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Endocrine Exam 1 > Module 1: Basic Principles of Endocrinology > Flashcards

Module 1: Basic Principles of Endocrinology Flashcards

1
Q

What is endocrinology?

A
  • science of hormones and glands that secrete them
  • science of endocrine systems (hormones), their diseases, and therapies
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2
Q

chemical released by a cell, gland, or organ in ONE PART of the body that affects cells in OTHER PARTS of the body (travels to distant sites)

A

Hormone

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3
Q

Hormones = internal secretion by __________ glands

A

ductless

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4
Q

What does intercellular communication require (3)?

A
  1. Signaling cell (origin of the signal)
  2. Messenger (chemical signal = hormone)
  3. Target cell (specific receptors)
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5
Q

Factor within cell

A

intracrine

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6
Q

the same cell, factor stays local

A

Autocrine

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7
Q

different cells in proximity, factor stays local

A

Paracrine

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8
Q

different cell - distant, factor carried in blood

A

Endocrine

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9
Q

Cortisol, aldosterone, catecholamines
metabolism, minerals/pressure, stress, immunity

A

adrenal gland

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10
Q

sex steroids, reproduction

A

gonads

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11
Q

What do endocrine glands often regulate?

A

other endocrine organs

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12
Q

Most endocrine glands produce ________ hormones

A

few

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13
Q

Pituitary gland produces ______ hormones

A

many

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14
Q

What do hormones from various endocrine organs influence?

A

the hypothalamus and pituitary

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15
Q

The hormone concentrations are:

A

very low

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16
Q

(T/F) Not all cells respond to a hormone

A

True

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17
Q

(T/F) Hormones contact all cells

A

True

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18
Q

What defines target tissue?

A

Receptor expression

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19
Q
  • Sensitive and Specific
  • Generates an intracellular signal
A

Receptor-hormone binding

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20
Q

Epinephrine, thyroid hormones (T3, T4)

A

Amines

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21
Q

Parathyroid hormone, insulin, ACTH

A

Peptides

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22
Q

Glucocorticoids, estrogens, vitamin D (from cholesterol)

A

Steroids

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23
Q

Lipophilic =

A

hydrophobic

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24
Q

Hydrophilic =

A

lipophobic

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25
Q
  • Relatively SMALL molecular weight
  • Cross membranes (lipid soluble)
  • NOT STORED inside signaling cells (e.g. steroids, THs)
  • Synthesis by MULTI-STEP enzymatic processes
  • Bind INTRACELLULAR receptors
  • Released SLOWER - work SLOWER - cleared SLOWER than hydrophilic
A

Lipophilic hormones

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26
Q
  • Proteins, peptides, amines (first messenger)
  • LARGE molecular weight (except amines)
  • mRNA-directed synthesis (if proteins)
  • DO NOT CROSS cell membrane
  • STORED in intracellular vesicles
  • Released FASTER - work FASTER - cleared FASTER than lipophilic
  • Bind to receptors ON PLASMA MEMBRANE
  • Use SECOND MESSENGER -> SIGNAL AMPLIFICATION
A

Hydrophilic hormones

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27
Q

Receptors:
- Found in the CYTOPLASM or NUCLEUS
- HORMONES + RECEPTOR COMPLEX -> nucleus to FUNCTION AS TRANSCRIPTION FACTOR -> mRNA synthesis -> protein synthesis
examples: steroids (cortisol, progesterone, estrogen), vitamin D, THs

A

Receptors of lipophilic hormones

28
Q

Receptors:
- PROTEINS in CELL MEMBRANE of target cells
- Bind with SPECIFICITY and HIGH AFFINITY
- Activate SECOND MESSENGERS to generate an intracellular signal
- Stimulate a functional change in the target cell

A

Receptors for hydrophilic hormones

29
Q

Receptors:
Receptor Tyrosine Kinases (RTK’s): (in cell membrane)
- Receptors for peptide hormones, growth factors, cytokines

A

Receptors for hydrophilic hormones

30
Q

Receptors:
7 Trans-membrane (7TM) family (GPCR): in cell membrane
- Receptors for peptide and amine hormones

A

Receptors for hydrophilic hormones

31
Q

Minimal hormone level that elicits a cellular response
- receptors are highly sensitive to low hormone levels

A

Sensitivity

32
Q

Receptors ability to bind a specific hormone (ability to differentiate different hormones)
- Receptors are highly specific to hormones within a family (some cross-reactivity)

A

Specificity

33
Q

How can hormones generate a biological response at very low levels?

A

Signal Amplification
- H + R <–> HR -> 2nd messenger (x500) -> effector (x500)

34
Q

What are most feedback loops?

A

most feedback loops are negative

35
Q
  • essential autoregulatory systems
  • regulate most endocrine systems
  • they could be used DIAGNOSTICALLY
  • they could be used THERAPEUTICALLY
  • abnormal leads to disorders
A

Feedback Systems

36
Q

when the product of a reaction leads to an increase in that reaction

A

positive feedback loop

37
Q
  • a reaction that causes a decrease in function
  • it occurs in response to some kind of stimulus
  • often, it causes the output of a system to be lessened; so, the feedback tends to stabilize the system.
A

negative feedback loop

38
Q

Hormone Transport:
__________- hormones are transported DISSOLVED in the extracellular fluid (blood) -> target

A

Hydrophilic

39
Q

Hormone Transport:
___________ hormones are transported BOUND to protein

A

Lipophilic

40
Q

What percentage of lipophilic hormones are protein-bound?

A

> 90% are protein-bound
(there are specific binding proteins)

41
Q

Why are>90% of steroid and thyroid hormones bound to plasma proteins in equilibrium?

A
  • they are lipophilic
  • act as a reservoir
  • reduce their waste in urine
  • protect against toxicity
  • the same principle applies to some drugs
  • binding proteins are specific to hormones
42
Q

What prevents hormone renal waste?

A

Protein binding

43
Q

Hormone Clearance:
Clearance is determined by…

A
  • Rate of synthesis and secretion
  • Rate of removal from circulation
44
Q

Hormone Clearance:
Metabolized and excreted by…

A
  • mainly by the liver (-> bile) and kidneys (->urine)
  • by other organs (e.g. lungs) and target tissues
  • Enzymes in circulation also degrade peptide hormones
  • Peptides/amines cleared faster than protein-bound hormones
45
Q

Hormones have daily variation influence by:

A
  • physiological statue
  • diet
  • time of the day (circadian)
  • time of the year (circannual)
  • treatments
  • stress
  • diseases
  • lack of variations can be pathologic
46
Q

How are hormones measured?

A

Immunoassays
- Enzyme-linked immunoassays (ELISA)
- Radioimmunoassay (RIA)
- Chemiluminescent immunoassay (CLIA)

47
Q

Hormone deficiency and hormone excess are problems at what level?

A

Endocrine gland level

48
Q

Hormone resistance is a problem at what level?

A

Receptor Signaling level
(e.g. downregulation)

49
Q

Type of endocrine disorder:
- Insufficient secretion of hormone
- Hypo…

A

Hormone deficiency

50
Q

Type of endocrine disorder:
- Excessive secretion of hormone
- Hyper…

A

Hormone excess

51
Q

Type of endocrine disorder:
- Hormone is secreted
- Actions are suboptimal (like hypo)
- Often increased concentrations

A

Hormone resistance

52
Q

How do we suspect that there is an endocrinopathy?

A
  1. Clinical Abnormalities
  2. Changes in Behavior
  3. Changes in blood variables
53
Q

How do we test endocrine systems?

A
  • Hormone concentrations
  • Dynamic Tests
54
Q

Single measurements
• Glucose, calcium (analytes)
• Insulin, cortisol, parathyroid hormone (PTH)

Paired measurements (feedback components)
• Glucose + Insulin
• Calcium + PTH
• Cortisol + ACTH

A

Hormone Concentrations

55
Q

Stimulation (for deficiencies / hypoactivity)
• Give glucose → measure insulin response (+) ↑↑
• Give ACTH → measure cortisol response (+) ↑↑

Suppression (for excess/hyperactivity)
• Give calcium → measure PTH response (-) ↓↓
• Give cortisol →measure ACTH response (-) ↓↓

A

Dynamic Tests

56
Q

What dynamic test evaluates the functionality of the endocrine system?

A

Stimulation
(for deficiencies/hypoactivity)

57
Q

Which dynamic test evaluates negative feedback?

A

Suppression
(for excess/hyperactivity)

58
Q

When testing the endocrine systems, what do you need to take into consideration?

A
  • take into account environmental factors, diseases, drugs, and other endocrine systems that alter hormones
  • interpret results in context of the whole animal
  • looking at isolated test results is rarely useful
  • equivocal results may require other tests
59
Q

Progesterone binds to an ___________ receptor

A

intracellular
(steroid)

60
Q

Glucagon binds to an _______________ receptor

A

cell membrane
(peptide)

61
Q

Protein-bound in circulation

A

Lipophilic hormone

62
Q

Reduces hormone excretion

A

Protein binding

63
Q

Likely a peptide hormone

A

Stored in granules

64
Q

Soluble in plasma

A

Epinephrine

65
Q

Tissue resistance

A

Requires higher levels to exert an effect

Endocrine Exam 1 (10 decks)

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