inflammation and infection. nonspecific skin 650,000 microbes/square inch; 100 trillion/ person...
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Inflammation and Infection
Nonspecific Skin
650,000 microbes/square inch; 100 trillion/ person (acts as a place holder)
Sebaceous (oil) and odoriferous (sweat) secrete antibacterial acids and enzymes
Mucous membranes trap invaders
Defense Mechanisms
Nonspecific Inflammatory response- isolate
invader, destroy it, and clean up debris
Specific much slower All cells have protein or saccharide
markers called ANTIGENS
Defense Mechanisms
Specific when an antigen of the invader
is identified, lymphocytes produce ANTIBODIES
This defense has ability to remember the invader and to produce more antibodies if the invader returns
Defense Mechanisms
Nonspecific cellular and vascular response to tissue TRAUMA
Only occurs where blood supply exists (no gangrene)
May be so intense that it harms the tissues Anaphylactic shock Autoimmune diseases
Inflammation
When any trauma happens, including injury, microbial infection, ischemia (decreased oxygen in cells), freezing, burning, electrocution, radiation, and chemical irritation
Inflammatory Process
MAST CELLS (histocytes) are in all cells When injured, they produce HISTAMINE
that causes blood vessels to dilate and increase blood flow
HYPEREMIA causes increased redness and heat in area
Hyperemia brings increased white blood cells (neutrophils also called polymorphonuclear cells- PMNs)
Inflammatory Process
These cells also line the endothelium of the vessels (capillaries become permeable)
Blood fluid called EXCUDATE leaks into tissue
Leaking causes swelling (edema) With edema, pressure is put on nerve
endings causing pain
Inflammatory Process
Inflammatory Process
5 Cardinal Signs of Inflammation
Vascular permeability also allows neutrophils to escape into tissues (DIAPEDESIS)
Neutrophils arrive in great numbers and readily move into action by a process called CHEMOTAXIS
Neutrophils detect chemicals released by bacteria, injured tissue, and proteins and they are then drawn to the area
Inflammatory Process
Begin phagocytosis (cell eating) Neutrophils life is short and they die
and then are mixed with blood fluid to make PUS
Inflammatory Process
In 3-4 days, large numbers of monocytes (large eater) arrive
More killing power and are on clean up crew This INFLAMMATION is considered acute
Inflammatory Process
After 7-10 days if the inflammation is still present, then the lymphocytes are brought in
They use a slower, more specific attack
Inflammatory Process
Last mare than 2 weeks Microscope shows large amounts of macrophages
and fewer neutrophils If macrophage cannot help, a granuloma might be
formed These are fibrous deposits of collagen and may
calcify Ex: Tuberculosis or foreign object like a splinter
Chronic Inflammation
LEISIONS can be external or internal They can often be identified from fluid
Serous exudate- clear, serum-like (Ex: blisters) Fibrinous exudate- fluid and large amounts of
fibrinogen (Ex: strep throat or if dried, a scab) Purulent exudate- full of dead neutrophils,
tissue debris, and pyogenic (pus forming) bacteria. If localized, it is called an abscess. If in a body cavity, it is called an empyema
Inflammatory Exudates
Include wounds, ulcers, wheals, blisters, vesicles, pustules, tumors, etc. Abscesses
Caused by streptococcal or staphylococcal bacteria
Body tries to keep it contained If a large abscess ruptures, it forms a tract or
opening in skin called a sinus If the tract connects two organs, it is called a
fistula
Inflammatory Lesions
Ulcers Deep loss of tissue, crater-like lesion Pressure sores or decubitus ulcers are common
problems in health care
Inflammatory Lesions
Cellulitis widespread, acute inflammatory process General edema and redness Caused by streptococcus or staphylococcus
Inflammatory Lesions
http://www.youtube.com/watch?v=FXSuEIMrPQk (Khan Academy)
http://www.youtube.com/watch?v=IuAfs970rjs
http://www.youtube.com/watch?v=IWMJIMzsEMg (animated)
http://www.youtube.com/watch?v=WJEc2GDEfz8 (cartoon)
Inflammation Videos
Tissue Repair*Cellular proliferation or division categories * mitotic- continually divide (Ex: skin and
mucosa of internal organs) * facultative mitotic- cells do not divide regularly but can be stimulated to
do so when needed (Ex: liver and kidney, but some tissue needs to be there)
* non-dividing cells- don’t divide EVER! (Ex: brain cells, heart muscle cells- repair is only scarring)
Tissue Repair and Healing
Methods of repair Regeneration
Involves mitotic cell division (bone, skin, bone marrow)
Fibrous Connective Tissue Repair Scar formation – bridge between
normal tissue and the wound, but DOES NOT restore function
Examples: brain tissue, heart muscle
Tissue Repair
http://www.youtube.com/watch?v=IYL6vg89uds
Primary Union (First Intention)*Wound edges are clean* Steps 1. line fills with serum, forming a scab 2. in 1-2 days, new capillaries bridge the gap
between the edges3. in a few days fibroblasts grow across the
deeper wound layers and begin to deposit collagen in fibrous network (granulation tissue)
4. collagen begins to contract pulling edges together and forming a scar**In a few weeks, incision will look healed but deep layers may not be for a month or more
Tissue Healing
Secondary Union (Secondary Intention) When dirty, or deeper degree of tissue damage
or cannot be pulled together Same process but with much more
inflammation to resolve Large numbers of capillaries, fibroblasts, and
collagen must be produced After a week, new soft tissue called granulation
tissue is formed and later replaced with collagen
Collagen contracts, pulling the wound edges together
Healing depends on size of wound- may need skin graph
Tissue Healing
Increased levels of dirt, bacteria, dead leukocytes, etc might make the body take months to eat up.
Wounds must be cleaned or DEBRIDED Other factors effecting healing time
Age, size of wound, location of wound, nutrition, immobility, and circulation
Organism virulence (strength) steroids
Delayed Wound Healing
Prolonged wound healing Poor or excessive scar formation
DEHISCENSE- scar does not have enough strength and separates at margin
Excessive collagen formation results in a raised scar called a keloid (more common in African- Americans)
ADHESIONS form scar tissue that adheres to a nearby organ (often after surgery)
Complications of Wound Healing
Complications or Wound Healing
Symptoms Fever Tachycardia Malaise Leukocytosis Septicemia
Tests Cutures- organism grown in agar, often with
sheep’s blood Culture and sensitivity tests- microorganisms
smeared on agar and small antibiotic-permeated disks are placed on the agar- killing zones are identified
Antigen-antibody (reactive tests or serologic tests) Skin testing (TB- Mantoux test) for induration
(positive test) Xpert test for MRSA- DNA testing
Testing for Infection