0-1 Chapter 17 - Endocrine System Flashcards Preview

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Flashcards in 0-1 Chapter 17 - Endocrine System Deck (202)
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1

four principal mechanisms of communication between cells

gap junctions
neurotransmitters
paracrine (local) hormones
Hormones

2

gap junctions

pores in cell membrane allow signaling molecules, nutrients, and electrolytes to move from cell to cell

3

neurotransmitters

released from neurons to travel across synaptic cleft to second cell

4

paracrine (local) hormones

secreted into tissue fluids to affect nearby cells

5

hormones

chemical messengers that travel in the bloodstream to other tissues and organs

6

endocrine system

glands, tissues, and cells that secrete hormones

7

endocrinology

the study of this system and the diagnosis and treatment of its disorders

8

endocrine glands

organs that are traditional sources of hormones

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hormones

chemical messengers that are transported by the bloodstream and stimulate physiological responses in cells of another tissue or organ, often a considerable distance away

10

major organs of endocrine system

pineal gland
hypothalamus
pituitary gland
thyroid gland
thymus
adrenal gland
pancreas
parathyroid gland
gonads

11

exocrine glands

–have ducts carry secretion to an epithelial surface or the mucosa of the digestive tract –‘external secretions’
–extracellular effects (food digestion)

12

endocrine glands

–no ducts
–contain dense, fenestrated capillary networks which allows easy uptake of hormones into bloodstream
–‘internal secretions’
–intracellular effects such as altering target cell metabolism

13

liver cells defy rigid classification

releases hormones, releases bile into ducts, releases albumin and blood-clotting factors into blood (not hormones)

14

Comparison of Nervous and Endocrine Systems (Differences)

both serve for internal communication

–nervous -both electrical and chemical
–endocrine -only chemical

15

Comparison of Nervous and Endocrine Systems (Differences)


speed and persistence of response

–nervous -reacts quickly (1 -10 msec), stops quickly
–endocrine -reacts slowly (hormone release in seconds or days), effect may continue for weeks

16

Comparison of Nervous and Endocrine Systems (Differences)


adaptation to long-term stimuli

–nervous -response declines (adapts quickly)
–endocrine -response persists (adapts slowly)

17

Comparison of Nervous and Endocrine Systems (Differences)


area of effect

–nervous -targeted and specific (one organ)
–endocrine -general, widespread effects (many organs)

18

Nervous and Endocrine Systems (Similarities)

several chemicals function as both hormones and neurotransmitters

–norepinephrine, cholecystokinin, thyrotropin-releasing hormone, dopamine and antidiuretic hormone

19

Nervous and Endocrine Systems (Similarities)

some hormones secreted by neuroendocrine cells

(neurons) that release their secretion into the bloodstream
–oxytocin and catecholamines

20

Nervous and Endocrine Systems (Similarities)

both systems with overlapping effects on same target cells

–norepinephrine and glucagon cause glycogen hydrolysis in liver

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Nervous and Endocrine Systems (Similarities)

systems regulate each other

–neurons trigger hormone secretion
–hormones stimulate or inhibit neurons

22

target organs or cells

those organs or cells that have receptorsfor a hormone and can respond to it.

23

Anatomy of Hypothalamus

•shaped like a flattened funnel
•forms floor and walls of third ventricle of the brain
•regulates primitive functions of the body from water balance and thermoregulation to sex drive and childbirth
•many of its functions carried out by pituitary gland

24

Pituitary Gland

(Hypophysis)
•suspended from hypothalamus by a stalk –infundibulum
•location and size
–housed in sella turcica of sphenoid bone
–size and shape of kidney bean

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infundibulum

suspends pituitary gland from hypothalamus

26

Pituitary Gland composed of two structures

composed of two structures with independent origins and separate functions
–adenohypophysis (anterior pituitary)
–neurohypophysis(posterior pituitary)

27

adenohypophysis

(anterior pituitary)
constitutes anterior three-quarters of pituitary
–has two segments:
•anterior lobe (pars distalis)
•pars tuberalissmall mass of cells adhering to stalk
–linked to hypothalamus by hypophyseal portal system

28

hypophysealportal system

•hypothalamic releasing and inhibiting hormones travel in hypophyseal portal system from hypothalamus to anterior pituitary
•hormones secreted by anterior pituitary

29

neurohypophysis

constitutes the posterior one-quarter of the pituitary
–has 3 parts:
•median eminence, infundibulum, and the posterior lobe (pars nervosa)

30

neurohypophysis is

nerve tissue, not a true gland
•nerve cell bodies in hypothalamus pass down the stalk as hypothalamo-hypophysealtract and end in posterior lobe
•hypothalamic neurons secrete hormones that are stored in neurohypophysis until released into blood