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.

Continue complete chapter click Immunity And Human Immune System- Class 12 Biology

For more CBSE 12th subject, topics, animated videos lectures, sample papers, Science notes for Class 11th and 12th, register with Takshila Learning.

Lessons-Worksheets-Question Papers-CBSE Class 2 English

Lessons-Worksheets-Question Papers-CBSE Class 2 English CBSE 2nd Class English – One and Many In this blog, we share the spelling rules used in the concept of One and Many. When there is only one of a naming word (noun), it is said to be a singular noun . When a noun shows more than one, it is said to be in the plural . We can add –S, -es, -ves or ies to show that there is more than one noun. For example, we say many birds, four biscuits, six brushes. But for the students of Class 2 , it’s very difficult and confusing to understand where to use s , es, ves or ies in the form of many. Don’t worry, it looks difficult, but it is very easy as in grammar each concept has a set of rules that need to practice. Noun ending with –s, -x, -o, -sh, -ch, and –ss form plurals by taking –es. Look at these pairs of words: Bus – Buses Brush – Brushes Continue ..... Click here ...

Class 3 English Practice Grammar Worksheet -The Adverb

Class 3 English Practice Grammar Worksheet -The Adverb Class 3 English – The Adverb – Kinds of Adverb Fill in the blanks with suitable Adverbs of place. Choose from the box. Up outside everywhere back down away here there ...

Bhakti Movement NCERT Class 12 History

Bhakti Movement NCERT Class 12 History The Bhakti movement was an effort to achieve salvation and emancipation by devotion to God. In Hindi, the word bhakti refers to fervent devotion to God. This movement, which stressed a single-minded, ardent devotion to God, is seen as the most characteristic act of religious progress during the Middle Ages. In the 12th and 13th centuries, Kabir Das was a key figure in the Bhakti Movement. As a result of the movement, Kabir Das' poems and religious writings attained widespread fame. Kabir Das was raised up by a Muslim family. However, his religious beliefs were influenced by his Hindu teacher Ramananda, who regarded Rama as the highest God. The first Sikh guru and the founder of Sikhism was Guru Nanak. He vehemently opposed prejudice based on customs, rivalry, and caste in religion. Nanak was raised in a Hindu household and from an early age began to exhibit spiritual tendencies. He helped the indigent and underprivileged. His followers began r...

Takshila Learning - Online Tutorials

Search This Blog