State the functions of mast cells in allergy response. OR State the function of interpherons.

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Q. State the functions of mast cells in allergy response.

(OR)

State the function of interpherons.

Punjab PsebCBSE Class XII Board 2019Subjective· 1mImportance★★★★★

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Part (a)Concept understanding — Lymphoid Organ Classification

Lymphoid Organ Classification – A First Look

Think of your body as a city that needs constant security. You have patrolling guards (white blood cells), but you also need training academies where new guards are made battle-ready, and checkpoints where suspicious activity is caught. In your immune system, those academies and checkpoints are the lymphoid organs.

The NCERT textbook classifies lymphoid organs into two broad groups based on where immune cells are born/trained versus where they carry out their work.

Primary Lymphoid Organs – The Training Academies

These are the sites where lymphocytes (the B-cells and T-cells of your immune army) are produced and matured. Without these, your body cannot create a functional immune system.

Bone Marrow – This soft tissue inside your bones is the birthplace of all blood cells, including lymphocytes. In mammals, B-cells mature right here (the 'B' in B-cell stands for Bone marrow).
Thymus – A small gland located behind your breastbone. Immature T-cells migrate from the bone marrow to the thymus, where they are "trained" to recognise self from non-self. The 'T' in T-cell stands for Thymus.

Important

Primary lymphoid organs are where lymphocytes become immunocompetent – meaning they learn to attack foreign invaders without attacking the body's own cells. If the thymus is removed at birth, the immune system is severely crippled.

Secondary Lymphoid Organs – The Checkpoints

Once lymphocytes are trained, they leave the primary organs and circulate through the blood and lymph. The secondary lymphoid organs are the sites where these mature lymphocytes actually encounter antigens (foreign substances) and launch an immune response.

Spleen – A fist-sized organ in the upper left abdomen. It filters blood, traps blood-borne pathogens, and is a major site for antibody production.
Lymph Nodes – Small, bean-shaped structures scattered throughout the body (neck, armpits, groin, etc.). They filter lymph fluid and are the first places where infections are "flagged" – that's why your neck nodes swell when you have a sore throat.
Mucosa-Associated Lymphoid Tissue (MALT) – Diffuse collections of lymphoid tissue in the linings of the respiratory, digestive, and urogenital tracts. Examples include tonsils (in the throat), Peyer's patches (in the small intestine), and the appendix.

Note

| Primary Organs | Secondary Organs |

|----------------|------------------|

| Bone marrow, Thymus | Spleen, Lymph nodes, MALT (tonsils, Peyer's patches, appendix) |

| Lymphocytes are produced & matured here | Lymphocytes encounter antigens & respond here | …

Part (b)Concept understanding — Lymphoid Organ Classification

Lymphoid Organ Classification – A First Look

The NCERT textbook classifies lymphoid organs into two broad groups based on where immune cells are born/trained versus where they carry out their work.

Primary Lymphoid Organs – The Training Academies

These are the sites where lymphocytes (the B-cells and T-cells of your immune army) are produced and matured. Without these, your body cannot create a functional immune system.

Bone Marrow – This soft tissue inside your bones is the birthplace of all blood cells, including lymphocytes. In mammals, B-cells mature right here (the 'B' in B-cell stands for Bone marrow).
Thymus – A small gland located behind your breastbone. Immature T-cells migrate from the bone marrow to the thymus, where they are "trained" to recognise self from non-self. The 'T' in T-cell stands for Thymus.

Important

Secondary Lymphoid Organs – The Checkpoints

Spleen – A fist-sized organ in the upper left abdomen. It filters blood, traps blood-borne pathogens, and is a major site for antibody production.
Lymph Nodes – Small, bean-shaped structures scattered throughout the body (neck, armpits, groin, etc.). They filter lymph fluid and are the first places where infections are "flagged" – that's why your neck nodes swell when you have a sore throat.
Mucosa-Associated Lymphoid Tissue (MALT) – Diffuse collections of lymphoid tissue in the linings of the respiratory, digestive, and urogenital tracts. Examples include tonsils (in the throat), Peyer's patches (in the small intestine), and the appendix.

Note

| Primary Organs | Secondary Organs |

|----------------|------------------|

| Bone marrow, Thymus | Spleen, Lymph nodes, MALT (tonsils, Peyer's patches, appendix) |

| Lymphocytes are produced & matured here | Lymphocytes encounter antigens & respond here | …

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Part (a): Mast cells release histamine and other mediators when an allergen binds their surface IgE, producing the immediate symptoms of allergy. Part (b): Interferons are proteins from virus-infected cells that make neighbouring healthy cells resistant to the virus, checking its spread.

Part (a)

Mast cells are granule-containing immune cells present in tissues, especially near blood vessels and mucosal surfaces. Their surface is coated with IgE antibodies specific to an allergen. When that allergen enters the body and cross-links the IgE, the mast cells are activated and undergo degranulation, releasing chemical mediators — chiefly histamine and serotonin. These mediators cause vasodilation, increased capillary permeability and smooth-muscle contraction, giving the familiar allergic response: sneezing, running nose, watery eyes, itching, swelling and difficulty in breathing (as in asthma). …

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Q.State the functions of mast cells in allergy response.

Part (a)

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