18.2 Endocrine System

Question 1

4 Mechanisms of intercellular communication

Answer 1

direct, paracrine, endocrine, synaptic

Question 2

Both nervous & endocrine systems regulated mainly by what type of feedback?

Answer 2

negative feedback

Question 3

3 classes of hormones

Answer 3

1. amino acid derivatives
2. peptide hormones
3. lipid derivatives

Question 4

amino acid derivatives synthesized from

Answer 4

tyrosine and tryptophan

Question 5

hormones synthesized from tyrosine

Answer 5

thyroid hormones

catecholamines: E, NE, & dopamine

Question 6

hormones synthesized from tryptophan

Answer 6

melatonin

Question 7

groups of peptide hormones

Answer 7

1. glycoproteins (>200 amino acids long)

2. short polypeptides, small proteins

Question 8

classes of lipid derivatives

Answer 8

1. eicosanoids

2. steroid hormones

Question 9

eicosanoids

Answer 9

signalling molecules derived from arachadonic acid..strong paracrine effects.. leukotrienes, prostaglandins, thromboxanes, prostacyclins

Question 10

steroid hormones

Answer 10

derived from cholesterol.. released by reproductive organs (androgens, estrogens, progestins), cortex of adrenal glands (corticosteroids), and kidneys (calcitrol)

Question 11

which hormones are likely to attach to transport proteins in the bloodstream?

Answer 11

thyroid hormones and steroid hormones

Question 12

glycoproteins

Answer 12

> 200 amino acids long.. ex: TSH, LH, FSH

Question 13

short chain polypeptides/small proteins

Answer 13

-includes all hormones secreted by hypothalamus, heart, thymus, digestive tract, pancreas, and posterior pituitary gland.
ADH, OXT (each 9 amino acids long)
GH (191 amino acids), PRL (198 amino acids)

Question 14

Hormones with receptors in plasma membranes

Answer 14

extracellular: catecholamines, peptide hormones
intracellular: eicosanoids

Question 15

first messenger

Answer 15

hormone

Question 16

second messengers

Answer 16

1. cAMP
2. cGMP
3. Calcium ions

Question 17

down regulation

Answer 17

presence of hormone decreases number of receptors

Question 18

up-regulation

Answer 18

absence of a hormone triggers increase in receptors.

Question 19

G protein

Answer 19

enzyme complex coupled to a membrane receptor..binds to GTP

Question 20

G protein & cAMP

Answer 20

• g protein activates adenylate cyclase, which converts ATP to cAMP, which functions as a second messenger to activate a kinase, leading to phosphorylation
• g protein stimulates PDE, inhibiting adenylate cyclase activity

Question 21

phosphodiesterase (PDE)

Answer 21

inactivates cAMP

Question 22

G proteins and Calcium ions

Answer 22

g protein activates phospholipase C (PLC), which triggers a cascade:

• production of diacylglycerol (DAG) and inositol triphosphate (IP3)
• IP3 triggers release of Ca2+ from intracellular reserves
• DAG and Ca2+ activate Protein Kinase C (PKC), which opens channels to extracellular Ca2+
• Ca2+ serve as messengers with calmodulin (protein)

Question 23

hormones with intracellular receptors

Answer 23

Steroid hormones diffuse through membrane (receptors in cytoplasm or nucleus), Thyroid hormones transported across membrane (receptors at mitochondria increase ATP production, nucleus)

Question 24

endocrine reflexes can be triggered by:

Answer 24

1. humoral stimuli
2. hormonal stimuli
3. neural stimuli

Question 25

endocrine reflexes are usually controlled by what type of feedback?

Answer 25

negative feedback

Question 26

simple endocrine reflexes control the hormone secretion of which organs/tissues?

Answer 26

heart, pancreas, parathyroid glands, and digestive tract.

Question 27

regulatory hormones of the hypothalamus control..

Answer 27

endocrine cells of anterior pituitary

Question 28

hormones secreted by anterior pituitary control..

Answer 28

endocrine cells in thyroid, adrenal cortex, and reproductive organs

Question 29

hypothalamus exerts direct neural control over..

Answer 29

endocrine cells of adrenal medullae