Which hormone plays a
significant role in the signs and symptoms of inflammation
a) Histamine
b) Serotonin
c) Bradykinin
d) Leukotrienes
Answer:
Bradykinin
Bradykinin
Bradykinin (BK, bradykinin-like substance) is a
potent vasodilator that causes smooth muscle contractions and dilates blood
vessels. Bradykinin is also a neurotransmitter and neuromodulator.
Bradykinin acts on receptors located on the
surface of smooth muscle cells throughout the body, including those in the
digestive tract, urinary bladder, uterus, heart, and vas deferens. Bradykinin
is present in saliva and tears as well as in urine. It causes the contraction
of smooth muscle cells in response to inflammation or injury within tissues.
When released into tissues during injury or inflammation, it causes chemical
reactions that promote healing and reduce pain.
Bradykinin is a peptide hormone that plays a critical role in the regulation of blood pressure, inflammation, and pain. In this article, we will discuss the structure, function, and physiological effects of bradykinin.
I.
Structure of Bradykinin
Bradykinin is a small peptide hormone consisting of nine amino acids: Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg. The peptide is generated from its precursor kininogen by the action of enzymes called kallikreins.
II.
Function of Bradykinin
Bradykinin
acts as a vasodilator, causing the dilation of blood vessels and a decrease in
blood pressure. It does this by binding to bradykinin receptors, which are G
protein-coupled receptors that activate intracellular signaling pathways.
In addition to its effects on blood pressure, bradykinin also plays a role in inflammation and pain. Bradykinin can increase vascular permeability, allowing immune cells to migrate to the site of injury or infection. Bradykinin also sensitizes nociceptors, the nerve endings that detect painful stimuli, contributing to the sensation of pain.
III.
Physiological Effects of Bradykinin
Bradykinin has a number of physiological effects, including:
- Vasodilation: Bradykinin is a potent vasodilator, causing the dilation of blood
vessels and a decrease in blood pressure.
- Increased
vascular permeability: Bradykinin
increases vascular permeability, allowing immune cells to migrate to the site
of injury or infection.
- Pain: Bradykinin sensitizes nociceptors, contributing to the sensation of pain. Inflammation: Bradykinin contributes to the inflammatory response by promoting the migration of immune cells to the site of injury or infection.
IV.
Role of Bradykinin in Disease
Abnormal regulation of bradykinin has been implicated in a number of diseases, including:
- Hereditary
angioedema: A genetic
disorder characterized by recurrent episodes of swelling in various parts of
the body, caused by a deficiency in a protein called C1 inhibitor that normally
regulates the activity of kallikreins.
- Hypertension: Some studies suggest that increased levels of bradykinin may
contribute to hypertension.
- Pain: Bradykinin has been implicated in the development of chronic pain
conditions, such as fibromyalgia and neuropathic pain.
V.
Conclusion
Bradykinin
is a peptide hormone that plays a critical role in the regulation of blood
pressure, inflammation, and pain. It acts as a vasodilator, increasing vascular
permeability, sensitizing nociceptors, and promoting the migration of immune
cells to the site of injury or infection. Abnormal regulation of bradykinin has
been implicated in a number of diseases, including hereditary angioedema,
hypertension, and chronic pain conditions.
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