Lecture 57- Hormone Synthesis, Regultion Of Hormone Secretion, And Hormone Receptors

Question 1

What does the endocrine system work together with to maintain homeostasis?

Answer 1

Nervous system

Question 2

What does the endocrine system regulate?

Answer 2

Growth, development, reproduction, blood pressure, ion concentration, behavior, aging

Question 3

What is the definition of hormone?

Answer 3

Chemical secreted into circulation in small amounts, delivered to target tissue … tissues then respond

Question 4

Where are most hormones synthesized in, and secreted by?

What are the exceptions?

Answer 4

Glands

Exceptions: GIT hormones secreted by clusters of endocrine cells, some made in hypothalamus, placenta, kidney

Question 5

What are common characteristics of endocrine cells and neurons?

Answer 5

-both secrete substances into blood
-some molecules are BOTH neurotransmitters and hormones
-mechanisms of action for hormones and neurotransmitters require a specific receptor
-similar processes of exocytosis of granules and synaptic vesicles

Question 6

(TRUE/FALSE) Both endocrine cells and neurons response to the same stimuli

Answer 6

TRUE

Question 7

What is homeostasis?

Answer 7

Ability of body to maintain a stable internal environment despite changes in external condition

Question 8

What are 3 mechanisms to restore and maintain a homeostasis?

Answer 8

Receptor
Control Center
Effector

Question 9

What are negative feedback loops? What are they absolutely essential to?

Answer 9

Negative feedback loop: system responds in a way to reverse direction of change

Essential to homeostasis

Question 10

(TRUE/FALSE) Positive feedback results in homeostasis

Answer 10

FALSE

Positive feedback does not result in homeostasis
*amplifies change in variable— blood clotting, parturition

Question 11

What are pathways that alter homeostasis?

Answer 11

Nutrition, toxins, psychological, physical, genetic, medical

Question 12

What are four hormone signaling pathways?

Answer 12

1. Endocrine/Telecrine
2. Neurocrine
3. Autocrine
4. Paracrine

Question 13

Describe the endocrine/telecrine hormone signaling pathway?

Answer 13

Travel a long distance in blood to target tissue

Question 14

Describe the neurocrine hormone signaling pathway?

Answer 14

Secreted by neurons into blood

Question 15

describe the Autocrine hormone signaling pathway?

Answer 15

Exerts effects on itself or very close identical cells

Question 16

Describe the paracrine hormone signaling pathway?

Answer 16

Close to target cells, usually through within same tissue, diffusing through interstitial fluid

Question 17

What is the structure of peptides and proteins?

Answer 17

Structure varies across species (growth hormone)
Amino Acid

Question 18

What is the structure of steroids?

Answer 18

-structure usually conserved across species
-cholesterol used to synthesize

Question 19

What is the structure of Amines?

Answer 19

-derived from tyrosine

Question 20

What is the structure of Eicosanoids?

Answer 20

-derived from fatty acids

Question 21

Why can growth factor hormones act on insulin receptors?

Answer 21

Because structure is very similar

Question 22

What are the steps in synthesis?

Answer 22

1. MRNa is transcribed and travels to cytoplasm
2. Message is translated on ribosome
3. Product is preprohormone—now transferred to ER
4. Signal peptide degraded in ER—resulted in prohormone, now transferred to Golgi
5. When endocrine cell stimulated, granule contents released

Question 23

(TRUE/FASLE) A stimulus always results in immediate release

Answer 23

FALSE

Transcription and translation are needed, so a stimulus does not always result in immediate release.

Question 24

What are catecholamines synthesized using?

Answer 24

Tyrosine

Question 25

What are thyroid hormones synthesized from?

Answer 25

Tyrosine and iodide

Question 26

Where are thyroid hormones stored?

Answer 26

In a follicle — thyroglobulin

*secretion requires retrieval follicles and release from storage protein

Question 27

Where are steroid hormones synthesized?

Answer 27

Cholesterol

*not usually stored, secretion requires synthesis

Question 28

Where are prostaglandins synthesized?

Answer 28

Arachidonic acid

Question 29

What are the two mechanisms of regulation of hormone secretion?

Answer 29

1. Neural mechanisms
2. Feedback mechanisms

Question 30

State the differences between long, short, and ultra short feedback loops.

Answer 30

Long loops- hormone released from target tissue funds back to original release point (pituitary or hypothalamus)
Short loop- negative feedback from pituitary to hypothalamus
Ultra short- hypothalamic hormone inhibiting its own secretion

Question 31

What is positive feedback?

Answer 31

A feature of hormone action causes MORE secretion of the hormone