Histamine Definitions

Question 1

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

Answer 1

Antagonism

Question 2

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

Answer 2

Agonism

Question 3

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

Answer 3

Antagonist

Question 4

A molecule that induces an effect (induces agonism).

Answer 4

Agonist

Question 5

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

Answer 5

Sir Henry Hallett Dale

Question 6

George Eliot

Answer 6

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

Question 7

Imidazole Ring

Answer 7

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

Question 8

Histidine

Answer 8

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

Question 9

Histidine Decarboxylase

Answer 9

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

Question 10

Mast Cells

Answer 10

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

Question 11

Ubiquitous

Answer 11

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

Question 12

Basophil

Answer 12

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.

Question 13

Enterochromaffin-like Cells

Answer 13

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

Question 14

Gastric Mucosa

Answer 14

The mucous layer in the stomach.

Question 15

Heparin

Answer 15

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

Question 16

Glycosaminoglycan

Answer 16

widespread function including growth and repair in cells.

Question 17

Prostaglandins

Answer 17

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

Question 18

ATPase

Answer 18

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

Question 19

VMAT2

Answer 19

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

Question 20

Anti-port

Answer 20

Exchanges one proton for one hydrophilic cation.

Question 21

Mediators

Answer 21

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

Question 22

Antigens

Answer 22

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

Question 23

Antibodies

Answer 23

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

Question 24

Serotonin

Answer 24

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

Question 25

Leukotrienes

Answer 25

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

Question 26

Translocation

Answer 26

the first step of degranulation

Question 27

Fusion

Answer 27

the final step of degranulation

Question 28

Docking

Answer 28

the second step of degranulation

Question 29

Vasodilation

Answer 29

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

Question 30

Edema

Answer 30

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

Question 31

Endogenous

Answer 31

From within the organism / cell.

Question 32

Exogenous

Answer 32

From outside the organism / cell

Question 33

ECL Cells

Answer 33

Enterochromaffin-like cells.

Question 34

PMF

Answer 34

proton motor force

Question 35

VMAT2

Answer 35

Vesicular monoamide transporter 2

Question 36

CNS

Answer 36

Central Nervous System

Question 37

Histamine

Answer 37

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

Question 38

ATPase

Answer 38

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

Question 39

Proton Motive Force

Answer 39

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

Question 40

VMAT2

Answer 40

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

Question 41

Release

Answer 41

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

Question 42

H1

Answer 42

smooth muscle, endothelium, brain

Question 43

H2

Answer 43

Gastric Mucosa, Cardia muscle, Mast cells, brian

Question 44

H3

Answer 44

brain, neurons

Question 45

H4

Answer 45

Immune cells

Question 46

Affinity

Answer 46

Potency (x axis); ability to bind to receptor

Question 47

Efficacy

Answer 47

ability to elicit a response; doability

Question 48

EC50

Answer 48

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

Question 49

AJ Clark and Occupancy Model

Answer 49

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

Question 50

Kon

Answer 50

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

Question 51

Koff

Answer 51

how long molecules stay bound (major contributor to affinity)

Question 52

KD

Answer 52

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

Question 53

KA

Answer 53

1/KD= ffinity of the receptor

Question 54

Logand Binding is...

Answer 54

Stochastic

Question 55

Agonist

Answer 55

elicits a response

Question 56

Antagonist

Answer 56

does NOT elicit response

Question 57

Pharmacological antagonism

Answer 57

antagonism on a single receptor

Question 58

Orphan receptors

Answer 58

are waiting to have ligand identified

Question 59

De-orphanized receptors

Answer 59

ligand of the receptor is identified

Question 60

Competitve antagonist=

Answer 60

surmountable

Question 61

Irreversible antagonist=

Answer 61

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