The first vascular reaction in inflammation is Vasodilation.

Explanation:

Inflammation is the body's protective response to tissue injury or infection. It is characterized by the classical signs of redness (rubor), heat (calor), swelling (tumor), pain (dolor), and loss of function (functio laesa). The initial vascular changes in the inflammatory process include:

1. Vasoconstriction: This is a temporary response that occurs immediately after injury to minimize blood loss. However, it is quickly followed by the more significant and prolonged phase of vasodilation.

2. Vasodilation: This is the first major vascular reaction in the inflammatory response. Vasodilation occurs due to the release of substances such as histamine, bradykinins, and prostaglandins from the damaged tissue cells and mast cells. These substances are known as vasodilators and they cause the smooth muscles surrounding the blood vessels to relax, leading to an increase in the diameter of the blood vessels. This results in increased blood flow to the injured area, which is essential for delivering white blood cells, nutrients, and oxygen to the site of inflammation. The increased blood flow is what causes the characteristic redness and heat of an inflamed area.

3. Increased vascular permeability: Although it is not the first vascular reaction, increased vascular permeability is a critical component of the inflammatory process. After vasodilation, the endothelial cells that line the blood vessels become more permeable, allowing plasma and proteins to leak out of the vessels into the surrounding tissue. This leads to the formation of an exudate, which is the accumulation of fluid and proteins that makes up the swelling (edema) seen in inflammation.

4. Marginisation or Pavementing: This is the process where neutrophils (a type of white blood cell) move along the walls of blood vessels towards the site of inflammation. It occurs later in the inflammatory response after the initial vasodilation and increased vascular permeability. These cells then migrate through the vessel walls into the tissue to combat pathogens and debris.

Chicken pox presents with multiple dermal lesions characteristically with vesicles, pustules which may secondarily ulcerate

Extensive cellulitis is most accurately described by the term "phlegmon

Phlegm is a thick, viscous substance produced by the respiratory tract, especially during a respiratory infection, which can be coughed up from the lungs or expelled from the nose. It is primarily composed of mucus, dead cells, and other substances.

Phlegmon is a term that is closely related to extensive cellulitis. It refers to a severe form of cellulitis where the infection has spread deeply into the subcutaneous tissues and is accompanied by significant inflammation, including the presence of pus and necrosis. Phlegmon is characterized by intense pain, swelling, redness, and warmth in the affected area. This condition often requires aggressive medical management, including intravenous antibiotics and surgical drainage if an abscess forms. It is an advanced and severe stage of cellulitis that can lead to systemic infection if not treated properly.

The newly formed collagen in the scar tissue is arranged differently compared to the organized collagen fibers in the unwounded skin, leading to a weaker structure. The 70-80% tensile strength is typically what is seen in well-healed sutured wounds. This remaining deficit is because scar tissue is less elastic and more prone to dehiscence (reopening) under tension compared to normal skin.

Sickle cell disease results from mutation, or change, of certain types of hemoglobin chains in red blood cells (the beta hemoglobin chains).

When the oxygen concentration in the blood is reduced, the red blood cell assumes the characteristic sickle shape. This causes the red blood cell to be stiff and rigid, and stops the smooth passage of the red blood cells through the narrow blood vessels.