Objectives For Inflammation and tissue repair

• Introduce student to the inflammation process

• Expose students to the mechanism of

inflammation and tissue repair

• Expose students to the process involved in cell and

tissues after inflammation.
 LEARNING OUTCOMES

• LO 1: Identify the inflammation process.

• LO 2: Describe the mechanism of inflammation and repair.

• LO 3: Describe the process involved in cell and tissue

regeneration.
INFLAMMATION AND REPAIR

• Acute inflammation
• Chronic inflammation
• Tissue repair
• Cell and tissue regeneration
• Factors that influence tissue repair
• Definition -
• Inflammation is a response of vascularized tissues to
infections and tissue damage that brings cells and molecules
of host defense from the circulation to the sites where they
are needed, to eliminate the offending agents.
• Inflammation - protective action of the body to a variety of
damaging stimuli, including trauma and infection.

• The body’s response to inflammation brings fluid, proteins and

cells from the blood into the damaged tissues where they are
needed.
PURPOSES OF INFLAMMATION

• It is a protective host response that delivers leukocytes and

plasma proteins from the blood to the sites of infection.
• - without inflammation, infections would go unchecked & wounds
would never heal .
• Serves to eliminate:- the initial cause of injury (microbes, toxins ,
causative agent )- consequences of such injury (necrotic cells or
tissue).
• Inflammation induces the process of repair to heal the damaged
tissue at the same time as it destroys, dilutes or walls off the
injurious agent.- by regeneration of parenchymal cells- filling of
the defect with fibrous tissue (scarring)
• IMPORTANCE OF INFLAMMATION
• Protective response that is essential for survival.

• Get rid the host of both the initial cause of cell injury (e.g.,
microbes, toxins) and the consequences of such injury (e.g.,
necrotic cells and tissues)

• Without inflammation, infections would go unchecked, wounds

would never heal, and injured tissues might remain permanent
festering sores.
• ACUTE INFLAMMATION

• Acute inflammatory response by the host to any agent is a

continuous process
it can be divided into following two events:
• I. Vascular events.
• II. Cellular events.
 Offending agent (Recognized by host cells and
molecules)

Leukocytes & plasma proteins are recruited from the

circulation to the site

Leukocytes & proteins are activated and work together to

destroy and eliminate the offending substance

The reaction is controlled and terminated.

The damaged tissue is repaired.

 ACUTE INFLAMMATION
• Acute inflammation is a rapid host response that serves to
deliver leukocytes and plasma proteins to sites of infection or
tissue injury
• Has three major components:
1. Alterations in vascular caliber – that lead to an increase in
blood flow.
2. Structural changes in the microvasculature – that permit
plasma proteins and leukocytes to leave the circulation.
3. Emigration of the leukocytes from microcirculation, their
accumulation at the site of injury, and their activation to
eliminate the offending agent.
Acute Inflammation
It typically develops within minutes or hours and is of short
duration, lasting for several hours or a few days.
Its main characteristics are the exudation of fluid and plasma
proteins (edema) and
When acute inflammation achieves its desired goal of
eliminating
the offenders, the reaction subsides, and residual injury is
repaired.
But if the initial response fails to clear the stimulus,
the reaction progresses to a protracted type of
inflammation that is called chronic inflammation.
 CHRONIC INFLAMMATION
•CHRONIC INFLAMMATION Characterized by:
Mild irritant with a prolonged action.
•Tissue response is gradual and prolonged (mild vascular
dilatation and congestion)
•Tissue destruction is progressive and gradually replaced by
fibrous tissue with thickening and narrowing of blood vessels
(endarteritis obliterans).
•Scanty fluid exudate
CHRONIC INFLAMMATION
•Chronic Inflammatory Cellular Exudate
Composed of: Lymphocytes
• Plasma cells
•Macrophages Giant cells
• Eosinophils in parasitic and allergic inflammation.

•Types of Chronic Inflammation

1- Chronic non-specific inflammation
•Different irritants produce inflammatory reaction of the
same microscopic picture-
•Chronic specific inflammation Each irritant produces
inflammation of a characteristic microscopic picture
 Acute Chronic
Permanent present of the
Cause Single injury
causing agent /bacteria, etc./
Weeks, months, years;
Duration Hours, days
depending on the causing agent
Presentative ↑ permeability, Proliferative fibroblasts
symptom exudation No exudation
Liquid
Proteins Macrophage Lymphocytes
Main
/proteases and Eosinophyl granulocytes
components
antiproteases/ Connective tissue hiperplasy
in the
PMN leukocytes
process
Macrophages
Connecting
reactions Thrombosis Immune response
• The external manifestations of inflammation,
• often called its cardinal signs, are :

• heat (calor in Latin),

• redness(rubor),
• swelling (tumor),
• pain (dolor), and
• loss of function (functio laesa).
• CAUSES OF INFLAMMATION
• Infections - (bacterial, viral, fungal, parasitic) and microbial
toxins- most common & medically imp causes of
inflammation.
• Tissue necrosis - Several molecules released from necrotic
cells are known to trigger inflammation
• Foreign bodies - (splinters, dirt, sutures) may elicit
inflammation by themselves or because they cause traumatic
tissue injury or carry microbes
• Immune reactions - (also called hypersensitivity) are
reactions in which the normally protective immune system
damages the individual’s own tissues
I. VASCULAR EVENTS
• Alteration in the microvasculature (arterioles, capillaries and
venules) is the earliest response to tissue injury.

• These alterations includes: haemodynamic changes and

changes in vascular permeability.
• Haemodynamic Changes

TRANSIENT VASOCONSTRICTION OF ARTERIOLES.

(3-5 minutes ,severe last more than 5 min)

PERSISTENT PROGRESSIVE VASODILATATION.

Vasodilatation - increased blood volume in microvascular bed of the area -
redness and warmth at the site of acute inflammation.

Increased LOCAL HYDROSTATIC PRESSURE resulting in transudation of

fluid into the extracellular space- Swelling.

SLOWING OR STASIS OF MICROCIRCULATION - increased concentration

of red cells & raised blood viscosity.

LEUCOCYTIC MARGINATION (mostly neutrophils) move and migrate

extravascular space – Emigration
 COMPONENTS OF THE HEMATOLOGIC SYSTEM
• Composition of Blood:
• Plasma
• Plasma proteins :albumin
• Blood cells
• FORMED IN BONE MARROW
• “HEMATOPOIESIS”

• Erythrocytes
• Leukocytes
• Thrombocytes
 NEVER LET MONKEYS EAT BANANAS!
THE FIVE TYPES OF LEUKOCYTES, IN ORDER OF PREVALENCE

• Never
(NEUTROPHILS)
• Let
(Lymphocytes)
• Monkeys
(Monocytes)
• Eat
(Eosinophils)
• Bananas
(Basophils)
 SUMMARY

• Inflammation, the local response of the vascularised living

tissue to injury.
• Could be acute or chronic.
• Several cells & molecules that play important roles in
inflammation.
• Inflammation has vascular and cellular events to eliminate
the cause.
• Vascular events include vasodilation and increased
permeability to deliver a protein rich fluid to site of
inflammation.