Pharmacology - Histamine and Anti-histamines (Exam 3) Flashcards
Chemically classified as an amine, an organic molecule based on the structure of ammonia
Histamine
Formed by the decarboxylation of the amino acid histidine
Histamine
Where are the highest levels of histamine storage?
Lungs
Intestinal mucosa
Skin
What is histamine stored in?
Vesicles within mast cells (mostly)
These cells synthesize histamine and store it within a complex w/ heparin or chondroitin sulfate in secretory granules
Mast cells
How is histamine released from secretory granules?
Exocytosis
Degranulation
Riya is allergy prone to bananas, and she makes large amounts of banana antibody and these ________ antibodies will attach themselves to ________ cells.
IgE; mast
True or False: The 1st time Riya experiences an allergic rxn to bananas is going to be much worse than the 2nd
FALSE, the 2nd time is much worse
3 major causes of histamine release
1) tissue injury
2) allergic rxns
3) drugs & foreign substances
Histamine release in response to tissue injury?
initial sharp phase of release (within minutes) that’s sustained over several hours
Initial histamine release ________ vascular permeability
increases
Antihistamines work best in the _________ phase of histamine release, rather than the sustained phase
initial
(once you go into anaphylaxis, it is too late for antihistamines)
What are some drugs that people are allergic to?
Morphine
Dextran
Antimalarial drugs
Antibiotics
Pharmacological effects of histamine on cardiovascular system
Vasodilation (decrease BP)
Increased permeability (edema)
Systemic hypotension
What is the triple effect (caused by histamine)?
- Redding @ injection site due to vasodilation
- Wheal or disc of edema within 1-2 mins
- Large bright crimson flare/halo surrounding the wheal
Pharmacological effects of histamine on smooth muscle of bronchioles
contraction of vascular smooth muscle -> difficult to breathe!
Histamine increases the secretion of ___________ glands
exocrine
Pharmacological effects of histamine on peripheral nervous system
Itching
Pain
How many histamine receptors are there?
4 receptors
H1, H2, H3, H4 (but we only care about H1 and H2)
What kind of receptors are histamine receptors?
GPCRs
What are H1 receptors responsible for causing?
Allergic conditions
What are H2 receptors responsible for causing?
Gastric acid secretions
Distribution of H1 receptors
Smooth muscle
Endothelium
CNS
Heart
Distribution of H2 receptors
Vascular smooth muscle
CNS
Heart
Neutrophils
Gastric parietal cells
Uterus
Function of H1 receptors (7 things)
Bronchoconstriction
Vasodilation
Separation of endothelial cells
Itching
Pain
Allergic rhinitis
Motion sickness
Function of H2 receptors (3 things)
Gastric acid secretion
Vasodilation
Inhibition of IgE dependent degranulation