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biochemistry endo > diversity of endocrine system > Flashcards

diversity of endocrine system Flashcards

1
Q

Major androgen or androgen precursor produced by adrenal cortex

A

Dehydroepiandrosterone (DHEA)

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2
Q

Most potent adrenal androgen rsults from reduction of androstenedione at C17

A

Testosterone

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3
Q 
Which among the following uses CGMP as its second messenger
A. ANP and NO
B. ACTH and calcitonin
C. Adinopectin and EPO
D. Acetylcholine and angiotensin II
A

A.
B-second messenger is cAMP
C- second messenger is kinase or phosphatase cascade
D.second messenger is calcium or phophatidylinositols

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4
Q

Most significant product and active form of testosterone

A

DHT

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5
Q

Primary estrogen of ovarian origin

A

17 B-Estradiol

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6
Q

First step in the amplification of hormonal response

A

Receptor-effector coupling

Coupling of hormone binding to signal transduction

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7
Q

Formed if the substrate of aromatase enzyme complex is testosterone

A

Estradiol

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8
Q

Source of androstenodione and testosterone

A

Theca cells

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9
Q

Progesterone, a precursor for all steroid hormones is produced and secreted by

A

Corpus luteum

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10
Q

Major source of estrogens in postmenopausal woman

A

Conversion of androstenedione to estrone

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11
Q

Which among the following is not involved in the conversion of tyrosine to epinephrine
A. Ring hydroxylayion
B. Decarboxylation
C. Side-chain hydroxylation to form norepinephrine
D, N-methylation to form epimephrine
E. None of the above

A

E.

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12
Q

Rate limiting enzyme for catecholamine biosynthesis

A 
Tyrosine hydroxylase
(Functions as a oxidoreductase with tetrahydropteridine as a cofactor
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13
Q

Catalyze the convetsion of dopamine to norepinephrine

A

Dopamin B-Hydroxylase

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14
Q

Precursor of T4 and T3

A

Thyroglobulin (provides the conformation required for tyrosyl coupling and iodide organification

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15
Q

The foloowing is the result of avute decrease Ca2+ concentration
A. Increase PTH mRNA
B. Increase rate of PTH synthesis and secretion
C. All of the above
D. None of the above

A

C.

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16
Q

Supply of T3 and T4 exists in the thyroglobulin that is stored where?

A

Stored in colloid in the lumen of thyroid follicle (released upon stimulation by TSH)

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17
Q 
Which of the following hormones has no intracellular resorvoir because they are secreted as they are made
A. T3 and T4
B. Insulin
C. Steroids and 1,25(OH)2D
D. Catecholamines and PTH
A

C.
A.stored for weeks
B. Stored for days
D. Stored for hours

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18
Q

Most of T3 and T4 is bound to

A

Thyroxine-binding globulin
Hormones when bound cannit be metabolized prolonging their half life.
T4 is more bound that T3

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19
Q

Main plasma binding protein of hydrocortisone is an a-globulin called

A

Transcortin or corticosteroid-binding globulin

Synthesis is incrased by estrogen

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20
Q

Estrogen is bound yo sex-hormone-binding protein while progestins is to

A

Coryicosteroid binding protein

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21
Q 
Insulin is bound to 
A.cGMP
B.cAMP
c. Calcium
D. Protein kinase
A

D.

Insulin uses tyrosine kinase

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22
Q

Cyclic AMP is a nucleotide generated from ATP through the action of

A

Adenylate cyclase

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23
Q 
Which among the following is synthesized from cholesterol
A. Catecholamines
B. Peptides
C. Adrenal steroid
D. Glycoproteins
A

C

A. Derived from tyrosine

24
Q 
Which among the following secondary messenger releases calcium
A.IP2
B. IP3
C. DAG
D. Tyrosine
A

B.

C-activates protein kinase

25
Q 
Which among the following is not an amino acid derivative hormone
A.epinephrine
B.serotonin
C.glutamic acid
D.leptin
A

D.it is from peptides and proteins

26
Q

Rate limiting step for steroid hormones is conversion of cholesterol to

A

Pregnenolone

27
Q

Which among the following hormones is not a principal class of fatty acidsA.leukotrienes
B.thromboxane
C.prostaglandin
D.histamine

A

D. Amino acid derivative

28
Q

Other term for Growth hormone releasing factor

A

Somatocrinin

In arcuate nucleus of hypothalamaus

29
Q

Inhibits growth hormones by hyperpolarizing the somatotropes

A

Somatostatin

30
Q

More potent inhibitor of growth hormone, glucagon and insulin than the natural hormone

A

Octreotide

31
Q

Synthesized by the placenta and seems to determine the duratiom of pregnanacy; released during stress response

A

Corticotropin releasing hormone

32
Q

Tripeptide hormone that stimulate release of thyroid stimulating hormone and prolactin buy the anterior pituitary

A

Thyrotropin releasing hormone

33
Q

A peptide hormone responsible for the release of FSH and LH from the anterior pituitary

A

Gonadotropin Releasing hormone 1

34
Q

Inhibit prolacyin release

A

Dopamine

35
Q

Which among the following have a normal or excess plasma GH, but lack liver GH receptors and have low levels of circulating IGF-1
A. Laron dwarfs
B. Pygmies
C. GH hormone degicient dwarfs

A

A

36
Q

Pituitary secretion is regukated and inhibited by

A

Dopamine neurons

37
Q

Structure and fuction same as growth hormone; has anti insulin property

A

HPL/CS

38
Q

In men, FSH enhances the production of androgen binding protein by the Sertoli cells of the testes and critical for

A

Spermatogenesis

39
Q

Prevent the disintegration of the corpuse luteum maintain progesterone production

A

HCG

40
Q

Mimic LH and helps restore and maintain testosterone production in the testes

A

hCG

In male-hcg injections are used to stimulate the leydig cells to synthesize testosterone

41
Q

What disease is caused by stimulating antibodies (Thyroid stimulating autoantibodies) to the TSH receptor and mimic TSH action by increasing intracelluar cAMP

A

Graves disease

42
Q

Oveproductoon of ACTH results in

A

Cushing syndrome

Results in Na, K, and P negative balance

43
Q

Gives the feeling of euphoria

A

Endorphins

44
Q

Which among the following differentvreceptos of the vasopressin causes corticotropin secretion from pituitary gland
A.V2
B. VIA
C.VIB

A

C
A-free water reabsorption
B-vasoconstriction,gluconeogenesis, platelwt aggregation, relese factor 8

45
Q

In thr follicular lumen, iodide is oxidized by an enzyme found only in thyroid tissue called

A

Thyroperoxidase

46
Q

Degrade the thyroglobulin releasing amino acids T3 and T4, which are secreted into the circulation

A

Lysosomal proteases

47
Q

Thryoxine-binding globulin prealbukin is also responsible for the transport of

A

Retinol-transthyretin (TTR)

48
Q

80% of circulating T4 is converted to T3. This conversion is inhibited by

A

PTU and propanolol

49
Q

Which among the following is not the action of thyroid hormones
A. Increase metabolic rate
B. Protein synthesis
C. Increase the body’s insensitivity to catecholamines
D. Regulate protein, fat and carbohydrate metabolism

A

C

50
Q

The immediate precursor of PTH which has a highly basic hexapeptide amino terminal extension

A

proPTH

51
Q

Which among the ff is not true
A.PTH increases reabsorption of phosphate in tge kidneys to decrease its excretion
B.PTh reduces renal Ca2+ clearance
C. PTH increase Ca2+ levels in ECF
D. PTH acts by binding to cAMP-coupled plasma membrane receptors

A

A

52
Q

Responsible for Ca2+ reabsorption in the intestine; most potent naturally occuring metabolite of vitamin D

A

Calcitriol

53
Q

Where in the body does Vit D is produced during photolysis reaction using 7-dehrydrocholesterol
A liver
B skin
C kidney

A

B.
A. Undergoes hydroxylation in endoplasmic reticulum by 24-hydroxylase
C. Monohydroxy D3 from the liver is converted to its active form by hydroxylation at position C1 by 1a-hydroxylase

54
Q

Which among the following is nod needed in the activation of Vit D
A.CP450
B. Iron sulfur protein, renal ferredoxin
C. Flavoprotein, renal ferredoxin reductase
D. Flavoprotein, renal ferredoxin synthase

A

D.

55
Q

Has the counter effects of parathyroid hormones and reduce synthesis of osteoporin and regulates Vitamin D.

A

Calcitonin

biochemistry endo (5 decks)

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