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Endocrinw System Flashcards

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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
Follicle-stimulating hormone (FSH) function
. Stimulates development of ovarian follicles or productionof androgen-binding protein by Sertoli cells in males
26
Luteinizing hormone
. Ovulation and formation of corpus luteum in females | . Controls synthesis of tester one by Leydig cells in males
27
Chromophobes
. Small cells w/o secretory granules . Could be undifferentiated cells
28
Cels in pars tuberalis
Gonadotrophs
29
Cells in pars intima
. Basophils: mostly corticotrophs . Chromophobes . Products include melanocyte-stimulating hormone (MSH)
30
Growth hormone cell adenoma
. If tumor occurs as child gigantism occurs, if adult acromegaly
31
Prolactinoma
. Causes amenorrhea in females . Galactorrhea . Dec. libido . Headaches
32
ACTH-secreting adenoma
Cushing’s disease
33
Neurohypophysis structure
. . 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
Oxytocin function
. Contraction of smooth muscle of uterine wall at parturition and myoepithelial cells of mammary gland
35
ADH function
. 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
Neurophysin I and II
. I: Carrier for oxytocin . II: binds ADH . Both hormones transported down axons and stored in nerve terminals in herring bodies
37
Neurogenic diabetes insipidus
. ADH is dec. or absent from head injury, tumor, or autoimmune damage of ADG secreting neurons . Polyuria common symptom
38
Pineal gland
. 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
Pineal gland functions
. 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
Pineocytomas
. 80% malignant | . Precocious Puberty or delayed onset of sexual maturation seen in 10% males w/ this
41
Thyroid gross anatomy
. 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
Thyroid embryology
. 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
Thyroid gland
. 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
Follicular cells of thyroid
. Rest on basement membrane . Height depends on activity . Lumens of follicles filled w/ colloid . Major component of colloid is thyroglobulin (iodinated glycoprotein)
45
Parafollicular cells of thyroid
. 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
Thyroid functions
. Store thyroglobulin . Follicular cells synthesize and secrete thyroid hormone (T3 and 4) . Regulated by TSH . Has exocrine and endocrine phases
47
Exocrine phase of thyroid
. Uptake of inorganic iodide from blood . Stimulated by TSH . Synthesis of thyroglobulin . Oxidation of iodide to iodine w/in colloid
48
Endocrine phase of thyroid
. 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
Parafollicular cells (C cells)
. 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
Goiter
. Hypertrophy of thyroid gland most commonly caused by iodine-deficient diet
51
Graves’ disease
. 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
Hashimoto’s thyroidits
. Autoimmune thyroiditis . Hypothyroidism . Accumulation of lymphocytes in stroma of thyroid . Caused by autoantibodies against thyroglobulin and other molecules in thyroid hormone production
53
Hypothyroidism in infants
. Results in mental retardation and short stature w/ skeletal abnormalities . Can be caused by maternal hypothyroidism
54
Parathyroid glands gross anatomy
. 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
Parathyroid gland embryology
. Inf. Parathyroid glands from 3rd branchial pouch | . Sup. Parathyroid glands from 4th branchial pouch
56
Parathyroid gland characteristics
. 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
Parathyroid gland functions
. 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
What occurs if you accidentally remove parathyroid gland?
. Hypocalcemia . Muscle cramping, twitching, spasms . Contractions of muscles in respiration can cause death
59
Hyperparathyroidism
. Caused by adenoma | . Inc. blood Ca causes renal stones or deposition of Ca in blood vessels
60
Adrenal gland gross anatomy
. Paired triangular glands located at sup. Pole of kidneys . Cortex and medulla . Blood drained from both cortex and medulla by central v.
61
Adrenal gland embryology
. 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
Adrenal gland characteristics
. 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
Zona glomerulosa
. 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
How is angiotensin II formed?
.. derived from conversion of angiotensin I in pulmonary circulation by angiotensin-converting enzyme (ACE)
65
Zona fasciculata
. 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
Effects of cortisol
. Metabolic: opposite to insulin, stim. Gluconeogenesis | . Anti-inflammatory: suppression of tissue responses to injury and inhibition of cellular and humoral immunity
67
Zona reticularis
. 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
Adrenal medulla functions
. 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
Conn’s syndrome
. Primary hyperaldosteronism from tumor localized in zona glomerulosa . Causes hypertension, low K levels . Same as symptoms from inc. renin secretion
70
Cushing’s disease
. 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
Addision’s disease
. 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
Exogenous Cushing’s syndrome
. Happens from taking oral corticosteroids for extended period of time

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