Understanding Inflammation & Healing: Phases, Effects, & Types, Study notes of Pathophysiology

Download Understanding Inflammation & Healing: Phases, Effects, & Types and more Study notes Pathophysiology in PDF only on Docsity!

Inflammation and Healing

BIO 375

Pathophysiology

Review of Normal Defenses

Review

of

Normal

Capillary

Exchange

Inflammation

 Inflammation is a biochemical and cellular process that occurs in vascularized tissues  Most of the essential components of the inflammatory process are found in the circulation and most of the early mediators of inflammation affect the vascular bed so as to increase the movement of plasma and blood cells from the blood into the tissues surrounding the injury.  These substances escaping from the circulation are called exudate and they defend the host against infection and facilitate tissue repair and healing  Inflammation and repair can be divided into several phases  The characteristics of the early inflammatory response differ from those of the later response  The different biochemical mediators and cells function together to:  Destroy injurious agents and remove them from the inflammatory site  Wall off and confine these agents so as to limit their effects on the host  Stimulate and enhance the immune response  Promote healing

Acute

Inflammation

Key Words:

• chemical mediators
• vasodilation
• hyperemia
• capillary permeability
• chemotaxis
• neutrophils
• diapedesis or emigration
• lysosomal enzymes In the area of injury, endothelial cells produce cell-adhesion molecules ( CAM s) that make their membranes sticky and they snag leukocytes. The leukocytes slow down and accumulate on the linings of capillaries and post capillary venules and then enter the damaged tissue by diapedesis. Chemicals released by basophils, mast cells, blood plasma and damaged tissue cells stimulate chemotaxis and phagocytosis.

Inflammation-Local Effects

 Redness  Warmth  Swelling or edema  Pain  Loss of function due to:  Lack of nutrition, e.g. liver cells  Swelling, e.g. joint movement

Local Effects-exudate formation

 Exudate refers to the interstitial fluid formed in the affected area.  Characteristics of exudate vary with cause of trauma:  Serous  Fibrinous  Purulent  Abscess  Bloody  Granuloma

Inflammation-Systemic Effects

 General manifestations:  Malaise  Fatigue  Headache  Anorexia  Fever

Chronic Inflammation

 Characteristics include:  Less swelling but more lymphocytes, macrophages and fibrocytes than acute inflammation  More collagen is produced in the area resulting in more scar tissue.  Granulomas may develop as an area is walled off by fibrous tissue as in tuberculosis  Frequently, more tissue destruction occurs in chronic inflammation Course of Inflammation and Healing

Drugs used to treat Inflammation

Types of Healing

 Resolution occurs when there is minimal damage, e.g. mild sunburn  Resolution is the restoration of original structure and physiological function  Regeneration is the healing process that occurs in damaged tissue when cells are replaced through mitosis by nearby cells.  Replacement by connective tissue occurs when there is extensive damage or the cells (e.g. brain or muscle) are incapable of mitosis (this is referred to as repair rather than resolution or regeneration) Healing by Regeneration: First and Second Intention

The Healing Process

 Blood clot forms and seals the area  Inflammation develops in the surrounding area  After 3-4 days, foreign material and cell debris have been removed by phagocytes, monocytes and macrophages  Granulation tissue grows into the gap from surrounding connective tissue

Complications of Healing

by Scar Formation

 Loss of function which results from loss of normal cells and lack of specialized structures of normal tissue, e.g. skin  Contracture is due to the fact that scar tissue is nonelastic and tends to shrink over time. This can restrict the movement of a joint and may eventually lead to fixation and deformity of the joint  Shortening of the scar tissue may also cause shortening or narrowing of structures, particularly tubes and ducts, e.g. hiatal hernia and difficultly in swallowing due to stenosis  Adhesions are bands of scar tissue joining two surfaces that are normally separate, e.g. intestinal or pleural adhesion

 Hypertrophic scar tissue is an excess of fibrous tissue which can shrink and distort and also includes keloid formation  Ulceration may occur due to impaired blood supply around the scar. This causes additional tissue breakdown and formation of ulcers, e.g. after stomach surgery  Plantar Keloid Earlobe Keloid 

Burns

 Burns are classified by the percentage of the body surface damaged and the depth of the skin damage.  Partial thickness involves the epidermis and part of the underlying dermis  Full thickness burns destroy all skin layers and require skin grafts for healing  Following severe burns, shock frequently occurs due to fluid and protein loss

 Infection is a threat due to loss of protection  Inhalation of toxic or irritating fumes may cause respiratory impairment  Healing of burns is a prolonged process and may require multiple skin grafts