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Questions and Answers
The immune system is important for preventing and limiting ______.
The immune system is important for preventing and limiting ______.
infection
Mature T and B lymphocytes are responsible for ______ immunity.
Mature T and B lymphocytes are responsible for ______ immunity.
adaptive
Short-lived white blood cells responsible for innate immunity include monocytes and ______.
Short-lived white blood cells responsible for innate immunity include monocytes and ______.
granulocytes
Gnotobiotic mice have no ______ in their gut.
Gnotobiotic mice have no ______ in their gut.
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A severe immune deficiency leads to ______ infections.
A severe immune deficiency leads to ______ infections.
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The reduced serum IgG in gnotobiotic mice indicates a deficiency in ______ organs.
The reduced serum IgG in gnotobiotic mice indicates a deficiency in ______ organs.
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Early exposure to certain ______ can protect against infections in the future.
Early exposure to certain ______ can protect against infections in the future.
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The ______ hypothesis suggests that early exposure to microorganisms is beneficial for the immune system.
The ______ hypothesis suggests that early exposure to microorganisms is beneficial for the immune system.
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Commensal bacteria are found in the skin and the ______.
Commensal bacteria are found in the skin and the ______.
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The Self-Nonself theory states that only ______ entities activate the immune system.
The Self-Nonself theory states that only ______ entities activate the immune system.
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The 'danger hypothesis' suggests that the immune response is triggered by ______ signals from damaged tissues.
The 'danger hypothesis' suggests that the immune response is triggered by ______ signals from damaged tissues.
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In healthy individuals, the immune system does not attack ______ antigens.
In healthy individuals, the immune system does not attack ______ antigens.
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Immune cells with high affinity for 'self' are destroyed in the ______.
Immune cells with high affinity for 'self' are destroyed in the ______.
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Sites like the brain and eye are considered areas of immune ______.
Sites like the brain and eye are considered areas of immune ______.
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The immune system's ability to respond more swiftly and efficiently during a second response is known as immune ______.
The immune system's ability to respond more swiftly and efficiently during a second response is known as immune ______.
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The immune system works to detect, kill, and differentiate between pathogens and ______.
The immune system works to detect, kill, and differentiate between pathogens and ______.
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The first line of the immune system includes intact skin and ______ membranes.
The first line of the immune system includes intact skin and ______ membranes.
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The innate immunity is also known as ______ immunity.
The innate immunity is also known as ______ immunity.
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B-lymphocytes are part of the ______ immunity.
B-lymphocytes are part of the ______ immunity.
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The process of differentiation of HSC into mature blood cells is called ______.
The process of differentiation of HSC into mature blood cells is called ______.
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The primary lymphoid organ responsible for the selection and maturation of T-cells is the ______.
The primary lymphoid organ responsible for the selection and maturation of T-cells is the ______.
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Spleen and lymph nodes are classified as ______ lymphoid organs.
Spleen and lymph nodes are classified as ______ lymphoid organs.
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Cytokines are messengers that facilitate ______ communication between cells.
Cytokines are messengers that facilitate ______ communication between cells.
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The ______ hormone secreted acts on the same cell that released it.
The ______ hormone secreted acts on the same cell that released it.
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Bone marrow supports the self-renewal of ______ stem cells.
Bone marrow supports the self-renewal of ______ stem cells.
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Cell surface receptors play a role in ______ signal transduction.
Cell surface receptors play a role in ______ signal transduction.
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The immune system helps to prevent and limit ______.
The immune system helps to prevent and limit ______.
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Gnotobiotic mice lack ______ in their gut.
Gnotobiotic mice lack ______ in their gut.
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Severe immune deficiency can lead to increased risk of ______.
Severe immune deficiency can lead to increased risk of ______.
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Immune cells are vulnerable to ______ damage from radiation.
Immune cells are vulnerable to ______ damage from radiation.
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Reduced size of lymphoid organs is observed in ______ mice.
Reduced size of lymphoid organs is observed in ______ mice.
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Natural killer cells are a type of ______ cell responsible for innate immunity.
Natural killer cells are a type of ______ cell responsible for innate immunity.
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Apoptosis occurs in ______ lymphocytes as a response to radiation exposure.
Apoptosis occurs in ______ lymphocytes as a response to radiation exposure.
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The __________ are where immune cells develop.
The __________ are where immune cells develop.
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The __________ is responsible for the selection and maturation of T-cells.
The __________ is responsible for the selection and maturation of T-cells.
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The process of creating mature blood cells from hematopoietic stem cells is known as __________.
The process of creating mature blood cells from hematopoietic stem cells is known as __________.
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____________ immunity is also referred to as adaptive immunity.
____________ immunity is also referred to as adaptive immunity.
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The __________ are responsible for the production of antibodies.
The __________ are responsible for the production of antibodies.
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Neutrophils are a type of __________ immune cell.
Neutrophils are a type of __________ immune cell.
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Intercellular signaling involves messengers called __________.
Intercellular signaling involves messengers called __________.
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The __________ lymphoid organs are where the immune response is generated.
The __________ lymphoid organs are where the immune response is generated.
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Cells of the immune system are derived from the __________ stem cell.
Cells of the immune system are derived from the __________ stem cell.
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Natural Killer cells are part of the __________ lineage in hematopoiesis.
Natural Killer cells are part of the __________ lineage in hematopoiesis.
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The concept of 'self-tolerance' means the immune system does not attack ______.
The concept of 'self-tolerance' means the immune system does not attack ______.
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The ______ hypothesis suggests that the immune response is triggered by danger signals.
The ______ hypothesis suggests that the immune response is triggered by danger signals.
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Immune ______ are responsible for removing debris and restoring homeostasis.
Immune ______ are responsible for removing debris and restoring homeostasis.
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The ability of the immune system to respond more efficiently upon a second encounter with the same pathogen indicates immune ______.
The ability of the immune system to respond more efficiently upon a second encounter with the same pathogen indicates immune ______.
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Sites like the brain and eye are considered areas of immune ______, where tolerance to non-self antigens is more pronounced.
Sites like the brain and eye are considered areas of immune ______, where tolerance to non-self antigens is more pronounced.
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Gnotobiotic mice are used to study the effects of ______ in the gut microbiome.
Gnotobiotic mice are used to study the effects of ______ in the gut microbiome.
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The immune system's ability to differentiate between pathogens and ______ is essential for proper immune function.
The immune system's ability to differentiate between pathogens and ______ is essential for proper immune function.
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The ancient theory proposed by Burnett is known as the Self-Nonself ______.
The ancient theory proposed by Burnett is known as the Self-Nonself ______.
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What is a consequence of total immune deficiency?
What is a consequence of total immune deficiency?
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Why is living in a sterile environment not advisable for humans?
Why is living in a sterile environment not advisable for humans?
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What happens to lymphoid organs in gnotobiotic mice?
What happens to lymphoid organs in gnotobiotic mice?
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What role does early exposure to antigens play in human immune function?
What role does early exposure to antigens play in human immune function?
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What type of immune cells are particularly sensitive to radiation?
What type of immune cells are particularly sensitive to radiation?
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Which statement correctly describes gnotobiotic mice?
Which statement correctly describes gnotobiotic mice?
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What is a potential risk of severe immune deficiency aside from recurrent infections?
What is a potential risk of severe immune deficiency aside from recurrent infections?
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Which factor primarily enhances the immune system's response during a second exposure to the same pathogen?
Which factor primarily enhances the immune system's response during a second exposure to the same pathogen?
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What happens to cytokine production in gnotobiotic mice?
What happens to cytokine production in gnotobiotic mice?
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What does the term 'self-tolerance' refer to in the context of the immune system?
What does the term 'self-tolerance' refer to in the context of the immune system?
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According to the danger hypothesis, what primarily triggers an immune response?
According to the danger hypothesis, what primarily triggers an immune response?
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Which of the following sites is considered to have immune privilege?
Which of the following sites is considered to have immune privilege?
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What aspect of the immune system allows it to differentiate between pathogens and commensals?
What aspect of the immune system allows it to differentiate between pathogens and commensals?
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Which phenomenon describes the immune system's enhanced ability to respond to previously encountered pathogens?
Which phenomenon describes the immune system's enhanced ability to respond to previously encountered pathogens?
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The concept of immune tolerance primarily helps to prevent the immune system from what action?
The concept of immune tolerance primarily helps to prevent the immune system from what action?
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What constitutes the primary role of the immune system in maintaining homeostasis?
What constitutes the primary role of the immune system in maintaining homeostasis?
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Which cell type is primarily responsible for the selection and maturation of T-cells?
Which cell type is primarily responsible for the selection and maturation of T-cells?
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What primarily occurs in the bone marrow related to hematopoiesis?
What primarily occurs in the bone marrow related to hematopoiesis?
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Which type of immunity is characterized as specific and adaptive?
Which type of immunity is characterized as specific and adaptive?
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What role do cytokines play in the immune system?
What role do cytokines play in the immune system?
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Which of the following organs is considered a primary lymphoid organ?
Which of the following organs is considered a primary lymphoid organ?
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What type of immune cells are derived from the lymphoid progenitor cells?
What type of immune cells are derived from the lymphoid progenitor cells?
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What class of signals do autocrine cytokines act upon?
What class of signals do autocrine cytokines act upon?
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During hematopoiesis, what is the primary function of hematopoietic stem cells (HSC)?
During hematopoiesis, what is the primary function of hematopoietic stem cells (HSC)?
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In which type of lymphoid organ does the immune response get organized and generated?
In which type of lymphoid organ does the immune response get organized and generated?
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What type of immunity is referred to as innate immunity?
What type of immunity is referred to as innate immunity?
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What is a consequence of having a severely deficient immune system?
What is a consequence of having a severely deficient immune system?
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What is a major reason why humans do not live in a sterile environment?
What is a major reason why humans do not live in a sterile environment?
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What are the effects of lethal irradiation on immune cells?
What are the effects of lethal irradiation on immune cells?
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How does early exposure to certain antigens contribute to long-term immunity?
How does early exposure to certain antigens contribute to long-term immunity?
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What characteristic is common in individuals with extreme immune deficiency?
What characteristic is common in individuals with extreme immune deficiency?
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Which condition is related to decreased immune cell function due to microbial absence?
Which condition is related to decreased immune cell function due to microbial absence?
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What does the Hygiene Hypothesis suggest about immune system development?
What does the Hygiene Hypothesis suggest about immune system development?
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Which theory suggests that only non-self entities activate the immune system?
Which theory suggests that only non-self entities activate the immune system?
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What concept describes the immune system's ability not to attack its own tissues?
What concept describes the immune system's ability not to attack its own tissues?
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In which organs is immune privilege particularly notable?
In which organs is immune privilege particularly notable?
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Which hypothesis emphasizes the triggering of an immune response by danger signals from damaged tissues?
Which hypothesis emphasizes the triggering of an immune response by danger signals from damaged tissues?
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What does the ability of the immune system to respond more efficiently during a secondary encounter with a pathogen indicate?
What does the ability of the immune system to respond more efficiently during a secondary encounter with a pathogen indicate?
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What is the primary function of the immune system regarding microorganisms?
What is the primary function of the immune system regarding microorganisms?
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Which concept represents the immune system's ability to recognize and remember previous pathogen encounters?
Which concept represents the immune system's ability to recognize and remember previous pathogen encounters?
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Which of the following options best reflects an area of the body where immune privilege is critically observed?
Which of the following options best reflects an area of the body where immune privilege is critically observed?
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What is the primary function of the thymus in relation to T-cells?
What is the primary function of the thymus in relation to T-cells?
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Which progenitor cell is responsible for generating T-cells in hematopoiesis?
Which progenitor cell is responsible for generating T-cells in hematopoiesis?
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Which of the following statements about cytokines is correct?
Which of the following statements about cytokines is correct?
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What role do primary lymphoid organs serve in the immune system?
What role do primary lymphoid organs serve in the immune system?
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Which cell type is involved in innate immunity?
Which cell type is involved in innate immunity?
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What is the primary function of bone marrow in the immune system?
What is the primary function of bone marrow in the immune system?
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Which cells are primarily involved in the adaptive immune response?
Which cells are primarily involved in the adaptive immune response?
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What type of signaling do paracrine messengers engage in?
What type of signaling do paracrine messengers engage in?
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Memory T cells are essential for which aspect of the immune response?
Memory T cells are essential for which aspect of the immune response?
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Which of the following is considered a secondary lymphoid organ?
Which of the following is considered a secondary lymphoid organ?
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What is the primary function of the thymus in the immune system?
What is the primary function of the thymus in the immune system?
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Where do hematopoietic stem cells (HSC) primarily reside?
Where do hematopoietic stem cells (HSC) primarily reside?
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What type of signaling involves messengers that act on the same cell that released them?
What type of signaling involves messengers that act on the same cell that released them?
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What is the role of cytokines in the immune system?
What is the role of cytokines in the immune system?
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What is NOT a primary lymphoid organ?
What is NOT a primary lymphoid organ?
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What type of cells are B-lymphocytes responsible for producing?
What type of cells are B-lymphocytes responsible for producing?
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Which cell type is involved in the innate immune response?
Which cell type is involved in the innate immune response?
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Which of the following describes the role of secondary lymphoid organs?
Which of the following describes the role of secondary lymphoid organs?
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Which type of cytokine signaling is involved in long-distance communication?
Which type of cytokine signaling is involved in long-distance communication?
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What happens to immune cells when exposed to lethal radiation?
What happens to immune cells when exposed to lethal radiation?
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What is one characteristic of gnotobiotic mice?
What is one characteristic of gnotobiotic mice?
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Which of the following is a consequence of extreme immune deficiency?
Which of the following is a consequence of extreme immune deficiency?
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Why is a sterile environment not ideal for the immune system?
Why is a sterile environment not ideal for the immune system?
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What is one effect of early exposure to certain bacteria?
What is one effect of early exposure to certain bacteria?
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What role do bone marrow stem cells play in the immune system?
What role do bone marrow stem cells play in the immune system?
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What term describes the hypothesis regarding the benefits of early exposure to microorganisms?
What term describes the hypothesis regarding the benefits of early exposure to microorganisms?
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How does an increased dose of radiation affect immune cells?
How does an increased dose of radiation affect immune cells?
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Which theory claims that only non-self entities activate the immune system?
Which theory claims that only non-self entities activate the immune system?
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What is the primary purpose of immune 'memory'?
What is the primary purpose of immune 'memory'?
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Which organ is known for having immune privilege, allowing some foreign antigens without triggering a strong immune response?
Which organ is known for having immune privilege, allowing some foreign antigens without triggering a strong immune response?
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What is essential for self-tolerance in the immune system?
What is essential for self-tolerance in the immune system?
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Which hypothesis argues that the immune response is triggered by danger signals from damaged tissues?
Which hypothesis argues that the immune response is triggered by danger signals from damaged tissues?
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What best describes commensal bacteria in the body?
What best describes commensal bacteria in the body?
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What is the role of the immune system in maintaining homeostasis?
What is the role of the immune system in maintaining homeostasis?
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Which of the following is a factor the immune system must differentiate between?
Which of the following is a factor the immune system must differentiate between?
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Study Notes
Introduction to the Immune System
- The immune system is crucial for preventing and limiting infections.
- Learning Objectives: Understand the importance, anatomy, and organization of the immune system; learn about immune cells; and introduce basic immunology concepts.
- The immune system prevents/limits infection.
Three Questions about Immunity
- Can humans survive without an immune system? What happens if the immune system is removed?
- Why don't humans solely try to live in a sterile environment?
- What constitutes a foreign body?
Severe Combined Immunodeficiency Disease (SCID)
- SCID is a condition where individuals live in sterile environments.
- David Vetter, a well-known case, lived 12 years in a sterile bubble to avoid infections.
- He had no contact with humans.
Lethal Irradiation
- Immune cells (e.g., T cells, B cells, monocytes, granulocytes, and NK cells) are susceptible to radiation.
- Radiation damages bone marrow stem cells.
- Radiation exposure can lead to immune deficiency resulting in recurrent infections.
Gnotobiotic Mice
- These mice are kept in sterile environments devoid of microbes.
- Observing germ-free mice reveals the effects of a sterile environment.
- Germ-free mice exhibit smaller lymphoid organs, reduced serum immunoglobulins, and abnormal development of Peyer's patches.
Hygiene Hypothesis
- The current clean environment can impact immune development.
- Vaginal birth vs. C-section are factors in immune development.
Immune System Anatomy and Organization
- The immune system has three lines of defense:
- First line: Intact skin and mucous membranes
- Second line: Innate (natural) immunity (includes barriers, complement, neutrophils, monocytes, macrophages, and NK cells)
- Third line: Acquired (adaptive) immunity (includes B lymphocytes, T lymphocytes, and antibodies)
Immune System Functional Units and Layers
- Immune system functional units are organs, cells, messengers (intracellular and intercellular), and macromolecules/molecules.
Cells of the Immune System
- All immune cells originate from hematopoietic stem cells (HSCs).
- HSCs differentiate into various blood cells like granulocytes, monocytes, erythrocytes, T cells, B cells, and NK cells.
- There's approximately one HSC in 50,000 bone marrow cells.
Hematopoiesis—Progenitor Cells & Sites
- Hematopoiesis is the process of blood cell development from HSCs.
- Myeloid progenitors create granulocytes, monocytes, eosinophils, basophils, megakaryocytes, and erythrocytes.
- Lymphoid progenitors create T cells, B cells, and NK cells.
- Hematopoiesis happens in different places: bone marrow, thymus.
Primary Lymphoid Organs
- The thymus is where T cells develop.
- Bone marrow manufactures and supports self-renewal of HSCs, differentiating them into mature blood cells.
Secondary Lymphoid Organs
- These organs generate and organize immune responses, including lymph nodes and spleen.
- Mucosal-associated lymphoid tissue (MALT) is a subset, including GALT (tonsils, adenoids, appendix, Peyer's patches) and BALT (bronchial-associated lymphoid tissue).
Intracellular Signal Transduction
- Cell receptors, transmembrane domains, adapter molecules, signaling molecules, and nuclear localization lead to gene transcription.
Intercellular Signaling
- Autocrine signals act on the same cell, paracrine signals act on nearby cells, and endocrine signals act on distant cells via the circulatory system.
- These messages are often called cytokines.
Foreign Antigens
- Pathogens, diseases (e.g., colds), organ transplants, prosthetic joints, and medical devices are all considered foreign.
What About...?
- Food, commensal bacteria (more bacteria than human cells in a body), gnotobiotic mice, sperm/vagina, babies in the uterus, and antibodies in breast milk can be examined for their possible effects on immunity.
Self and Nonself
- There are three primary theories on self and nonself:
- Self-nonself (Burnett): only non-self activates the immune system
- Infectious nonself (Janeway): pathogen-associated molecular patterns (PAMPs) activate the system.
- Danger hypothesis (Matzinger): danger signals from damaged tissues trigger the system.
Tolerance
- Self-tolerance is the immune system's ability not to attack itself.
- Tolerance also involves discriminating between pathogens and commensals (normal body microbes).
- Immune cells with high affinity for self are eliminated in the thymus.
Immune Privilege
- Specific sites (e.g., brain, eye, testes, fetus, uterus) tolerate foreign/non-self antigens to maintain homeostasis, and there's a trade-off between potential damage and benefit.
- The gut is considered a location of immune privilege.
Immune Memory
- The immune system remembers previous encounters with pathogens improving response speed and efficiency during subsequent exposures, and likely 'stores information' as memory to facilitate this response.
The Immune System's Role
- The immune system prevents and limits infections through detecting microorganisms, killing them, differentiating them from non-pathogens, and removing debris. It restores homeostasis and supports normal organ development.
Next Lectures
- Upcoming lectures will focus on innate and adaptive immunity.
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Description
Explore the vital role of the immune system in protecting the body from infections. This quiz covers the anatomy, organization, and key concepts in immunology, including conditions like SCID. Test your knowledge about immunity and the effects of environmental factors on immune health.
