Histamine Definitions Flashcards

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1
Q

occupation of a single receptor by an antagonist interferes with the response of the agonist.

A

Antagonism

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2
Q

occupation of a single receptor by an agonist leads to a response.

A

Agonism

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3
Q

A molecule that induces antagonism. Removes the effect of the agonist.

A

Antagonist

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4
Q

A molecule that induces an effect (induces agonism).

A

Agonist

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5
Q

discovered the biological effects of histamine. Won the Nobel prize in 1936 for medicine + physiology. Received a Studentship from the Victorian novelist, George Eliot.

A

Sir Henry Hallett Dale

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6
Q

George Eliot

A

Created the Lewes Studentship that was awarded to Sir Henry Hallett Dale.

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7
Q

Imidazole Ring

A

A ring (structure) that exists on histamine. It contains two nitrogens.

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8
Q

Histidine

A

An amino acid. The non-toxic form of histamine. Has an amine group and a carboxyl group attached to a central carbon.

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9
Q

Histidine Decarboxylase

A

Removes the carboxyl group from histidine (decarboxylates). This produces an amine (histamine) and CO2. This is found intracellular in the cytoplasm.

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10
Q

Mast Cells

A

Ubiquitous cells. Have granules that contain histamine and other things.

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11
Q

Ubiquitous

A

Coming in many different forms and present in a number of tissues.

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12
Q

Basophil

A

a type of white blood cell. The least common type of granulocyte, representing only about 0.5 - 1% of circulatory white blood cells. Contains histamine.

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13
Q

Enterochromaffin-like Cells

A

Communicate in paracrine fashion. Contain histamine that when released plays a major role in stimulating gastric secretion. Found in the gastric mucosa.

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14
Q

Gastric Mucosa

A

The mucous layer in the stomach.

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15
Q

Heparin

A

another molecule found in the granules of Mast Cells. Naturally ocuring glycosaminoglycan. Part of its function is aiding in growth and repair in cells.

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16
Q

Glycosaminoglycan

A

widespread function including growth and repair in cells.

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17
Q

Prostaglandins

A

found in the granules of Mast Cells. Involved in dealing with injury and illness.

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18
Q

ATPase

A

an enzyme found in granular membrane that transports protons into the cell to create a proton motor force.

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19
Q

VMAT2

A

an anti-port that exchanges one proton for one histamine.

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20
Q

Anti-port

A

Exchanges one proton for one hydrophilic cation.

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21
Q

Mediators

A

other things held within the granule: ATP, heparin, prostaglandins.

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22
Q

Antigens

A

any substance that causes your immune system to produce antibodies against it.

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23
Q

Antibodies

A

proteins generated by our immune system in response to antibodies to fight against infectious agents.

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24
Q

Serotonin

A

a chemical signalling molecule. Known to cause satisfaction, happiness, and optimism in CNS. Also has many other functions.

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25
Q

Leukotrienes

A

Causes tightening of airway muscles and the production of excess mucus and fluid.

26
Q

Translocation

A

the first step of degranulation

27
Q

Fusion

A

the final step of degranulation

28
Q

Docking

A

the second step of degranulation

29
Q

Vasodilation

A

the dilation of veins, occurs as a result of histamine affection venous cells.

30
Q

Edema

A

Fluid accumulation (occurs when stung by a bee), occurs as a result of histamine affecting vasculature.

31
Q

Endogenous

A

From within the organism / cell.

32
Q

Exogenous

A

From outside the organism / cell

33
Q

ECL Cells

A

Enterochromaffin-like cells.

34
Q

PMF

A

proton motor force

35
Q

VMAT2

A

Vesicular monoamide transporter 2

36
Q

CNS

A

Central Nervous System

37
Q

Histamine

A

Example of a messenger molecule. Basophils, mast cells, neurons, and Enterochomaffin-like cells

38
Q

ATPase

A

transports protons from cytosol into the granule to create the proton motive force

39
Q

Proton Motive Force

A

ATPase creates a concentration gradient (more protons inside granule than in cytosol) which supports the transport mechanism VMAT2

40
Q

VMAT2

A

uses the proton gradient to swap a proton with a histamine molecule (going inside a granule). VMAT2 is an antiport which means it moves two molecules or ions in opposite directions between a membrane

41
Q

Release

A

Activation/ degranulation caused by physical/chemical stimulii. Release has a 3 step process: Translocation, docking and fusion

42
Q

H1

A

smooth muscle, endothelium, brain

43
Q

H2

A

Gastric Mucosa, Cardia muscle, Mast cells, brian

44
Q

H3

A

brain, neurons

45
Q

H4

A

Immune cells

46
Q

Affinity

A

Potency (x axis); ability to bind to receptor

47
Q

Efficacy

A

ability to elicit a response; doability

48
Q

EC50

A

concentration required to elicit a 50% response, measure of affinity

49
Q

AJ Clark and Occupancy Model

A

Drugs occupy receptors; response is proportional to receptor occupation; one molecule= one receptor= one unit response; always more drug molecules than receptors available

50
Q

Kon

A

ability to get on the receptor (how fast molecules access receptors)

51
Q

Koff

A

how long molecules stay bound (major contributor to affinity)

52
Q

KD

A

concentration required to saturate half of the receptors=Koff/Kon

53
Q

KA

A

1/KD= ffinity of the receptor

54
Q

Logand Binding is…

A

Stochastic

55
Q

Agonist

A

elicits a response

56
Q

Antagonist

A

does NOT elicit response

57
Q

Pharmacological antagonism

A

antagonism on a single receptor

58
Q

Orphan receptors

A

are waiting to have ligand identified

59
Q

De-orphanized receptors

A

ligand of the receptor is identified

60
Q

Competitve antagonist=

A

surmountable

61
Q

Irreversible antagonist=

A

non-surmountable antagonism; cannot be washed out and decreases max response