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BIOL 432 > Endocrine System Overview > Flashcards

Endocrine System Overview Flashcards

1
Q

endocrine system

A

glands and tissues which secrete hormones

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2
Q

endocrine glands

A

specialized groups of cells that release hormones internally within the body

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3
Q

where do endocrine glands typically release hormones?

A

into interstitial space/ extracellular fluid for entry into the bloodstream

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4
Q

what are hormones?

A

chemical messengers

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5
Q

what do hormones do?

A

signal information between cells/organs to affect the actions and functions of distant organ systems

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6
Q

define molecular endocrinology

A

study of the molecular basis for the synthesis, actions and regulations of hormones and their receptors

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7
Q

how do hormones act?

A

are chemicals that act as signaling molecules to traffic specific info from one cell to another

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8
Q

hormones travel through ____ such as the ____

A

a medium, extracellular fluid or the bloodstream

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9
Q

a single hormone might…

A

regulate multiple physiological processes ( and have distinct effects in different target cells)

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10
Q

physiological processes might be regulated by _____ hormones

A

multiple different

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11
Q

general actions of hormones

A
  • fetal development
  • cell growth (and cancer)
  • digestion
  • metabolism of carbs, lipids, proteins/amino acids, nucleic acids
  • ion and water balance
  • renal function
  • cardiovascular function and circulatory system
  • respiration
  • skeletal function
  • reproductive function
  • immune system function
  • CNS function
  • stress responses
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12
Q

what does dysfunction or dysregulation of hormone levels cause?

A

pathological chances like an endocrine disease or disorder

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13
Q

T/F: hormone levels in circulation must be tightly regulated

A

true

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14
Q

how is hormone regulation accomplished by?

A
  • by controlling hormone production/release
  • controlling ability of hormones to access target cells
  • through hormone removal (degradation)
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15
Q

hormones can regulate…

A

their own production and release as well as that for other hormones

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16
Q

define juxtacrine

A

contact dependent signaling between neighboring cells

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17
Q

how does juxtacrine signaling work?

A

via gap junctions, or between a membrane ligand of one cell and cell surface receptor of adjacent cell

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18
Q

what is an example of juxtacrine signaling?

A

notch signaling

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19
Q

autocrine

A

ligand is released by the signaling cell, then acts on the same cell that produced it

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20
Q

paracrine

A

ligand is released by the signaling cell, then acts on a nearby cell

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21
Q

endocrine

A

ligand is transported by the circulatory system

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22
Q

what cells (distant, nearby, same) does endocrine act on?

A

distant cells

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23
Q

where do hormones secrete from? (15 places)

A

Pineal gland
Hypothalamus
Pituitary gland
Thyroid and parathyroid glands
Thymus
Adrenal
Pancreas
Ovaries/ Testis
Placenta (during pregnancy)
**Kidneys
**Heart
**GI tract
**Adipose
**Liver
**Bone

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24
Q

“_______” endocrine organs contain ______ that release hormones into EC space, where they eventually access circulating plasma

A

classic, ductless glandular structures

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25
Q

“_______” endocrine glands also secrete major hormones

A

non traditional

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26
Q

the endocrine system works in tandem with the ______, particularly via the ______ that is a ________

A

nervous system, hypothalamus, a primary link between the two systems

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27
Q

how does the nervous system communicate between cells?

A

via chemical messengers (ligands and receptors)

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28
Q

T/F: chemical messengers can be both NT’s and hormones

A

true, depends on where secreted and act on.
-> example is norepinephrine

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29
Q

what is the key difference between the endocrine and nervous sytem?

A

the NS uses electrical action potentials along neurons, and NTs across small distances

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30
Q

signaling in the nervous system

A
  • signals are transmitted (electrically) much faster (response times in seconds)
  • more specifically targeted
  • generally shorter lived
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31
Q

signaling in endocrine system

A
  • wider range of signal distribution
  • tends to have higher affinity receptors (therefore can respond to lower concentrations of ligand)
  • takes longer for signals to spread (min to hrs)
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32
Q

how do hormones act without entering circulation?

A

in autocrine or paracrine fashion

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33
Q

direct

A

endocrine glands innervated by nerves of NS

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34
Q

example of direct

A

nerves that innervate pancreas and cause release of hormones (eg insulin)

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35
Q

indirect

A

NS produces neurotransmitter or neurohormone that acts on cells of ES

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36
Q

cytokines

A

small proteins with cell signaling functions (similar to many peptide hormone functions)

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37
Q

cytokines have a _______ in the immune system

A

fundamental role

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38
Q

immune system

A

maintain homeostasis, prevent/fight infection, recognize own self vs pathology

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39
Q

cytokines are typically…

A

short lived, act locally
- autocrine, paracrine, juxtacrine signaling but NOT endocrine

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40
Q

a specific cytokine may often be ______

A

produced by multiple cell types
-> ES has more specific cell types produce specific hormones

41
Q

cytokines are “______”

A

hormone like, they bind specific receptors eg MHC and toll-like receptors

42
Q

MHC and toll-like receptors

A

have similar structure/functions to peptide hormone receptors

43
Q

what are the three ways of cross talk btwn ES and IS?

A
  1. endocrine tissues are affected by immune modulators, such as cytokines
  2. autoimmune diseases that affect endocrine tissues
  3. the immune system is highly receptive to endocrine signals
44
Q

endocrine tissues are affected by immune modulators such as cytokines, why?

A

Possibly because receptors are functionally similar – cytokine could interact with a receptor for a peptide hormone
-> E.g. immune cytokines can cause release of hormones such as ACTH, prolactin, GnRH if their receptors are present

45
Q

how is the immune system highly receptive to endocrine signals?

A

many immune cells have receptor for hormones, so hormones can cause signaling effects within immune cells
-> Eg. Differential susceptibility to autoimmune diseases and infections between men and women – more prevalent in women
—> Influenced by sex hormones – differences in levels of estradiol and
androgens

46
Q

classically hormones are named after…

A

the effect they cause
-> eg follicle stimulating hormones, growth hormone

47
Q

problem with classically naming hormones?

A

A hormone may exert many effects, or different effects depending on cell types, or effects may depend on whether acutely or chronically elevated, etc
-> E.g. FSH has different effects on female and male ES

48
Q

ways to classify hormones aside from their function:

A
  • By where they’re produced/secreted (and in response to what stimuli)
  • By their chemical structure
  • By their solubility
  • By their receptor location (cell surface vs. cytosolic/nuclear)
  • By their receptor sub-type (Cell surface receptors vs Cytosolic or nuclear receptors)
  • By whether they act as receptor agonists or receptor antagonists
  • By key intracellular messengers (e.g., cAMP, cGMP, inositol trisphosphate (IP3), Ca2+) & effector mechanisms in their signal transducMon pathway
49
Q

cell surface receptors

A

G-protein-coupled receptors, Receptor tyrosine kinases (growth factor receptors), Cytokine receptors, Guanylyl cyclase receptors

50
Q

cytosolic or nuclear receptors

A

intracellular receptors

51
Q

chemical structure

A

protein, peptide, amino acid derivative, monoamine, steroid, or fatty acid derivative

52
Q

Hormone biological activity depends on

A

interactions with specific receptors – ligand
binding to specific receptor causes signal transduction responses (effector systems) in target
cell

53
Q

What modifications might proteins and peptides undergo for full biological activity?

A

might be modified and/or dimerized or cleaved for full biological activity.

54
Q

proteins & peptides: are encoded by

A

cellular genes; increased gene expression is often a key part of biosynthesis. regulation of gene expression is necessary

55
Q

What processes are often required to generate biologically active mature forms of proteins and peptides?

A

Precursor processing, post-translational modification, assembly/dimerization/cleavage are often required for the generation of biologically active mature forms.

56
Q

proteins & peptides: hydrophilic or hydrophobic?

A

hydrophilic

57
Q

Where are proteins and peptides often stored in endocrine cells?

A

in secretory vesicles/granules in endocrine cells for later release.

58
Q

What happens to proteins and peptides once they are released from secretory vesicles?

A

Once released from vesicles, proteins and peptides can be easily transported through circulation.

59
Q

How do proteins and peptides act on target cells?

A

via cell surface receptors and cannot enter the cell.

60
Q

What role do amino acid derivatives and monoamines play in biosynthesis?

A

are a key part of biosynthesis, involving the sequestering of precursors and increased activity of enzymes needed for hormone production through the modification of amino acid precursors.

61
Q

What processes are often required to generate active mature forms of amino acid derivatives and monoamines?

A

Precursor processing, post-translational modification, and assembly are often required to generate active mature forms of these hormones.

62
Q

Are monoamines hydrophilic or hydrophobic?

A

hydrophilic

63
Q

are thyroid hormones hydrophilic or hydrophobic?

A

hydrophobic

64
Q

How do monoamines, such as norepinephrine and epinephrine, act on target cells?

A

via cell surface receptors

65
Q

How do thyroid hormones act on target cells?

A

nuclear receptors

66
Q

What is the primary source from which steroids are derived?

A

cholesterol

67
Q

What is a key step in the biosynthesis of steroids?

A

The translocation of cholesterol to mitochondria and the activation of enzymes needed for hormone production.

68
Q

are steroids hydrophilic or hydrophobic?

A

hydrophobic

69
Q

How do steroids pass through cellular membranes?

A

lipid membranes

70
Q

Are steroids stored in secretory vesicles, and how are they synthesized?

A

no ; they are synthesized on demand.

71
Q

What is often required for the circulation of steroids in the bloodstream?

A

blood binding proteins

72
Q

How do steroids typically act on target cells, and what receptors do they engage?

A

Steroids typically act via nuclear receptors, although some can activate both cell surface and intracellular receptors.
-> ie. glucocorticoid and estrogen receptors can be present on both cell surfaces and within cells, and these receptors act in different ways.

73
Q

What is the nature of fatty acid derivatives, and how are they synthesized?

A

are hydrophobic and synthesized on demand

74
Q

Describe the half-life and range of action of fatty acid derivatives.

A

have a very short half-life and act in an autocrine or paracrine manner, not entering circulation or acting long-range throughout the body

75
Q

Are fatty acid derivatives strictly hormones?

A

No, fatty acid derivatives are “hormone-like” but not strictly hormones.

76
Q

What role do prostaglandins play in the body?

A

involved in mediating responses to injury and illness, controlling inflammation, blood flow, and other processes.

77
Q

How do fatty acid derivatives, particularly prostaglandins, act on target cells?

A

cell surface receptors

78
Q

receptor agonist

A

triggers the effector mechanisms and elicit a biological response

79
Q

receptor antagonist

A

binds to the receptor but does not activate the effector mechanisms; blocks/dampens a biological response

80
Q

example of receptor antagonist

A

by occupying the receptor/blocking access of an agonist
-> ligand or drug that fits in biochemical ‘pocket’ of receptor, but does not cause downstream effects

81
Q

partial agonist-partial antagonist

A

limited ability to activate the effector mechanisms
- response less than half that caused by a full agonist

82
Q

mixed agonist-antagonist

A

acts as agonist in some cases, antagonist in others
- depending on dose, cell type, receptor; what the downstream effect is
-> eg if it needs other components to cause the effect
- more pharmacological term - eg drugs that are designed to block specific receptors in some cases or in certian tissues

83
Q

steroid hormone receptors

A

all act as transcription factors when activated

84
Q

response element

A

specific sequence on DNA that TF binds to

85
Q

additivity

A

effects of 2 or more hormones together is equivalent to the sum of their individual effects
- 1 + 1 = 2
- eg combined effect on increasing blood glucose levels of glucagon + epinephrine together

86
Q

synergy

A

effects of 2 or more hormones together is greater than the sum of their individual effects
- 1 + 1 > 2
- eg combined effect on blood glucose of glucagon + epinephrine + cortisol together ( could be due to down stream effects, such as if one hormone increases the number of receptors for another)

87
Q

hormone levels and actions must be tightly regulated, this is accomplished by…

A
  • controlling hormone sythesis/precursor processing/release
  • controlling ability of hormones to access target cells/receptors
  • hormone metabolism
88
Q

controlling hormone sythnesis/precursor processing/release

A
  • natural important point of acute control for a hormone
  • Synthesis (e.g., gene expression, precursor availability, enzyme activity)
  • Processing (e.g., prohormone conversion/cleavage, modification or assembly)
  • Secrection (controlled by signaling events triggered by exogenous regulators/2nd messengers)
89
Q

controlling ability of hormones to access target cells/receptors

A
  • Hormone transport (e.g., blood binding proteins)
  • Changes to receptor expression or cellular localization
  • Interations with other regulatory proteins/hormones (e.g., receptor antagonists)
90
Q

hormone metabolism

A
  • Conversions/structural changes that increase or decrease activity of hormone
  • Degradation of ligand (and/or receptor) over time
91
Q

negative feedback loops

A

response tends to return variable back to original levels (holding a set point to maintain homeostasis)

92
Q

positive feedback loop

A

response changes further changes from a set point… amplifies change. specific threshold or separate input is needed to limit the positive feedback loop

93
Q

tropic hormone

A

a hormone that cause the release of another hormone

94
Q

hormones in plasma

A

either free form (=bio active form) or bound to other molecules, eg blood binding proteins

95
Q

blood binding proteins affect…

A

the controlled release and stability of the pool of hormones
- increase hormone solubility (eg steroid hormones are hydrophobic - low solubility in aqueous solutions)
- provide reservoir of hormone (making hormone pool more stable - more uniform/disbituion, slowing hormone metabolism/breakdown)

96
Q

interactions btwn hormones and their receptors depends on…

A
  • number of receptors
  • affinity of hormone for the receptor
  • concentration of circulating hormone
97
Q

regulation at the level of the receptors is also an important point of endocrine function control

A
  • increasing or decreasing receptor synthesis
  • internalization vs cell membrane localization of cell surface receptors
  • desensitization of receptors (‘uncoupled’ from signal transduction pathway, due to such mechanisms as phosphorylation of the receptor)
98
Q

dysregulation of hormone levels or dysfunction in cellular responses to hormones can…

A

cause pathological changes (ie endocrine dz or disorder)

BIOL 432 (19 decks)

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