Endocrine System

Question 1

3 different ways endocrine cells cluster together

Answer 1

1. within a distinct organ (thyroid) 2. clusters of cells within other organs (pancreas) 3. extensive array of dispersed cells (GI neuroendocrine)

Question 2

endocrine organs are ductless glands

Answer 2

ok

Question 3

what are neuroendocrine cells?

Answer 3

neurons within the brain that produce neurohormones and release them into the blood stream

Question 4

what determines hormone specificity?

Answer 4

the receptors determine the specificity of the endocrine system

Question 5

describe paracrine and autocrine secretions

Answer 5

local hormones released into the interstitial fluid. paracrine secretions act on nearby cells, autocrine reacts on the cells that released them

Question 6

what are the 4 groups of hormones

Answer 6

proteins (insulin, HGH), small peptide molecules (vasopressin), steroids, amino acid derivatives and arachidonic analogs (adrenaline, noreadrenaline, thyroid hormones

Question 7

describe how the solubility of a hormone affects its receptors

Answer 7

water soluble hormones link to membrane receptors and second messenger systems. lipid soluble hormones can move through the membrane and often bind nuclear receptors

Question 8

under what circumstances would you get up and down regulation?

Answer 8

down regulation- excessive hormone, lower sensitivity. up regulation- lacking hormone, raised sensitivity

Question 9

what are the primary endocrine organs?

Answer 9

pituitary, thyroid, parathyroid, adrenal, and pineal glands

Question 10

what are the secondary endocrine organs?

Answer 10

hypothalamus, thymus, pancreas, ovaries, testes, kidneys, stomach, liver, small intestine, skin, heart and placenta

Question 11

describe the differing embryologic origins of the hypophysis

Answer 11

neurohypophysis- posterior lobe. develops from the diencephalon and adenohypophysis (anterior lobe) develops from the oral cavity (Rathkes pouch)

Question 12

how do hormones reach the posterior pituitary?

Answer 12

hypothalamo-hypophyseal tract. transmits oxytocin and ADH from supra optic and paraventricular nuclei in hypothalamus to Herring bodies (neurosecratory granules)

Question 13

what are the 3 parts of the adenohypophysis?

Answer 13

pars distalis- largest, containing the secretory cells. pars tuberalis surrounds the infundibulum. vestigial pars intermedia- remnants of rathkes pouch.

Question 14

describe 3 ways hormones can interact with another

Answer 14

permissiveness- one hormone is necessary for another to be effective. synergism- amplify the effects of each other. antagonism- opposite effects

Question 15

what are 3 general stimuli that control hormone release?

Answer 15

humoral stimuli- responses to changing blood levels of specific solutes. neural stimuli- respond to nerve impulses. hormonal stimuli- respond to other endocrine glands

Question 16

what are the 3 parts of the adenohypophysis

Answer 16

median eminence, infundibular stem, pars nervosa

Question 17

what are the chromophil cells and where are they found?

Answer 17

they are found in the adenohypophysis. they are granules with acidophils and basophils

Question 18

what are the 2 classes of hormones in the adenohypophysis?

Answer 18

tropic and nontropic. tropic- ACTH, TSH, FSH, LH. nontropic- HGH and prolactin

Question 19

what are the 3 types of basophils in the adenohypophysis

Answer 19

gonadotropes, thyrotropes, and corticotropes

Question 20

what are the 2 types of acidophils in the adenohyophysis?

Answer 20

somatotropes and mammotropes- secrete HGH and prolactin

Question 21

most hormones are controlled with negative feedback. which one is controlled by positive feedback?

Answer 21

oxytocin- stretching of the cervix causes more oxytocin

Question 22

what hormone stimulates the anterior pituitary to release its thyroid hormone?

Answer 22

TRH from the hypothalamus

Question 23

what is the hormone that the anterior pituitary releases in response to TRH? what does it do?

Answer 23

TSH. Stimulates secretion and production of thyroid hormones

Question 24

what is the characteristic morphology of the thyroid

Answer 24

large follicles filled with colloid and bordered by follicular cells

Question 25

how is the follicular cell indicative of thyroid activity

Answer 25

squamous- inactive; columnar- active

Question 26

describe the storage and release of thyroid hormones

Answer 26

they are stored as a colloid in the follicles in a form called thyroglobulin, which is rich in iodinated tyrosine. when the thyroglobulin is reabsorbed from the follicle, the cell breaks down the thyroglobulin into T3 and T4, which are the hormones

Question 27

what are the important functions of the thyroid hormones?

Answer 27

maintain basal metabolic rate, regulate heat production, influence body and tissue growth, play a role in development of the nervous system

Question 28

what are the 3 hormones the thyroid produces?

Answer 28

t3, t4, calcitonin- produced by the parafollicular cells

Question 29

how many parathyroid glands are their usually?

Answer 29

4

Question 30

are the developmental origins of the thyroid and parathyroid the same?

Answer 30

no- para develops from pharyngeal pouches. thyroid from the base of the tongue.

Question 31

what are the 2 cell types in parathyroid

Answer 31

oxyphils- large, acidophilic cells with unknown purpose that increases in number with age. chief cells secrete PTH

Question 32

what does parathyroid hormone do?

Answer 32

increase blood calcium levels by increasing osteoclast activity

Question 33

differentiate between the functions of the zone glomerulosa, fasciculata, reticularis in the adrenal cortex

Answer 33

glomerulosa- clusters of aldosterone secreting cells, fasciculata- columns of cortisol secerting cells, reticularis-produces weak androgens

Question 34

which hormone is a glucocorticoid and which is a mineralcorticoid?

Answer 34

gluco- cortisol, mineral- aldosterone

Question 35

what stimulates glucocorticoid secretion?

Answer 35

ACTH stimulates cortisol release

Question 36

what do glucocorticoids do?

Answer 36

triggers breakdown of lipids, carbs, and proteins in most tissues

Question 37

what stimulates mineralcorticoids?

Answer 37

renin/angiotensin

Question 38

what does angiontensin do?

Answer 38

increase absorption of Na and Cl

Question 39

what does the adrenal medulla derive from?

Answer 39

neural crest cells

Question 40

what does the adernal medulla secrete?

Answer 40

epinephrine and norepinephrine

Question 41

how is the blood flow for function of the medulla?

Answer 41

one blood flow goes directly to the medulla, the other is a portal system that picks up glucocorticoids, which is essential for the methyl transferase enzyme which converts norepinephrine to epinephrine

Question 42

what does the pineal gland develop from?

Answer 42

the roof of the diencephalon

Question 43

what does the pineal gland produce?

Answer 43

melatonin- important for circadian rhythms

Question 44

what is meant by the endocrine pancreas?

Answer 44

most of the pancreas is exocrine. endocrine refers to the islets of langerhans

Question 45

what are the 4 different cell populations and what do they produce?

Answer 45

alpha (peripherally located)- glucagon- increases blood glucose, beta- insulin (centrally located)- decreases blood glucose, delta- somatostatin- inhibits glucagon, insulin, GH and TSH and HCL in stomach. F cells- pancreatic polypeptide- stimulates gastric cheif cells, inhibits bile and pancreatic exocrine secretions, decreases intestinal motility