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ANSC 424 > Powerpoint 1 > Flashcards

Powerpoint 1 Flashcards

1
Q

Modern vs. Classical definition of hormone

A

Classical: Chemical messenger released by 1 type of cells and carried in bloodstream to act on specific target cells.

Modern: Includes factors produced and used locally without entering the blood stream

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2
Q

What is endocrinology about?

A

communication between cells - multicellular organisms have to communicate

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3
Q

What 3 aspects is endocrinology required for?

A
  1. Development form the fertilized egg to the adult organism (differentiation)
  2. Maintenance of the envr. in which cells can live (homeostasis)
  3. reproduction
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4
Q

Number of cells in human adult vs number of people in entire population:

A

Cells in human adult: 10^14

^ about 10,000 times the entire population

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5
Q

How many protein incoming genes coordinate all of the cells in the human body? How is this coordination achieved?

A

21,000 via networking (gene interaction)

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6
Q

What are the 3 layers of signalling networks?

A
  1. within cells
  2. between groups of cells (tissues)
  3. between tissues (organs?)
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7
Q

Life evolved about ________ years ago, but multicellular organisms evolves less than ________ years ago.

A

3.8 billion

600 million

Shows how complex these networks are

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8
Q

What are recipient cells?

A

Cells that recognize hormone signals and respond to them.

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9
Q

Recipient cells are exposed to many signals at the same time, therefore they response is:

A

an integrated response to all these signals

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10
Q

What are the two main control systems of the body and what is the difference between the two?

Together, what are they responsible for?

A

Nervous system - there is a direct connection between organs concerned.

Endocrine system - sending chemical messages (hormones) into the circulation (radio station)

Monitoring internal and external environments and making adaptive changes (homeostasis)

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11
Q

Out of the endocrine and nervous system, which is slower?

A

Endocrine is much slower because signals must be translocated and diffused

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12
Q

Endocrine cells:

A

Secrete HORMONES into blood vessels. Target cells may be distant

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13
Q

Paracrine cells:

A

Secrete HORMONES which act locally on neighbouring cells

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14
Q

Autocrine cells:

A

Secrete HORMONES which acts on themselves or on identical neighbouring cells

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15
Q

Neuroendocrine cells:

A

Secrete MOLECULES from axon terminals into the blood stream

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16
Q

Neurotransmitter cells:

A

Secrete MOLECULES from axon terminals to activate adjacent neurons

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17
Q

What are 2 general characteristics of hormones?

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

2. Very specific receptor (1 hormone, 1 receptor)

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18
Q

What 5 type of molecules can a hormone be?

A
  1. peptides (3 to >180 aa)
  2. modified aa
  3. cholesterol based (steroid)
  4. synthesized from FAs (prostaglandins)
  5. gases (nitric oxide)
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19
Q

Where might cells that synthesize hormones be located?

A
  1. clustered in endocrine glands

2. interspersed as single cells in organs

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20
Q

What are the 3 main classes of hormone - give examples of each?

A
  • Lipid: steroids, eicosanoids
  • Proteins: short polypeptides, large proteins
  • AA derivatives
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21
Q

Lipid hormones: Steroids

Derivative of what?
Size of molecule?
Source?
Found where?

A
  1. cholesterol
  2. large (hydrocarbon ring)
  3. diet, de novo synthesis
  4. cell membrane
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22
Q

Chemical vs. 3D structure of testosterone and estrogen

A

Chemically very similar

3D structure differs markedly

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23
Q

What two endocrine glands are steroid hormones produced in?

A

Adrenal glands and Gonads (testis and ovaries)

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24
Q

What two types of molecules do adrenal glands secret and what do each affect?

A
  1. Mineralocorticoids: affect mineral homeostasis

2. Glucocorticoids: Affect glucose metabolism and immune function

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25
Q

What 3 type of molecules do Gonads (testes and ovaries) secrete?

A
  1. estrogen
  2. progestin/progestagens
  3. androgens
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26
Q

What are 4 examples of Eicosanoids?

A

Prostaglandins

Thromboxanes, leukotrienes, prostacyclins

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27
Q

What are two characteristics of prostaglandins?

A
  1. inflammatory reaction

2. reproduction

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28
Q

Prostaglandins and related compounds are collectively known as ____________.

A

Eicosanoids

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29
Q

What are eicosanoids produced from?

A

arachidonic acid

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30
Q

What is arachidonic acid characterized as?

A

a 20-C polyunsaturated fatty acid (5,8,11,14-eicosatetraenoic acid)

31
Q

What molecule is a good example of a prostaglandin?

A

PGH2 (prostaglandin H2)

32
Q

What are the two major pathways of eicosanoid metablolism? (draw it out)

A

Linear and Cyclic

33
Q

What enzyme catalyzes the “committed step” in the cyclic pathway of eicosanoid metabolism?

A

PGH2 synthase

34
Q

What are 2 characteristics of the products produced from the cyclic pathway of eicosanoid metabolism?

A
  1. They have specific effects on target cells close to their site of formation.
  2. There are rapidly degraded, so they are not transported to distal sites within the body
35
Q

What are 3 examples of neurohormones? How many amino acids do each contain?

A
  1. GnRH (10)
  2. Oxytocin (9)
  3. TRH (3)
36
Q
  1. What is the hormone arginine vasopressin associated with?
  2. What is the hormone Oxytocin associated with?

How do these hormones differ?

A
  1. Vasoconstriction/water retention
  2. milk ejection/labour

Differ in aa #3 and #8. Very small differences profoundly affect physiological effects

37
Q

What are 3 characteristics of large polypeptide protein hormones?

A
  1. linear chain
  2. subunits are linked by disulphide bridges
  3. 3D structure is critical for interaction with receptor

(everything folds into its minimal energetic form)

38
Q

What two locations in the body produce hormones from tyrosine? What hormones are produced from tyrosine here?

A
  1. Thyroids: thyroxine (T4) and triiodothyronine (T3)

2. Adrenal medulla: epinephrine, norepinephrine, dopamine

39
Q

Tyrosine metabolite hormones produced from the adrenal medulla are often used as what?

A

neurotransmitters

40
Q

What are 3 characteristics of the composition on endocrine glands?

A
  1. Parenchyma (mass of secretory cells)
  2. Highly vascularized blood vessels
  3. no ducts
41
Q

What two types of cells produce hormones?

A
  1. specialized secretory

2. neurons

42
Q

In what 3 locations can you find cells that produce neuronal hormones?

A
  1. hypothalamus
  2. posterior pituitary
  3. adrenal medulla
43
Q

Where are storage peptide hormones stored?

A

secretory vesicles (granules) in cytoplasm

44
Q

How are peptide hormones stored in granules moved to the cell membrane?

A

microtubules (cytoskeleton) and microfilaments

45
Q

What do cells require in order to activate and release a stored pro hormone?

A

stimulus - may be a hormonal stimulus

46
Q

What do stimuluses that activate and release stored hormones from granules normally change in cells?

A

Ca2+ permeability of the cell membrane (opening of Ca channels)

47
Q

What is the major difference between the synthesis of peptide hormones and steroid hormones?

A

Peptide hormones are stored in granules and released out of cell instantaneously upon receiving stimulus. They are pre-made, stored, and waiting to be released.

Steroid hormones must be CREATED and then released.

48
Q

Where are cholesterol molecules stored? What are they stored as?

A
  1. cytosol

2. cholesterol esters in lipid droplets

49
Q

What is the progression of the formation of a cholesterol molecule from its storage in lipid droplets to its exit from the cell?

A

Cholesterol esters from lipid droplets in cytosol move into mitochondria where they are converted to pregnenolone. They are then transported to the smooth ER and transformed into the appropriate hormone. They then exit cell

50
Q

Is there storage of steroid hormones in cells?

A

no

51
Q

What type of hormones are hydrophilic and can circulate freely in blood?

A

peptide and protein hormones

52
Q

What are two examples of hormones that are more hydrophobic and require carrier proteins?

A

thyroxin, steroid hormones

53
Q

What are two examples of hormone transport molecules (binding proteins) in blood?

A
  1. thyroxin globulin

2. cortisol binding protein

54
Q

How do binding proteins act as a buffer in the blood?

A

By transporting the hormone and protecting it from degradation in the liver

55
Q

When is a hormone biologically active / not?

A

active: free form

not-active: bound to transport molecule - it must dissociate from binding protein in order to bind to receptor

56
Q

Do peptide hormones of large protein hormones have a larger half life in circulation?

A

large protein hormones

57
Q

The blood concentration of what 3 substances controls synthesis and secretion of hormones?

A
  1. Ca
  2. Glucose
  3. Water
58
Q

Endocrine disorders: what does a lack of GH cause in:

  1. Children
  2. Adults
A
  1. dwarfism

2. atrophy of muscle tissue

59
Q

Endocrine disorders: what disease does a lack of cortisol and aldosterone cause? What is the mechanism?

A

Addison disease. Lack of hormone increases ACTH secretion by the pituitary (removes negative feedback). Co-secreted melanocyte stimulating hormone also increases. Leads to excessive freckling.

60
Q

What is the most common endocrine disorder? Due to what?

A

Diabetes mellitus. May be due to lack of secretion of insulin from the beta-cells of the cells of Langerhans in the pancreas. Can also be caused by a receptor defect (does not respond to insulin administration)

61
Q

What is a 24 hour endocrine rhythm cycle called?

A

circadian rhythm

62
Q

What are endocrine rhythm cycles called that are longer than 24 hours? 1 example?

A

infradian rhythm

ex: 28 day menstrual cycle

63
Q

What are 2 examples of circadian rhythms?

A
  1. cortisol secretion: maximal between 4-8 am

2. Gh and PRL: maximal 1 hr after going to sleep

64
Q

What is the difference in the release time of gonadotrophin during puberty vs adult?

A

Puberty: mainly at night

Adults: pulsatile fashion (burst-like – not constant over time)

65
Q

What must be taken into account while measuring hormone levels?

A

Rhythms

66
Q

What do bioassays measure?

A

response of animal or cell to a hormone

67
Q

How did human pregnancy use to be determined between 1930 - 1950s?

A

THE RABBIT TEST: hCG is produced by placenta 8 days after fertilization. Urine injected into rabbit and if hCG was present, then the rabbits ovaries would ovulate and form corpora lutea. The rabbit would then be killed to determine pregnancy (+/- corpora lutea)

68
Q

2 cons of bioassays?

A
  1. time consuming

2. do not accurately measure levels of hormone

69
Q

Radioimmunoassays (RIA) work off of what principle?

A

competitive binding of anybody to its antigen

70
Q

How do enzymoimmunoassays (EIA) differ from RIAs?

What is an example of an enzymoimmunoassay?

What is a similar technique called?

A

ALSO work on the principle of competitive binding of an antibody to its antigen BUT EIAs do not require radioactive tags. Rather, the antibody the antibody is tagged with a compound that changes colour in response to binding with the antigen.

Ex. home pregnancy test

Enzyme-linked immunosorbent assay (ELISA)

71
Q

RIAs and EIAs can be used on _______ and/or ______ samples depending on the hormone

A
  1. blood

2. urine

72
Q

What are 3 other common endocrinology techniques (+ examples)?

A
  1. Indirect measurements of hormone levels. Ex: blood glucose levels are more useful than insulin levels to diagnose/treat diabetes mellitus
  2. Proactive and Suppression tests. In some hormones, it is easier to assess the status by maximally stimulating or suppressing hormone release and comparing the result average healthy individuals. This is especially useful with hormones that are fluctuating normally during the day, therefore fewer blood/urine samples required
  3. Imaging studies - magnetic resonance imaging (MRI) and computer tomography (CT) - allows visualization of endocrine glands and perhaps tumours
73
Q

What two systems are used in gene editing?

A

CRISPR
Cas9

Collect autologous cells from patient and modify it in vitro to correct lesion the re-introduce to patient

ANSC 424 (7 decks)

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