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Flashcards in 71 - Basics Deck (44):
1

What are the 3 major characteristics of a "classic" endocrine gland?

- Ductless
- Secrete hormones directly into the bloodstream or extracellular space
- The organ is dedicated primarily to endocrine function

2

What are some e.g.'s of non-classical endocrine organs?

- Brain (hypothalamus especially)
- Kidney (renin, vit. D, EPO)
- Heart (ANP, BNP)
- Liver (IGF-1)
- GI: stomach/small intestine (5-HT, ghrelin)
- Adipose tissue (leptin)

3

Define homeostasis as it relates to the endocrine system.

The state of equilibrium (balance between opposing measures) in the body w/r/t various functions and to the chemical compositions of the fluids and tissues

4

In endocrine homeostasis, discuss the concept of "hyper".

Overproduction of a hormone and/or hypersensitivity to its hormonal affects.

5

In endocrine homeostasis, discuss the concept of "hypo".

Underproduction of a hormone and/or insensitivity to its hormonal affects.

6

In endocrine pathology, primary defects affect a ____________ endocrine gland.

Classical

7

If an endocrine pathology doesn't affect a classical gland, it's either a ________ or _______ defect.

Secondary or teritary

8

What's the etiological category of cretinism?

(iodine deficiency, most common cause of retardation world-wide)

Congenital

9

What's the different b/w congenital and genetic?

Congenital: present at birth; not necessarily genetic

10

What's the etiological category of multiple endocrine neoplasia (MEN)?

(multiple endocrine glands have tumors)

Genetic

11

What's the etiological category of environmental factors such as PCBs, DES, and/or BCP?

Endocrine disruptors

12

What's the etiological category of Sheehan's syndrome?

(postpartum hemorrhage/shock; results in massive pituitary cell death)

Trauma/stress

13

What's the etiological category of thyroidectomy?

Surgical

14

What's the etiological category of glucocorticoid therapy?

(e.g. Chrohn's disease, etc.)

Therapeutic

15

What's the etiological category of neoplastic tumors or small lung cell carcinoma?

(SCLC: cancer not in an endocrine gland, but secretes hormones typically released by the pituitary)

Malignant and benign tumors

16

What's the etiological category of T1DM?

Infections/immunological problems (Autoimmune, in T1DM)

17

Distinguish amongst endocrine, paracrine, and autocrine.

- Endo: hormones secreted into blood, act on downstream targets
- Para: hormones secreted into ISF, act on nearby cells
- Auto: hormones secreted into ISF, act back on same cell

18

Neurotransmission is a type of (endo/para/auto-crine) signaling.

Paracrine

19

Endo vs. paracrine:
1. Which signaling has more specificity of target?
2. Which has a greater importance on receptors for specificity?
3. Which must be released in greater concentration?

1. Paracrine
2. Endocrine (travels farther)
3. Endocrine (gets diluted)

20

Which are biologically active: free hormones, bound hormones, or both?

Free hormones only

21

What major class of hormones uses binding proteins most often for xport?

Steroid hormones (lipophilic)

22

Do binding proteins change the 1/2-life of their bound hormone?

Yes, increase 1/2-life

23

What's the major nonspecific binding protein?

Albumin

24

What's the binding protein for estrogens and testosterone?

Sex hormone binding globulin (SHBG)

25

What's the binding protein for cortisol and corticosterone?

Corticotrophin binding globulin (CBG)

26

What are the 2 binding proteins for TH?

- Thyroid binding globulin (TBG)
- Transthyretin (TTR)

27

Is most hormone in the blood bound or unbound?

Almost all bound

28

When hormones are bound to albumin they're not considered bioactive but they are considered bio-___________.

available (pretty to use hormone bound to albumin if you need to)

29

What are the 3 steps of the old model for hormone delivery to target cell? (just read)

1. Steroid hormone released at membrane
2. Freely diffuses across lipid bilayer
3. Finds extracellular target

30

*What are the 3 steps of the new model for hormone delivery to target cell?

1. Hormone/protein complex binds to megalin
2. Formation of endocytic vesicle
3. Hormone dissociates and is released from vesicle

31

According to wikipedia, what are the effects of ubiquitination?

- Can signal for ptn degradation via the proteasome
- Can alter ptn cellular location
- Can affect ptn activity
- Can promote or prevent protein interactions

32

*What are 3 major categories by which a protein receptor can be regulated?
(just read at first)

1. Agonists/antagonists
2. Affect hormone duration: internalization/dissociation/ubiquitination
3. Ligand (hormone) autoregulation

33

Hormones bind receptors w/____ specificity and ____ affinity.

High, high

34

Define specificity.

Ability to distinguish b/w similar substances

35

Define Kd (same as Km).
What is the relationship b/w Kd and affinity?

Ligand conc. that occupies 50% of the binding sites
- Inverse relationship w/affinity

36

Define Ki.

Ability to displace ligand at 50% of maximum activity
- How much of something else do I need to add before I can knock it off?

37

*What are the characteristics of lipoPHOBIC hormone receptors?

- Bind to cell surface receptors
- Coupled to 2nd messenger signaling pw's including: cAMP, IP3/DAG
- Rapid internalization or degradation

38

*What are 3 eg's of lipophobic hormone receptor classes?

- GPCRs (most)
- Receptor-linked kinases = GH, PRL, EPO.
- Receptor kinases = insulin, ANP

39

*What are the characteristics of lipoPHILIC hormone receptors?

- Bind mainly to intracellular receptors (some exceptions).
- Often bound to large chaperone proteins in cytoplasm (often heat shock proteins)
- Usually SLOW biological response – requires TS/TL events.
- Can repress or activate transcription.

40

*Does TH bind a lipophilic or lipophobic receptor?
Discuss its somewhat unique properties.

Lipophobic
- THs bind nuclear steroid receptors (superfamily even tho they're not steroid hormones)
- When receptor is NOT bound to ligand = transcriptional repression. Ligand (TH) binding activates gene TH.

41

What type of cell surface receptors do peptide/protein hormones typically bind?

GPCR (activate 2nd msger)

42

How does a Receptor-Linked Kinase hormone receptor function?
Do they have intrinsic catalytic activity?

Ligand binding causes dimer formation – activates intracellular kinase
- DO NOT have intrinsic catalytic activity
(GH, PRL, EPO)

43

Do Receptor Kinases have intrinsic catalytic activity?

Yes
(Insulin, ANP)

44

Factors affecting hormone bioavailability? (read)

Hormone Transport:
- Binding proteins – “free” vs bound
- Kinetics: half-life

Target Tissues:
- Receptors – mutations, desensitization, down/upregulation,
- Chaperone/Heat shock proteins

Hormone synthesis/release:
- Enzymatic activity
- Processing/Packaging

Regulatory mechanisms:
- Feedback
- Circadian rhythms
- Aging
- Pulsatility
- Metabolism/Degradation