Basics of Endocrinology: PP 1

Question 1

endocrine release mechanism

Answer 1

products released INTO the blood (ex: pancreas-insulin)

Question 2

intracrine release mechanism

Answer 2

products released WITHIN OWN CELL

Question 3

autocrine release mechanism

Answer 3

products released onto SECRETING CELL

Question 4

paracrine release mechanism

Answer 4

products released onto ADJACENT CELL

Question 5

exocrine release mechanism

Answer 5

products released via DUCTS (ex: sweat glands, salivary glands, mammary cells, pancreas w/ digestive juices)

Question 6

ectocrine release mechanism

Answer 6

products released into the ENVIRONMENT (ex: pheromones)

Question 7

chemical messenger

Answer 7

substance produced in a cell that affects the functions of other cells

Question 8

hormone

Answer 8

a chemical messenger that’s released into the bloodstream/tissue fluid system that affects the function of target cells

Question 9

neurotransmitter

Answer 9

a chemical messenger that acts on the neural synapse

Question 10

peptide hormone

Answer 10

• a hormone composed of a sequences of amino acids

- polar and HYDROPHILIC (lipid phobic)

Question 11

Steps to peptide protein synthesis–transcription

Answer 11

(occurs in nucleus)

1. INITIATION: RNA polymerase binds to a promoter on DNA
   a. this will signal the DNA to unwind
2. ELONGATION: addition of complementary RNA base pairs to unwound DNA
3. TERMINATION: RNA polymerase crosses a “stop” (termination) sequence at DNA
   a. mRNA detaches from the DNA
4. mRNA transported from nucleus–>cytoplasm–> ribosomes, where it will undergo translation

Question 12

Steps to peptide protein synthesis–translation

Answer 12

(occurs in ribosomes)

1. INITIATION: construction of initiation complex so translation can begin
   a. tRNA attaches to small ribosomal unit
   b. complex will bind to DNA and scan to find the start codon, bind to start codon
   c. large ribosomal subunit joins to form initiation complex
2. ELONGATION: amino acids brought to ribosomes by tRNA’s–> linked to form a chain (this is the preprohormone)
3. TERMINATION: stop codon–> release of preprohormone from complex

Question 13

Preprohormone–> hormone steps

Answer 13

1. signal peptide removed in the rough ER (preprohormone–> prohormone) by enzymes
2. pro hormone passes from the ER to the Golgi via transport vesicles
3. secretory vesicles containing enzymes and the pro hormone bud off the golgi
   a. enzymes chop the pro hormone into into active peptides and fragments
4. vesicles release the contents via exocytosis
5. hormone moves via the blood circulation: soluble in the blood b/c it is polar and hydrophilic

Question 14

Peptide hormones: hypothalamus

Answer 14

1. CRH
2. GnRH
3. GnIH
4. GHRH
5. GHIH
6. TRH

Question 15

Peptide hormones: Anterior Pituitary

Answer 15

1. TSH
2. FSH
3. LH
4. GH
5. Prolactin
6. ACTH

Question 16

Peptide hormones: Posterior Pituitary

Answer 16

1. Vasopressin

2. Oxytocin

Question 17

hypophysiotropic hypogonadism

Answer 17

failure to reach sexual maturation; low/absent levels of LH

Question 18

kisspeptin (kiss1) and hypophysiotropic hypogonadism

Answer 18

• mice without kiss1 gene failed to undergo sexual maturation and had immature sex organs, low gonadotropin levels, and low sex steroid concentrations, infertile
• gonadotropin release can be stimulated with GnRH injection–> suggesting that this problem^ is with GnRH release

Question 19

Target: Peptide hormones

Answer 19

membrane receptors; affect their targets via secondary messengers

Question 20

Monoamine Hormones

Answer 20

hormones derived from a single amino acid

1. Catecholamines: derived from tyrosine, catechol with amine side group
   a. epinephrine, norepinephrine, dopamine
   - -^made in the adrenal medulla
2. Indolamines
   a. serotonin, melatonin cycle
3. Thyroid hormones
   a. T3 and T4

Question 21

Catecholamines

Answer 21

tyrosine–> DOPA–> dopamine–> norepinephrine–> epinephrine

Question 22

serotonin–> melatonin

Answer 22

tryptophan–(2-step enzymatic reaction to serotonin)–> in darkness, norepinephrine increases cAMP—> increased synthesis of N-acetyltransferase–> N-acetylserotonin–> melatonin

Question 23

Steroid hormones

Answer 23

• structurally composed of a 4 ring base (3 6-carbon rings and 1-5 carbon ring)
• NONPOLAR and HYDROPHOBIC (aka lipidphilic)
• basic building block= cholesterol
• must bind to a carrier protein to move in the blood

Question 24

Steroid hormones: adrenal cortex

Answer 24

1. mineral corticoids
   a. aldosterone
2. glucocorticoids
   a. cortisol
   b. corticosterone
   c. DHEA
3. androgens (pregnenolone–> androgens)
4. progesterone (progestins precursors to androgens^)

Question 25

steroid hormones: ovary

Answer 25

1. estrogens: estriol, estradiol, estrone | 2. progesterone

Question 26

steroid hormones: testes

Answer 26

1. androgens | a. testosterone, dihydrotestosterone, androstenedione

Question 27

Synthesis of mineral corticoids and glucocorticoids

Answer 27

cholesterol (mitochondria)--> pregnenolone (smooth ER)--> progesterone (mitochondria)--> ... (separate pathways)... aldosterone, cortisol

Question 28

synthesis of androgens and estrogens: pathway

Answer 28

cholesterol (mitochondria)--> pregnenolone (smooth ER)--> progesterone (smooth ER)--> testosterone--> estradiol, estrone, estriol androgens precursors to all estrogens b/c of AROMATIZATION

Question 29

aromatization

Answer 29

-conversion of androgens (testosterone) to estrogens via 3 step reaction: hydroxylation, oxidation, and demethylation

Question 30

lipid based hormones

Answer 30

1. prostaglandins: 20 carbon fatty acid skeletons

Question 31

7 types of hormonal regulation

Answer 31

1. physiological by-products generated in response to action 2. stimulatory/inhibitory effects of hormones 3. positive feedback 4. negative feedback 5. receptor regulation a. up-regulation b. down-regulation 6. hetero-specific priming 7. pulsatile secretion

Question 32

calcium and parathyroid hormone

Answer 32

ex: parathyroid hormone: when blood levels of calcium decrease, the parathyroid hormone is released leading to an increased concentration of blood calcium to an optimal level, leading to a negative feedback on the parathyroid to stop releasing parathyroid hormone

Question 33

positive feedback

Answer 33

production of a product stimulations additional hormone production -hormone--> target tissue--> product--> endo gland--> more hormone...

Question 34

negative feedback

Answer 34

product feeds back on the source of the hormone to stop hormone production

Question 35

up-regulation

Answer 35

hormone causes an increase in the production of receptors for that hormone

Question 36

down-regulation

Answer 36

overproduction of a hormone--> occupation of all available receptor's so that there is no biological effects -ex: high insulin--> decrease in number of insulin receptors

Question 37

heterospecific priming

Answer 37

hormones recegulating receptors of other hormones, so that one hormone induces the production of receptor's for another hormone

Question 38

pulsatile secretion

Answer 38

episodic secretion of hormones in bursts/spurts - benefits? a hormone-free period recovery period allows for receptors to necessarily be replenished--> allow for a biological response ex: pulsatile secretions of GnRH--> pulsatile secretions of LH--> testosterone--> negative feedback of testosterone on GnRH...