Endocrine Glands Part 1 Flashcards by sophie rosen

endocrine system communicates via

chemical messengers (hormones)

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chemical messengers (hormones) are secretory products of

endocrine cells

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hormones are carried by — to target tissue containing receptors

bloodstream

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Endocrine organs composed of secretory cells of --- origin,
characterized by (2)

epithelial

prominent nuclei & numerous organelles

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Endocrine system lacks

ducts

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Endocrine system secretes hormones into surrounding

interstitial space

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endocrine system possess rich blood supply with fenestrated capillary networks to (2)

absorb & transport hormones

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• Endocrine organs integrate function of — systems

physiologic

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— coordinates endocrine functions of body—acts as

intermediary between autonomic nervous system & endocrine system

Hypothalamus

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Most endocrine glands form

discreet organs

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in pancreas, (2) tissue intermixed

endocrine & exocrine

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Pituitary Gland =

hypophysis

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pituitary gland ~– diameter, specialized appendage of —

1cm

brain

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Pituitary Gland lies beneath

third ventricle in sella turcica (“Turkish saddle”) of sphenoid bone

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Secretion of pituitary hormones controlled by —, with complex blood supply

hypothalamus

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Pituitary Gland includes

hypophyseal portal system

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hypophyseal portal system allows communication with

hypothalamus

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Hypothalamus controls secretion of anterior pituitary via

hypothalamic regulating factors (hormones)

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– factors stimulate secretion;

- – factors inhibit secretion

Releasing

inhibitory

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Direct acting hormones—

have non-endocrine target organ

e.g., GH, ADH, MSH, oxytocin, prolactin

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trophic hormones—

target organ is another endocrine gland

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

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(3) all pituitary dependent endocrine glands

Thyroid gland, adrenal cortex, & gonads

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Functionally, anatomically, & embryologically, pituitary divided into

anterior & posterior portions

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Anterior portion contains — &

posterior contains —

glandular epithelial tissue

neural secretory tissue

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"master gland"

anterior pituitary

master gland=

adenohypophysis = pars anterior = pars distalis

anterior pituitary is specialized glandular tissue, arises from evagination of ectoderm from oral cavity in region of pharynx called

Rathke’s pouch

Rathke’s pouch differentiates into 3 distinct | regions of anterior pituitary:

pars distalis pars intermedia pars tuberalis

pars distalis—

bulk of anterior pituitary

pars intermedia—

thin layer between anterior & posterior pituitary

pars intermedia secretes (2)

MSH | ACTH

pars intermedia frequently contains

cystic remnants of Rathke’s pouch

pars tuberalis—

extension of anterior pituitary

pars tuberalis forms

collar ~pituitary stalk (=infundibulum)

``` Pars distalis secretes bulk of pituitary hormones, including both (2) ```

direct acting & trophic hormones

Direct acting hormones—(2)

GH & prolactin

Trophic hormones—(4)

TSH, ACTH, FSH, LH

Secretory cells of anterior pituitary traditionally classified as (2)

chromophils (which stain) or | chromophobes (don’t)

2 types of chromophils:

acidophils | basophils

Acidophils— (2)

stain with acidic dye; | pink on H&E

Basophils—(2)

stain with basic dye; | pale blue to light purple on H&E

Chromophobes— (3)

small cells, don’t take up either dye, clear on H&E

chromophobes represent

inactive cells

types of acidophils (2)

somatotrophs | mammotrophs

Somatotrophs— ~--% of cells; sec --

50 | GH

Mammotrophs— (= lactotrophs) ~--% of cells; secrete ---

20 | prolactin (controls lactation)

types of basophils (3)

thyrotrophs gonadotrophs corticotrophs

• Thyrotrophs— ~--% of cells; secrete ---

5 | TSH (= thyrotropin)

Gonadotrophs— ~--% of cells; secrete (2)

5 | FSH & LH

Corticotrophs— ~--% of cells; secrete (3)

20 | ACTH, MSH, endorphins

Posterior pituitary=

= neurohypophysis = pars nervosa

where is Posterior pituitary located

ventral to hypothalamus

plus short stalk, ---, which contains axons of neurosecretory origin

infundibulum

Consists of downgrowth of nervous tissue from floor of

diencephalon (third ventricle)

Composed of support cells called (2)

pituicytes & neurosecretory nerve axons

These axons store & release products from

nerve cell bodies in hypothalamus

Secretion of posterior pituitary hormones by axons from nerve cells in hypothalamus known as

neurosecretion

neurosecretion is regulated by

hypothalamic hypophyseal feedback loop

Hypothalamus secretes 2 hormones via posterior pituitary—

ADH (=vasopressin) & oxytocin

Stored in neurosecretory granules in dilations of axons of posterior pituitary known as

Herring bodies

ADH—controls blood pressure by altering

permeability of renal collecting tubules

if you decrease production of ADH,

increase urine production (as in diabetes insidious)

ADH is synthesized by neuron cell bodies in --- --- of hypothalamus

supraoptic nucleus

Oxytocin—promotes smooth Mm contraction in (2)

uterus & breast (especially during labor & lactation)

oxytocin is synthesized by neuron cell bodies in --- --- of hypothalamus

paraventricular nucleus

Thyroid Gland

Bilateral, lobulated, endocrine gland on anterior/ventral neck

L & R sides of thyroid gland connected by narrow ---

isthmus

thyroid gland is surrounded by

loose connective tissue capsule with fine connective tissue septa

thyroid gland is embryologically derived from

epithelial down growth of fetal tongue

Thyroid gland unique among endocrine glands in storage of large amounts of inactive hormone, an eosinophilic glycoprotein colloid called ---

thyroglobulin

thyroglobulin is stored in

extracellular follicles

structural units of thyroid gland

extracellular follicles are lined by

simple, cuboidal epithelium

Follicular epithelial cells concentrate iodine 30-40X blood levels, secrete it as --- via apical microvilli

thyroglobulin

Iodination results in

active hormone

Active thyroid hormones—(2)

T3 (triiodothyronine) & T4 (tetraiodothyronine, = thyroxine)

-- is deiodinated in liver to form --, more potent, biologically active form

T4 | T3

T3 regulates

BMR (also growth & development of nervous system)

Thyroid hormone deficiency during fetal development impairs (2)

neural development & myelination

Thyroid hormone deficiency during fetal development impairs neural development & myelination—results in (2)

physical stunting & mental retardation (cretinism)

Secondary secretory cells in thyroid gland—

parafollicular cells (= C cells, clear cells)

C cells are located at (2)

periphery of follicles, | or scattered within connective tissue

In lower vertebrates, c cells make up separate ---

organ

C cells secrete

calcitonin

calcitonin regulates

blood Ca levels along with parathyroid hormone

decrease in serum calcium inhibits

osteoclasts

Synthesis, storage & release of thyroid hormones under control of

TSH from anterior pituitary (adenohypophysis)

Thyroid pathology—

goiter

enlargement of thyroid

goiter may be indicative of (2)

hyperthyroidism | hypothyroidism

Hyperthyroidism—

increase in number & size of follicle cells

Hypothyroidism—

autoimmune rxn; results in decrease in size of gland

Insufficient dietary iodine results in decrease of

TH production, possible hypertrophy with non-functional thyroglobulin

Endocrine Glands Part 1 Flashcards

(93 cards)