1. Explain how immunizations work to protect the body against pathogens and antigens. Refer to B-cells and T-cells in your answer. Discuss how and why science would need to find a way to discourage thymus atrophy if human life is ever to expand beyond around 120 years. 2. Describe the sources of antibodies in humans from pre-birth to old age, including how our bodies change over time as we age.

3. You suspect a patient is suffering from a systemic inflammatory response. What two things could you check relatively easily to detect signs of such a response, and which one of those two symptoms may on its own require emergency intervention?

4. A running joke among viewers of the medical drama House was that “it’s never lupus,” even though it frequently came up as a possible diagnosis to the patient-of-the-week’s symptoms. Why is lupus sometimes a difficult disease to diagnose but would often come up as doctors discuss a patient’s symptoms? What is the treatment regimen for Lupus?

5. Compare and contrast passive and active immunity, covering at least four functions, components, or mechanisms related to immune response. Include at least one way in which they are similar and one way in which they are different.

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The immune system, which is integrated into all physiological systems, protects the body against infections and other external and internal insults by utilizing three distinct layers, depending on the nature of the threat: physical (e.g., skin, epithelial lining of the gastrointestinal and respiratory tracts) and biochemical barriers (e.g., secretions, mucus, and gastric acid), numerous different immune cells (e.g., granulocytes, CD4 or CD8 T and B cells), and antibodies (i.e., immunoglobulins). The first line of defense is innate immunity, which combines physical and biochemical barriers with a non-specific, leukocyte-mediated cellular response to defend against pathogens.

Neonates are physiologically immunodeficient, meaning both their innate and adaptive immunological responses are greatly suppressed. Once born, a child’s immune system responds favorably to protein antigens and less so to glycoproteins and polysaccharides. In fact, many of the infections acquired by neonates are caused by low-virulence organisms like staphylococcus and pseudomonas.

Clinically, the Systemic Inflammatory Response Syndrome (SIRS) is identified by two or more symptoms including fever or hypothermia, tachycardia, tachypnoea and change in blood leucocyte count.

One way the body protects against pathogens and antigens is through humoral immunity. White blood cells produce antibodies that circulate through the body’s blood and lymph, also known as the body’s humors. They search for and destroy the pathogens in the humoral systems. T-cells become programmed to identify a different type of pathogen or antigen. If the immune system doesn’t have a fitting T-cell to fight a pathogen or antigen, it will activate B-cells. These cells recognize the pathogen and destroy it through the production of an antibody. They not only produce one type of antibody, but they have the ability to produce antibodies that are required to destroy specific diseases. They go through their data banks attempting to find the antibody that will fit with the invader, and if one doesn’t exist, they will generate one over time. If human life were to ever expand beyond 120 years, science would need to find a way to discourage thymus atrophy.

Active immunity occurs when our own immune system is responsible for protecting us from a pathogen. Passive immunity occurs when we are protected from a pathogen by immunity gained from someone else.

Ans.

Mistakes during DNA replication, such as addition of an incorrect nucleotide base in daughter strand or breaks in daughter strand that leads to change in nucleotide sequence of DNA, are known as DNA replication errors.

The enzyme DNA ligase repairs the breaks or irregularities in the DNA molecules, such as joining of Okajaki fragments. Therefore, defects in DNA ligase that take apart chunks of DNA would cause an error during DNA replication.

Thus, the correct answer is 'option B).'