Study Set Content:
The bronchoconstriction induced in these patients
probably represents a hyperactive neural response, since
such patients also respond excessively to many other
stimuli, and the response to histamine can be blocked by
autonomic blocking drugs such as (blank)
agents as well as by
ganglion blocking, H1-receptor antagonists.
– Histamine causes
(blank) of intestinal smooth muscle,
contraction
– Histamine causes
contraction of intestinal smooth muscle, and histamine-induced
contraction of (blank) is a standard bioassay for this
amine.
guinea pig ileum
The human gut is not as sensitive as that of the guinea
pig, but large doses of histamine may cause (blank),
partly as a result of this effect. This action of histamine is
mediated by
diarrhea, H1 receptors.
In humans, histamine
generally has (blank) effects on the smooth muscle of
the eye and genitourinary tract.
insignificant
However, pregnant women suffering anaphylactic
reactions may (blank) as a result of histamine-induced
contractions, and in some species the sensitivity of the
uterus is sufficient to form the basis for a bioassay.
abort
Histamine has long been recognized as a
powerful (blank) of gastric acid secretion and of gastric
pepsin and intrinsic factor production.
stimulant
The effect is caused by
activation of (blank) on gastric parietal cells
H2 receptors
The effect is caused by
activation of H2 receptors on gastric parietal cells and is
associated with increased
adenylyl cyclase activity, cAMP
concentration, and intracellular Ca2+ concentration.
Other stimulants of gastric acid secretion such as
acetylcholine and gastrin do not increase
cAMP
Other stimulants of gastric acid secretion such as
acetylcholine and gastrin do not increase cAMP even
though their maximal effects on acid output can be
reduced--but not abolished-by
H2 -receptor antagonists.
Histamine also (blank) secretion in the small and
large intestine.
stimulates
In contrast, H3 -selective histamine agonists (blank) acid
secretion stimulated by food or pentagastrin in several
species.
inhibit
Recent studies of (blank) mice demonstrate that absence of this receptor results in
animals with increased food intake, decreased energy
expenditure, and obesity.
H3-receptor knockout
absence of H3-receptor knockout They also show (blank) and increased blood
levels of
insulin resistance, leptin and insulin
Intradermal injection of histamine
causes a characteristic (blank) response
that was first described many years ago.
the triple response (red spot, edema, and flare)
The effect involves three separate cell types:
o smooth muscle in the microcirculation
o capillary or venular endothelium
o sensory nerve endings
At the site of injection, a (blank) appears owing to
dilation of small vessels, followed soon by an (blank) at the injection site and a (blank)
surrounding the wheal. The flare is said to be caused by
an axon reflex. A sensation of itching may accompany
these effects.
reddening, edematous
wheal, red irregular flare
The flare is said to be caused by
an (blank). A sensation of itching may accompany
these effects.
axon reflex
– In addition to the local stimulation of peripheral
pain nerve endings via H3 and H1 receptors, histamine may
play a role in (blank) in the central nervous system.
nociception
