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Metabolic endocrinology > Section 1 > Flashcards

Section 1 Flashcards

1
Q

What does hormone mean in greek

Classical and modern definition of hormones

A

I excite, I arouse

Chemical messenger released by one type of cells and carried in the bloodstream to act on specific target cellls. Includes factors produced and used locally without entering the blood stream

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2
Q

Who is father of endocrinology

A

Ernest Starling

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3
Q

Why communication between cells is required

A
  • development from the fertilzed egg to the adult organism (differentiation)
  • Maintenance of the environment in which cells can live (homeostasis)
  • Reproduction

In multicellular organisms cells have to communicate

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4
Q

3 layers of signaling networks

A

Within the cells (intracellular)

Between groups of cells (tissues) intercellular

Between tissues (intertissual)

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5
Q

What process opposes networks change?

A

Homeostasis

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6
Q

How old is the earth

when life evolved

when multicellular organisms evovled

A

earth-4.5 billion years

life-3.8 billion years

Multicellular- 600 million

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7
Q

Main control systems of the body

A

Nerbous system (direct connection between organs concerned)

Endocrine system (sending chemcial messages hoemones into circulation)

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8
Q

Different types of cells producing signals

A

Neuroendocrine- epinephrine form medulla

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9
Q

In what concentrations hormones are usually present and they can be made of

A
  • Very low in concentration
  • (ng/ml) or (pg/ml)

-Can be peptides (3 to > 180 aa), modified aa,
cholesterol based (steroids), synthesized from fatty
acids (prostaglandins) or gases (nitric oxide)

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10
Q

How many receptors each hormone has

A

only 1

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11
Q

decribe general pathway of cellular repsonse to a hormone for membrane bound receptor

A

-Recognition of
signal by receptor
-Change of
intracellular
network of proteins
-Activation of
target genes or
proteins
-Cellular response

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12
Q

What chemical nature anad their subclasses hormones can be

A

1) Lipids
-Steroids
-Eicosanoids
2) Proteins
-Short polypeptides
-Large proteins:
Chemical modification through glycosylation
3) Amino acid derivatives

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13
Q

What response a hormone can induce in general

A

Metabolic enzyme (activation/inactivation)->altered metabolism

Gene regulatory protein->altered gene expression

Cytoskeletal protein->altered cell shape or movement

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14
Q

What usual signals cell receive and when it willundergo programmed death

A

Basic ABC signals are always there

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15
Q

Derivatives of cholesterol: what structure they have, what properties, source and where found in cell

A

– Large molecule
• Hydrocarbon ring

oh group

hydrocarbon tail
– Highly hydrophobic
– Source
• Diet
• De Novo synthesis
– Found in cell membrane

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16
Q

derivatives of cholesterol and what characteristic they share

A

– Vitamin D
– Bile acid
• Lipid digestion
– Steroid hormones
• Sex steroids
• Adrenal steroids
– All cholesterol
derivatives contain
sterol ring

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17
Q

Do male and female sex hormones look alike?

A

Testosterone and estradiol have chemically very similar formula

The difference is in functional group and methyl group

But structurally 2 hormones are vey different

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18
Q

Steroid hormones classes and subclasses and what do they do

A

-Adrenal
• Mineralocorticoids
– Affect mineral homeostasis
• Glucocorticoids
– Affect glucose metabolism and
immune function
-Gonads (testis and ovaries)
• Estrogens
• Progestogens
• Androgens

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19
Q

Lipid hormones are metabolites of what acid

A

20 c fatty acid (arachidonic acid)

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20
Q

what chemicals can be produced from arachidonic acid and function

A

-Prostaglandins
– Produced by numerous
tissues and organs
• Originally isolated from
prostate gland secretion
• Inflammatory reaction
• Reproduction

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21
Q

Prostaglandinds and related compounds are collectively known as

A

Eicosanoids

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22
Q

IUPAC name for arachidonic acid

A

5,8,11,14-eicosatetraenoic acid

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23
Q

Example of SCAAs that serve as neurohormones

A

GnRH(10)

Oxytocin(9)

TRH(3)

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24
Q

Difference in structure and function of arginine vasopressin and oxytocin

A

vasopressin has 3-Phe and 8-Arg

Oxytocin 3-Ile, 8-Leu

Arginine vasopressin: Vasoconstriction/Water retention
Oxytocin: Milk ejection/Labor

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25
Q

Subunits in large hormones are linked by

A

Disulfide bridges insulin, growth hormone)

26
Q

tyrosine metabolites

A

Thyroxine (T4)

Triiodothyronine (t3)

27
Q

Adrenal medulla produces what AAs metabolites

A

Epinephrine

Norepinephrine

Dopamine

28
Q

How cells producing hormones can be localized

A

Cells that synthesize hormones may be clustered in endocrine gland or be interspersed as single cells in organs

29
Q

Endocrine gands composition

A

Parenchyma (mass of cells)
• Secretory cells
– Blood vessels
• Highly vascularized
– No ducts

30
Q

Permanent or transsitient endocrine glands

A

Pituitary, adrenal, pancreas
– Ovarian follicle and corpus
luteum

31
Q

where neurins produce hormones

A

– Hypothalamus
– Posterior pituitary
– Adrenal medulla

32
Q

How protein hormones are synthesized

A

– Transcription
– Translation
– Physical/chemical modification
• Cleaving of long amino acid chain (preprohormones) to
generate small peptide hormones (GnRH, oxytocin, TRH)
• Interaction and linking of subunits
• 3-D structure

33
Q

what part of DNA is coding proteins

A

exons

34
Q

3 types of translational modifications that mRNA undergoes

A

poly A tail

Splicing

Capping

35
Q

When hormones becomem functional?

A

Hormones are synthesized as prohormones and then they are made fully functional at post translational modifications

36
Q

What happens the first thing to the protein after translation if its destiny to be hormone

A

Cleavage of signaling peptide and it becomes a prohormone

37
Q

4 types of post translational modifications to a prohormone

A

1) disulphide bonds formation ( that will help in creating three-dimensional structure) and/or cleavage of amino-acid terminal pro-hormone sequence (growth hormone or parathyroid hormone)
2) along protein is synthesized in the beginning and then it is broken down into different parts and only the parts that are needed for the cell are going to be left. The rest are ging to be digested (glucagon from pro-glucagon gene in alpha cells. The same gene in other cells of intestine, the other portion of the gene is going to be retained->GLP
3) one portion is cut out and other portions are reoriented (insulin)
4) alpha and beta portions of the hormone are synthesized in different genes and then are brought together (tropin hormones)

38
Q

Signal peptide are cleaved by ___

A

Peptidases

39
Q

formation of disulfide bridges happens at what AAs

A

Cysteins

40
Q

Where hormones can be stored

A

In vesicles or granules from Golgi complex

41
Q

Movement of vesicles to the cell mebrane is performed by

A

Microtubules (cytoskeleton) and microfilament

42
Q

What vesicles with prohormone might also have and what is required to release prohormone

A

Activating peptidases (active only when they are released from vesicles), makes a prohormone into active hormone

Signal is required to release a stored prohormone (exocytosis)- T and V SMEAR proteins with Ca release inducing exocytosis

43
Q

How cells secreting protein hormones and steroid hormones are different

A

In steroid cells there are less rough ER and more smooth

44
Q

Describe the process of steroid hormone synthesis

A

Cholesterol is transported to mitochondria and converted to pregnenolone. It is transported out of mitochondria into smooth ER, where it is converted to progesterone and then it can be processes further depending on the cell type

45
Q

are steroid hormones stored

A

No

46
Q

What hormones can freely circulate in blood

A

Protein hormones and catecholamines

47
Q

Why steroid hormones are not stored

A

Because they are lipid soluble and they can pass through vesicles

48
Q

Steroid hormones are transported by

A

Specific proteins for each hormones

Thyroxin binding globulin, etc.

49
Q

Binding proteins act as a buffer influencing ____

A

half-life and bioavailability

50
Q

Short protein hormones and peptides are degraed by __ aand thus they have __ life

Large protein hormones haave ___ life

A

Proteolytic enzymes

Short half-life

Longer half-life, because of extensive glycosylation

51
Q

What can control synthesis ad secretion of hormones

A

=Neural inputs
– Brain
– Hypothalamus
= Hormonal stimulation/inhibition
– Releasing factors/hormones
– Inhibitory factors
– Feedback system
= Metabolic status
– Stress
– Blood concentrations of substances
• Ca
• Glucose
• Water

52
Q

Explain general 2 hormone feedback system

A
53
Q

Endocrine disorders classification

A

v Overproduction
v Underproduction
v Altered tissue response
v Tumors of endocrine organ
v Excessive hormone metabolism

54
Q

Lack of GH will cause

A

– Children: Dwarfism
– Adults: Atrophy of muscle tissue etc.

55
Q

Lack of cortisol and aldosterone will lead to ___ disease and what are the signs

A

Addison disease. Lack of hormones increases ACTH secretion
by the pituitary (removes –ve feedback). Co-secreted
melanocyte stimulating hormone also increases. Leads to
bronzing (darkening)

56
Q

where hormones are usually metabolized

A

Liver, some of them in the lungs

57
Q

What step in steroid hormone synthesis can lead to defective hormone

A

Any defective enzyme in the path synthesis will lead to accumulation of intermediates

58
Q

2 types of rhythms that entraine the brain to regulate hormone release

A

24 hour cycle:circadian rhytgm

Longer cycles: infradian rhytm (28 day menstrual cycle)

59
Q

When rhytms should be taken in account and when they can be change and example of circadian rhythms+hormones

A

Examples of circadian rhythms:
– Cortisol secretion: maximal
between 4-8 a.m.
– GH, PRL maximal secretion 1h
after going to sleep
v Rhythms may change during
development
– Gonadotrophin: Released
mainly at night during puberty.
Released in a pulsatile fashion
in adults.
v Rhythms have to be taken into
account when measuring hormone
levels

60
Q

Circadian rhythm proteins are secreted where

A

In the liver ( getting signals from hypothalumus or hormone signal)

61
Q

Hourses are seasonal animals because

A

They breed only in summer

Metabolic endocrinology (9 decks)

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