CELLULAR RESPONSE TO INJURY, ACUTE INFLAMMATION,HEALING AND REPAIR,CHRONIC INFLAMMATION

BY;JEGANATHAN.C2ND YEAR M.SCDEPT. OF BIOMEDICAL SCIENCE

CELL INJURY

● Cells actively control the composition of their immediate environment and intracellular milieu within a narrow range of physiological parameters(homeostasis)

CELL INJURY

Mechanisms of Cell Injury

● Depletion of ATP● Mitochondrial Damage● Influx of Intracellular Calcium and Loss of Calcium

Homeostasis● Accumulation of Oxygen-Derived free radical

(Oxidative stress)● Defects in Membrane Permeability

Morphology of Cell Injury and Necrosis

● Cell Injury – Reversible● – Irreversible

● Cell Death – Necrosis● – Apoptosis

Cell Injury and Death

● Reversible Injuryo Cell swelling develops when cells are incapable of fluid an

ion homeostasis (↓ed function of ATP dependant pumps).o Fatty change the accumulation of lipid vacuoles in the

cytoplasm.● Irreversible injury (Necrosis)o Two basic processes underlie the morphologic changes of

necrosis▪ Denaturation of protein▪ Enzymatic digestion of cell components

Reversible vs irreversible cell injury

● Reversible injury● * Decreased ATP levels● * Ion imbalance● * Swelling

● Decreased pH● Fatty change (liver)

Irreversible injury* Amorphous densities in mitochondria* Severe membrane damage* Lysosomal rupture• Extensive DNA

damage

Morphology of Cell Injury

● Plasma membrane alteration● Mitochondrial Changes● Dilation of Endoplasmic reticulum● Nuclear Alteration

Reversible Injury

Cellular swellingFatty change

HEALING AND REPAIR

REPAIR

● Process by which the cells in the body regenerate and repair to reduce the size of the damage or necrotic area and replace it with new loiving tissue.

PROCESS

● Recall phase

● Resolution phase

● Regeneration phase

● Repair phase

Soft Tissue Healing

● Inflammatory Phase (0-6 days)

● Proliferation Phase (3-21 days)

● Regeneration and Maturation Phase (up to 1+ year)

Skin Tissue

● Epidermis

● Dermis

● Subcutaneous Layer

Skin Injury Classification

● Abrasions

● Blisters

● Skin Bruises

● Incisions

● Lacerations

● Avulsions

● Punctures

Muscles

● Epimysium

● Perimysium

● Endomysium

● Fasciculus

● Muscle Fibers

● Myofibrils

Bones

● Calcium Carbonate

● Calcium Phosphate

● Collagen

● Water

Bone Injury Classification

● Fractures

● Closed

● Compounded

● Transverse

● Comminuted

● Oblique

● Epiphyseal

● Spiral

● Greenstick

● Avulsion

● Impacted

● Depressed

Nerves

● Afferent Nerves (Affectors)

● Efferent Nerves (Effectors)

Nerve Injury Classification

● Tensile forces cause stretching of the nerve fibers.

● Grade I: Neurapraxia: temporary loss of sensation and/or motor function.

● Grade II: Axonotmesis: significant motor and mild sensory losses.

● Grade III: Neurotmesis: motor and sensory losses persisting for up to one year.

Acute & Chronic

Inflammation

INFLAMMATION

Inflammation:Inflammation is the reaction of blood vessels, leading to the accumulation

of fluid (Serum) and leukocytes in extra vascular tissue.

Role of tissue and cells in inflammation

The circulating cells are:

● Neutrophils.

● Monocytes.

● Eosinophils.

● Lymphocytes.

● Basophils.

● Platelets.

Sign & Symptoms Of InflammationThese are:

● Fever (increase temperature).

● Pain.

● Tissue damage.

● Swelling of tissue.

● Redness of tissue.

● Loss of movements or restricted movement, if near joints.

Types Of Inflammation

Inflammation is divided into

I - Acute inflammation, which occurs over seconds, minutes, hours, and days.

II - Chronic inflammation, which occurs over longer times, days & months.

Acute Inflammation

● Acute inflammation, begins within seconds to minutes following the injury of tissues.

● The damage may be purely physical, or it may involve the activation of an immune response.

Chronic Inflammation

Chronic inflammation is of longer duration and is associated histologically with the presence of:

● Lymphocytes and macrophages.

● The proliferation of blood vessels.

● Fibrosis and tissue necrosis.

Response Of Inflammation

The main processes are:

I - Increased blood flow.

II - Increased permeability.

III - Migration of neutrophils.

IV - Chemotaxis.

V - Leucocytes recruitment & activation.

Response of Acute Inflammation

● Increased Blood Flow, increased permeability and Edema in Inflammation:

● The increased blood flow & increased permeability are readily visible within a few minutes following a scratch that does not break the skin.

Response of Acute Inflammation

● At first, there is pale red line of scratch.

● Later on there is accumulation of inflammatory cells lead swelling, (inflammation).

● Finally, there is accumulation of interstitial fluid cause edema.

Acute Inflammation

Acute Inflammation(Acute Bronchitis)

Chronic inflammation

● It is the inflammation of prolong duration (weeks or months).

● It is occurred as:

● Following acute inflammation.

● Occurs, incidentally as active inflammation.

● With tissue destruction.

With repair process.

Chronic Inflammation(Chronic Bronchitis)

Chronic Bronchitis

Causes of Chronic inflammation

I - Persistent infection:

● Bacteria.

● Viruses.

● Fungi.

● Parasites

Chronic Inflammation

Causes of Chronic inflammation

II - Prolonged exposure to potentially toxic agents:

● Endogenous, (atherosclerosis).

● Exogenous, ( particulate silica-Silicosis).

Causes of Chronic inflammation

III - Autoimmunity:

Occurs in:

● Rheumatoid arthritis.

● Lupus erythmatosus.

Chronic Inflammation(Rheumatoid arthritis)

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