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Flashcards in Endocrine Physiology Deck (32)
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1

What is the endocrine system responsible for?

homeostasis

2

What 6 things are regulated by the endocrine system?

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

3

What are the 9 classical endocrine glands?

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

4

What are the 3 classes of hormones?

- peptides and proteins
- steroids
- amines

5

What are peptides and proteins synthesized from?

amino acids

6

Describe the steps involved in the synthesis of peptide hormones

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

7

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

- the adrenal cortex
- gonads
- corpus luteum
- placenta

8

All steroid hormones are derivatives of what?

cholesterol

9

What are the 6 steroid hormones?

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

10

What are amine hormones derivatives of?

tyrosine

11

What are the 4 amine hormones?

- catecholamines (epinephrine, norepinephrine, and dopamine)
- thyroid hormones

12

Adjustments in secretion of hormones is accomplished via what?

neural or feedback mechanisms

13

Neural mechanisms are illustrated by what?

By the secretion of catecholamines into the circulation

14

Which mechanism is more common?

feedback mechanisms

15

What are the 2 types of feedback mechanisms?

Negative and Positive

16

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

negative feedback

17

What does negative feedback mean in endocrine systems?

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

18

What is the net result of any version of feedback?

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

19

What is an example of negative feedback?

The hypothalamic-pituitary axis

20

Is positive feedback very common?

No

21

What is the basis of positive feedback?

Some feature of hormone action causes more secretion of the hormone

22

What are a couple examples of positive feedback?

- the opening of Na+ channels during the upstroke of an AP
- oxytocin

23

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

limiting

augmenting

24

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

the dose-response relationship

25

Describe the dose-response relationship

The magnitude of a hormone response is correlated with hormone concentration

26

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

increases and then levels off

27

What is sensitivity?

The hormone concentration that produces 50% of the maximal response

28

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

decrease

29

What are 2 ways in which sensitivity can be altered?

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

30

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

down-regulation or up-regulation