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Host Defense System and Infectious Agents
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Host Defense System and Infectious Agents
Host Defense and Immune System Overview
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1
Question
What is the role of T-Cells in the immune response?
Answer
T-Cells initiate an adaptive immune response if necessary, based on the antigens presented to them by antigen-presenting cells like monocytes.
2
Question
Explain the process of agglutination by antibodies.
Answer
Agglutination is when antibodies cross-link cells, e.g., bacteria, creating a 'clump' that can enhance phagocytosis and clearance from the body.
3
Question
Define inflammation in the context of the immune response.
Answer
Inflammation is a localized tissue response to injury or infection characterized by redness, heat, swelling, and pain, facilitating the arrival of immune cells to the affected area.
4
Question
What distinguishes prokaryotes from eukaryotes?
Answer
Prokaryotes lack a cell nucleus and any other membrane-bound organelles. In contrast, eukaryotes have cells that contain complex structures enclosed within membranes.
5
Question
What are some physiological processes that occur in the second line of defense?
Answer
Physiological processes in the second line of defense include inflammation, fever, and the actions of immune cells like neutrophils, macrophages, and dendritic cells.
6
Question
What are the two main types of T-Cells and their functions?
Answer
The two main types of T-Cells are: 1) Helper T-Cells (CD4+ T-Cells) that assist in activating other immune cells, and 2) Cytotoxic T-Cells (CD8+ T-Cells) that directly kill infected or cancerous cells.
7
Question
What are the key functions of T-lymphocytes and B-lymphocytes in the Adaptive immune system?
Answer
T-lymphocytes help directly kill infected host cells or activate other immune cells, while B-lymphocytes are responsible for producing antibodies that specifically target antigens.
8
Question
Outline the steps of the interferon mechanism in preventing viral spread.
Answer
1. An infected cell releases IFN-alpha and IFN-beta. 2. These interferons bind to receptors on nearby uninfected cells. 3. In response, the normal cells synthesize antiviral proteins. 4. Additionally, macrophages are stimulated to produce IFN-gamma.
9
Question
What is the function of phagocytic cells in the immune response?
Answer
Phagocytic cells, such as neutrophils, macrophages, and dendritic cells, engulf and destroy infectious agents to protect the body from infections.
10
Question
How does increased capillary permeability contribute to the inflammatory response?
Answer
Increased capillary permeability allows for the leakage of fluids and proteins into the interstitial space, aiding in the delivery of immune cells and factors needed for the inflammatory response.
11
Question
What are the four basic signs of inflammation?
Answer
The four basic signs of inflammation are redness (increased blood flow), heat (increased metabolic activity), swelling (fluid leakage into interstitial space), and pain (stimulation of pain receptors).
12
Question
What is the role of basophils and mast cells in inflammation?
Answer
Basophils and mast cells release chemicals such as histamine and heparin. Histamine increases capillary permeability, allowing fluids and immune cells to enter tissue sites of inflammation. Heparin is an anticoagulant that prevents blood clotting at infection sites, promoting better blood flow during inflammation.
13
Question
What is chemotaxis?
Answer
Chemotaxis is the movement of immune cells, such as neutrophils, towards the site of inflammation in response to chemical signals.
14
Question
What effect does vasodilation have during the inflammatory response?
Answer
Vasodilation increases blood flow to the affected area, facilitating the delivery of immune cells and nutrients required for healing.
15
Question
What is the difference between innate and adaptive immunity?
Answer
Innate immunity provides immediate, non-specific defense against pathogens (e.g., the actions of monocytes), while adaptive immunity is a delayed, specific response that involves T-cells and B-cells targeting specific pathogens.
16
Question
What is the Innate immune system?
Answer
The Innate immune system consists of defenses we are born with, providing immediate response against a wide range of substances, utilizing components such as physical barriers (skin, mucosal membranes) and internal processes (like inflammation and the activities of neutrophils, macrophages, and other leukocytes).
17
Question
What physiological changes occur in the body due to the presence of a fever?
Answer
Fever increases metabolic rate, promotes tissue repair, and reduces the activity of infectious agents. However, excessively high fevers can lead to brain damage or death.
18
Question
Describe the role of interferons in viral infections.
Answer
Interferons (IFN) are antiviral proteins released by infected cells that prevent the spread of viruses by binding to receptors on neighboring cells, prompting them to synthesize antiviral proteins.
19
Question
What chemicals do basophils and mast cells release, and what are their functions?
Answer
Basophils and mast cells release several key chemicals: Histamine (causes vasodilation and increases vascular permeability), Heparin (prevents blood coagulation), and Eicosanoids (increase inflammation).
20
Question
What is the primary function of eosinophils, and how do they operate?
Answer
Eosinophils are primarily involved in combating parasitic infections. They release cytotoxic chemicals that directly attack parasites, mostly in the gastrointestinal tract, to help clear the infection.
21
Question
List the five major types of infectious agents.
Answer
1. Bacteria 2. Viruses 3. Fungi 4. Protozoans 5. Multicellular parasites.
22
Question
What are the two main actions of interferon during a viral infection?
Answer
1. Telling neighboring cells to make antiviral proteins that destroy viral RNA or stop protein synthesis. 2. Recruiting NK cells to attack infected cells.
23
Question
Describe the role of histamine in inflammation.
Answer
Histamine, released by basophils and mast cells, promotes vasodilation, which increases blood flow to the affected area, and enhances vascular permeability, allowing immune cells to exit the bloodstream and reach the site of infection or injury.
24
Question
Explain the difference between MHC class I and class II molecules.
Answer
MHC class I molecules are expressed on all nucleated cells and present endogenous antigens (e.g., from virus-infected or cancerous cells), which are recognized by CD8+ cytotoxic T-cells. MHC class II molecules are expressed primarily on APCs (like dendritic cells, macrophages, or B-cells) and present exogenous antigens to CD4+ helper T-cells.
25
Question
What are CAMs and their significance in the immune response?
Answer
Cell adhesion molecules (CAMs) are proteins located on the surface of endothelial cells that facilitate the binding of immune cells (like neutrophils) during the margination process, crucial for effective immune response.
26
Question
What roles do the hair in the nasal cavity play as a first line of defense?
Answer
They help trap and filter out pathogens from inhaled air.
27
Question
What are leukocytes?
Answer
Leukocytes are white blood cells that respond to infections and play a key role in the immune response.
28
Question
Outline the four basic steps involved in the inflammatory process.
Answer
1. Chemotaxis and recognition of injured tissue. 2. Vascular changes including vasodilation and increased capillary permeability. 3. Recruitment of immune cells (margination, diapedesis, chemotaxis). 4. Delivery of plasma proteins and increased fluid uptake by lymphatic capillaries.
29
Question
What is an immunogen? Provide an example.
Answer
An immunogen is a type of antigen that specifically induces an immune response. For instance, a bacterial protein that elicits the production of antibodies or activates T-cell responses is considered an immunogen.
30
Question
What is the role of dendritic cells in the immune response?
Answer
Dendritic cells serve as antigen-presenting cells that capture and present antigens to T-cells, initiating the adaptive immune response.