Types and Functions of Histamine Receptors

Question 1

what kind of receptors do histamine use

Answer 1

G protein coupled membrane spanning proteins with 7 domaine

Question 2

the origin of the effects of histamine in hypersensitivity

Answer 2

originate from its binding to H1 receptors on the venous side of the vessel wall.

causes vasodilation, increased permeability of capillaries (main effects of histamine)

directly causes causes pain by binding to H1 receptors on peripheral nerves and by the mechanical pressure on these nerves due to tissue swelling

Question 3

H1 receptor origins

Answer 3

sensory nerves - pain
nasal and bronchial (mucus secretion)
bronchial/intestinal smooth muscle constriction

Question 4

H2 receptor origins

Answer 4

stomach - gastric acid secretion

Question 5

broadly speaking, where would you locate histamine receptors?

Answer 5

in areas where environmental antigens might be encountered

nasal/passage
trachea/bronchi/lungs
stomach
intestines 
skin

Question 6

What kind of receptor–protein type–does histamine use?

Answer 6

a G coupled protein receptor

Question 7

what makes the H1-receptor so important?

Answer 7

it’s the receptor associated with hypersensitivity: these are located on vessel walls (especially the venous side)…

Question 8

how does H1 receptor “directly” cause pain in the presence of histamine?

Answer 8

H1 receptors are located on peripheral nerves: biding causes swelling, and the pressure of the swelling on the nerves causes pain

Question 9

Tissue specific expression of H1…

Answer 9

Nasal + bronchial = mucus secretion

Bronchial + intestinal = smooth muscle contraction

Sensory nerves = pain

Question 10

Tissue specific expression of H2

Answer 10

stomach = gastric acid secretion

Question 11

Tissue co-expression of H1 and H2

Answer 11

Heart - heart rate
Blood vessels - peripheral resistance
skin cap. blood vessels - dilation/perm/pain sens.