LEC36: Endocrine System I Flashcards Preview

Structures: Part Deux > LEC36: Endocrine System I > Flashcards

Flashcards in LEC36: Endocrine System I Deck (102):
0

what is within endocrine I

pituitary, hypothalamus, pineal

1

what's within endocrine II?

thyroid, C (parafollicular) cells, parathyroid, adrenal - cortex & medulla, pancreas - islets of langerhans, diffuse endocrine system

2

exocrine duct formation and release

downgrowth of epithelium into CT > duct forms at surface > contents release from duct, at epithelium surface

3

endrocine duct formation

proliferation of cells, downgrowth into CT > breaks from epithelium > follicular endocrine gland forms w/ cord of cells/capillaries surrounding

4

endocrine follicle structure

ring of endocrine cells divided by epithelial cells in center; lumen in center; capillaries infiltrate CT between follicles

5

hormone defn

chemical substances synthesized by endocrine cells and secreted

6

3 ways hormones can effect cells once secreted

1) into bloodstream > distant target cells
2) into tissue space > adjacent or nearby target cell
3) onto own cell surface > own target cells

7

why hormones synthesized/secreted?

1) to influence metabolic activities of target cells
2) in conjunction w/ nervous system, coordinate & integrate fxns of all physiological systems

8

hormonal signaling mechanisms (3)

1) endocrine signaling
2) paracrine signaling
3) autocrine signaling

9

how endocrine signaling works

endocrine follicle gland has lumen, blood vessel goes through > hormone secreted into blood > attaches to membrane receptor or receptor in cytosol at distant target cell > tells distant cell to make hormone
i.e. pituitary hormones

10

how do paracrine signals work

endocrine cell inside hormone travels through CT > effect nearby cell, a few cells away from endocrine cell > hormone sits on membrane receptor to tell target cell to produce

i.e. somatostatin inhibits insulin secretion in islets of langerhans

11

how does autocrine signaling work

hormone/growth factor sits on membrane receptor of its own cell
i.e. insulin, TGF-beta

12

chemically, hormone types (3)

1) peptides and glycoproteins
2) steroids
3) amino acids

13

examples of peptides, glycoproteins hormones

hormones of pituitary, parathyroid, C cells of the thyroid, islets of Langernas and GI tract

14

examples of steroid hormones

hormones of adrenal cortex, ovary and testis

15

examples of amino acid (tyrosine) hormones

hormones of thyroid, adrenal medulla

16

hormonal distinguishment by morphology (2)

1) peptide/glyprotein hormone producing cells contain granules (electron dense on EM!), which store hormones
2) steroid hormone-producing cells store and release hormones into circulation right away (eosinophilic stain!), no granules for storage

17

endocrine glands whose sole functions are hormone production

pituitary, pineal, thyroid, parathyroid, adrenal

18

endocrine tissues found in association w/ organs which have other functions

pancreas, ovary, testis, kidney, liver

19

ovary's exocrine function

release of ovum

20

testis's endocrine and exocrine functions

endocrine: testosterone
exocrine: sperm

21

kidney's endocrine and exocrine functions

endocrine: make renin, prostaglandins
exocrine: renal tubule absorption/reabsorption into tubules

22

liver's endocrine and exocrine functions

endocrine: makes glucose amino acid albumin, > circulation
exocrine: makes many metabolites which > metabolism, secrete bile to gall bladder

23

diffuse endocrine system

endocrine tissue > single hormone-producing cells diffusely scattered in digestive, respiratory systems

24

where is pituitary located

beneath floor of III ventricle, connected to hypothalamus

25

where is diencephalon, what does it consist of?

between forebrain and midbrain
forms wall of ventricle or cisterna
consists of thalamus, hypothalamus, epithalamus

26

which part of thalamus and of hypothalamus forms floor of III ventricle?

ventral part of thalamus
median eminence of hypothalamus

27

where does floor of III ventricle extend into?

site of pituitary gland

28

why is pituitary gland "master" gland?

although tiny, it controls most of endocrine functions of the body

29

where does pituitary gland sit?

in hypophyseal fossa, a bony depression of the sella turcia (hump) of the sphenoid bone (in middle cranial fossa)

30

where is median eminence of hypothalamus, what does it connect to?

between/just posterior to optic chiasma
connects by stalk to pituitary gland

31

2 parts of pituitary gland

1) adenohypophysis, anterior pituitary, aka pars distalis - glandular
2) neurohypophysis, posterior pituitary, aka pars nervosa

32

pars distalis means

hormones of anterior pituitary

33

pars distalis contains

most endocrine cells of pituitary

34

pars nervosa means

hormones of posterior pituitary

35

parts of anterior pituitary

1) pars distalis
2) pars tuberalis
3) pars intermedia

36

parts of posterior pituitary

1) pars nervosa
2) infundiibulum
3) median eminence

37

what does posterior pituitary (neurohypophysis) develop from

nervous tissue of hypothalamus

39

what does anterior pituitary (adenohypophysis) develop from

ectoderm of roof of the mouth

40

how does pituitary gland develop?

1) hypothalamus invaginates, grows down toward rathke's pouch of fossa, becomes stalk, while neurectoderm tissue of roof of mouth grows toward hypoficial fassa
2) rathke's pouch approaches pars nervosa; pouch space becomes narrow, forms pars distalis and pars intermedia

41

what does pars nervosa develop from?

distal end of hypothalamus

42

what does rathke's pouch become?

anterior part: anterior part of pars distalis
posterior part: pars intermedia

43

where does rathke's pouch develop from?

roof of the mouth

44

what is between pars nervosa and pars distalis?

pars intermedia

45

how/where does pituitary gland connect to the hypothalamus?

pars nervosa connects to stalk to hypothalamus
functional and physical connection

46

how/why do pars nervosa and pars distalis stain differently?

pars distalis stains darker b/c has endocrine cells

47

characteristics of pars distalis

1) endocrine cell clusters
2) reticular fibers, Type III collagen, support
3) FENESTRATED/SINUSOIDAL CAPILLARIES throughout for rapid diffusion of hormones into circulation

48

chromophils

affinity for dye
1) acidophils- affinity for acidic dye
2) basophils- affinity for basic dyes

49

chromophobes

degranulated acidophils/basophils, granules don't stain by antibodies

50

how many populations/types of endocrine cells are there

5

51

how would you localize endocrine hormones

immunocytochemical staining
make an antibody against a hormone, localize it

52

why 6 hormones but 5 cell types

because both FSH and LH expressed by 1 cell type, gonadotrophs

53

6 hormones localizable with immunocytochemical staining

growth hormone, prolactin, corticotropin (ACTH), thyrotropin (TSH), follicle stimulating hormone (FSH), luteinizing hormone (LH)

54

how can you tell anterior pituitary cell in EM?

anterior pituitary hormones are stored in granules, which has marker that stains positively

55

how are endocrine cell types named?

for the hormones they secrete

56

acidophils of pars distalis?

1) somatotrophs
2) mammatrophs

57

what do somatotrophs secrete, what proportion is this of all pars distalis?

growth hormone (GH)
50%

58

what do mammatrophs secrete, what proportion is this of all pars distalis?

prolactin
20%

59

basophils of pars distalis?

1) corticotrophs
2) thyrotrophs
3) gonadotrophs

60

what do corticotrophs secrete, what proportion is this of all pars distalis?

corticotropin (ACTH)
20%

61

what do thyrotrophs secrete, what proportion is this of all pars distalis?

thyrotropin (TSH)
5%

62

what do gonadotrophs secrete, what proportion is this of all pars distalis?

1) follicle stimulating hormone (FSH)
2) luteinizing hormone (LH)
5%

63

how are pars distalis hormones controlled?

secretion of pars distalis hormones controlled by HYPOTHALAMUS via HYPOTHALAMIC RELEASING or INHIBITING HORMONES

64

function of hypophyseal (pituitary) portal system?

in pituitary gland
provides anatomical-function link between hypothalamus & pars distalis of anteiror pituitary

65

blood supply to pituitary gland?

inferior & superior hypophyseal artery - branchs of coratid

66

how does hypophyseal portal system work

inferior/superior hypophyseal arteries enter pituitary gland at pars distalis
> break into vein, venule
> go to endocrine cells of pars distalis, surround capillaries
> hormones > circulation

67

what do neurosecretory cells in hypothalamus do?

control pars distalis hormone secretion by making releasing and inhibiting hormones

68

what do releasing and inhibiting hormones of hypothalamus neurosecretory cells target?

anterior pituitary hormones
therefore effect target organ cells

69

what are the hypothalamic hormones?

1) GH-releasing hormone
2) corticotropin-releasing hormone
3) TSH-releasing hormone
4) gonadotropin-releasing hormone
5) dopamine
6) somatostatin

70

GH-releasing hormone function?

stimulates GH release

71

corticotropin-releasing hormone function?

stimulates ACTH release

72

TSH-releasing hormone function?

stimulates TSH release

73

gonadotropin-releasing hormone function?

stimulates FSH and LH release

74

dopamine function?

INHIBITS prolactin release - unique b/c inhibition!

75

somatostatin function?

aka global inhibitor - always inhibits, wherever it acts
INHIBITS GH release
ex: inhibits glucose release in pancreas

76

when is pars intermedia well pronounced?

in animals, not in humans

77

what does pars intermedia secrete

2 types of melanocyte-stimulating hormone:
B-MSH: skin pigmentation
A-MSH: anti-appetite

78

what are melanocyte-stimulating hormones product of?

pro-opiomelanocortin (POMC)

79

what do pars intermedia granules and corticotrophs both synthesize

pro-opiomelanocortin

80

what can pro-opiomelanocortin split into

1) ACTH
2) lipotropins for lipid metabolism
3) endorphins for endogenous opioids
4) MSHs B and A for skin pigmentation and anti-appetite

81

what hormones does pars nervosa secrete

1) antidiuretic hormone (ADH; vasopressin)
2) oxytocin

82

what do pars nervosa hormones bind to

a carry protein neurphysin

83

what produces ADH?

neurons in the supraoptic nuclei of the hypothalamus

84

what produces oxytocin?

neurons in the paraventricular nuclei of the hypothalamus

85

what is the hypothalamohypophyseal tract

axon tract that carries hormones (ADH, oxytocin) from neuron of hypothalamus to pars nervosa of pituitary

86

ADH function?

water absorption in collecting ducts, convoluted tubules of kidneys

87

oxytocin functions?

1) acts on myoepithelial contraction- physically expelling milk from mammary glands
2) uterine contraction

88

what are pituicytes?

neuroglia - supporting cells of hypothalamo-hypophyseal tract

89

what is hypothalamo-hypophyseal tract made of

100,000 unmyelinated axons

90

what are herring bodies

swellings along axon of hypothalamo-hypophyseal tract; collecting sites of granules of hormones ADH and oxytocin, which bind in herring bodies to neurophysin

91

what controls release of ADH/oxytocin, where are they released?

into blood
caused by neurostimuli from hypothalamus > hormone released from granule > down axon terminal > circulation

92

neurosecretion defn

how oxytocin/ADH released because their release from herring bodies controlled by neurostimuli

93

where is pineal gland

it is a diverticulum of posterior diencephalon, at posterior end of III ventricle

94

what covers pineal gland?

pia mater

95

structures of pineal gland?

lobules separated by CT septa; neuroglial cells (pinealocytes) inside lobules; corpora arenacea outside

96

corpora arenacea- where and what is it?

outside pineal gland
extracellular calcified bodies containing CaPO4, MgPO4, carbonate in an organic matrix
increase with age

97

what controls day/night cycle (diurnal rhythms) of the body?

melatonin, "hormone of the darkness"

98

why is melatonin "hormone of the darkness"?

synthesis induced by darkness and suppressed by light

99

what is melatonin synthesized from?

the amino acid tryptophan, via serotonin

100

what effect does melatonin have on reproduction?

has anti-reproductive effects by decreasing gonadotropin (FSH, LH) release

101

relationship between melatonin and jet lag?

use of melatonin may help counteract drowsiness, disorientation related to jet lag because helps reacclimate to correct time zone

102

what happens if remove pineal gland from animal?

gonadotropin production increases
reproductive organs enlarge