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Flashcards in T3 endocrine principles Deck (48)
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1

Polypeptide and protein homoromes are usually synthesized as:
A. zymogens
B. preprohormones
C. sterols
D. prepeptides

Preprohormones

2

How are polypeptide and protein hormones released?

via exocytosis, mediated by calcium ions.

3

Where are polypeptide and protein hormones stored until they are released?

secretory vesicles until they are needed.

4

What are some examples of polypeptide and protein hormones?

GH, prolactin, TSH

5

What are steroid hormones synthesized from?
A. polypeptides
B. cholesterol
C. proteins
D. amino acids

cholesterol

6

What types of hormones are lipid soluble and readily diffuse across cell membranes?

steroid hormones

7

Explain steroid hormone structure.

consist of three cyclohexyl rings and one cyclopentyl ring

8

How are steroid hormones stored?

They are stored as large quantities of cholesterol esters rather than the hormones themselves.

9

From what are amine hormones derived?

tyrosine

10

What kind of hormones are thyroid and adrenal medullary hormones?

amine hormones

11

How are amine hormone formed?

by the actions of enzymes in cytoplasmic compartments of glandular cells

12

What hormones are incorporated into macromolecules of thyroglobulin and stored in thyroid gland follicles?

thyroid hormones, which are amine hormones

13

What hormones are formed in adrenal medullar and stored in vesicles until needed?

catecholamines (epinephrine and norepinephrine), which are amine hormones.

14

What are the locations of receptors for hormones?
A. In or on the surface of the cell membranes
B. In the cell cytoplasm
C. In the cell nucleus
D. All of the above

All of the above;
-In or on the surface of the cell membranes
-In the cell cytoplasm
-In the cell nucleus

15

What is the effect of down regulation of a hormone receptor?

decreases the target tissue's responsiveness to the hormones

16

What are some reasons for the down regulation of receptors?

-inactivation of some of the intracellular protein signaling molecules
-temporary sequestration of the receptor inside the cell
-inactivation of some of the receptor molecules
-destruction of the receptors by lysosomes after they are internalized
-decreased production of receptors

17

What is the effect of up regulation of a hormone receptor?

increases the target tissue's responsiveness to the hormones

18

What are some reasons for the up regulation of receptors?

-the stimulating hormone may induce greater than normal formation of receptor or intracellular signaling molecules
-the stimulating hormone may induce greater availability of the receptor for interaction with the hormone

19

What are the types of hormone receptors?

-ion channel linked receptors
-G protein linked receptors
-intracellular hormone receptors

20

What kinds of receptors are:
-used primarily in neurotransmitters
-found in the post-synaptic membrane
-binding leads to conformation change resulting in opening of ion channels such as sodium, calcium, or potassium

Ion channel linked hormone receptors

21

What kinds of receptors are:
-coupled with groups of cell membrane proteins called heterotrimeric GTP-binding proteins
-all have 7 transmembrane segments
-some are inhibitory and some are stimulatory

G protein linked hormone receptors

22

What kinds of receptors are:
-intracellular receptors for lipid soluble hormones
-activated hormone receptor complex binds to promotor sequence of DNA

Intracellular hormone receptors

23

What kinds of receptors are:
-single-pass transmembrane receptors
-receptor is part extracellular
-has an intracellular enzyme
-example is leptin receptor (JAK-STAT)

enzyme linked hormone receptors

24

_________ prevents over-activity of hormone systems.

negative feedback

25

Feedback regulation of hormones can occur at what levels?
A. gene transcription
B. gene translation
C. processing of hormones
D. releasing of stored hormones
E. All of the above

All of the above;
-gene transcription
-gene translation
-processing of hormones
-releasing of stored hormones

26

What is an example of a positive feedback mechanism?

-LH surge prior to ovulation
-oxytocin acting on uterine contractions during childbirth

27

Periodic variations in hormone release are due to what?

-seasonal changes
-various stages in development and aging

28

What are the four signal transduction mechanisms talked about in lecture?

-adenyl cyclase - cAMP second messenger sys
-cell membrane phospholipid second messenger sys
-calcium-calmodulin phospholipid second messenger sys
-hormone acting directly on DNA

29

What is the mechanism of the cAMP second messenger system?

-binding of hormone with receptor allows coupling to G protein
-G protein stimulates adenyl cyclase
-adenyl cyclase catalyzes ATP --> cAMP
-cAMP activates kinase that phosphor proteins
-this activates a cascade of enz

30

What is the mechanism of cell membrane phospholipid second messenger?

-hormone active transmembrane receptors that activate enzyme phospholipase C
-phospholipase C catalyzes the breakdown of phospholipids in the cell membrane

31

What is the mechanism of calcium-calmodulin phospholipid second messenger?

-Ca2+ entry may be initiated by changes in mem potential that open ca channels or a hormone interacting with mem receptors that open ca channels
-Ca2+ ions bind with calmodulin, when 3-4 binding sites are full, calmodulin can initiate either activation or inhibition of protein kinases.

32

What is the mechanism of hormones acting directly on DNA?

-steroid hormones diffuse across cell membrane, bind w receptors in cytoplasm, receptor protein-steroid complex moves to nucleus, complex then binds DNA.
-NOTE: this system take longer than membrane receptor mediated signaling

33

What is the mechanism of thyroid hormones?

-bind directly with receptors in nucleus
-activate genetic mechs for many (100+) proteins, many of which enhance metabolic activity
-once bound to DNA, remain there for days to weeks and continue to function

34

Anterior pituitary has five cell types. What are they?

-somatotropes (acidophils)
-corticotropes
-thyrotropes
-gonadotropes
-lactotropes

35

What do somatotropes produce?

Growth hormone/HGF (human growth factor)

36

What to corticotropes produce?

adrenocorticotropic hormone (ACTH)

37

What to thyrotropes produce?

thyroid stimulating hormone (TSH)

38

What to gonadotropes produce?

LH and FSH

39

What to lactotropes produce?

Prolactin

40

Where are magnocellular neurons located?

supraoptic and paraventricular nuclei

41

Where is ADH formed?

supraoptic nuclei

42

Where is oxytocin formed?

primarily in the paraventricular nuclei

43

What controls anterior pituitary via hypothalamic releasing factors and inhibitory hormone factors?

hypothalamus

44

What is the collecting center for information concerning internal well-being?

hypothalamus

45

What hormone:
-increases deposition of protein by chondrocytic and osteogenic cells
-increases rate of reproduction of chondrocytic and osteogenic cells
-converts chondrocytes into osteogenic cells
-strongly stimulates osteoblasts

growth hormone

46

How does growth hormone influence protein synthesis?

-directly enhances transport of aa through cell mems into cytoplasm
-increase RNA translation and transcription rate
-decreases protein catabolism

47

What are the effects of fatty acid mobilization by growth hormone?

-causes release of fatty acids from adipose tissue
-enhances conversion of fatty acids to acetyl-CoA

48

Growth hormone can decrease glucose utilization. What are the effects of decreased glucose utilization?

-decreases glucose uptake in tissues such as skeletal muscle and fat
-increases glucose production by liver
-increases insulin
-note: GH effects are diabetogenic