Hormone Synthesis, Regulation, and Mechanisms of Action

Question 1

Name some endocrine glands

Answer 1

hypothalamus
anterior pituitary
posterior pituitary
thyroid
parathyroid
pancreas
adrenal medulla
kidney

Question 2

Which endocrine gland is the core of the endocrine system?

Answer 2

pituitary gland

Question 3

Endocrine

Answer 3

hormone travels to a distant target

ex: insulin is secreted by beta islet cells and acts on skeletal muscle to increase glucose uptake

Question 4

Paracrine

Answer 4

hormone acts on neighboring target

ex: insulin acts on nearby alpha islet cells to suppress secretion of glucagon

Question 5

Autocrine

Answer 5

hormone acts on its own releasing cell

ex: insulin acts on beta islet cells to inhibit release of insulin

Question 6

Name the 3 classes of hormones

Answer 6

peptides and proteins
amino acid derivatives
steroids

Question 7

Name the biosynthetic pathways for the 3 classes of hormones

Answer 7

peptides and proteins - amino acids
amino acid derivatives - tyrosine and tryptophan
steroids - cholesterol

Question 8

How are peptide and protein hormones synthesized?

Answer 8

mRNA - translation to preprohormone - ER, conversion from prepro to prohormone - Golgi, pro packaged for secretion - enzymes in package break pro to hormone

Question 9

Name the amine hormones

Answer 9

catecholamines (NE, E, and DPA)

thyroid hormones

Question 10

Characteristics of steroid hormone synthesis

Answer 10

lipid derivative of cholesterol
very rapidly secreted from cells
all steroids bind to plasma proteins produced by the liver

Question 11

What are eicosanoids?

Answer 11

large group of molecules derived from polyunsaturated fatty acids

Question 12

Name some eicosanoids

Answer 12

prostaglandins
prostacyclins
leukotrienes
thromboxanes

Question 13

What is the primary precursors for eicosanoids?

Answer 13

arachodonic acid

Question 14

How are hormones regulated?

Answer 14

system of control based on stimulation and inhibition of secretory cells

Question 15

Negative feedback

Answer 15

output of a pathway inhibits inputs to the pathway

some feature of hormone action, either directly or indirectly, inhibits further secretion of the hormone

Question 16

Positive feedback

Answer 16

hormone action causes more secretion, elevating concentration

some feature of the hormone action causes more secretion of the hormone

Question 17

Is positive feedback homeostatic?

Answer 17

no

Question 18

What is a great example of negative feedback?

Answer 18

Glucose causes release of insulin - insulin facilitates entry of glucose into cells - glucose levels in blood fall - insulin not released anymore

Question 19

What 3 factors determine the concentration of hormone?

Answer 19

rate of production
rate of delivery
rate of degradation and elimination

Question 20

Receptor

Answer 20

a protein that contains hormone recognition sites that bind their hormone with high affinity and selectivity

Question 21

Sensitivity

Answer 21

hormone concentration that produces 50% of the maximal response
(if more hormone required to produce 50% of maximal response, then target tissue has decreased sensitivity)

Question 22

A target tissue’s responsiveness or sensitivity to a hormone can be changed by what 2 factors?

Answer 22

change the affinity of the receptors for the hormone

change the number of receptors

Question 23

Down-regulation

Answer 23

number of receptors or the affinity of the receptors for the hormone has decreased

Question 24

Reasons for down-regulation

Answer 24

decreasing synthesis of new receptors
increasing degradation of existing receptors
inactivating receptors

Question 25

Up-regulation

Answer 25

number of receptors or the affinity of the receptors for the hormone has increased

Question 26

Reasons for up-regulation

Answer 26

increasing synthesis of new receptors decreasing degradation of existing receptors activating receptors

Question 27

How do hormones change their target cells? (2)

Answer 27

activation of enzymes and other molecules via 2nd messengers | modulation of gene expression via gene transcription

Question 28

What are the 2 types of hormone receptors?

Answer 28

cell surface receptors | intracellular receptors

Question 29

What hormones bind to cell surface receptors?

Answer 29

proteins peptides catecholamines eicosanoids

Question 30

What hormones bind to intracellular receptors?

Answer 30

steroids | thyroid hormones

Question 31

Name some second messengers

Answer 31

adenylyl cyclase (cAMP) phospholipase C tyrosine kinase guanylate cyclase (cGMP)