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Dr. Shaikh Mujeeb Ahmed Assistant Professor AlMaarefa College

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1 Dr. Shaikh Mujeeb Ahmed Assistant Professor AlMaarefa College
IMMUNITY HMIM BLOCK 224 Dr. Shaikh Mujeeb Ahmed Assistant Professor AlMaarefa College

2 Objectives General overview of the immune system
Different components of innate & acquired immunity. Phases of immune response.

3 What is Immunity ? Immunity is the body’s ability to resist or eliminate potentially harmful foreign materials or abnormal cells.

4 What are the types of immunity
Innate (natural) immunity Acquired (adaptive) immunity

5 What is meant by innate immunity ?
These nonspecific responses are inherent (innate or built-in) defense mechanisms that nonselective defend against foreign or abnormal material of any type, even on initial exposure to it.

6 What is it includes? Barriers Defensive cells Chemical defenses
Physical Chemical Defensive cells WBCs Macrophages Natural killer cells (NK) Chemical defenses Complement system

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8 Barriers Integumentary system Mucus membrane & lysozyme

9 Cells Langerhans cells Phagocytes Natural killer cells
Basophils and mast cells

10 Chemicals Interferon Complement system inflammation

11 Interferon α, β, and γ interferon By infected cells
Block viral reproduction

12 Innate Immunity Mechanism of Action of Interferon in Preventing Viral Replication

13 Complement System Series of ~ 20 proteins Activated by microorganisms
Will coat the microorganisms Adherence reactions phagocytic cells have receptors for C3 Biological active fragments produce reactive oxygen intermediates Membrane lesions Activate mast cells Inactivated---specific inhibitory proteins if complement doesn’t bind quickly then ecome inactivated

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15 Acquired (adaptive) immunity
specific immune responses selectively targeted against a particular foreign material to which the body has already been exposed. The foreign material may be an antigen or a hapten

16 Immune Response Antigen
Antigen – “any substance when introduced into the body stimulates the production of an antibody” Bacteria, fungus, parasite Viral particles Other foreign material Pathogen – an Antigen which causes disease

17 Immune Response Antibodies
Antibody – “a Y-shaped protein, found on the surface of B-Cells or free in the blood, that neutralize antigen by binding specifically to it” Also known as an Immunoglobulin Antigen

18 Hapten Not antigenic by itself
When combines with protein it become an antigen

19 Adaptive immunity Two types
Active immunity – direct encounter with the antigen. Passive immunity – without encounter with the antigen Antibodies transferred from mother to the fetus. Immunization by injecting antibodies

20 Active immunity Cell mediated immunity (T cell immunity)
Antibody mediated (humoral/ B cell) immunity

21 T and B Lymphocytes

22 Origins of B and T lymphocytes
After early childhood most new lymphocytes are derived from peripheral lymphocyte colonies rather than from bone marrow

23 Interactions between T- and B-Cells
T- memory Cell T-supressor Pre-T Cell T-Cell T8-ctotoxic T4-helper Bone Marrow Pre-B Cell B-Cell Plasma Cell B- memory Cell IgG IgA IgM IgD IgE

24 Phases of immune mechanism
Initial phase Entry of antigen and its contact with the specific receptor on lymphocytic membrane. Central phase Cooperation among different subset of lymphocytes that proliferate and differentiate to form T & B lymphocyte + memory cells Effector phase Inactivation of antigen by sensitized T & B lymphocytes

25 References Human physiology by Lauralee Sherwood, seventh edition
Text book physiology by Guyton &Hall,11th edition Text book of physiology by Linda .s contanzo,third edition


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