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FoundSci Unit 6 > Exocrine/Endocrine Glands I > Flashcards

Exocrine/Endocrine Glands I Flashcards

1
Q

All endocrine glands lack ____

A

ducts

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2
Q

Most but not all exocrine glands have ____

A

ducts

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3
Q

What are 3 ways to classify exocrine glands?

A

What it secretes (type of secretion product)

How it secretes

Gland morphology

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4
Q

What are the 4 types of secretion products of exocrine glands?

A

Mucous glands

Serous glands

Mixed (seromucous) glands

Sebaceous glands

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5
Q

What do mucous glands secrete?

A

Secrete mucus

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6
Q

What do serous glands secrete?

A

Secrete watery fluids

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7
Q

What do mixed glands secrete?

A

Secrete fluids of intermediate viscosity

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8
Q

What do sebaceous glands secrete?

A

Secrete sebum

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9
Q

What are acini?

A

Ball-like clusters formed by exocrine cells

Usually have central lumen that connects to a duct

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10
Q

What are the secretions and functions of mucuous glands?

A

Secretions are mucus. Mucinogen forms mucin when hydrated. Heavily glycosylated glycoproteins that form gels

Functions:
Protection (traps pathogens, resist stomach acids)
Lubrication (gel allows solid wastes to slide through)

Examples: goblet cells, gastric mucous cells

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11
Q

What are the secretions and functions of serous glands?

A

Secretions are watery and rich in nonglycosylated/poorly glycosylated proteins like enzymes and antibodies

Function:
Varies depending on composition and gland location

Examples: Exocrine pancreas, parotid gland, lacrimal glands

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12
Q

What are the secretions and functions of seromucous glands?

A

Secretions are mix of mucus and serous components. Proportions vary by gland

Function:

Varies depending on composition and gland locaton

Examples: Mixed but mostly serous acini (submandibular gland, prostate gland), mixed but mostly mucous acini (sublingual gland)

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13
Q

What are serous demilunes?

A

Artefacts of formalin fixation

Only occur in mixed acini

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14
Q

What are the secretions and functions of sebaceous glands?

A

Secretion is sebum - rich in lipids, fatty acids, wax esters, and squalene

Always associated with hair follicles

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15
Q

What can affect the rate of sebum secretion?

A

Androgens stimulate it

Estrogens inhibit it

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16
Q

What are the secretion modes of glands?

A

Merocrine secretion - exocytosis into lumen, most common, least destructive

Apocrine secretion - entire apical end of cell pinches off, mammary glands, moderately destructive

Holocrine secretion - cell disintegration, sebaceous glands only, most destructive

Endocrine secretion - Endocrine glands - exocytosis towards BM, crosses BM to blood stream

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17
Q

What is the function of apocrine secretion mode?

A

Allows cell to secrete complex protein rich and lipid rich mixtures, all at once

Helps gland release large amounts of fluid secretions quickly

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18
Q

What are the 2 glands classified by gland morphology?

A

Unicellular exocrine glands - goblet cells only, mianly in epithelia lining respiratory and intestinal tracts

Multicellular exocrine glands - secretory sheets, smaller intraepithelial glands, complex multicellular glands (common, almost all exocrine glands in body)

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19
Q

What is the general structure of complex multicellular glands?

A

Parenchyma - parts of gland or organ that are specialized for gland/organ function.

Secretory units - group of secretory cells that secrete and release secretory products

Ducts - conduits that transport secretory products out of secretory units and out of gland, nonsecretor but may modify the products

Stroma - collagenous CT, reticular CT, and blood vessels and nerves that supply the gland

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20
Q

What are tubular glands?

A

Secretory unit that can be straight, coiled, or branched

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21
Q

What are acinar glands?

A

Secretory units are acini

Any spherical exocrine secretory unit

When lumens of acini are larges, they are sometimes called alveolar glands

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22
Q

What are tubuloacinar glands?

A

Have both tubular and acinar portions

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23
Q

What is the function and structure of myoepithelial cells?

A

Contractile cells that squeeze an entire secretory unit (usually acinus) in order to move secretions out of the acinus and into a duct

Facilitate the rapid expression of glands

They are epithelial cells with some bonus smooth muscle characteristics - lots of contractile filaments (actin and myosin)

Connect to exocrine secretory cells via cell junctions (desmosomes and gap junctions)

24
Q

What does the endocrine system include?

A

Endocrine glands

Large clusters of endocrine cells in other organs

Diffuse neuroendocrine system cells (DNES cells) - isolated endocrine cells in other tissues

25
Q

What are endocrine cells?

A

Glandular epithelial cells

Synthesize and release hormones into the bloodstream

Usually to distance tissues

Always lack ducts

26
Q

What are ways to classify hormones?

A

Water soluble or lipid soluble

Steroid hormones - derived from cholesterol

Peptide hormones - composed of amino acids

Amine hormones - derived from tyrosine

27
Q

What can trigger hormone release?

A

CNS regulates release of many hormone - often regulated via interactions between hypothalamus and pituitary gland

Serum concentration can trigger secretion

Environmental cues - day/night cycle

28
Q

What is the function and structure of the hypothalamus?

A

Part of limbic system

Located below thalamus

Contains several basal nuclei - grey matter

Command center that coordinates endocrine functions and integrates them with those of ANS in order to regulate body homeostasis, circadian rhythm, metabolism growth, reproduction

Coordinates endocrine system functions indirectly by releasing hormones that act on pituitary gland

29
Q

What are the characteristics and function of the pituitary gland?

A

Well-vascularized neuroendocrine organ

Below hypothalamus and connected via a short stalk

Master gland whose hormone secretion act on target organs and glands throughout the body

30
Q

What are the two divisions of the pituitary gland?

A

Anterior lobe (adenohypophysis) - mainly glandular tissue (endocrine), pars distalis, parts intermedia, and pars tuberalis

Posterior lobe (neurohypophysis) - mainly axons of neurons whose somas are in the hypothalamus, pars nervosa and infundibulum

Most hormones that hypothalamus secretes acts on cells of anterior lobe

31
Q

Neurosecretory cells

A

Specialized neurons that synthesize and release hormone

Make hypothalamic hormones that travel in bloodstream to anterior lobe of pituitary - releasing hormones or inhibitory hormones

Make in the supraoptic and paraventricular nuclei neurohypophyseal hormones that will be temporarily stored in the posterior lobe - ADH (antidiuretic hormone) and oxytocin

32
Q

How do hypothalamic hormones act on endocrine cells in anterior lobe?

A

Made in neurosecretory cell somas in hypothalamus and travel to axon terminals, which are in median eminence of the hypothalamus

Axon terminals release hypothalamic hormones into ECM -> enter the primary capillary plexus

Then they go to the hypophyseal portal and then to the secondary capillary plexus

Exit secondary capillary plexus to enter the parenchyma of anterior lobe and then act on endocrine cells there

33
Q

What are examples of hypothalamic hormones?

A

Somatropin-releasing hormone (SRH)

Somatostatin

Prolactin-releasing hormone (PRH)

Dopamine

Corticotropin-releasing hormone (CRH)

Thyrotropin-releasing hormone (TRH)

Gonadtropin-releasing hormone (GnRH)

34
Q

What does somatotropin-releasing hormone (SRH) act on and what is its function?

A

Acts on somatotrophs

Stimulates somatotropin (GH) release

35
Q

What does somatostain act on and what is its function?

A

Somatotrophs

Inhibits somatotropin release

36
Q

What does prolactin-releasing hormone (PRH) act on and what is its function?

A

Mammotrophs

Stimulates prolactin release

37
Q

What does dopamine act on and what is its function?

A

Mammotrophs

Inhibits prolactin release

38
Q

What does corticotropin-releasing hormone act on and what is its function?

A

Acts on corticotrophs

Stimulates release of pro-opiomelanocortin, a precursor of ACTH and MSH

39
Q

What does thyrotropin releasing hormone (TRH) act on and what is its function?

A

Acts on thyrotrophs

Stimulates release of thyroid-stimulating hormone (thyrotropin)

40
Q

What does gonadotropin-releasing hormone (GnRH) act on and what is its function?

A

Acts on gonadotrophs

Stimulates release of FSH and LH

41
Q

How are neurohypophyseal hormones temporarily stored in the posterior lobe before release?

A

ADH and oxytocin are synthesized in somas of neurosecretroy cells in the supraoptic and paraventricular nuclei of hypothalamus

These neurons’ unmyelinated axons form the hypothalamohypophyseal tract which descends through infundibulum and into the pars nervosa of the posterior lobe

ADH and oxytocin accumulate in axon terminal until their release is triggered by nerve stimulation

Axon terminals release ADH and oxytocin into ECM which enter fenestrated capillaries in pars nervosa and travel to target organs

42
Q

What are neurohypophyseal hormones?

A

Made in the hypothalamus

Send to posterior lobe of pituitary gland for storage (in Herring bodies)

Later released into the bloodstream

ADH

Oxytocin

43
Q

What does ADH act on and what are its functions?

A

Acts on kidney, smooth muscle in arterioles

Increases collecting tubules’ permeability to water (producing more concentrated urine) and constricts arterioles

44
Q

What does oxytocin act on and what are its main functions?

A

Acts on the uterus and mammary gland

Stimulates contraction of smooth muscle cells in uterus during labor

Stimulates contraction of myoepithelial cells in mammary gland during nursing (which releases milk)

45
Q

What is important about the anterior pituitary gland histology?

A

Fenestrated capillaries between cords in parenchyma allow hypothalamic hormones to exit bloodstream quickly and allow anterior pituitary hormones to enter bloodstream quickly

Capillaries are part of the parenchyma in endocrine gland because hormones are released into bloodstream

46
Q

What are the adenohypophysis cells?

A

Chromophobes

Chromophils

Acidophils - somatotrophs (synthesize and secrete somatotropin) and mammotrophs (synthesize and secrete prolactin)

Basophils:
Corticotrophs - synthesize and secrete POMC

Thyrotrophs - synthesize and secrete TSH

Gonadotrophs - synthesize and secrete FSH and LH

47
Q

What are the acidophil cells and what hormones do they secrete?

A

Somatotrophs - secrete somatotropin which acts on most cells

Mammotrophs - secrete prolactin which acts on mammary gland

48
Q

What are basophil cells and what hormones do they secrete?

A

Corticotrophs - ACTH (adrenocorticotrophic hormone) which acts on the adrenal cortex + MSH (melanocyte stimulating hormone) which acts on melanocytes

Thyrotrophs - TSH (thyroid stimulating hormone) which acts on the thyroid gland

Gonadotrophs - FSH which acts on ovaries and testes + LH which acts on the ovaries and testes

49
Q

What are the functions of somatotropin which are released by somatotrophs?

A

Induces growth in most tissues

Indirectly stimulates growth of cartilage in growth plates (increases production of insulin growth factors 1 & 2)

50
Q

What is the function of prolactin which is released is mammotrophs?

A

Stimulates milk synthesis

51
Q

What is the function of ACTH released by corticotrophs?

A

Stimulates glucocorticoids secretion

52
Q

What is the function of MSH released by corticotrophs?

A

Stimulates melanin synthesis

53
Q

What is the function of TSH which is released by thyrotrophs?

A

Stimulates synthesis and release of T3 and T4 hormones

54
Q

What is the function of FSH released by gonadotrophs?

A

Ovaries - stimulates oocyte development and stimulates estrogen secretion

Testes - stimulates spermatogenesis

55
Q

What is the function of LH released by gonadotrophs?

A

Ovaries - stimulates ovulation, stimulates corpus luteum formation, stimulates progesterone secretion

Testes - stimulates testosterone synthesis

56
Q

What is the histology of the neurohypophysis (posterior pituitary gland)?

A

Posterior lobe is not glandular

Hormones are not synthesized in posterior lobe

Posterior lobe is neurosecretory

Herring bodies - axon terminals that are swollen with accumulated hormones

Pituicytes - neuroglia derived from astrocytes, provide physiological support to axons and cover axon terminals and capillaries with their processes

FoundSci Unit 6 (14 decks)

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