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28 Cards in this Set
- Front
- Back
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1. What are 4 categories of hormone function?
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1. Regulation of utilization and storage of fuels
2. Maintenance of complex internal environment **intercellular communication between systems 3. Regulation of reproduction 4. Regulation of growth and development |
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2. What are the 3 basic mechanisms for intercellular communication?
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1. Endocrine
-hormone secreted into blood -action on target tissue far from tissues that produce it 2. Paracrine -act on nearby cell -have secretory cell and adjacent target cell 3. Autocrine -target site is on same cell |
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3. What are the three structural classes of hormones?
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1. Protein hormones
-polypeptides / glycoproteins -come from transcription of genes 2. Steroid / Steroid-related -mostly come from cholesterol -retinoic acid does not come from cholesterol 3. Amines |
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4. From what is epinephrine synthesized from?
What is epinephrine? What is the precursor for epinephrine? Where is it synthesized? |
Tyrosine
Catecholamine Norepinephrine (made in neurons) Adrenal medulla |
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5. What is thyroid hormone (T3/T4) derived from?
Where are the iodine's located? What do T3/T4 and epinephrine regulate? |
Tyrosine
**takes 2 tyrosine to make thyroid hormone (coupled through ether linkage) 3 to 4 I- are on the benzene rings Fuel metabolism |
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6. Where are peptide hormones synthesized?
What do all peptide hormones have? How does there synthesis occur? (four steps) |
On the rough ER
A signal sequence at the N-terminus 1. Signal sequence binds to signal recognition particle 2. Complex is directed to the ER 3. Signal sequence is cleaved 4. Fully translated protein is released into the ER lumen |
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7. Can peptide hormones cross the plasma membrane?
What does this require all peptide hormones to have? What does this contain? |
No!
All have precursor hormone that is not active Pro-hormone contains signal sequence |
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8. How is the pro-hormone activated?
What happens to it once activated? (two things) What happens when stimulated? |
Specific proteases cleave pro-hormone
1. Packaged into secretory vesicles 2. Stored in vesicles until cell receives signal Vesicles fuse with plasma membrane and hormones released by exocytosis |
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9. What are steroid hormone derived from?
Can steroid hormones cross the plasma membrane? What is the rate-limiting step in steroid synthesis? |
Derived from cholesterol
**Except retinoic acid, thyroid hormone Hydrophobic so can cross plasma membrane Formation of pregnenolone (21 C precursor) |
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10. Can steroids be easily stored?
How is the release of steroids regulated? |
No!
Regulated by enzymes in biosynthetic pathway **Enzyme expression regulation **Enzyme activity regulated by phosphorylation |
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11. Describe steroid hormone biosynthesis.
Give # of carbons |
1. Cholesterol (27 C)
2. Pregnenolone (21 C) 3. Progesterone (21C) 4a. Androstenedione (19 C) 4b. Aldosterone (21 C) 4c. Cortisol (21 C) 5a. Testosterone (19 C)=> -dihydrotestosterone -estradiol (18 C) |
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12. How do hormones exert their biological effects?
Three ways... |
1. Hormones interact with receptors on target cells
-need to bind and have long lived interaction -bind to receptor to have biological effect on cell 2. The hormone-receptor interaction is high affinity -tiny amounts of hormone will interact with receptor 3. The hormone-receptor interaction is highly specific |
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13. What are two functional classes of hormone receptors?
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1. Cell-surface receptors
**peptide hormones don't have to get into cell 2. Intracellular receptors **have to get into cell |
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14. Are steroid hormones....
1. soluble 2. require carrier protein 3. plasma t1/2 4. receptor 5. mediator? |
1. Lipids soluble
2. Require carrier protein 3. Half life of hours to days (partly due to being bound to carrier protein) 4. Intracellular receptor 5. Receptor-hormone mediator |
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15. Are peptide hormones and catecholamines....
1. soluble 2. require carrier protein 3. plasma t1/2 4. receptor 5. mediator? |
1. Water soluble
2. No carrier protein 3. Half life of minutes 4. Cell surface receptors (can't have direct biological effects - work through 2nd messenger) 5. Second messenger mediator |
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16. What are the two messages in peptide hormone signaling?
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1. First message
-peptide hormone binding to cell surface receptor 2. Second message -intracellular chemical produced |
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17. What are cell surface receptor classes?
Two classes and examples of each |
1. Instrinsic kinase activity
-insulin (phosphorylate tyrosine on own receptor) -GH, PRL associated JAK kinase 2. G-protein coupling -enzymes -ion channels -adenylate cyclase (cAMP) |
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18. What are 4 key features of 2nd messenger systems?
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1. Specificity (comes from hormone binding to receptor)
2. Amplification of 1st message 3. Augmentation 4. Rapid signal termination |
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19. What is the organization of G-protein?
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Three subunits
**Trimer is inactive -associated with non-stimulated receptor Hormone binds and trimer becomes active |
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20. What is the alpha subunit?
How is it activated? What can Gα do to enzymes? (two things) |
It as GTPase
Inactive with GDP Active with GTP Dissociates from βγ and alters activities of enzymes and ion channels 1. Stimulate (Gs) 2. Inhibit (Gi) |
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21. How does cAMP amplify?
(two ways) How is there rapid signal termination? (three things) How is there augmentation? |
1. AC generates many cAMP's
2. PKA phosphorylates many proteins 1. Degrade cAMP (phosphodiesterase) 2. G protein inactive 3. Phophatases remove Pi from proteins Different receptors both activate cAMP system (i.e. glucagon and epinephrine in liver) |
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22. What is PIP2?
What does phospholipase C do? What are IP3 and DAG? What does IP3 do? |
A special lipid
Cleaves IP3 from PIP2 2nd messengers Stimulates Ca+ release from ER -stimulate muscle contraction and break down of glycogen |
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23. How does IP3/Ca2+/DAG 2nd messenger system amplify?
(three ways) Augment? How is there rapid signal termination? (three ways) |
1. PC generates may IP3/DAG
2. IP3 release many cytosolic Ca 3. PKC (protein kinase C) and CAM (calmodulin kinase) phosphorylate many proteins Different receptors/signals activate same enzyme (i.e. in skeletal muscle, glycogen and phosphorylase) 1. Cytosolic Ca decreased 2. G protein inactive 3. Phosphatases remove Pi from proteins |
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24. What are steroid hormone receptors?
Where are the receptors for steroids? |
Transactivators of transcription
**regulate expression of genes Nuclear receptors inside cell **bind to HRE (hormone response element) on DNA |
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25. Where do steroid hormones act?
How can hormone potency be regulated? What do steroid hormones do? |
Act inside the cell
**only free hormone can enter Carrier proteins regulate how much hormone is inside/outside the cell Regulate transcription of genes -stimulate or inhibit |
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26. Hormone levels fluctuate so how are they regulated?
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1. Feedback inhibition
**regulates hormone levels in the blood 2. Degradation **peptide hormones are degraded |
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27. What type of hormones exhibit feedback inhibition?
What is an example? |
Steroid hormones
Cortisol Cortisol inhibits CRH release and ACTH release |
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28. What degrades peptide hormones?
Where are these found? (two places) What is the most common type of degradation? Where is the peptide hormone degraded? What happens to the receptors? |
Proteases
1. In blood 2. In the cell surface Receptor-mediated endocytosis In lysosomes Receptors recycled to cell surface |
