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Histology > Endocrinw System > Flashcards

Endocrinw System Flashcards

1
Q

T/F endocrine system has ducts

A

F, ductless glands

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2
Q

Diffuse neuroendocrine system (DNES)

A

. Single endocrine cells

. Seen in respiratory and GI

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3
Q

Nonepithelial cells w/ endocrine function

A

. Atrial myocardial cells w/in heart

. Juxtaglomerular apparatus in kidney

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4
Q

Endocrine cell signaling

A

. secrete hormones distributed to blood to distant target cells

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5
Q

Neuroendocrine signaling

A

. Neuronal secretory products carried to blood to distant cells

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6
Q

Paracrine cell signaling

A

. Secreted molecules act locally
. Regulates activity of nearby cells
. Synaptic cell signaling by release of neurotransmitters is specific type of paracrine signaling

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7
Q

Autocrine cell signaling

A

. Cells regulated by signaling molecules that they produce themselves

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8
Q

Protein and peptide hormones

A 
. Neuropeptides and growth factors 
. Synthesized as precursors 
. Stored in secretory vesicles 
. Water soluble 
. Circulate in blood as unbound molecules 
. Bind to surface receptors 
. Can’t be administered orally
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9
Q

Steroid hormones

A 
... from cholesterol 
. Bind to intracelllular receptors 
. Lipid-soluble 
. Not stored in producing cell 
. Can be taken orally
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10
Q

Nitric oxide

A

. Paracrine molecules in circulatory, immune, and nervous system

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11
Q

Eicosanoids

A

. Arachidonic acid is main precursor
. Include PGEs
. Autocrine and paracrine
. Bind to cell surface receptors

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12
Q

Organs in neuroendocrine system

A

. Hypothalamus
. Hypophysis
. Pineal gland

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13
Q

Hypothalamus

A

. Brain region w/ 12 hypothalamic hypophysiotropic nuclei
. Neurosecretory cells release neuropeptides (releasing and inhibitory hormones and factors)
. Hormones carried in blood, have pos. And neg/ effects on hypophysis
. Paraventricular and supraoptic nuclei of hypothalamus have neurons that give rise to axons that form hypothalamic hypophyseal tract
. Terminals of neurons in pars nervosa gf hypophysis

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14
Q

Hypophysis gross anatomy

A

. Pituitary
. Master endocrine gland
. Pea-sized (500-900 mg in adults, larger in women)
. Below hypothalamus in sella turcica in sphenoid bone in middle cranial fossa
. Suspended from hypothalamus by infundibulum
. Infundibulum contains neural and vascular connections to hypothalamus

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15
Q

Pituitary gland embryology

A

. Adenohypophysis: from Rathke’s pouch (evagination) of ectodermal lining of primitive oral cavity, extends upwards toward neurohypophysis
. Neurohypophysis: neural tissue from infundibular downgrowth of diencephalon

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16
Q

Parts of adenohypophysis

A

. Pars distalis: ant. Lobe, main part of gland (75%)
. Pars tuberalis: forms collar around infundibulum
. Pars intermedia: rudimentary in adults, thin wedge separating pars distalis from neurohypophysis, has Rathke’s cysts filled w/ colloid that are remnants for Rathke’s pouch

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17
Q

Parts of neurohypophysis

A

. Pars nervosa: post. Lobe or neural lobe
. Infundibular stalk: connects pars nervosa to hypothalamus
. Median eminence: funnel-like extension of hypothalamus

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18
Q

Pituitary gland blood supply

A

. Sup. Hypophyseal aa. From internal carotid enter median eminence and upper part of infundibular stalk forming primary capillary plexus
. Plexus receives products of neurosecretory cells from hypothalamus
. Capillaries give rise to hypophyseal portal system (venule network)
. Portal system drains into pars distalis and forms secondary capillary plexus
. Inf. Hypophyseal aa. Supply pars nervosa and form 3rd capillary plexus

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19
Q

Adenohypophysis structure

A

. Cords of epithelial cells
. Small amt CT
. Fenestrated capillaries

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20
Q

Hormone pathway in adenohypophysis

A

. Secreted hormones diffuse into capillaries,

. Drain via hypophyseal vv. Into dural venous sinuses

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21
Q

Adenohypophysis secretory cell classification

A

. Chromophills (acidophilus and basophils)

. Chromophobes

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22
Q

Acidophils in pituitary

A

. Cytoplasmic granules
. Somatotrophs: 40-50% of ant. Hypophysis cells, secrete GH (somatotropin) to induce growth, stimulated by somatotropin-releasing hormone, inhibited by somatostatin from hypothalamus
. Mammotrophs: 10-20% ant. Hypophysis cells, secrete prolactin, stimulated by prolactin-releasing hormone and thyrotropin-releasing hormone (TRH), inhibited by dopamine

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23
Q

Basophils in pituitary

A

. Corticotrophs: 10% ant. Cells, secrete ACTH, stimulated by corticotropin-releasing hormone from hypothalamus, inhibited by cortisol in blood
. Thyrotrophs: 5% ant. Cells, produce TSH, stimulated by TRH, inhibited by inc. concentrations of thyroid hormones
. Gonadotrophs: 10% ant. Cells produce FSH and LH, stimulated by gonadotropin-releasing hormone from hypothalamus

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24
Q

Function of ACTH

A

, stimulate adrenal cortex

. Inc. skin pigmentation

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25
Q

Follicle-stimulating hormone (FSH) function

A

. Stimulates development of ovarian follicles or productionof androgen-binding protein by Sertoli cells in males

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26
Q

Luteinizing hormone

A

. Ovulation and formation of corpus luteum in females

. Controls synthesis of tester one by Leydig cells in males

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27
Q

Chromophobes

A

. Small cells w/o secretory granules . Could be undifferentiated cells

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28
Q

Cels in pars tuberalis

A

Gonadotrophs

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29
Q

Cells in pars intima

A

. Basophils: mostly corticotrophs
. Chromophobes
. Products include melanocyte-stimulating hormone (MSH)

30
Q

Growth hormone cell adenoma

A

. If tumor occurs as child gigantism occurs, if adult acromegaly

31
Q

Prolactinoma

A

. Causes amenorrhea in females
. Galactorrhea
. Dec. libido
. Headaches

32
Q

ACTH-secreting adenoma

A

Cushing’s disease

33
Q

Neurohypophysis structure

A

. . Bundles of unmyelinated axons of neurosecretory neurons
. Cell bodies found in paraventricular and supraoptic nuclei of hypothalamus
. Supported by pituicytes (glial-like cells)
. Produces oxytocin and ADH

34
Q

Oxytocin function

A

. Contraction of smooth muscle of uterine wall at parturition and myoepithelial cells of mammary gland

35
Q

ADH function

A

. Acts on collecting ducts and distal convoluted tubules of kidney
. Inc. H2O permeability
. Inc. bp. By smooth muscle constriction in arterioles
. Inc. osmotic presssure/dec. blood volume stimulates it’s release

36
Q

Neurophysin I and II

A

. I: Carrier for oxytocin
. II: binds ADH
. Both hormones transported down axons and stored in nerve terminals in herring bodies

37
Q

Neurogenic diabetes insipidus

A

. ADH is dec. or absent from head injury, tumor, or autoimmune damage of ADG secreting neurons
. Polyuria common symptom

38
Q

Pineal gland

A

. Endocrine organ w/ neurosecretory cells
. In center of brain behind 3rd ventricle
. Highly vascular
. Pinealocytes and interstitial cells
. Has pineal calcifications (corpora arenacea/brain sand) that inc. w/ age
. Doesn’t have direct connection to brain
. Innervated by postganglionic sympathetic fibers from sup. Cervical ganglion

39
Q

Pineal gland functions

A

. Pinealocytes secrete melatonin that is inc. or dec. w/ amt of light
. Melatonin released by passive diffusion into circulation
. Acts on hypothalamus and hypophysis to inhibit gonadotropin and GH secretion
. Melatonin integrates photoperiods and modulates circadian rhythms
. Induces sleepiness

40
Q

Pineocytomas

A

. 80% malignant

. Precocious Puberty or delayed onset of sexual maturation seen in 10% males w/ this

41
Q

Thyroid gross anatomy

A

. Butterfly shaped, bilobed gland, 15-25g
. 2 lobes connected via thin isthmus
. In ant. Neck inf. To larynx
. Lobes on each side of trachea

42
Q

Thyroid embryology

A

. Endodermal downgrowth at base of tongue
. Thyroglossal duct transient structure that connects developing gland to point of origin (foramen cecum)
. Parafollicular cells originate from neural crest

43
Q

Thyroid gland

A

. Has follicles formed by single layer cuboidal epithelial follicular cells enclosing central cavity
. CT capsule around gland
. Blood supply from sup. And inf. Thyroid aa.
. Sup., middle, and inf. Thyroid vv. Drain blood from gland

44
Q

Follicular cells of thyroid

A

. Rest on basement membrane
. Height depends on activity
. Lumens of follicles filled w/ colloid
. Major component of colloid is thyroglobulin (iodinated glycoprotein)

45
Q

Parafollicular cells of thyroid

A

. Called C cells
. Form minor component of gland (0.1% mass, 10% cells)
. Found individually or in small groups at periphery of follicular wall in basement membrane but w/o contact w/ follicular lumen
. C cells separated from interstitium by follicular basal lamina

46
Q

Thyroid functions

A

. Store thyroglobulin
. Follicular cells synthesize and secrete thyroid hormone (T3 and 4)
. Regulated by TSH
. Has exocrine and endocrine phases

47
Q

Exocrine phase of thyroid

A

. Uptake of inorganic iodide from blood
. Stimulated by TSH
. Synthesis of thyroglobulin
. Oxidation of iodide to iodine w/in colloid

48
Q

Endocrine phase of thyroid

A

. TSH-stimulated endocytosis of iodinated thyroglobulin into follicular cell
. Fusion of colloid droplets lysosomes
. Lysosomal degradation of iodothyroglobulin to release T3,T4, and other intermediates
. T3 and T4 released across basal lamina of follicular cells into fenestrated blood capillaries
. T3 has shorter half life and more potent and less abundant than T4
. T4 90% of secreted thyroid hormones

49
Q

Parafollicular cells (C cells)

A

. Produce and store calcitonin (or thyrocalcitonin) in small cytoplasmic granules
. Calcitonin lowers blood Ca levels by inhibiting bone resorption and inc. Ca absorption by bone
. Release of calcitonin is directly regulated by blood Ca levels (High Ca stimulates)
. Part of diffuse neuroendocrine system

50
Q

Goiter

A

. Hypertrophy of thyroid gland most commonly caused by iodine-deficient diet

51
Q

Graves’ disease

A

. Autoimmune disease affecting women
. Caused by antibody that is agonist to TSH receptor
. Binding of autoantibodies to TSH receptors
. Causes unregulated synthesis of thyroid hormone

52
Q

Hashimoto’s thyroidits

A

. Autoimmune thyroiditis
. Hypothyroidism
. Accumulation of lymphocytes in stroma of thyroid
. Caused by autoantibodies against thyroglobulin and other molecules in thyroid hormone production

53
Q

Hypothyroidism in infants

A

. Results in mental retardation and short stature w/ skeletal abnormalities
. Can be caused by maternal hypothyroidism

54
Q

Parathyroid glands gross anatomy

A

. 4 pea-sized glands on post. Surface of thyroid glands
. Btw thyroid CT capsule and surrounding CT of neck
. Distinguished in surgery from other tissue bc they bleed a lot

55
Q

Parathyroid gland embryology

A

. Inf. Parathyroid glands from 3rd branchial pouch

. Sup. Parathyroid glands from 4th branchial pouch

56
Q

Parathyroid gland characteristics

A

. Chief cells: more of them, round euchromaic nuclei and clear cytoplasm
. Oxyphil: esosinophilic from mitochondria, pyknotic nuclei, not found until puberty, inc. w/ age after that
. Stroma fat cells appear and end of 1st decade of life and inc. w/ age

57
Q

Parathyroid gland functions

A

. Chief cells produce PTH: regulate Ca and P levels
. PTH stimulates resorption of mineralized bone by osteoclasts and release of Ca in blood
. PTH activates vit. D production in kidney which when vit. D stimulates intestinal resorption of Ca

58
Q

What occurs if you accidentally remove parathyroid gland?

A

. Hypocalcemia
. Muscle cramping, twitching, spasms
. Contractions of muscles in respiration can cause death

59
Q

Hyperparathyroidism

A

. Caused by adenoma

. Inc. blood Ca causes renal stones or deposition of Ca in blood vessels

60
Q

Adrenal gland gross anatomy

A

. Paired triangular glands located at sup. Pole of kidneys
. Cortex and medulla
. Blood drained from both cortex and medulla by central v.

61
Q

Adrenal gland embryology

A

. Cortex from mesoderm
. Medulla from neural crest ectoderm (migrates from sympathetic ganglia into fetal cortex)
. CT capsule forms and envelops adrenal gland during development

62
Q

Adrenal gland characteristics

A

. Cortex (0-90% gland) essential for life
. Cortex zones: zona glomerulosa, zona fasciculata, and zona reticularis
. Medulla not essential
. Medulla has chromatin cells: modified postganglionic neurons w/o postganglionic processes, secrete catecholamines (E for 80% cells, NE for rest)

63
Q

Zona glomerulosa

A

. 10-15% of adrenal cortex
. Under capsule
. Made of closely packed clusters of parenchyma cells
. Secretes mineralcorticoids (aldosterone)
. Angiotensin II-dependent (stimulates it)
. Aldosterone acts on distal convoluted tubules and collecting ducts in kidney
. Inc. Na reabsorption and K and H excretion (regulates Na and K homeostasis and H2O balance)

64
Q

How is angiotensin II formed?

A

.. derived from conversion of angiotensin I in pulmonary circulation by angiotensin-converting enzyme (ACE)

65
Q

Zona fasciculata

A

. 75% adrenal cortex
. Middle region
. Radially oriented cords of polyhedral cells (look like steroid cells w/ smooth ER, mitochondria w/ tubular cristae)
. Cords separated by fenestrated capsules
. Secrete glucocorticoids (cortisol)
. Cortisol not stored in cells, synthesis is stimulated by ACTH

66
Q

Effects of cortisol

A

. Metabolic: opposite to insulin, stim. Gluconeogenesis

. Anti-inflammatory: suppression of tissue responses to injury and inhibition of cellular and humoral immunity

67
Q

Zona reticularis

A

. 5-15% adrenal cortex
. Adjacent to medulla
. Anastomosing network of cords of acidophilic cells separated by fenestrated capillaries
. Secretes androgens (DHEA, androstenedione)
. Under ACTH control
. Major source androgens in women

68
Q

Adrenal medulla functions

A

. E and NE stored in granules
. Bind to alpha and beta adrenergic receptors
. Released in response to nerve stimulation by preganglionic sympathetic nerve fibers carried in splanchnic nn.
. Inc. HR, bp, CO

69
Q

Conn’s syndrome

A

. Primary hyperaldosteronism from tumor localized in zona glomerulosa
. Causes hypertension, low K levels
. Same as symptoms from inc. renin secretion

70
Q

Cushing’s disease

A

. Inc. in aldosterone, cortisol, and adrenal androgen production secondary to ACTH production
. Cushing’s syndrome from adrenocortical adenoma causing overproduction of same hormones
. Causes muscle weakness w/ thin extremities, moon face, buffalo hump, truncates obesity from high insulin, abdominal striae from impaired collagen, osteoporosis, and immunosuppression

71
Q

Addision’s disease

A

. Autoimmune disorder
. Destroys adrenal cortex and chronic adrenal insufficiency
. Cortisol insufficiency inc. ACTH
. Inc. skin pigmentation
. Loss of mineralcorticoids causes hypotension and circulatory shock

72
Q

Exogenous Cushing’s syndrome

A

. Happens from taking oral corticosteroids for extended period of time

Histology (22 decks)

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