Question

Histamine, leukotrienes, prostaglandins, and bradykinin are examples of which of the following? a. chemical mediators primarily found in the digestive system b. chemical mediators that promote inflammation c. antimicrobial peptides found on the skin d. complement proteins that form MACs

Short answer

Option b: chemical mediators that promote inflammation.

Step-by-step solution

Read and Understand the Question

Determine what the question is asking about histamine, leukotrienes, prostaglandins, and bradykinin. Specifically, identify the common function or characteristic shared by these substances.

Analyze Each Option

Look at each option given: a, b, c, and d. Determine whether histamine, leukotrienes, prostaglandins, and bradykinin fit into these categories based on their common function or characteristic.

Evaluate Option a

Option a suggests that these substances are chemical mediators primarily found in the digestive system. Research or recall that these substances are primarily involved in processes other than digestion. Thus, eliminate option a.

Evaluate Option b

Option b suggests that these substances are chemical mediators that promote inflammation. Recall that histamine, leukotrienes, prostaglandins, and bradykinin are all involved in the inflammatory response. This fits the description well. Keep option b as a potential correct answer.

Evaluate Option c

Option c suggests that these substances are antimicrobial peptides found on the skin. Recall that histamine, leukotrienes, prostaglandins, and bradykinin are not primarily known for being antimicrobial peptides. Eliminate option c.

Evaluate Option d

Option d suggests that these substances are complement proteins that form Membrane Attack Complexes (MACs). Recall that complement proteins like C5b, C6, C7, C8, and C9 form MACs, not histamine, leukotrienes, prostaglandins, or bradykinin. Eliminate option d.

Choose the Correct Answer

Based on the analysis, the most fitting description for histamine, leukotrienes, prostaglandins, and bradykinin is option b: chemical mediators that promote inflammation.

Key concepts

Histamine

Histamine is a compound that plays a crucial role in the inflammatory response. It is stored in granules by cells, particularly mast cells and basophils. When these cells are stimulated, histamine is released into the surrounding tissue. This release leads to several physiological changes:

• Increased permeability of blood vessels, allowing white blood cells and proteins to enter the affected tissue.
• Dilation of blood vessels, which increases blood flow to the area.
• Stimulation of nerve endings, which can cause itching or pain.

Histamine is also involved in allergic reactions, such as those experienced during hay fever or insect stings. It is the target of many antihistamine drugs designed to reduce allergic symptoms.

Prostaglandins

Prostaglandins are a group of lipid compounds that are produced by almost every cell in the body. They have a variety of roles, many of which are related to inflammation. Prostaglandins are derived from fatty acids and synthesized at the site of tissue damage or infection. Their primary functions include:

• Promoting inflammation by provoking fever, pain, and swelling.
• Regulating the contraction and relaxation of smooth muscle, including those in the uterus and blood vessels.
• Influencing blood flow and the formation of blood clots.

Because prostaglandins are involved in pain and fever, drugs like NSAIDs (Nonsteroidal Anti-Inflammatory Drugs) target their production to provide relief.

Bradykinin

Bradykinin is a peptide that contributes to the inflammatory response by causing blood vessels to dilate (expand) and become more permeable. It works in conjunction with other inflammatory mediators to elicit several key effects:

• Inducing vasodilation, which increases blood flow to injury sites.
• Enhancing vascular permeability, allowing immune cells to reach affected tissues more easily.
• Triggering pain receptors, contributing to the sensation of pain during inflammation.

Bradykinin is also known to play a role in lowering blood pressure by promoting the excretion of sodium in the kidneys.

Leukotrienes

Leukotrienes are a family of eicosanoid chemical mediators derived from arachidonic acid. These compounds are produced primarily by leukocytes (white blood cells) and play a substantial role in the inflammatory response. Key actions of leukotrienes include:

• Attracting white blood cells to the site of inflammation, a process known as chemotaxis.
• Increasing vascular permeability, which allows fluid and immune cells to move into tissues affected by inflammation.
• Provoking bronchoconstriction, which can lead to symptoms of asthma.

Leukotriene modifiers are medications used to manage and treat conditions such as asthma and allergic rhinitis by blocking the effects of leukotrienes.