Question

8. Define and describe the following terms: a. Mast cells b. Histamine c. Leucotrines d. Prostaglandins e. Platelet-activating factor

Answer 1

A.) Mast cells --- mast cell precursors are formed in bone marrow and released into the blood in an undifferentiated state until they reach the tissue, they have a large number of cytoplasmic granules containing histamine, mast cells play a role in allergic responses.

B ) histamine -- it is a nitrogenous compound , involves in local immune responses and also acts as neurotransmitter. It is released by a variety of cells in response to tissue injury. It causes vasodilation and increase permeability of capillaries.

C.) Leukotrienes--- are hydroxy fatty acid derivatives of arachidonic acid and do not contain a ring structure. leukotrienes are distinguished by containing a conjugated triene double bond arrangement. They are involved in chemotaxis, inflammation and allergic reactions.

D.) Prostaglandins- prostaglandins are all derivatives of the hypothetical C20 fatty acid prostanoic acid in which carbon atoms 8 to 12 comprise a cyclopentane ring. This stimulate uterine contraction, lowering blood pressure, vasodilation and inflammation and pain.

E.) Platelet activatingfactor-- it is a ether glycerophospholipid , found in mammals . It is a potent signal molecule that causes platelet aggregation and dilation of blood vessels . In ether glycerophospholipid , the ether-linked chain may be saturated or may contain .a double bond between C-1 and C-2.