Biology Immune System notes

What is adaptive immunity?

Adaptive immunity is a specific immune response that develops after exposure to pathogens, characterized by the activation and amplification of lymphocytes.

What distinguishes the third line of defense in the immune system?

The third line of defense, or adaptive immunity, specifically targets and remembers pathogens through the action of lymphocytes, primarily B cells and T cells.

What are the main types of lymphocytes involved in the adaptive immune response?

The two main types of lymphocytes are B cells, responsible for humoral immune responses, and T cells, which mediate cellular immune responses.

How do B cells function in the immune system?

B cells are responsible for producing antibodies to neutralize antigens, playing a critical role in the humoral immune response.

Describe the concept of 'Challenge and Response' in adaptive immunity.

The immune system requires exposure to an antigen in order to initiate a response, which includes the proliferation of B cells that produce specific antibodies.

What happens when an antigen binds to a B cell receptor?

The binding of an antigen triggers B cell activation, leading to cell division and the formation of Plasma B cells and Memory B cells.

What role do Plasma B cells play after activation?

Plasma B cells rapidly produce and secrete large quantities of antibodies into circulation to combat pathogens.

Define antibodies and their general function in the immune system.

Antibodies are glycoproteins synthesized by B cells that specifically bind to antigens to help neutralize pathogens or mark them for destruction.

How do antibodies facilitate the targeting of pathogens?

Antibodies bind to specific foreign antigens, forming an antibody/antigen complex that enhances the recognition and clearance of pathogens by phagocytes.

What distinguishes Memory B cells from Plasma B cells?

Memory B cells are long-lived cells that retain the ability to quickly produce antibodies upon re-exposure to the same antigen, while Plasma B cells are short-lived and produce immediate antibody responses.

Explain the process of clonal selection in B cells.

Clonal selection occurs when a B cell binds to a specific antigen, leading to its activation and subsequent proliferation, producing many identical clones, some of which become Plasma or Memory B cells.

Where do lymphocytes develop, and how does their maturation differ?

Lymphocytes originate from stem cells in the bone marrow; T cells mature in the thymus, while B cells mature in the bone marrow itself.

List the key functions of T cells in the adaptive immune response.

T cells assist in identifying infected cells, activating other immune cells, and directly killing infected cells through cellular immune responses.

What role do Helper T cells play in modulating immune responses?

Helper T cells bind to antigens presented by antigen-presenting cells and secrete cytokines that enhance the activation and functioning of other immune cells.

What happens to Killer T cells when they are activated?

Once activated, Killer T cells target and destroy infected cells by recognizing infected body cells that display foreign antigens.

How long does the immune response take during the initial exposure to an antigen?

The timeline for the immune response during first exposure typically spans 10 to 17 days to reach peak Plasma B cell activity.

What variations are seen in the immune response during subsequent exposures?

Subsequent exposures decrease the response time to 2 to 7 days, produce a stronger response, and sustain a longer duration due to existing Memory B and T cells.

Define the term 'antigen' in the context of immunology.

An antigen is any substance, typically a protein or polysaccharide, that can provoke an immune response, including pathogens, toxins, and foreign proteins.

How do lymphocytes assess their self-reactivity during development?

During development, lymphocytes undergo a testing process where those that react to self-antigens are eliminated to prevent autoimmunity.

What can be the result of the failure of self-reactivity checks in the immune system?

Failure of these checks can lead to autoimmune diseases, where the immune system mistakenly targets the body’s own cells.

What is naturally acquired active immunity?

Naturally acquired active immunity develops when a person contracts an infection, resulting in the production of antibodies and memory cells specific to that pathogen.

Explain naturally acquired passive immunity and how it is obtained.

Naturally acquired passive immunity occurs when antibodies are transferred from mother to child through pregnancy or breastfeeding, providing temporary protection.

Define artificially acquired active immunity and its method of administration.

Artificially acquired active immunity arises when an individual receives a vaccine containing inactivated or attenuated pathogens, prompting the body to produce a protective immune response.

What does artificially acquired passive immunity entail?

Artificially acquired passive immunity involves the transfer of antibodies from an immune individual into a non-immune individual through injection or serum.

Describe the activation sequence of Plasma B cells during an immune response.

Once activated by binding to an antigen, Plasma B cells rapidly proliferate and release a high volume of specific antibodies into the bloodstream.

What is the function of Memory B cells after the immune response is resolved?

Memory B cells persist long-term in the body, enabling them to mount a rapid and robust response upon re-exposure to the same antigen.

How do T cells achieve recognition and response to antigens?

T cells possess unique antigen receptors that specifically bind to peptide fragments of antigens presented by major histocompatibility complex (MHC) molecules on other cells.

What influences the differentiation of immature lymphocytes during development?

Differentiation is influenced by exposure to specific antigens and the rearrangement of their receptor genes, allowing specificity in response.

How many unique specificities can the immune system accommodate in B and T cells?

The immune system can accommodate millions of distinct specificities due to the vast diversity of receptor genes among B and T cells.

What happens to self-reactive B and T cells during their development?

Self-reactive lymphocytes that bind to the body's tissues are either rendered inactive through clonal deletion or undergo apoptosis to avoid autoimmunity.

Discuss how the immune system maintains its capacity to adapt.

The immune system’s adaptability stems from the immense variety of B and T cells, each capable of recognizing different antigens, allowing a tailored response to diverse pathogens.

Describe how Helper T cells contribute to Killer T cell activation.

Helper T cells produce cytokines that stimulate and promote the growth and activation of Killer T cells, enhancing the cellular immune response.

What role do cytokines play in the immune response?

Cytokines are critical signaling molecules that facilitate communication among immune cells, regulating and amplifying immune responses.

What function do phagocytes serve in the immune system?

Phagocytes, such as macrophages, are immune cells that engulf and digest pathogens and debris, playing a crucial role in innate immunity and triggering adaptive responses.

What process allows phagocytes to recognize antibody-coated pathogens?

Phagocytes use Fc receptors to bind to the constant region of antibodies that are attached to pathogens, aiding in their recognition and destruction.

Describe the importance of the clonal expansion phase following activation of B cells.

Clonal expansion allows for the rapid proliferation of B cells into thousands of clones, enhancing the quantity of antibodies available for a quick immune response.

What is the difference between innate and adaptive immunity?

Innate immunity provides immediate but non-specific defense against pathogens, while adaptive immunity develops over time and provides a targeted and memory-based response.

How do vaccination strategies utilize principles of adaptive immunity?

Vaccination exposes the immune system to a non-pathogenic form of an antigen, prompting the development of memory cells for quick defense upon future exposure.

In what way do innate immune cells interact with adaptive immune cells?

Innate immune cells present antigens to T cells and release cytokines that help shape the adaptive immune response.

What is the significance of immunological memory?

Immunological memory allows for a faster and more effective immune response during subsequent exposure to previously encountered pathogens.

Explain how antigenic variation in pathogens can impact vaccine effectiveness.

Antigenic variation refers to changes in the surface proteins of pathogens, which can render vaccines less effective by preventing the immune system from recognizing the altered antigens.

Describe the overall importance of the adaptive immune system in health.

The adaptive immune system is crucial for recognizing and eliminating pathogens, developing immunity for future encounters, and preventing diseases and infections.

What is a pathogen?

A pathogen is any disease-carrying agent, including bacteria, viruses, protists, and fungi.

What are bacteria?

Bacteria are single-celled microorganisms that can cause diseases in humans, animals, and plants.

How do bacteria typically reproduce?

Bacteria reproduce asexually through a process called binary fission, where a single cell divides into two identical cells.

What is a virus?

A virus is a tiny infectious agent that requires a living host cell to replicate and cannot reproduce on its own.

What is unique about viral reproduction?

Viruses replicate by hijacking the cellular machinery of host cells to produce new viral particles.

What are protists?

Protists are a diverse group of eukaryotic microorganisms, some of which can cause diseases, such as malaria.

How do protists differ from bacteria?

Protists are eukaryotic and generally larger and more complex than prokaryotic bacteria.

What are fungi?

Fungi are a kingdom of organisms that include yeasts, molds, and mushrooms, some of which can cause infections in humans.

What role do fungi play in ecosystems?

Fungi break down organic matter and recycle nutrients, playing a critical role in ecosystem health.

What are the two types of immune responses?

The two types of immune responses are innate immunity and acquired immunity.

Define innate immunity.

Innate immunity is a non-specific immune response that does not distinguish between different pathogens and is present from birth.

What characterizes acquired immunity?

Acquired immunity is a specific immune response that develops only after exposure to a particular pathogen.

What is the first line of defense in innate immunity?

The first line of defense includes external defenses such as skin, mucous membranes, and chemical secretions.

How does the skin serve as a barrier to pathogens?

The skin provides a physical barrier that is difficult for pathogens to penetrate and secretes substances that inhibit microbial growth.

What is the function of mucous membranes?

Mucous membranes line body tracts and secrete mucus that traps pathogens and particles, preventing their entry into the body.

What are phagocytic cells?

Phagocytic cells are a type of white blood cell that engulf and digest invading microbes.

What is the primary role of macrophages?

Macrophages are large, long-lived phagocytes that engulf pathogens and debris and initiate immune responses.

What do eosinophils do?

Eosinophils primarily combat large parasitic infections by discharging destructive enzymes.

What are neutrophils?

Neutrophils are the most abundant type of white blood cell and play a key role in the immune response, attacking pathogens through various methods.

What are natural killer (NK) cells?

Natural killer cells destroy infected cells and cancerous cells by attacking their membranes.

What is the role of antimicrobial proteins?

Antimicrobial proteins directly attack microbes or impede their reproduction, thereby enhancing immune defense.

What is lysozyme?

Lysozyme is an enzyme that digests the cell walls of many bacteria, serving as a natural antibacterial agent.

What is the function of interferons?

Interferons are proteins secreted by virus-infected cells that signal neighboring cells to produce antiviral defenses.

Describe the inflammatory response.

The inflammatory response is a localized reaction to tissue damage or infection, characterized by redness, heat, swelling, and pain.

What happens to capillaries during inflammation?

Capillaries dilate and increase their permeability to allow more immune cells and proteins to reach the affected tissue.

What triggers a fever?

A fever is triggered by a widespread immune response to severe infection or tissue damage, leading to increased body temperature.

How does a fever help the immune system?

A fever inhibits the growth of some microbes and enhances phagocytosis and tissue repair.

What distinguishes external defenses from internal defenses?

External defenses prevent pathogen entry, while internal defenses, like phagocytic cells, respond to pathogens that have entered the body.

What is the role of macrophages in tissue repair?

Macrophages clean up debris and release signals that promote tissue repair after an immune response.

What strategy do neutrophils use for direct attacking?

Neutrophils utilize phagocytosis, release of antimicrobial proteins, and generation of neutrophil extracellular traps (NETs) to combat microbes.

How does the immune system distinguish between self and non-self?

The immune system recognizes antigens on pathogens and distinguishes them from the body’s own cells through specific immune receptors.

What does the term 'acquired immunity' refer to in detail?

Acquired immunity refers to the specific immune response developed over time through exposure to various pathogens.

How is innate immunity different from adaptive immunity?

Innate immunity provides a rapid and broad, non-specific response, while adaptive immunity is slower but highly specific.

What triggers the activation of the adaptive immune response?

The adaptive immune response is activated when the body encounters a new pathogen, requiring the presentation of specific antigens.

What role do cytokines play in immune responses?

Cytokines are signaling molecules that regulate immune responses by facilitating communication between immune cells.

How does a vaccine utilize acquired immunity?

Vaccines expose the immune system to inactivated or weakened pathogens to stimulate memory cell formation for future protection.

What role do antigen-presenting cells (APCs) play in immune responses?

APCs capture and present antigens to T cells, initiating the adaptive immune response.

How does the body respond to the presence of a pathogen?

The body responds to a pathogen by activating various immune mechanisms, including both innate and adaptive responses.

What are the signs of tissue inflammation?

Signs of tissue inflammation include redness, warmth, swelling, and pain at the site of injury or infection.

Describe the process of phagocytosis.

Phagocytosis involves the engulfing of a pathogen by a phagocyte, forming a vesicle that fuses with a lysosome to digest the pathogen.

What is vaccination?

Vaccination is the purposeful administration of antigenic material to produce immunity to a disease.

What types of vaccines use live but weakened forms of pathogens?

Live attenuated vaccines use weakened forms of pathogens to stimulate an immune response.

What do killed or inactivated vaccines contain?

Killed or inactivated vaccines contain pathogens that have been destroyed or rendered inactive.

What are purified material vaccines?

Purified material vaccines consist of specific proteins or parts of pathogens used to stimulate an immune response.

How do vaccines stimulate the immune system?

Vaccines stimulate clonal selection and the development of memory cells without causing disease symptoms.

How does the body respond to a natural infection after vaccination?

If a disease infection occurs after vaccination, the body reacts as if it is the second exposure to the disease.

Why is vaccination considered cost-effective?

Vaccination is often viewed as the most effective and cost-effective method for preventing infectious diseases.

What is a significant benefit of widespread vaccination?

Widespread vaccination can lead to the eradication of diseases from populations.

How does vaccination reduce mortality?

Vaccination reduces deaths from diseases by preventing infections.

What impact does vaccination have on disabilities?

Vaccination reduces disabilities caused by infectious diseases.

How does vaccination affect work productivity?

Vaccination decreases loss of work days due to illness.

What is a limitation of vaccine-induced immunity compared to natural immunity?

Vaccine-induced immunity may be less effective than natural immunity in some cases.

What are common side effects of vaccinations?

Side effects of vaccination can include soreness at the injection site, fever, and allergic reactions.

What are antibiotics?

Antibiotics are substances that kill bacteria or inhibit their growth.