Human Physiology Week 2b

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Questions and Answers

What is the role of an antibody in the immune response?

To directly kill pathogens

To neutralize an antigen (correct)

To form antigens

To trigger the immune response

What characterizes a granular leukocyte?

Has a very large nucleus

Contains distinct granules in the cytoplasm (correct)

Is the most numerous type of white blood cell

Lacks granules in the cytoplasm

Which cell type is a major component of the agranular leukocytes?

Lymphocytes (correct)

Basophils

Neutrophils

Eosinophils

Which of the following best describes the function of a macrophage?

To ingest and clear cellular debris Signup and view all the answers

What is an epitope?

The site on an antigen where an antibody binds Signup and view all the answers

Which of the following components is part of the innate immune system?

Phagocytes Signup and view all the answers

What primarily distinguishes the acquired immune system from the innate immune system?

It relies on specific responses to particular invaders. Signup and view all the answers

What is the role of B cells in the acquired immune system?

Produce antibodies. Signup and view all the answers

Which term is used to describe the immunity provided specifically by T cells?

Cell-mediated immunity Signup and view all the answers

In the context of the immune system, what does the term 'humoral' refer to?

The antibodies found in bodily fluids. Signup and view all the answers

What is the primary role of the immune system in relation to inflammation management?

It provides a foundation for understanding and managing inflammation. Signup and view all the answers

Which of the following substances is categorized as an antigen?

A polysaccharide on a foreign invader's body. Signup and view all the answers

What type of diseases are mentioned as being influenced by the immune system?

Autoimmune diseases. Signup and view all the answers

What characterizes an antibody in the immune system?

It is a protein formed in response to an antigen. Signup and view all the answers

Why might understanding the immune system be crucial for physical therapy practice?

It assists in the management of inflammation and related diseases. Signup and view all the answers

What is a key characteristic of innate immunity?

It is non-specific and acts quickly against various threats. Signup and view all the answers

Which statement accurately describes the response time of adaptive immunity compared to innate immunity?

Adaptive immunity takes days to respond, while innate immunity acts within hours. Signup and view all the answers

What role do B-lymphocytes play in the immune response?

They produce antibodies against pathogens. Signup and view all the answers

How do T-lymphocytes primarily contribute to the immune system's response?

By recognizing and interacting with antigen-presenting cells. Signup and view all the answers

What is the function of macrophages in innate immunity?

They engulf and digest microbes and debris. Signup and view all the answers

Study Notes

Overview of the Immune System

Understanding the immune system is essential for managing inflammation, a crucial aspect of physical therapy.
Knowledge of the immune system aids in recognizing and treating immune-mediated diseases, such as rheumatoid arthritis and Guillain-Barre syndrome.

Key Terminology

Antigen: A substance that triggers an immune response, often a protein or polysaccharide found on pathogens.
Antibody: A protein produced by the immune system in response to an antigen, aimed at neutralizing or stopping the antigen's effects.
Epitope: The specific part of an antigen that an antibody binds to.
Pathogen: A microorganism that causes infectious diseases, possessing various antigens with associated epitopes.

Immune System Components

Leukocytes (White Blood Cells): Divided into two main categories:
- Granular Leukocytes: Contain granules in their cytoplasm and include:
  - Neutrophils: The most abundant type (60-70% of leukocytes), neutral staining.
  - Eosinophils: Stain red, making up 2-4% of leukocytes, involved in combating multicellular parasites and allergies.
  - Basophils: Rare (0.5-1% of leukocytes), stain blue, play a role in allergic reactions.
- Agranular Leukocytes: Lack granules and include:
  - Lymphocytes: Key players in adaptive immunity, central to the immune response.
    - B Cells: Responsible for antibody production.
    - T Cells: Involved in cell-mediated immunity, targeting infected or abnormal cells.
    - Natural Killer (NK) Cells: Target and destroy infected or cancerous cells.
  - Monocytes: Larger cells, differentiated into macrophages, which engulf and digest pathogens.

Immune System Organization

Innate Immunity: The non-specific first line of defense against pathogens, including:
- Physical barriers (e.g., skin, mucus membranes).
- Bloodborne components (e.g., phagocytes like macrophages and neutrophils).
- Complement proteins that aid in pathogen destruction.
Adaptive Immunity: The specific response to pathogens, involving:
- B-cell Immunity (Humoral Immunity): Antibody production against specific antigens.
- T-cell Immunity (Cell-Mediated Immunity): Targeted killing of infected or abnormal cells.

Functioning of the Immune System

The innate immune system acts quickly (within hours) to block pathogens without discrimination.
The adaptive immune system takes longer to respond (days), focusing on specific threats:
- B cells produce antibodies after recognizing and binding to specific antigens.
- T cells work with antigen-presenting cells (like macrophages) to identify and eliminate threats.
Proliferation: Both B and T cells multiply upon activation, producing numerous cells to effectively combat the identified pathogen.

Coordination of Immune Responses

Both innate and adaptive immune systems cooperate seamlessly to protect the body.
Complement System: Series of proteins that enhance the ability of antibodies and phagocytic cells to clear pathogens.
Understanding of the immune system structure is essential for effective patient management and treatment in physical therapy practices.### Adaptive Immune Response Overview
Effector T cells are the end products of the initial phases of the adaptive immune response, taking several days to develop.
Various types of effector T cells will be discussed as their functions are revealed.

Antigen Presenting Cells (APCs)

Antigen presenting cells, often macrophages, collect and present antigens to lymphocytes.
Macrophages engulf cellular debris, displaying antigens on their surface for recognition by T cells and other immune cells.
Interaction between antigens on APCs and receptors on lymphocytes triggers immune responses, determining whether an inflammatory response is necessary.

Lymphocyte Formation

Lymphocytes originate from pluripotent hematopoietic stem cells in the bone marrow.
Undifferentiated lymphocyte stem cells can mature into T cells or B cells.
T cells mature in the thymus, resulting in immunocompetent T cells that can respond to pathogens.

Types of T Cells

Regulatory T Cells: Help modulate the immune response, including activating or suppressing inflammation.
Helper T Cells: Activate other immune cells through cytokine secretion and help initiate the inflammatory response.
Cytotoxic T Cells: Destroy infected cells by recognizing antigens presented by infected cells.
Memory T Cells: Remain in the body for long-term immunity, ready to respond to previously encountered pathogens.

B Cell Formation

B cells mature in the bone marrow and are essential for humoral immunity.
Plasma Cells: Produce antibodies that neutralize pathogens.
Memory B Cells: Long-lasting cells that recognize antigens for rapid response upon future encounters.

Immune System Processes

Humoral Immunity: Involves B cells and the production of antibodies that bind to pathogens to neutralize them or mark them for destruction by other immune cells.
Cell-mediated Immunity: Involves T cells that directly attack infected cells.

Immune Response Mechanisms

Antibodies can neutralize pathogens directly by preventing their function.
Antibodies can activate complementary proteins for additional defense.
Phagocytosis by neutrophils and macrophages is another vital pathway for destroying tagged pathogens.

T Cell Activation Mechanism

Activation occurs when a T cell's receptor binds to a specific antigen presented by a macrophage.
This binding leads to cytokine release, resulting in T cell proliferation, activation, and an enhanced immune response against infections.

Summary of Key Cell Functions

B Cells: Produce antibodies to neutralize pathogens; plasma cells are the antibody-containing form.
Helper T Cells: Activate other immune cells and initiate inflammatory responses through antigen recognition.
Cytotoxic T Cells: Target and kill cells infected with pathogens by recognizing specific antigens.
Memory Cells: Both B and T cells persist and respond more efficiently to previously encountered pathogens.

Important Terminology

Antigen: A substance that induces an immune response.
Cytokines: Signaling proteins released by cells that affect cell communication and immune response activation.
Phagocytosis: The process by which certain cells engulf and digest pathogens.### Immune Response Overview
Cytotoxic T lymphocytes kill infected cells to eliminate infections.
Regulatory T lymphocytes suppress immune responses, signaling T helper cells and cytotoxic T cells to stop their activities.
Natural killer cells are lymphocytes that attack antigen-presenting cells without prior activation, functioning similarly to cytotoxic T cells.

Role of Lymph Nodes

Lymph nodes serve as sites for immune cell interaction, especially for dendritic cells and naive T and B cells.
Naive T and B cells are those not yet exposed to antigens and circulate in blood via arteries to reach lymph nodes.
When dendritic cells present specific antigens to naive T and B cells, it triggers activation of adaptive immune responses.

T Cell Activation and Function

Activated T cells leave lymph nodes, enter circulation, and can migrate out of blood vessels to the site of infection.
Helper T cells enhance inflammatory responses, while cytotoxic T cells directly kill infected cells.

B Cell Activation

Helper T cells provide signals for B cells to proliferate and differentiate into cells that produce highly specific antibodies.
Initial antibodies formed are primarily IgM, followed by class switching to more specific IgG antibodies as the immune response matures.
Affinity maturation allows for the production of high-affinity antibodies and memory B cells for long-term immunity.

Passive Immunity Types

Natural passive immunity occurs when antibodies are transferred from mother to fetus through the placenta or breast milk, protecting the fetus from infections.
Artificial passive immunity involves the transfer of preformed antibodies from a recovered individual to someone currently infected (e.g., convalescent plasma therapy), speeding up immune response without the need for individual antibody production.

Clinical Examples of Antibody Response

IgM is the first antibody produced in response to an infection, indicating an active infection, while IgG indicates past exposure or a longer-term immune response.
In infectious mononucleosis caused by Epstein-Barr Virus, IgM presence suggests current infection, while a positive IgG indicates a past infection.
In Lyme disease, IgM levels rise several days post-infection, peaking after weeks, which is essential for accurate diagnosis within the correct time frame post-exposure.

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Explore the fascinating and complex world of the immune system. This quiz will guide you through the basic science, various cells, and chemicals involved in immunity. Don't be intimidated; understanding the immune system is key to appreciating how our bodies defend themselves.

Human Physiology Week 2b - Immune System

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