Transcript Inflammation and Infection

Inflammation and Infection
Defense Mechanisms
 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
Inflammation
 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
Inflammatory Process
 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
5 Cardinal Signs of
Inflammation
Inflammatory Process
 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
Chronic Inflammation
 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
Inflammatory Exudates
 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 Lesions
 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
Inflammation Videos
 http://www.youtube.com/watch?v=FXSuEIMrPQk
(Khan Academy)
 http://www.youtube.com/watch?v=IuAfs970rjs
 https://www.youtube.com/watch?v=Non4MkYQpYA
(animated)
 http://www.youtube.com/watch?v=WJEc2GDEfz8
(cartoon)
Tissue Repair and Healing
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
 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 Healing
 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 edges
3. 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
Delayed Wound 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
Complications of 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 or Wound Healing
Testing for Infection
 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 agarkilling 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