Histamine- comes from mast cells, basophils, platelets. Causes vasodilation, increased vascular permeability, endothelial activation.
Serotonin- comes from platelets, causes vasoconstriction.
Prostaglandins- comes from mast cells and leukocytes. Causes vasodilation, pain, and fever.
Leukotrienes- comes from mast cells and leukocytes. Causes increased vascular permeability, chemotaxis, leukocyte adhesion and activation.
Platelet-activating factor- Comes from leukocytes and mast cells. Causes vasodilation, increased vascular permeability, leukocyte adhesion, chemotaxis, degranulation, oxidative burst.
Reactive Oxygen Species- Comes from leukocytes. Causes killing of microbes that are phagocytosed and tissue damage (high levels cause thrombosis and increased permeability, breakdown of ECM, and direct injury to other cell types).
Nitric Oxide (NO)- Comes from endothelium and microphages. Causes vascular smooth muscle relaxation, vasodilation and killing of microbes (cytotoxic agent).
Cytokines (TNF, IL-1, IL-6)- Come from macrophages, endothelial cells, mast cells. Locally cause endothelial activation (expression of adhesion molecules). Systemically cause fever, metabolic abnormalities, hypotension.
Chemokines- Come from leukocytes and activated macrophages. Cause chemotaxis and leukocyte activation.
Activation of thrombin and formation of fibrin.
INTRINSIC PATHWAY: Begins with factor XII and through a cascade of enzymatic reactions activates factors XI, IX, and VII in sequence. All the components that ultimately lead to fibrin clot formation are intrinsic to the circulating plasma and no surface is required to initiate the process.
EXTRINSIC PATHWAY: Requires exposure of tissue factor on the surface of the injured vessel wall to initiate the arm of the cascade beginning with factor VII.
*Activation of the extrinsic or intrinsic clotting pathway results in production of activated factor X (the two pathways CONVERGE), and activation proceeds in sequence of factors II (prothrombin) and I (fibrinogen). Clot formation occurs after proteolytic conversion of fibrinogen to fibrin.
Propagation of the clotting reaction ensues with a sequence of 4 enzymatic reactions, each of which involves a proteolytic enzyme that generates the next enzyme in the cascade by cleavage of a proenzyme and a phospholipid surface, such as a platelet membrane. Factor VIIa combines with factor IXA to form the intrinsic factor complex, which is responsible for the bulk of conversion of factor X to Xa. Factor Xa combines with factor Va, on the activated platelet membrane surface, to form the PROTHROMBINASE COMPLEX which is responsible for converting prothrombin to thrombin. Thrombin has multiple factors in the clotting process, such as conversion of fibrinogen to fibrin and activations of many factors (including XII which stabilizes the fibrin clot), as well as activation of platelets. Once formed, thrombin leaves the membrane surface and converts fibrinogen by two cleavage steps into FIBRIN (the clot) and two small peptides termed fibrinopeptides A and B.
*Calcium ion is needed for these cascades
Macrophages, fibroblasts, epithelial cells, endothelial cells, keratinocytes. RE-EPITHELIZATION.
Epiderma resurfacing, fibroplasia, angiogenesis, ECM deposition, contraction. Characterized by fibroblast migration, deposition of ECM and formation of granulation tissue.
Migration of keratinocytes. PDGF and TGF-beta attract fibroblasts to the wound, they proliferate and make a matrix of fibroconnectin. Fibroblasts make immature collagen, fibrilar collagen from the connective tissue in wound healing.
Lymph flows through a system of lymphatic vessels (lymphatics) similar to blood vessels. Begins with LYMPHATIC CAPILLARIES, which are associated with blood capillaries.
They converge to form COLLECTING VESSELS which often travel alongside veins and arteries and share a common connective tissue sheath.
The collecting vessels empty into LYMPH NODES. The lymph trickles slowly through a node, where bacteria are phagocytized and immune cells monitor the fluid for foreign antigens. It leaves the other side of the node through another collecting vessel, traveling on and often encountering additional lymph nodes before returning to the blood.
Eventually, the collecting vessels converge to form larger LYMPHATIC TRUNKS, each of which drains a major portion of the body. There are 6 principal trunks: jugular, subclavian, bronchomediastinal, intercostal, intestinal, and lumbar trunks.
The lymphatic trunks converge to form two COLLECTING DUCTS, the largest of the lymphatic vessels. The right lymphatic duct receives lymphatic drainage from the right upper limb and the right side of the thorax and head and empties into the right subclavian vein. The Thoracic duct drains all the body below the diaphragm, and the left upper limb and the left side of the head, neck, and thorax.
*No pump, low pressure and speed- mechanism of flow is rhythmic contractions of the lymphatic vessels themselves.
*Flow is one way, it collects from the tissue and always deposits at the subclavian veins of the heart.
Abnormal tissue found in or on organism.
Primary skin lesions involve a variation in color or texture of the skin, they are the initial reaction to pathologically altered tissue.
Secondary skin lesions take place in primary lesion as result of infection, scratching, trauma.
Common terms- rashes, macules, patches, papules, plaques, nodules, vesicles, pastules, bullae, erosions, and ulcers.
Macule- flat, pigmented, circumscribed area less than 1 cm. Ex. freckle, flat mole
Papule- Solid, elevated, less than 1 cm, skin color or pigmented. Ex. wart, pimple.
Nodule- Palpable, circumscribed lesion. Larger and deeper than papule. Extends into dermal area. Ex. tumor.
Tumor- Sold, elevated, larger than 2cm, extends into dermal and subcutaneous layers.
Wheal- Elevated, firm, rounded, with localized skin edema (swelling). Varies in size, shape, color. Paler in the center, accompanied by itching. Ex. hives, bug bite.
Vesicle: Elevated, circumscribed, fluid filled, less than 0.5cm. Ex. shingles, chickenpox.
Pustule- Small, raised, circumscribed lesion that contains pus. Less than 1cm. Ex. acne, psoriasis.
Bulla- Vesicle or blister larger than 1 cm. Ex. second degree bur, poison ivy.
Excoriations- Linear scratch marks or traumatized abrasions of the epidermis. Scratch.
Fissure- Small slit or cracklike sore that extends into dermal layer. Caused by inflammation or drying.
Ulcer- Open sore or lesion that extends to the dermis and heals with scaring. Ex. basal cell carcinoma.
Wounds that drain purulent (pus) material, with bacteria identified on culture. IDed by edema (swelling w fluid), erythema (redness), and tenderness. Bacteria alone doesnt constitute an infection bc large numbers of bacteria can be present normally.
Deep infections present with fever and leukocytosis.
Common symptoms: Exudate, induration (hardness, mass formation), erythema, fever, biofilm, bad smell, necrotic tissue, slough tissue (yellow, tan, green, brown; moist in appearance)