Skip to main content

Immunity And Human Immune System- Class 12 Biology

Immunity And Human Immune System- Class 12 Biology

The science dealing with the various phenomena of immunity, induced sensitivity and allergy is called immunology.
Types of Immunity:
There is two major types of immunity: innate and acquired immunity.
(A) Innate or Natural or Nonspecific Immunity (L. innatus = inborn)
Innate immunity is inherited by an organism from the parents and protects it from birth throughout life. Innate or nonspecific immunity lacks specific responses to specific invaders. This type of immunity is provided by various barriers present in our body. Innate immunity consists of four types of barriers— physical, physiological, cellular and cytokine barriers.

(B) Acquired Immunity (= Adaptive or Specific Immunity)

The immunity that an individual acquires after the birth is called acquired or adaptive or specific immunity. It is specific and mediated by antibodies or lymphocytes or both which make the antigen harmless.
It not only relieves the victim of the infectious disease but also prevents its further attack in future. The memory cells formed by В cells and T cells are the basis of acquired immunity. Thus acquired immunity consists of specialized В and T lymphocytes and Antibodies.

Characteristics of Acquired Immunity:

(i) Specificity:
It is the ability to differentiate between various foreign molecules (for­eign antigens).
(ii) Diversity:
It can recognize a vast variety of foreign molecules (foreign antigens).
(iii) Discrimination between Self and Non-self:
It can recognize and respond to foreign molecules (non-self) and can avoid responding to those molecules that are present in the body (self) of the animal.
(iv) Memory:
When the immune system encounters a specific foreign agent, (e.g., a microbe) for the first time, it generates an immune response and eliminates the invader. This is called the first encounter. The immune system retains the memory of the first encounter. As a result, a second encounter occurs more quickly and stronger than the first encounter.
For more CBSE 12th subject, topics, animated videos lectures, sample papers, Science notes for Class 11th and 12th, register with Takshila Learning.

Comments

Popular posts from this blog

Magnetic and non-magnetic material Class 6 Science

Magnetic and non-magnetic material  Class 6 Science A magnet is a substance that is drawn to certain magnetic materials like iron, cobalt, and nickel. Magnets have the ability to draw iron to them. Natural magnets are rocks that naturally draw iron. Non-magnetic materials include things like wood, rubber, coins, feathers, leather, etc. that are not drawn to iron. Magnet characteristics It pulls magnetic materials, such as iron. The magnet's two ends are referred to as its poles. The magnet's diametrically opposed poles are drawn together. Heating, hammering, or dropping causes it to lose its characteristics. On the basis of properties types of Magnets Temporary magnets are those magnets that are magnetic for only a little duration. Typically, iron, cobalt, or nickel are used to make them. When they are close to the powerful magnet, they act like a magnet. When they are yanked away from the powerful magnet, they stop being magnetic. Permanent magnets are magnets that have magne...

Best Sample papers for Bank PO Exam Download

Sample papers for Bank PO Exam | Question Paper for Bank PO : Institute of banking Personnel Selection (IBPS) Department issued a Notification of IBPS PO 2017  exam announced in October month. IBPS Probationary Officer (PO) Online Application Form process will be begin from July 2017. This is a hard exam for all students so aware of its value. Large number of  candidates will participate in this exam. So all candidates should prepare well for it. Check out IBPS, Bank PO Sample papers, Question Paper Pattern, SBI  PO Syllabus ,   IBPS Syllabus  and other IBPS PO Preparation 2017 This paper is identical to any Bank PO Question Paper Pattern. Check whole IBPS Bank “PO question paper” subject wise. IBPS (PO) Paper Pattern Analysis with Syllabus and main topics of IBPS Exam 2017. PO Question Paper Pattern, Bank PO sample Papers for IBPS Bank Exam IBPS PO Exam will be conducted at three levels 1st- PO Preliminary Exam 2nd- PO Mains Exam 3rd- PO Common ...

Online/Offline CBSE Coaching Classes for class 9

CBSE Coaching Class 9 :-   In a move to make the digital India and Skill India dream into a reality, we are providing the best courses to our students in e-learning mode. Our program consists of entire 9th class syllabus in a fun learning method with various ways like sounds and animations. Our content is in 2-D & 3-D animation for better understanding of students. So That students will be understand every thing clearly and it makes the learning easy and entertaining. We are offering the following subjects for class 9th Standard:   Maths Class Physics Class Chemistry Class Biology Class Our E-learning provides the best and trained teachers with highly qualified for the respective subjects, they help to improve the students’ performance and to teach the every concept clear and easy in better way. Our main motive is to help students to learn well and gain more marks with making  their basic concept strong and good knowledge base ...