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Questions and Answers
What is considered the first line of defense in innate immunity?
What is considered the first line of defense in innate immunity?
Which of the following describes a chemical factor of the first line of defense?
Which of the following describes a chemical factor of the first line of defense?
What structure produces mucus as part of the physical barrier in the body?
What structure produces mucus as part of the physical barrier in the body?
Which line of defense is activated when the body experiences inflammation?
Which line of defense is activated when the body experiences inflammation?
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What is the role of keratin in the epidermis?
What is the role of keratin in the epidermis?
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Which immune response involves specialized lymphocytes such as T cells and B cells?
Which immune response involves specialized lymphocytes such as T cells and B cells?
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Which physical factor helps to wash away microorganisms from the eye surface?
Which physical factor helps to wash away microorganisms from the eye surface?
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What can cause infections in the skin, especially from normal skin flora?
What can cause infections in the skin, especially from normal skin flora?
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Which term describes the branch of biology concerned with the body's defense reactions?
Which term describes the branch of biology concerned with the body's defense reactions?
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What is the significance of Toll-like receptors (TLR) in immunology?
What is the significance of Toll-like receptors (TLR) in immunology?
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What type of immunity provides protection against any pathogen regardless of species?
What type of immunity provides protection against any pathogen regardless of species?
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Which of the following is NOT a characteristic of innate immunity?
Which of the following is NOT a characteristic of innate immunity?
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What is the role of specialized lymphocytes in specific (acquired) immunity?
What is the role of specialized lymphocytes in specific (acquired) immunity?
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Which statement best describes the innate defense system?
Which statement best describes the innate defense system?
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Which discovery was recognized with the 2011 Nobel Prize in Physiology or Medicine?
Which discovery was recognized with the 2011 Nobel Prize in Physiology or Medicine?
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What components are involved in innate (nonspecific) immunity's first line of defense?
What components are involved in innate (nonspecific) immunity's first line of defense?
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What role does the normal microbiota in the vagina play in relation to Candida albicans?
What role does the normal microbiota in the vagina play in relation to Candida albicans?
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Which of the following is NOT part of the second line of defense in the immune response?
Which of the following is NOT part of the second line of defense in the immune response?
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Which type of leukocyte is responsible for producing toxic proteins against certain parasites?
Which type of leukocyte is responsible for producing toxic proteins against certain parasites?
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What is the primary function of dendritic cells in the immune system?
What is the primary function of dendritic cells in the immune system?
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Which of the following statements about monocytes is true?
Which of the following statements about monocytes is true?
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Natural killer (NK) cells are primarily responsible for which of the following actions?
Natural killer (NK) cells are primarily responsible for which of the following actions?
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What is the process of phagocytosis primarily characterized by?
What is the process of phagocytosis primarily characterized by?
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What type of immunity do B cells and T cells participate in?
What type of immunity do B cells and T cells participate in?
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Study Notes
Immunology Overview
- Immunology is the branch of biology studying the body's defense reactions.
- Immunity is derived from the Latin word "immunis," meaning "free of burden."
- Pathogenic microorganisms (bacteria, viruses, fungi, and parasites) are present in the environment and can cause disease.
- Without an immune system, humans would constantly become ill and possibly die due to infections.
Innate Immunity
- Innate immunity constitutes the body's first line of defense against infectious agents, serving as the body's early warning system.
- It provides a non-specific defense against any pathogen, regardless of its type.
- Innate immunity is a two-line defense system, including physical factors (skin and mucous membranes) and a second line of defense involving phagocytes, inflammation, fever, and antimicrobial substances.
- Innate immunity lacks a memory component, meaning it cannot recognize or respond to previously encountered pathogens.
Specific (Adaptive) Immunity
- Specific immunity is the body's third line of defense, which is acquired throughout life.
- It's a specific response to a particular microbe.
- Specific immunity has long-term memory for specific antigens.
- This immunity is based on specialized immune cells (B and T cells) and specific proteins like antibodies.
Innate vs. Adaptive Immunity
| Feature | Innate Immunity | Adaptive Immunity |
|---|---|---|
| Defense Line | First and second line | Third line |
| Specificity | Non-specific | Specific |
| Memory | No memory | Long-term memory |
| Cells involved | Phagocytes, natural killer cells, etc. | B cells, T cells |
| Response Time | Rapid | Slower |
Nonspecific (Innate) Resistance
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First Line of Defense:
- Physical factors: skin, mucous membranes, mucus, tears, saliva, hairs, cilia, urine, vomiting, and defecation.
- Chemical factors: sebum, perspiration, lysozyme, gastric juice. The skin's epidermis (outer layer) is a strong physical barrier due to the keratin protein.
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Mucous Membranes: Consist of epithelial layers and connective tissue; line the gastrointestinal, respiratory, and genitourinary tracts. Mucus, a glycoprotein, is produced by goblet cells.
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Lachrymal Apparatus: Tears produced by the lacrimal glands protect the eye surface.
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Salivary Glands: Saliva produced by salivary glands dilutes microorganisms and removes them from the teeth and mouth;
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Hair: Nose hairs trap airborne microorganisms, dust, and pollutants.
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Cilia: Cilia in the respiratory tract move foreign particles upward toward the throat.
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Urine: Flow of urine prevents microbial colonization of the urinary tract.
Chemical Factors
- Sebum: Produced by sebaceous glands, contains unsaturated fatty acids to prevent bacterial and fungal growth.
- Perspiration: Produced by sweat glands helps regulate temperature and remove microorganisms.
- Lysozyme: Enzyme found in tears, saliva, nasal secretions, urine, and tissue fluids, that breaks down peptidoglycan in the cell walls of gram-positive bacteria.
- Gastric Juice: The high acidity of the stomach destroys most bacteria and bacterial toxins (pH 1.2-3), while some pathogens survive acidic conditions.
Normal Microbiota
- Normal microbiota prevents pathogen overgrowth by competing for nutrients, producing harmful substances that inhibit pathogens, and altering environmental conditions.
Phagocytosis
- This is the cellular process of engulfing and destroying solid particles like bacteria, debris, and pathogens.
- Phagocytosis has four steps: chemotaxis, adherence, ingestion, and digestion.
- Lysosomal bactericidal factors include hydrolytic enzymes (e.g., lysozyme, lipase, protease) and toxic oxygen products (e.g., hydrogen peroxide, singlet oxygen).
Inflammation
- Inflammation is the body's defensive response to tissue damage (from microbial infections, physical damage, or chemical agents).
- Inflammation is characterized by redness, pain, heat, and swelling.
- Inflammation has beneficial functions, including destroying and removing injurious agents, limiting microbial effects, and repairing damaged tissues.
- Inflammation is divided into Vasodilation and increased permeability of blood vessels (caused by chemical mediators), Phagocyte migration (Neutrophils, Monocytes), and Tissue Repair (skin regeneration).
Fever
- Fever is an abnormally high body temperature, controlled by the hypothalamus.
- Typically set at 37°C, infection can cause a rise in the body temperature related to the cytokines (e.g., IL-1) released from macrophages that triggers the hypothalamus to release prostaglandins that reset the hypothalamic thermostat, and increase body temperature.
- High temperatures can slow down the growth rate of bacteria and viruses and increase the body's immune response.
Antimicrobial Substances
- Interferons and complement proteins are a part of the body's antimicrobial arsenal.
- Interferons are proteins that help prevent viral infections.
- Complement proteins enhance various aspects of the immune system.
Formed Elements of Blood
- Blood consists of plasma and formed elements (erythrocytes, leukocytes, and platelets).
- Leukocytes (white blood cells) are crucial for the immune system, further categorized into granulocytes and agranulocytes.
Granulocytes
- Neutrophils are highly phagocytic and motile, active in initial infection phases.
- Basophils release substances like histamine, playing a role in inflammation and allergic responses.
- Eosinophils produce toxic proteins against parasites.
Agranulocytes
- Dendritic cells have extensions resembling nerve cells, abundant in skin, mucosal membranes, and lymph nodes. They are antigen-presenting cells.
- Monocytes are phagocytic after leaving the blood and becoming macrophages.
- Lymphocytes (B and T cells) are vital for specific immunity, responsible for antibody production (B cells) and cell-mediated immunity (T cells).
Natural Killer (NK) Cells
- Found in blood, spleen, lymph nodes, and bone marrow.
- NK cells kill various infected body cells and tumor cells by recognizing and destroying abnormal cells.
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Description
This quiz covers the fundamentals of immunology, focusing on the body's defense mechanisms against pathogens. Learn about innate immunity, its role as the first line of defense, and its characteristics. Explore how the immune system protects us from infections and illness.
