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ENRE > Histology of Endocrine Organs > Flashcards

Histology of Endocrine Organs Flashcards

1
Q

How does the endocrine sys vary from the nervous sys?

A

nervous = needs membrane depolarization; quick and short-lived

endocrine = distributed throughout body, bind to spec receptors; slower but longer

*some neurons secrete hormones*

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2
Q

What are the 3 classes of hormones?

A

peptide/proteins: largest class (GH, PTH)

biogenic amines: produced by altering specific AAs (Thyroid hormone, epinephrine)

steroid hormones: lipids derived from cholesterol (estrogen, testosterone)

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3
Q

What are teh 3 stimuli controlling hormone release?

A

humoral = release controlled by monitoring levels of ions and nutrients

neuronal = release stimulated by nerve signals

hormonal = release caused by hormone by another endocrine organ or cell

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4
Q

What embryonic tissue are endocrine glands derived from?

A

ectoderm

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5
Q

How are endocrine glands generally organized?

A

epitheliod cells arranged as cords/follicles and some as isolated individual cells

*well vascularized

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6
Q

Where is the hypothalamus located?

A

below thalamus

behind optic chiasma

surrounding the 3rd ventricle

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7
Q

Upon which bone does the pituitary gland sit?

A

hypophyseal fossa of the sphenoid bone

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8
Q

How is the pituitary gland attached to the hypothalamus?

A

by thin stalk = infundibulum

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9
Q

How are the hypothalamus and the posterior pituitary connected?

A

hypothalamus produces oxytocin and ADH –> stored and released by the post pit

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10
Q

What are the direct targets of hypothalamic hormones?

A

releasing and inhibiting hormones –> ant pit

oxytocin and ADH –> post pit –> kidney and uterus

sympathetic innervation –> adrenal medulla

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11
Q

What are the 5 main organs indirectly influenced by the hypothalamus?

A

thyroid

adrenal cortex

mammary gland

gonads

bone

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12
Q

What is the basic embryologic origin of the pituitary?

A

ectodermal placode –> rathke’s pouch at 3 weeks –> near final location by 8 weeks

infundibulum forms post pit and infundibular stalk

rathke’s pouch forms rest of pituitary

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13
Q

What types of cells make up the posterior pituitary?

A

axons from hypothalamus and support/glial cells

(axons carry ADH and oxytocin)

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14
Q

What is the pars distalis?

Pars nervosa?

A

pars distalis = anterior pituitary

pars nervosa = posterior pituitary

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15
Q

What are the major cell types in the anterior pituitary?

A

somatotrophic (GH)

thyrotropic (TSH)

corticotropic (ACTH and MSH)

gonadotropic (FSH and LH)

mammotropic (prolactin)

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16
Q

What cells are acidophils in the ant pit?

A

somatotrophs

mammotrophs

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17
Q

What cells are basophils (stain dark purple) in the ant pit?

A

corticotrophs

thyrotrophs

gonadotrophs

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18
Q

What is the pars intermedia?

A

btw pars distalis and pars nervosa

function unknown

small basophils and colloid-filled follicles lined by cuboidal epithelium

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19
Q

What cell types are found in the pars nervosa?

A

unmyelinated axons

herring bodies in axons = expanded nerve terminals storing ADH/oxytocin

pituicytes (glial-like)

fenestrated capillaries

20
Q

What are the 2 parts of the infundibulum?

A

neural portion = connecting pars nervosa and hypothalamus; unmyelinated axons

adenohypophysis = surrounding pars tuberalis enveloping infundibular stalk; cuboidal cells arranged in cords

21
Q

What makes up the hypophyseal portal system?

A

superior hypophyseal artery –> goes to stalk –> capillary bed to pick up hormones from hypothalamus –> hypophyseal portal vs –> secondary capillary plexus in ant pit to get hormones from ant pit

22
Q

What is the blood supply like in the posterior pituitary?

A

inferior hypophyseal artery goes in –> ADH and oxytocin go into fenestrated capillaries (single capillary bed) –> blood goes out through single vein

23
Q

What is gigantism?

A

excess production of GH due to tumor

if before growth plates close –> can grow to 8 feet tall

if after plates close –> enlargement of extremities and organs

24
Q

What are pituitary dwarfs?

A

hyposecretion of GH –> normal body proportion, but rarely exceed 4 feet tall

25
Q

Where is the pineal gland?

A

out pocketing of diencephalon’s roof of 3rd ventricle

covered in pia mater

26
Q

What does the pineal gland produce?

A

melatonin

serotonin

27
Q

What cells make up the pineal gland?

A

pinealocytes

neuroglia

calcified granular material (brain sand) = important marker for midline brain

28
Q

What vessels supply the thyroid?

A

superior thyroid vessels

inferior thyroid vessels

29
Q

What characterizes the histology of the thyroid?

A

follicles = simple cuboidal to columnar epithelium surrounding colloid

30
Q

How does the thyroid store hormones and why is this distinct?

A

thyroglobulin = storage form of T3 and T4

stored in colloid = outside the cell

only gland to store hormone outside the cell

31
Q

How does thyroid histology vary based on activity?

A

follicular cells look more columnar if synthesizing or secreting a lot (more active)

32
Q

How is thyroid hormone synthesized?

A

thyroglob synthesized in RER –> glycosylated in the golgi –> secreted by exocytosis into lumen of follicle

33
Q

How is thyroid hormone secreted?

A

iodinated apical surface –> T3 and T4 bound to thyroglobulin –> TSH stim endocytosis of thyroglob –> T3 and T4 freed –> released from basal surface of follicle cell into circulation

34
Q

What are parafollicular C cells?

A

cells in thyroid that lie just outside follicles; stain lighter

secrete calcitonin –> lowers calcium levels thru kidneys, osteoclasts, and osteoblasts

35
Q

What is the basic hypothalamic-ant pit-thyroid axis?

A

Stimulus (low body temp) –> hypothalamus secretes thyroitropin-releasing hormone (TRH) –> ant pit releases TSH –> follicular cells release TH –> act on target cells –> heat production in target cells sensed by hypothalamus –> TRH reduced

TH also blocks interactions of TRH on ant pit

36
Q

Where are parathyroid glands located?

What do they do?

A

on posterior surface of the thyroid gland

release PTH –> regulates serum calcium and phosphate levels

37
Q

What are the cell types in the parathyroid?

A

chief/ principle cells: release PTH, smaller and stain darker

oxyphil cells: function unknown, darker and stain lighter

38
Q

How is calcium regulated by PTH?

A

blood levels drop below 9.6 mg/dL –> PTH released

osteoclasts –> resorb bone and release its calcium stores

kidneys –> reabsorb Ca; convert Vit to calcitriol –> increases Ca absorption by intestines

blood Ca increases –> further PTH inhibited

39
Q

What are the zones of the adrenal gland from superficial to deep and what do they release?

A

capsule

zona glomerulosa: mineralcorticoids (aldosterone)

zona fasciculata: glucocorticoids

zona reticularis: androgens

adrenal medulla: NE and Epi

40
Q

What types of cells release epi and NE?

A

chromaffin cells in medulla = clusters of large, spherical cells

epi cells = smaller w/ lighter granules

norepi cells = larger with darker granules

41
Q

What is Cushing’s syndrome caused by?

A

hypersecretion of glucorticoids

either ACTH-secreting pit tumor or tumor in adrenal cortex

42
Q

What is addison’s disease?

A

hyposecretion of usually both glucocorticoids and mineralcorticoids

43
Q

What is the endocrine portion of the pancreas?

A

pancreatic islets = lightly stained blobs amongst acini

44
Q

What are the cell types in the endocrine pancreas?

A

alpha cells: secrete glucagon

beta cells: secrete insulin

delta cells: secrete somatostatin

F cells: secrete pancreatic polypeptide

45
Q

What does somatostatin do?

A

released by pancreatic delta cells –> slows release of insulin and glucagon

stimulated by high levels of nutrients in blood

46
Q

What does pancreatic polypeptide do?

A

secreted by pancreatic F cells –> inhibits release of somatostatin

47
Q

How is the pancreas supplied with blood?

A

dual supply: acinar and insuloacinar

blood goes thru insuloacinar –> capillaries leaving islets go to acini –> hormones have local action on acini

independent acinar vascular sys also supplies acini

ENRE (21 decks)

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