histamine Flashcards
where is H1 used
cardiovascular system
smooth muscle
periphery nerves
where is H2 used
regulates gastric acid secretion in stomach
increases rate and output of heart
where is H3 used
found in the CNS
where is H4 used
found on inflammatory cells
action of histamine on H1
vasodilation
increasing vascular permiability
pain and stimulation of peripheral nerves
smooth muscle contractions
action of H1 vasodilation I
causes increased blood supply
redness
action of H1 increased vascular permiability II
swelling clotting proteins fluid antibodies all out of blood
action of H1 stimulation of peripheral nerves III
release of NT and vasodilation (stimulation)
redness (stimulation)
histamine goes to cns and causes pain / itch
action of H1 smooth muscle contraction iV
causes bronchial smooth muscle contraction
asthmatics more suseptible to small doses of his
also able to contract smooth muscle in the GI and reproductive tracts
H1 antagonist
mepyramine
cetirizine
mepyramine how is it taken and side effects
orally
drowsiness and effects cholinergic receptors
cetirizine why was it made
made because it has less side effects with drowsiness
uses of H1 antagonists
treatment of allergies
Sedative actions
Local anaesthetic actions
Motion sickness - safe though they can cause drowsiness
actions of histamine on H2
stimulates gastric acid secretion
regulates cardiac output and rate
modulates action of immune cells
action of H2 regulation of gastric acid i
peripheral nerves —-ach—- mast cells release his —-causes H+ out K+in and cl- out
aspirin inhibits prostagladin synthesis which increases gastric acid secretion
action of H2 cardiac system ii
stimulates isolated heart preparations which increase rate and force
dues to direct and indirect cardiac movement
indirect uses nor from adrenergic nerves
action of H2 other effects iii
provide negative feedback inhibiting the release of HIS from mast cells
antagonist of H2
cimetidine
how is it administered and what does it do
orally
inhibits cytochrome p450
can retard the metabolism of a range of different drugs
uses of H2 antagonists
gastric ulcers
reflux oesophagitis
action of histamine on H3
functions as a neurotransmitter
originates in the hypothalamus extends to all parts of the brain
release follows distinct circadian patterns
H3 antagonists
no clinical uses
thioperamide
what is thioperamined used for
research
actions of Histamine on H4
regulate cytokine network in inflammatory response
not really understood
