Every day we expose to a large number of harmful agents, but our immune system defends against disease from harmful organisms. The network of Proteins, Cells, and organs that protects the body against infection agents or harmfull
What is immunity?
The Individuals to Fight against diseases causing Organisms is called Immunity. The Proteins and cells are fight against harm full agents such as Bacteria, Viruses, Animal Parasite. The Proteins and cells are fight against harm full agents such as Bacteria, Viruses, Animal Parasite.
The Branch of Biology that Deals with immunity or The Study of Immunity System is Called Immunology. Edward Jenner is the the Father of Microbiology. Immunity is defined as the resistance to Infections. The Immunity it is carried by Disposal of foreign materials. To Understand the Immunology We have to Know basic Concepts. They are Lines of Defence, Cells, Organs and Soluble Mediators of the Immunity System.
Lines of Immunity System:
To Understand the immunology we have to know basics concepts of lines of defence, Cells, Organs and Soluble Mediators of Immunity System
- If Bacteria, Viruses, Fungai are trying to enter the body to Prevent the entry by Skin (Skin is the Largest Organ in the Body), Mucus Membrane and Lysozymes of Saliva. This is the First line of Defence. It is Physical Barrier to in wanding the body.
- If Cross the First line of Defence and Enter the body Phagocytes, Nature Killer Cells, Anti-Microbial Substances etc.., Destroy them. This is called Second Line of Defence.
- If cross the Second line of Defence Then Antibodies and lymphocytes will fight with the Harmfull Agents. This is called Third Line of Defence.
B-Cells
- Anti-bodies that are Produced from lymphocytes that are Capable to Capture the antigens is called B-Cells.
- B – Cells are produced in Adults from Bone Marrow.
- B – Cells are Produced in foetus from Liver.
- B – Cells are Produced in Birds from Bursa of Fabricius.
- Various Antibodies are Synthesized from Mature B – Cells.
- Mature B-cells are called Immuno Competent B-Cells.
- These are Reaches Secondary Lymphoid Organs.
T-Cells
- T-Cells are not capable of Producing Antibodies.
- T-Cells Cannot Recognise the Free and Circulating antigens.
- It is Produced from Bone Marrow.
- It reaches the Thymus Gland.
- T-Cells are Differentiate into Mature T-Cells 0r Immuno Component
Types of T-cells:
- Based on the molecules, it diveded into Two types:
- they are CD4 Cells or T4 Cells and CD8 Cells or T8 Cells
- Based on Functions of T-cells are Two Types.
- They are T Helper Cells or TH Cells and T Cytotoxic Cells or Tc Cells.
T Helper Cells:
- T Helper Cells also CD4+ Cells
- It Recognise The Antigens Presented By the APC.
- They help B-Cells in Producing antibodies.
Organs of Immunity System
Based on Functions These are Divided into Two Types:
They are : 1. Primary Lymphoid Organs
2. Secondary Lymphoid Organs.
Primary Lympoid Organs:
Thymus Gland:
- It is a Soft Organ.
- It is Thyme leaf shape.
- Colour : Pinkish Grey
- Weight : 10 – 15Gms and Grows until Puberty.
- It is Present behind the Sternum and between the lungs, above the heart.
- It is the Training Center of T-Lymphocytes.
- It Develops from Epithelium of 3rd and 4th Pharyngeal Pouches.
- It Starts from 6th month of gestation Period.
- Number of Lobes
- Human having 2 Lobes
- Birds having 7 Lobes
Cortex
- It is Tightly Packed with Immature Lymphocytes.
- It contains Lymphocytes and Reticular Cells.
- These Lymphocytes are Multiply Rapidly
- Reticular Cells larger than Lymphocytes
Medulla
- It is a Vascular Structure.
- It Contains maximum number of Mature Cells.
- The Muture Cells are moves from Cortex to Medulla.
- It Contains both Reticulate Epithilial Cells and Lymphocytes.
- Lymphocytes are Scattered.
- Reticular Epithelial Cells is More than Lymphocytes No
