biology-class-12-unit-09-chapter-02-biologyin-human-welfare-human-health-and-disease-l-2-4-jloozg136ou

### <Success style="font-size:25px"> Biologyin Human Welfare Human Health And Disease L-2 </Success>
### <primary style="font-size:24px"> Secondary lymphoid organs </primary>
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- **Lymph nodes**

- Trap the microbes and other antigens which are present in the lymph or the **tissue fluid**
 
 - They contain B- and T-cells, and also macrophages

- **Spleen**

- Body's largest lymphatic organ
 - Facilitates immune responses to **blood borne** antigens
 - Acts as filter of the blood
 - Also eliminates worn-out blood cells and platelets
 - Contains lymphocytes and phagocytes

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<footer style = "font-size: 18px"> $\rightarrow$  $\rightarrow$ <span style = "color:blue"> Secondary lymphoid organs </span> $\rightarrow$ Secondary lymphoid organs $\rightarrow$ Secondary lymphoid organs </footer>

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### <primary style="font-size:24px"> Secondary lymphoid organs </primary>
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- **Malt**

- Mucosa Associated Lymphoid Tissue

- Makes up 50% of lymphoid tissue

- Tissue fluid is filtered by it

- Found close to moist epithelial surfaces e.g mucous membranes of the digestive, respiratory and reproductive systems

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<footer style = "font-size: 18px">Secondary lymphoid organs $\rightarrow$ Secondary lymphoid organs $\rightarrow$ <span style = "color:blue"> Secondary lymphoid organs </span> $\rightarrow$ Acquired immunity $\rightarrow$ Memory </footer>

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### <primary style="font-size:24px"> Memory </primary>
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- When body encounters a pathogen for the first time, a response is produced, called **Primary Response**

- It is of low intensity
 
- Subsequent encounter with same pathogen elicits a highly intensified **Secondary/ anamnestic response**

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<footer style = "font-size: 18px">Secondary lymphoid organs $\rightarrow$ Acquired immunity $\rightarrow$ <span style = "color:blue"> Memory </span> $\rightarrow$ Humoral immunity $\rightarrow$ Humoral immunity </footer>

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### <primary style="font-size:24px"> Humoral immunity </primary>
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- The humoral immune response fights pathogens that are free in the bodily fluids, or "humors"
 - It relies on antigens to detect these pathogens
 - An antigen is a biomolecule, such as a protein or sugar, that binds to a specific antibody
 - An antigen is any substance that triggers the production of antibodies by your immune system in response to its presence
 - B cells are the major cell type involved in the humoral immune response
 - When a foreign antigen is detected, B cells recognize that antigen and produce **antibodies** for fighting off the foreign invader

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<footer style = "font-size: 18px">Acquired immunity $\rightarrow$ Memory $\rightarrow$ <span style = "color:blue"> Humoral immunity </span> $\rightarrow$ Humoral immunity $\rightarrow$ Antibodies </footer>

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### <primary style="font-size:24px"> Antibodies </primary>
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- Also known as immunoglobulin (lg)
 - Proteins
 - Highly specific
 - Produced by B cells after stimulation by an antigen
 - Occur in the blood, in gastric and mucus secretions, and in breast milk
 - 5 Types: IgA, IgD, IgE, IgG, IgM
 - When in contact with the target or antigen they bind to the target

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<footer style = "font-size: 18px">Humoral immunity $\rightarrow$ Humoral immunity $\rightarrow$ <span style = "color:blue"> Antibodies </span> $\rightarrow$ Antibodies action $\rightarrow$ Antibodies Action </footer>

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### <primary style="font-size:24px"> Antibodies action </primary>
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- Can bind to viruses or bacteria, which interferes with the chemical interactions required for them to infector bind to other cells

- May create bridges between different particles containing antigenic sites, clumping them all together and preventing their proper functioning

- Opsonize pathogen cells, wherein they mark them for destruction by phagocytes, such as macrophages or neutrophils

- The neutralized antibody-coated pathogens can then be filtered by the spleen to be eliminated in urine or feces

- Stimulate inflammation, while their presence in mucus and on the skin prevents pathogen attack

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<footer style = "font-size: 18px">Humoral immunity $\rightarrow$ Antibodies $\rightarrow$ <span style = "color:blue"> Antibodies action </span> $\rightarrow$ Antibodies Action $\rightarrow$ Cell mediated immunity </footer>

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### <primary style="font-size:24px"> Cell mediated immunity </primary>
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- Cells displaying foreign antigens bind to T cells
 
- Activation of T cells

- Proliferation of T cells according to the type of antigen

- Cytotoxic T cells destroy the antigen producing cells  
 
- Helper T Cells stimulate production of **antibodies**

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<footer style = "font-size: 18px">Antibodies action $\rightarrow$ Antibodies Action $\rightarrow$ <span style = "color:blue"> Cell mediated immunity </span> $\rightarrow$ Cell mediated immunity $\rightarrow$ Cell mediated immunity </footer>

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### <primary style="font-size:24px"> Cell mediated immunity </primary>
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- Antigen(cancel) = Antibdy generating

- B cells $\uparrow$ + T cells

- $\downarrow$

- Antibodies highly specific. H<sub>2</sub>,L<sub>2</sub>

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<footer style = "font-size: 18px">Cell mediated immunity $\rightarrow$ Cell mediated immunity $\rightarrow$ <span style = "color:blue"> Cell mediated immunity </span> $\rightarrow$ What causes graft rejection ? $\rightarrow$ Immunity </footer>

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### <primary style="font-size:24px"> What causes graft rejection ? </primary>
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- The body differentiates between self and non self through
- Antigens  
- Type of immunity that causes graft rejection
- Cell mediated immunity
- Chances of rejection can be decreased
- Tissue matching/ blood matching
- Donor should be a close relative
- Immuno-suppresant drugs

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<footer style = "font-size: 18px">Cell mediated immunity $\rightarrow$ Cell mediated immunity $\rightarrow$ <span style = "color:blue"> What causes graft rejection ? </span> $\rightarrow$ Immunity $\rightarrow$ Active vs Passive immunity </footer>

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### <primary style="font-size:24px"> Immunity </primary>
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- **Passive immunity**

- Gained by use of pre formed antibodies

- **Active immunity**

- Antibodies are produced by the host body
- Slow 
- Example vaccination

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<footer style = "font-size: 18px">Cell mediated immunity $\rightarrow$ What causes graft rejection ? $\rightarrow$ <span style = "color:blue"> Immunity </span> $\rightarrow$ Active vs Passive immunity $\rightarrow$ Vaccination </footer>

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### <primary style="font-size:24px"> Vaccination </primary>
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- Principle - memory of immune system

- **History**

- Buddhist monks drank snake venom to confer immunity to snake bite

- **Variolation** (smearing of a skin tear with cowpox to confer immunity to smallpox) was practiced in 17th century China

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<footer style = "font-size: 18px">Immunity $\rightarrow$ Active vs Passive immunity $\rightarrow$ <span style = "color:blue"> Vaccination </span> $\rightarrow$ Vaccination $\rightarrow$ Vaccination </footer>

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### <primary style="font-size:24px"> Vaccination </primary>
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- **History**

- **Edward Jenner** is considered the founder of vaccinology in the West

- In 1796, he inoculated a 13 year-old-boy with vaccinia virus (cowpox), and demonstrated immunity to smallpox

- In 1798, the first smallpox vaccine was developed

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<footer style = "font-size: 18px">Active vs Passive immunity $\rightarrow$ Vaccination $\rightarrow$ <span style = "color:blue"> Vaccination </span> $\rightarrow$ Vaccination $\rightarrow$ Allergies </footer>

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### <primary style="font-size:24px"> Allergies </primary>
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- Exaggerated response of the immune system to certain antigens

- **Common allergens:** normally harmless substances, such as pollens, foods, and house dust mite

- **Antibodies involved -** IgE type

- Caused by release of **histamine** and **serotonin** from mast cells

- **Symptoms** sneezing, watery eyes, runny nose, difficulty in breathing

- **Treatment** anti-histamines, adrenalin, steroids

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<footer style = "font-size: 18px">Vaccination $\rightarrow$ Vaccination $\rightarrow$ <span style = "color:blue"> Allergies </span> $\rightarrow$ What causes allergies $\rightarrow$ What causes allergies </footer>

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### <primary style="font-size:24px"> What causes allergies </primary>
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- Now these cells can then identify particular allergens the next time they come in contact with the body 
 
- At this stage there are no physical symptoms of an allergy

- The next time that the same allergen is encountered the mast cells identify it as an intruder and produce histamine and other chemicals

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<footer style = "font-size: 18px">Allergies $\rightarrow$ What causes allergies $\rightarrow$ <span style = "color:blue"> What causes allergies </span> $\rightarrow$ Auto immunity $\rightarrow$ Think over </footer>

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### <primary style="font-size:24px"> Auto immunity </primary>
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- Failure of the body's immune system to recognize its own cells and tissues as "**self**"

- Instead, immune responses are launched against these cells and tissues as if they were foreign or invading bodies

- Any disease that results from such an aberrant immune response is termed an autoimmune disease

- Examples: include celiac disease, diabetes mellitus type 1, RA

- **WHY??**

- Genetic factors

- Other causes still unknown

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<footer style = "font-size: 18px">What causes allergies $\rightarrow$ What causes allergies $\rightarrow$ <span style = "color:blue"> Auto immunity </span> $\rightarrow$ Think over $\rightarrow$ Thank you </footer>