C5 - Section 1. AN OVERVIEW OF THE ENDOCRINE SYSTEM

Question 1

Endocrinology is a field of medicine which studies hormones and their actions.

Question 2

These hormones are produced from endocrine glands.

Question 3

The endocrine system is a finely integrated system whereby the hypothalamus, pituitary & target glands continually communicate through feedback inhibition & stimulation, to control all aspects of metabolism, growth and reproduction (Henry) and by understanding this interplay, and carefully manipulating these systems via provocative and suppressive stimuli, it is possible to characterize an underlying abnormality and provide directed treatment

Question 4

Secretory products transported in the bloodstream from their place of synthesis to a distant location where they exert their action.

Question 5

These are chemical substances that have a specific regulatory effect on the activity of a certain organ or organs or cell types.

Question 6

Hormones have the following important functions:

Answer 6

 Control rates of certain chemical reactions
 Transport substances across cell membranes
 Help regulate water and electrolyte balance
 Play a role in reproduction

Question 7

Three General classes of Hormones

Answer 7

Steroid Hormones
Polypeptides and Proteins
Hormones derived from amino acids

Question 8

generally hydrophobic

Answer 8

Steroid Hormones

Question 9

Many circulate in plasma bound to high-affinity proteins

Answer 9

Steroid Hormones

Question 10

Small % are free for biologic activity

Answer 10

Steroid Hormones

Question 11

Half-life: 60 – 100 mins.

Answer 11

Steroid Hormones

Question 12

water-soluble

Answer 12

Polypeptides and Proteins

Question 13

Circulate unbound in plasma

Answer 13

Polypeptides and Proteins

Question 14

Half-life: vary from 5 to 60 mins.

Answer 14

Polypeptides and Proteins

Question 15

Initiate their response by binding to cell membrane receptor

Answer 15

Polypeptides and Proteins

Question 16

Half-lives vary

Answer 16

Hormones derived from amino acids

Question 17

Examples:
Thyroxine – protein-bound (Half-life: almost 1 week)
Epinephrine – not proteinbound (Half-life: <1 min.)

Answer 17

Hormones derived from amino acids

Question 18

– protein-bound (Half-life: almost 1 week)

Answer 18

Thyroxine

Question 19

– not proteinbound (Half-life: <1 min.)

Answer 19

Epinephrine

Question 20

Types of Hormone Action according to Tietz

Question 21

hormone synthesized in one location & released into plasma

Answer 21

1. Endocrine

Question 22

Binds to specific receptors in cells at a distant site to elicit characteristic response

Answer 22

1. Endocrine

Question 23

hormone synthesized in nerve ending & released into EC space

Answer 23

2. Neuroendocrine

Question 24

Interacts w/ receptors of cells at distant site

Answer 24

2. Neuroendocrine

Question 25

hormone synthesized in neurons & released into EC space

Answer 25

3. Neurocrine

Question 26

Binds to receptor in nearby cell & affects its function

Answer 26

3. Neurocrine

Question 27

hormone synthesized in neurons & released from nerve endings

Answer 27

4. Neurotransmission

Question 28

Crosses synapse & binds to specific receptors in another neuron

Answer 28

4. Neurotransmission

Question 29

hormone synthesized in endocrine cells & released into EC space

Answer 29

5. Paracrine

Question 30

Binds to specific receptor of nearby cell & affects its function

Answer 30

5. Paracrine

Question 31

hormone synthesized in endocrine cells & released into lumen of gut

Answer 31

6. Exocrine

Question 32

The biological response to a hormone is initiated by the binding of the hormone to target cell receptors

Question 33

provide the target cell with a mechanism for recognizing & concentrating the hormone

Answer 33

Receptors

Question 34

activates the target cell to begin the chain of events that constitutes the biological effect(s) of that hormone

Answer 34

hormone-receptor complex

Question 35

3 ways in which control of Hormonal Secretion occurs

Question 36

1.Releasing (trophic) hormones from the (?) control secretions of the anterior pituitary.

Answer 36

HYPOTHALAMUS

Question 37

2. The (?) influences certain endocrine glands directly.

Answer 37

NERVOUS SYSTEM

Question 38

2. (?): respond directly to changes in fluid composition.

Answer 38

FREESTANDING GLANDS

Question 39

Mechanism of Hormone Secretion

Question 40

An increase in one hormone would result in the increase of a second hormone

Answer 40

Positive Feedback Mechanism

Question 41

An increase in one hormone causes a decrease in the second hormone

Answer 41

Negative Feedback Mechanism