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FHB Block 4 > Basics of Endocrinology I > Flashcards

Basics of Endocrinology I Flashcards

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1
Q

What is the defining feature of classic endocrine glands?

A

They are ductless!

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2
Q

Where do the secrete hormones?

A

Directly into the blood or extracellular spaces

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3
Q

What are the non-classical endocrine glands?

A

Brain (esp. hypothalamus), Kidneys, Heart, Liver, GI, Adipose Tissue

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4
Q

What is the endocrine function of the the brain?

A

“releasing hormones”

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5
Q

What is the endocrine function of the kidneys??

A

Release of renin, Vit. D, EPO

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6
Q

What is the endocrine function of the heart?

A

release of ANP/BNP

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7
Q

What is the endocrine function of the liver?

A

Release of IGF-1 (insulin like growth factor-1)

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8
Q

What is the endocrine function of GI tissue?

A

stomach, small GI release serotonin, ghrelin

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9
Q

what is the endocrine function of adipose tissue?

A

Release of leptin

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10
Q

Discuss the concept of homeostasis in regards to hormones

A

There is a balance of hormones in the body - hormones are always present, in a regulated amount. Too much or too little of a given hormone can cause problems

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11
Q

What can give a hyper response to a hormone?

A

Too much of the hormone or too much of the hormone receptor

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12
Q

What can give a hypo response?

A

Too little hormone or too little receptor

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13
Q

What are endocrine pathologies characterized by?

A

A hormone imbalance

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14
Q

Where can the defect be in an endocrine pathology?

A

At the level of the gland –> primary

One or two steps away –> secondary/tertiary

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15
Q

Give an example of and describe an endocrine pathology that is congenital

A

Cretinism: due to an iodine deficiency during development

results in: short stature, mental retardation, delayed motor development

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16
Q

Give an example of and describe an endocrine pathology that is genetic

A

Multiple Endocrine Neoplasia (MEN): Characterized by 2-3 tumors in multiple endocrine glands (parathyroid, pituitary, entero-pancreatic)

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17
Q

Give an example of and describe an endocrine pathology that can give rise to malignant or benign tumors

A

Neoplastic tissues, small lung cell carcinoma

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18
Q

Give an example of and describe an endocrine pathology stemming from an infection/immunological problem

A

autoimmune - Diabetes type I

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19
Q

Give an example of and describe an endocrine pathology stemming from environmental factors

A

PCBs, DES, birth control

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20
Q

Give an example of and describe en endocrine pathology stemming from trauma/stress

A

Sheehan’s syndrome: postpartum hemorrhage and shock - results in massive pituitary death

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21
Q

Give an example of and describe an endocrine pathology related to surgery

A

Thyroid gland removal (often parathyroid injury)

22
Q

Give an example of and describe an endocrine pathology stemming from a therapy

A

Glucocorticoids (Crohn’s disease, others)

23
Q

What is the most common endocrine pathology, and what are some important facts about it?

A

Type II diabetes!

7th leading cause of death
affects 9.3% of population (2 mil new cases per year)
highly correlated with obesity

24
Q

Define endocrine action

A

Hormone release into the blood, acting on downstream tissue

25
Q

Define paracrine action

A

Hormone released into the interstitial space, acting on nearby cells

26
Q

Define autocrine action

A

Hormone released into the interstitial space that will act on the same cell that released it

27
Q

Discuss some differences in the regulation of hormone action between endocrine and paracrine signaling in regards to the source and distribution of the hormone

A

Source:
endocrine - gland, no specificity to target
paracrine - adjacent cell, major determinant of target

Distribution:
Endocrine - Universal, dilution big
Paracrine - ECM, binding proteins, diffusion distance, proteases

28
Q

What are things to consider regarding the signal being passed to the target cell?

A

specificity/sensitivity, # of receptors, downstream pathways, metabolism of receptors, other ligands, inhibitory pathways, etc.

29
Q

What class of hormones are usually attached to hormone binding proteins in the blood?

A

Steroids

30
Q

What are the hormones other than steroids that bind to hormone binding proteins?

A

IGF-1, GH, T4/T3

31
Q

What is the purpose of hormone binding proteins?

A

Increases the half life of the hormone

32
Q

What is a pharmacological consequence of hormone binding proteins?

A

Bound hormones are not active and as some are released right at the target site, you may not see any measurable free/active hormone in the blood

33
Q

What does sex hormone binding globulin (SHBG) bind?

A

estrogens and testosterone

34
Q

What does corticosteroid binding globulin (CBG) bind?

A

cortisol and corticosterone

35
Q

What does thyroxine binding globulin (TBG) and transthyretin (TTR) bind?

A

thyroid hormone

36
Q

What does albumin bind?

A

most lipophilic compounds in blood

37
Q

What is notable about hormones bound to albumin?

A

They are bioavailable!

38
Q

Discuss the two methods of hormone delivery to their target

A

The hormone can be released at the cell surface, translocate the plasma membrane, and exert its effect on the cell

Or, the hormone/protein complex binds to megalin, there is the formation of an endocytic vesicle, after which the hormone will dissociate and e released from the vesicle

39
Q

Why would a cell undergo the vesicle delivery of hormone?

A

The vesicle could be targeted to a specific part of the cell

Protects the hormone from degradation

40
Q

Describe some features of hormone receptors

A

no receptor = no action (antagonist, agonist)

determines duration: extracellular receptors are internalized and dissociated, internal receptors are ubiquinated

autoregulation by ligand: up/down regulated based on ligand levels

41
Q

With what specificity and affinity do hormones bind their receptors?

A

High affinity and high specificity

42
Q

Define specificity

A

ability to distinguish between similar substances

43
Q

Define affinity

A

How much a receptor will hold on to a ligand once bound

measured as Kd: ligand concentration at which 50% of binding sites are filled (smaller number = higher affinity)

Ki: ability to displace ligand at 50% maximal activity

44
Q

What are some general features of lipophobic receptors, and what are the different classes?

A

Bind to cell surface receptors

coupled to second messenger pathways like cAMP, IP3, DAG

rapid internalization/degradation

Classes:

1: Ion channels
2: G-protein coupled
3: Receptor-linked Kinases
4: Receptor Kinases

45
Q

Discuss the features and function of cell surface class 1 ion channels

A

binding of ligand causes conformational change that results in opening of channel

Neurotransmitters typically activate these types of receptors

46
Q

Discuss the features and functions of cell surface class 2 G-protein coupled receptors

A

Most protein and peptide hormones bind to this kind of receptors

Ligand binding activates second messenger signaling cascades

47
Q

Discuss the features and functions of cell surface class 3 receptor-linked kinases

A

DO NOT have intrinsic catalytic activity

Ligand binding results in dimerization, activates the intracellular kinase

examples: GH, prolactin, EPO

48
Q

Discuss the features and functions of cell surface class 4 receptor kinases

A

Have intrinsic catalytic activity that is stimulated by ligand binding - autophosphorylation on intracellular domain

Insulin and atrial natriuretic peptide bind to this kind of receptor

49
Q

What are some general functions of lipophilic hormone receptors

A

Bind mainly to intracellular receptors

often attached to large chaperone proteins in the cytoplasm (heat shock proteins)

usually slow biological response - requires transcription/translation

can repress or activate transcription

50
Q

What is an example of a lipophilic hormone?

A

Thyroid hormone binds nuclear receptor, when receptor binds ligand there is gene activation

51
Q

What are the factors affecting hormone bioavailability?

A

Hormone transport: binding proteins and kinetics

Target tissues: receptor regulation and chaperone/heat shock proteins

Hormone synthesis/release: enzymatic activity and processing/packaging

Regulatory mechanisms: eedback, circadian rhythms, aging, pulsatility, metabolism/degradation

FHB Block 4 (13 decks)

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