaries (elongated endothelial nuclei)
  • -makes cortisol (glucocorticoids)
90
Q

glucocorticoids

A 
aka cortisol
made in zona fasciculata layer of adrenal gland cortex
1. glucose metabolism (gluconeogenesis)
2. anti-inflammatory agent
3. controlled by ACTH
91
Q

zona reticularis

A

inner most layer of adrenal gland cortex

produces/makes androgens

92
Q

gonadicorticoids

A

aka androgens
produced in zona reticular layer of adrenal gland cortex
1. precursor for sex hormones
–DHEA-dehydroepiandrosterone, converted to estrogen and testosterone in ovaries and testes
2. controlled by ACTH

93
Q

adrenal medulla:

cell types

A
  1. chromaffin cells

production of catecholamines (epinephrine and norepinephrine and some dopamine)

94
Q

chromaffin cells

A

neuroendocrine cells–modified, axonless neurons
-neural crest-derived
-synthesize catecholamines from phenylalanine and tyrosine
-80% epinephrine (adrenaline0
-20% noreepinephrine (noradrenaline)
plus small amounts of dopamine

95
Q

chromaffin cells behave like what type of cells?

A

sympathetic neurons–2 neuron chain process

  1. 1st nerve–releases cholinergic (acetylcholine) to chromaffin cells.
  2. crhomaffin cells are postsynaptic neurons that then release adrenaline and noradrenaline (20:1) but released into blood stream and not onto target cell like sympathetic neurons.
    - -this process is slower bc hormones have to travel through blood to arrive at its target cells
96
Q

effects of adrenaline and noradrenaline on body?

A

increased HR
increased BP
dilate bronchioles
dilate coronary arteries

histology exam 3 (5 decks)

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