Inflammation and Wound healing Flashcards
What are the 3 types of cell injuries?
1) Sublethal injury
2) Lethal injury
3)Cell adaptation to sublethal injury
Define sublethal injury
Alters function without causing cell destruction. Potentially reversible if the harmful stimulus is removed
Define lethal injury
Irreversible process that causes cell death
Define cell adaptation to sublethal injury
1) Hypertrophy
2) Hyperplasia
3) Atrophy
4) Metaplasia
5) dysplasia
Define hypertrophy
An expansion in the size of cells which results in increase tissue mass without cell division. Basically surrounding tissue around the cell gets bigger
Define hyperplasia
Multiplication of cells as a result of increased cellular division. Basically cells multiply an example is endometriosis
Define atrophy
Decrease in the size of a tissue or organ as a result of a reduction in the number or size of individual cells. Usually caused by diseases, low blood supply and nutritional deficiency. Basically cells shrink
Define metaplasia
Transformation of once cell type into another in response to a change in physiologic condition or an external irritant. Basically the cell changes forms
Define dysplasia
Abnormal differential of dividing cells that results in changes in their size, shape and appearance
What causes lethal cell injury?
- Hypoxia or ischemic injury
- Chemical or physic injury
- Viruses, bacteria
Define apoptosis
Programmed cell death
- Anticipated event that occurs in some regenerating tissue to create homeostasis
Define necrosis
Tissue death that occurs as a result of traumatic injury, infection or exposure to toxic chemical
What are 4 defences against injury?
1) Skin and mucous membranes
2) Mononuclear phagocyte system
3) Inflammatory response
4) Immune system
Define mononuclear phagocyte system
Consist of monocytes and macrophages (phagocytes) and their precursor cells.
- Monocytes and macrophages originate in the bone marrow
- Monocytes spend a few days in blood then change into macrophages
- Function include recognizing foreign material and replacing old or damaged cells
Define inflammatory response
Response to cell injury causes by pathogens, irritants or chronic health conditions
- inflammation does NOT mean infection
What are the 4 phases of the inflammatory response?
1) Vascular response
2) Cellular response
3) Formation of exudate
4) Healing
Define the 1st phase inflammatory response
Vascular response:
1) the arterioles in the area undergo vasoconstriction which is stimulated by the SNS.
2) Then platelets adhere to vessels and make a seal on the injured area which forms a fibrin platelet clot
3) Release proinflammatory mediators such as histamine which causes vasodilation
4) Then increases blood flow to the area called hyperemia and filtration pressure increases = increase in capillary permeability
What is the purpose of fibrin in the vascular stage?
Functions to minimize blood loss and trap bacteria, prevent their spread and start the healing process
Define the 2nd phase of the inflammatory response
Phagocytes produce mediators to inhibit vascular smooth muscle contraction and growth platelet aggregation
- Chemotaxis occurs: directional migration of WBC and ensures accumulation of neutrophils and monocytes at site of injury
Diapedesis: neutrophils, monocytes and macrophages collect along the capillary wall. Cells destroy and remove foreign material
Define neutrophils
First leukocyte at site of inflammation.
- They only last 24-48hours (short time)
They phagocyte bacteria aka engulf them
What is pus?
Dead neutrophils and digested bacteria
What else can release more neutrophils if needed?
Bone marrow. This will result in elevated WBC
What if there’s not enough neutrophils?
Bone marrow releases immature for of neutrophils called bands. This makes the body “shift to the left” which makes this a Systemic response. Basically it is BAD to be in this stage like you will most likely die or need immediate medical intervention. Your body is releasing stuff from the bone marrow which is a big NO NO. this conditions is seen in pts with acute bacterial infection
After the neutrophils what comes next?
Monocytes come in. arrive within 7 days after onset and can multiply if needed. They clean up anything the neutrophils weren’t able to do
What comes after monocytes?
- Lymphocytes: primary role is humoral and cell mediated immunity
- Eosinophils: released in large quantities during allergic reaction
- Basophils: carry histamine and heparin and release during inflammation
What are clinical manifestation of exudate formation?
Redness (hyperemia from vasodilation), heat, pain, swelling
What are some systemic manifestations to complement activation and release of cytokines?
- Leukocytosis with a shift to the left
- Increase pulse and heart rate
Fever
Describe fever for exudate formation
watch youtube
What are 3 types of inflammation?
1) Acute: healing occurs in 2-3 weeks
- Neutrophil predominant cell type
- Elevated C-reactive protein
2) Subacute: features of acute process but lasts longer
3) Chronic: lasts for weeks, months or years.
Injurious agent persists, repeated tissue injuries and lymphocytes and macrophages predominant cell type
What are the 2 types of healing process for cells?
1) Regeneration - replacement of lost cells and tissues with the same type
2) Repair - healing as a result of lost cells being replaced by connective tissues aka scar tissue
Usually occurs by primary, secondary or tertiary intention
Which cells are stronger regeneration or repair?
regeneration
What cells do not regenerate and occur with scar tissue?
Cardiac muscle cells do not regenerate
What is primary intention?
Wound is closed with suture a
What is secondary intention?
Wound is left open and allowed to heal with scar formation
What is tertiary intention?
Wound is intentionally left open because if it is closed immediately, healing could be impaired by contamination, infection, edema or poor circulation. They leave it open then when its ready they will close it with a suture
What are the 3 phases of primary intention healing?
1) Inflammatory phase - migration of epithelial cells and clots serving as meshwork for starting capillary growth
2) Granulation phase - secretion of collagen
3) Scar contracture - remodelling collagen and strengthening of scar
What factors delay healing?
1) Nutrition
2) Inadequate blood supply
3) Smoking
What is an important host defense?
fever
What is an acute intervention for healing?
Rest
Ice/heat
Compression
Elevation
what does histamine do for inflammation control?
causes vasodilation and stimulates contraction
what does serotonin do?
causes vasodilation and stimulates smooth muscle contraction
what does kinins do?
stimulation of pain
what does complement components do?
stimulates histamine release, stimulates chemotaxis
what does fibrinopeptides do?
stimulates chemotaxis for neutrophils and monocytes
what does prostaglandins and leukotrienes do?
prostaglandin = vasodilation
leukotrienes = stimulates chemotaxis
what do cytokines do?
act as a messenger between cells
what are the 4 local manifestations of inflammation and their meaning?
1) redness : hyperaemia from vasodilation
2) heat : increased metabolism at inflammatory site
3) pain: change in pH; never stimulation
4) fluid shift to interstitial space; fluid exudate accumulation
what is serous exudate?
thin watery clear - normal
what is fibrinous exudate?
thin watery and cloudy. this is an indication of fibrin strands present - normal
what is serosanguinous exudate?
pink blood and watery
what is sanguineous exudate?
red blood, indication of fresh bleeding
what is purulent exudate?
yellow thick and sticky pus
what is haemorraghic exudate?
dark red. thick and sticky
what is catarrhal exudate?
mucous. this exudate found in mucus membrane
