Exam 3- Endocrinology Overview

Question 1

what do endocrine cells do?

Answer 1

release hormones into interstitial fluid (not ducts)

Question 2

where do hormones released into the interstitial go?

Answer 2

enter the blood or act locally

Question 3

what regulates secretion of hormones?

Answer 3

neural mechanisms and feedback mechanisms

Question 4

what are two examples of negative feedback mechanisms for hormonal secretion?

Answer 4

hypothalamic-pituitary-gonadal axis
glucose-sensitive insulin release

Question 5

is negative or positive feedback with hormonal secretion more common in biological systems?

Answer 5

negative feedback is much more common

Question 6

what are two examples of positive feedback on secretion of hormones?

Answer 6

estrogen-induced surge of luteinizing hormone (LH) preceding ovulation
oxytocin-induced contraction of uterus leading to parturition

Question 7

what does the anterior pituitary synthesize, if anything?

Answer 7

many hormones

Question 8

does the posterior pituitary synthesize hormones?

Answer 8

no, only releases ones from the hypothalamus

Question 9

what are the three categories of hormones based on where they act relative to where they are produced?

Answer 9

classical hormones
local hormones
neurohormones

Question 10

what releases neurohormones? where do they act?

Answer 10

neurons
across synaptic cleft
into blood stream and elsewhere (autocrine)

Question 11

where do steroid and fatty acid hormones bind?

Answer 11

primarily intracellular receptors

Question 12

what do the chemical and solubility properties of hormones influence?

Answer 12

cellular site of action
how they are stored/secreted
how they are transported

Question 13

what are the four classes of hormones based on their chemical structure?

Answer 13

peptide and protein hormones
steroid hormones
fatty acid compounds
amino acid derivatives

Question 14

how are hormones stored in granules released?

Answer 14

Ca2+-dependent exocytosis

Question 15

what are steroid hormones formed from?

Answer 15

cholesterol

Question 16

what hormones are derived from Tyrosine?

Answer 16

thyroid hormone
catecholamines

Question 17

what hormones are synthesized from Tryptophan?

Answer 17

serotonin
melatonin

Question 18

what are eicosenoids?

Answer 18

lipid-soluble, local signaling molecules synthesized from fatty acids (usually arachidonic acid) in cell membranes

Question 19

what non-specific transport proteins are synthesized in the liver?

Answer 19

albumin
prealbumin
thyroid hormones

Question 20

what specific transport proteins are synthesized in the liver?

Answer 20

corticosteroid-binding globulin (CBG)
vitamin D-binding globulin (DBG)
thyroxine-binding globulin (TBG)
sex hormone-binding globulin (SHBG)

Question 21

are hormones biologically active when bound?

Answer 21

no

Question 22

why is binding of hormones to transport proteins important?

Answer 22

serves as reservoir of hormones to draw from
stabilizes free hormone levels (“buffers”)
increases lifespan of hormones in blood

Question 23

how are peptide hormones and catecholamines eliminated?

Answer 23

enzymatic degradation and excretion in urine or bile
degrade intracellularly after binds

Question 24

what organ eliminates steroid hormones and thyroid hormones?

Answer 24

kidneys: liver converts to water soluble compounds by conjugating with glucuronic acid

Question 25

what/where are endocrine cells?

Answer 25

discrete glands cells within organs or tissues that have other functions neuroendocrine cells immune cells

Question 26

what happens when hormone levels are low in negative feedback?

Answer 26

secretion of hormone is stimulated

Question 27

true/false: the posterior pituitary and the anterior pituitary are endocrine glands

Answer 27

false: only anterior pituitary is endocrine gland posterior pituitary releases hormones from hypothalamus

Question 28

where do peptide and protein hormones bind?

Answer 28

cell membranes

Question 29

what is the classical protein synthesis biosynthetic pathway?

Answer 29

gene transcribed to mRNA (nucleus) mRNA to preprohormone (cytoplasm) signal peptide removed to make prohormone (ER) secretory vesicles, proteolytic enzymes cleave to make hormone (Golgi) Ca-dependent exocytosis of secretory vesicles

Question 30

where does the synthesis of steroid hormones take place?

Answer 30

adrenal cortex gonads and corpus luteum placenta

Question 31

what are the steroid hormones?

Answer 31

cortisol aldosterone estradiol progesterone testosterone 1, 25-dihydroxycholecalciferol

Question 32

how are eicosenoid effects mediated?

Answer 32

G-protein coupled receptors

Question 33

what groups are eicosenoids?

Answer 33

prostaglandins prostacyclins thromboxanes leukotrienes

Question 34

true/false: water soluble hormones can circulate free, but lipid-soluble hormones must be bound to water soluble transport molecules

Answer 34

true

Question 35

what does an increase in binding protein lead to with the hormone levels?

Answer 35

initial decrease in free feedback mechanisms will lead to increased secretion of hormone

Question 36

how are lipid-soluble hormones eliminated?

Answer 36

broken down inside target cells after binding to receptors

Question 37

how are steroid and thyroid hormones eliminated?

Answer 37

converted to water-soluble by liver with glucuronic acid, eliminated by kidneys

Question 38

what are the five categories of mechanism for hormone action?

Answer 38

adenylyl cyclase mechanism (cAMP) phospholipase C mechanism (IP3/Ca++) steroid hormone mechanism tyrosine kinase mechanism guanylate cyclase mechanism (cGMP)

Question 39

how is arachidonic acid formed?

Answer 39

phospholipase A2 cleaves after inflammatory stimuli

Question 40

how can a cell have up-regulation for hormone receptors when hormone levels are low?

Answer 40

increase affinity and/or number of receptors increased synthesis or decreased degradation of receptors