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FHB Block 4 > L2- Basics part 2 > Flashcards

L2- Basics part 2 Flashcards

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1
Q

Amine hormones are derived from what precursor?

A

Amino acids:

Catecholamines: from single tyrosine
Indoleamines: from single tryptophan

Thyroid hormone: from 2 tyrosines

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2
Q

Most hormones are of what type (structurally)?

A

Most hormones are peptides or proteins

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3
Q

What is the relative half life of catecholamines and indoleamines?

A

Very short- these hormones act very fast and are rapidly degraded

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4
Q

How do catecholamines and indoleamines travel in the blood? How do they activate their ligand?

A

Catecholamines and indoleamines travel freely in the blood. They always bind to a membrane receptor to activate secondary messengers for their effect

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5
Q

Compare the synthesis of catecholamines to the synthesis of indoleamines

A

Cats: Converted from tyrosine by tyrosine hydroxylase (the rate limiting step)

Indoleamines: converted from tryptophan by tryptophan hydroxylase

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6
Q

Name 3 catecholamines

A

Dopamine –> norepinephrine –> epinephrine

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7
Q

Which is the active form of dopamine?

A

L-Dopa

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8
Q

Where in the body is dopamine made?

A

1) Brain: Substantia nigra, ventral tegmental area and the arcuate nucleus
2) Adrenal gland- dopamine is converted to norepinephrine in the adrenal medulla

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9
Q

What is the action of dopamine?

A

Dopamine inhibits prolactin release from the anterior pituitary

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10
Q

Discuss the timing of tyrosine hydroxylase activity in the arcuate nucleus

A

Tyrosine hydroxylase is constitutively active and therefore making high concentrations of dopamine in the arcuate nucleus

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11
Q

What enzyme catalyzes the conversion of dopamine to norepinephrine?

A

Dopamine beta-hydroxylase

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12
Q

What type of neurons release NE?

A

Sympathetic postganglionic neurons release NE

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13
Q

What is the significance of chromaffin cells of the adrenal medulla?

A

Chromaffin cells of the adrenal medulla are homologous to post-sympathetic neurons and release hormones into the blood

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14
Q

Name 2 indoleamines

A

Serotonin

Melatonin

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15
Q

Where is 95% of serotonin, the “happiness hormone” produced?

A

95% of serotonin is produced by enterochromaffin cells in the gut.

It acts as a vasoconstrictor and stimulates smooth muscle contraction in the intestines

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16
Q

What is the more chemical name for serotonin?

A

5-hydroxytryptamine

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17
Q

What are SSRIs?

A

Selective Serotonin reuptake inhibitors: they block the reabsorption of serotonin back into the presynaptic cleft, which increases the concentration of serotonin in the synaptic cleft

They are used to treat depression and other mental health disorders

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18
Q

Why do SSRIs lose their efficacy over time?

A

Downregulation/desensitization of the serotonin receptors

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19
Q

What are the two primary mechanisms of monoamine metabolism?

A

Deamination and methylation

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20
Q

What is the role of monoamine oxidase (MAO)?

A

MAO inactivates catecholamines and indoleamines through oxidative deamination

21
Q

What are monoamine oxidase inhibitors used for clinically?

A

Used to treat depression and anxiety disorders

22
Q

WHat is the mechanism of catechol-O-methyltransferase (COMT)?

A

Adds a methyl group to catecholamines

23
Q

What enzyme is responsible for the oxidation of aldehydes?

A

Aldehyde dehydrogenase

24
Q

How is vanillylmandelic acid is used clinically?

A

Vanillylmandelic acid is used clinically as an important urinary indicator of excessive catecholamines

25
Q

In what three organs are catecholamines metabolized?

A

Adrenal Medulla, Liver, Kidney

26
Q

Serotonin is converted to what hormone in the pineal gland? What is the rate limiting enzyme?

A

Melatonin- by n-acetyltransferase (SNA)

27
Q

When is melatonin released?

A

during the night.

SNA is most active at nighttime –> Melatonin is undetectable during the day and peaks in the middle of the night.

28
Q

How does light information get to the pineal gland?

A

Light is conveyed to the SCN via the retinohypothalamic tract. The SCN transmits the information to the

29
Q

How does melatonin affect reproduction?

A

Melatonin is a potent inhibitor of reproduction. It causes decreased spermatogenesis and testis size in males.

30
Q

Most hypothalamic and pituitary hormones are what type of hormone (structure wise)?

A

Peptides and proteins

31
Q

Differentiate preprohormone from prohormone from hormone.

A

Preprohormone: Signal peptide still attached to hormone + copeptide

Prohormone: hormone + copeptide

Hormone: just hormone

32
Q

What form of a hormone is usually delivered to patients?

A

Prohormones: hormones + copeptides

33
Q

How does hormone size relate to its half-life?

A

In general, smaller peptides have shorter half-lives

34
Q

Steroid hormones are all derived from what precursor?

A

Cholesterol

35
Q

What is the first step in the biosynthesis of steroid hormones?

A

STAR moves cholesterol from the outer to inner mitochondrial membrane

p450scc protein converts cholesterol to pregnenolone

Mutations in the star protein are embryonic lethal

36
Q

Which steroid hormones are released from the adrenal cortex?

A

Cortisol, mineralocorticoids, DHEA, androstenedione

37
Q

Which steroid hormone is released from the kidney?

A

Vitamin D

38
Q

Which steroid hormone is released from the placenta?

A

progesterone, estriol

39
Q

Which steroid hormone is released from the testis?

A

testosterone

40
Q

Which steroid hormones is released from the ovaries?

A

17beta-E2 and progesterone

41
Q

Name 4 examples of positive feedback cycles in the body

A

Parturition (childbirth)- contractions stimulate oxytocin release

Lactation- suckling stimulates oxytocin release

Ovulation- LH stimulates E2, stimulates more LH

Blood clotting- platelets activate more platelets

42
Q

What are the three components of the endocrine axis.

A

The endocrine is a three tiered biological system consisting of hypothalamic neurons, anterior pituitary cells, and a peripheral endocrine gland.

It is important for diagnosing cause of endocrine disorder

43
Q

Primary disorders refer to what part of the endocrine axis?

A

Primary = peripheral gland disorders

44
Q

Secondary disorders refers to what part of the endocrine axis?

A

Secondary disorders are disorders of the pituitary gland

45
Q

Tertiary disorders refers to what part of the endocrine axis?

A

Tertiary = hypothalamus

46
Q

Differentiate long loop vs short loop feedback of the endocrine axis

A

short loop: Pituitary inhibition of the hypothalamus

Long loop: Peripheral gland inhibition of pituitary or hypothalamic hormone release

47
Q

Are hormone levels consistent throughout an individual’s life?

A

No- hormone levels change with age

48
Q

How are ANP and BNP used clinically?

A

High levels indicate heart and renal failure

Lower levels are seen with obesity
Levels increase with age
Levels are nearly double in women as compared with men

FHB Block 4 (15 decks)

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