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Endocrinology > Lecture 2 > Flashcards

Lecture 2 Flashcards

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1
Q

What are the 3 molecular classes of hormones?

A

1) amines
2) peptide/proteins
3) steroids

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2
Q

What are some examples of hormones in the amine category?

A

catecholamines
indoleamines
thyroid hormone

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3
Q

Catecholamines are derived from a single __________

A

tyrosine

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4
Q

Indolamines are derived from a single ___________

A

trypotophan

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5
Q

Thyroid hormone is derived from ____ _____________

A

2 tyrosines

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6
Q

What type of hormones have the shortest half life?

A

amines (2-3 minutes)

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7
Q

What is the half life of T4?

A

8 days

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8
Q

What is the half life of T3?

A

24 hours

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9
Q

What is the half life of proteins?

A

4-170 minutes

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10
Q

What is the half life of steroids?

A

minutes to several hours

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11
Q

Are catecholamines/indoleamines bound or free in the blood?

A

FREE (travel very quickly and are used rapidly)

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12
Q

How do catecholamines/indoleamines enact their signaling?

A

bind to membrane receptor to activate second messenger signaling

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13
Q

How do catecholamines/indoleamines enact their signaling?

A

bind to membrane receptor to activate second messenger signaling ALWAYS

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14
Q

What is the main difference between catecholamines and indoleamines?

A

SYNTHESIS

tyrosine - cat
tryptophan - indol

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15
Q

What are 3 catecholamines?

A

1) Dopamine
2) Norepinephrine
3) Epinephrine

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16
Q

What is the rate limiting step in catecholamine synthesis?

A

Tyrosine hydroxylase (used as a marker for dopaminergic activity)

catalyzes reaction of tyrosine to L-DOPA

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17
Q

Where does conversion of DOPA occur?

A

adrenal medulla

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18
Q

What is dopamine converted into?

A

NE and E (adrenaline)

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19
Q

What is the main endocrine function of dopamine?

A

INHIBIT prolactin release from the anterior pituitary

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20
Q

Dopamine neurons arise from the _________ _________ in the hypothalamus

A

arcuate nucleus

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21
Q

What are the 3 places in the brain where dopamine is made?

A

1) Substantia nigra
2) ventral tegmental area
3) arcuate nucleus of hypothalamus

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22
Q

In addition to the brain, where else is dopamine made?

A

adrenal medulla (where it is converted to NE)

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23
Q

True or false: dopaminergic neurons of the arcuate nucleus are always firing to tonically inhibit prolactin?

A

TRUE

always being released because tyrosine hydroxylase is tonically active

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24
Q

What enzyme catalyzes the conversion of dopamine to NE?

A

dopamine beta-hydroxylase

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25
What leg of the ANS stimulates dopamine beta hydroxylase?
sympathetics
26
What type of neuron releases NE?
sympathetic post ganglionic
27
What innervates the adrenal medulla where conversion to NE occurs?
splanchnic nerves
28
Does NE act via alpha or beta adrenergic receptors?
BOTH
29
What cells the of the adrenal medulla release NE?
chromaffin cells (homologous to postsynaptic sympathetic neurons)
30
What cells the of the adrenal medulla release NE?
chromaffin cells (homologous to postsynaptic sympathetic neurons)
31
What is the rate limiting enzyme of indoleamine synthesis?
Tryptophan hydroxylase
32
What is an example of an indoleamine?
serotonin
33
Where is serotonin made?
95% in the gut | 5% raphe's nucleus
34
What does serotonin do?
act as a vasoconstrictor, stimulates smooth muscle contraction in intestine
35
Where is serotonin made?
95% in the gut (ECCs) | 5% raphe's nucleus
36
What does serotonin do?
act as a vasoconstrictor, stimulates smooth muscle contraction in intestine
37
What is the molecular formula for tryptophan to melotonin?
tryptophan ------> serotonin -----> melotonin
38
What is the rate limiting enzyme for serotonin to melatonin conversion?
N-acetyltransferase (SNA)
39
Where is melatonin produced?
pineal gland
40
What is the neurotransmitter in the brain that is referred to as the "happiness hormone"
Serotonin
41
What is the molecular basis of SSRIs? (selective serotonin reuptake inhibitors)
increase concentration of serotonin at the synaptic cleft by BLOCKING reuptake so serotinin can sit in the cleft longer
42
What is a complication with the logic of SSRIs?
lots of serotonin downregulates receptors so you cannot see effect of SSRIS - nothing to respond to increased amount of neurotransmitter in the cleft
43
What enzyme catalyzes conversion of L-DOPA to dopamine?
Dopa decarboxylase
44
What is the clinical importance of monoamine oxidase inhibitors? (MAO inhibitors)
catalyzes deamination of monoamines, increases dopamine (used in depression)
45
What 2 classes of drugs enact monoamine inactivation?
1) DDC inhibitors (increase L-Dopa conc): Carbidopa and Benzerazide 2) COMT inhibitor (prevents inactivation and degradation of catecholamines): Entacpone 3) MAO inhibitors
46
What is MAO and what does it do?
monoamine oxidase - catalyzes oxidative deamination of all monoamines
47
What MAOs are present in humans?
MAOA and MAOB
48
What effect does Entacapone have on dopamine
inhibits COMT (inhibits deactivation outside of cell)
49
What effect does Carbidopa and Benzerazide have on dopamine?
inhibits conversion outside cell
50
When is N-acetyltransferase active in the converting serotonin to melatonin?
during the night
51
How does melatonin affect reproduction?
inhibits it! decreased spermatogenesis and testis size
52
How is melatonin secretion regulated?
light info is conveyed to the SCN via the retinohypothalamic tract (RHT) which then the SCN transmits that info to the pineal gland
53
Peptide hormones are transcribed as ______________
preprohormones
54
Peptide hormones are transcribed as ______________
preprohormones
55
Once the signal peptide is cleaved, a prohormone is formed which includes _________ and _______
hormone and copeptides
56
Once the signal peptide is cleaved, a prohormone is formed which includes _________ and _______
hormone and copeptides
57
What has a longer half life, hypothalamic or pituitary hormones?
Pituitary
58
What hormone has the longest half life?
IGF-1
59
Steroids are all derived from __________ precursor
cholesterol
60
What is the central precursor which forms all steroid hormones?
Pregnenolone (forms aldosterone, cortisol, estrogens/androgens)
61
What is responsible for carriage of cholesterol from the outer mitochondria to the inner?
StAR
62
What is the main endocrine axis?
HPA (hypothalamic - pituitary) hormones can regulate any part of axis)
63
Short loop feedback is from _______ to _______
pituitary to hypothalamus
64
Long loop feedback is from __________ to __________
endocrine to hypothalamus
65
Long loop feedback is from __________ to __________
endocrine to hypothalamus
66
What are the 4 examples of positive feedback systems in the human body?
1) Partuition (more contractions, more oxytocin until birth stops) 2) Lactation (more suckling, more oxytocin until baby stops feeding) 3) Ovulation (LH stimulates estradiol which stimulates more LH until oocyte is released) 4) Blood clotting (tissue injury activates platelets which activate more platelets until clotting stops)
67
What is the only NON-reproductive positive feedback?
blood clotting
68
What is the only NON-reproductive positive feedback?
blood clotting
69
What is the HPA flow for T3/T4 hormones?
TRH (hypo) --> TSH (ant. pit.) --> T4/T3
70
What is a primary thyroid problem?
problem with T4/T3 secretion
71
Where is a secondary thyroid problem?
pituitary (TSH secretion)
72
Where is the problem in a tertiary thyroid problem?
hypothalamus
73
How would you diagnose a secondary thyroid problem?
Undetectable TSH and unresponsive to TRH
74
What is euthyroid sick syndrome?
normal TSH and thyroid but low T4/T3 (hypothyroid symptoms)
75
What hormone is looked at to assess heart failure?
BNP
76
Which heart hormone has a longer half life?
BNP
77
What do ANP and BNP do?
promote water shedding - opposite effect of AVP and aldosterone
78
What do ANP and BNP do?
promote water shedding - opposite effect of AVP and aldosterone
79
Do women or men have higher ANP and BNP?
women (increases with age)

Endocrinology (16 decks)

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