Endocrine Physiology

Question 1

What is the endocrine system responsible for?

Answer 1

homeostasis

Question 2

What 6 things are regulated by the endocrine system?

Answer 2

• growth
• development
• reproduction
• blood pressure
• concentrations of substances in blood
• behavior

Question 3

What are the 9 classical endocrine glands?

Answer 3

• hypothalamus
• anterior and posterior lobes of the pituitary
• thyroid
• parathyroid
• adrenal cortex
• adrenal medulla
• gonads
• placenta
• pancreas

Question 4

What are the 3 classes of hormones?

Answer 4

• peptides and proteins
• steroids
• amines

Question 5

What are peptides and proteins synthesized from?

Answer 5

amino acids

Question 6

Describe the steps involved in the synthesis of peptide hormones

Answer 6

1) DNA is transcribed into mRNA
2) mRNA is translated on the ribosomes to the first protein product, a prepohormone
3) the signal peptide is removed in the endoplasmic reticulum, converting the perpohormone to a prohormone
4) the prohormone is transferred to the Golgi apparatus
5) the final hormone is stored in secretory vesicles until the endocrine cell is stimulated

Question 7

Steroid hormones are synthesized and secreted by what 4 endocrine glands?

Answer 7

• the adrenal cortex
• gonads
• corpus luteum
• placenta

Question 8

All steroid hormones are derivatives of what?

Answer 8

cholesterol

Question 9

What are the 6 steroid hormones?

Answer 9

• cortisol
• aldosterone
• estradiol and astriol
• progesterone
• testosterone
• 1,25-dihydroxycholecalciferol

Question 10

What are amine hormones derivatives of?

Answer 10

tyrosine

Question 11

What are the 4 amine hormones?

Answer 11

• catecholamines (epinephrine, norepinephrine, and dopamine)

- thyroid hormones

Question 12

Adjustments in secretion of hormones is accomplished via what?

Answer 12

neural or feedback mechanisms

Question 13

Neural mechanisms are illustrated by what?

Answer 13

By the secretion of catecholamines into the circulation

Question 14

Which mechanism is more common?

Answer 14

feedback mechanisms

Question 15

What are the 2 types of feedback mechanisms?

Answer 15

Negative and Positive

Question 16

Which type of feedback is the most important and common mechanism for regulating hormone secretion?

Answer 16

negative feedback

Question 17

What does negative feedback mean in endocrine systems?

Answer 17

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

Question 18

What is the net result of any version of feedback?

Answer 18

When hormone levels are judged to be adequate or high, further secretion of the hormone is inhibited.

When hormone levels are judged to be inadequate or low, secretion of the hormone is stimulated

Question 19

What is an example of negative feedback?

Answer 19

The hypothalamic-pituitary axis

Question 20

Is positive feedback very common?

Answer 20

No

Question 21

What is the basis of positive feedback?

Answer 21

Some feature of hormone action causes more secretion of the hormone

Question 22

What are a couple examples of positive feedback?

Answer 22

• the opening of Na+ channels during the upstroke of an AP

- oxytocin

Question 23

Negative feedback is self-_____, whereas positive feedback is self-_____.

Answer 23

limiting

augmenting

Question 24

The responsiveness of a target tissue to a hormone is expressed via what relationship?

Answer 24

the dose-response relationship

Question 25

Describe the dose-response relationship

Answer 25

The magnitude of a hormone response is correlated with hormone concentration

Question 26

As hormone concentration increases, the response usually ______ and does what?

Answer 26

increases and then levels off

Question 27

What is sensitivity?

Answer 27

The hormone concentration that produces 50% of the maximal response

Question 28

If more hormone is required to produce 50% of the maximal response, than there has been a _____ in sensitivity of the target tissue.

Answer 28

decrease

Question 29

What are 2 ways in which sensitivity can be altered?

Answer 29

- by changing the number of receptors | - by changing the affinity of the receptors for the hormone

Question 30

A change in the number or affinity of receptors is called what?

Answer 30

down-regulation or up-regulation

Question 31

Down-regulation is a mechanism in which a hormone ______ the number or affinity of its receptors in a target tissue.

Answer 31

decreases

Question 32

Up-regulation is a mechanism in which a hormone ______ the number or affinity of its receptors in a target tissue.

Answer 32

increases