Human Physiology Week 2b

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Questions and Answers

What is the primary role of the innate immune system?

To produce antibodies in response to specific pathogens.

To indiscriminately block and eliminate foreign substances. (correct)

To recognize and remember past infections.

To specifically target and eliminate harmful microorganisms.

Which cells are primarily responsible for producing antibodies?

Phagocytes

B cells (correct)

T cells

Natural killer cells

What does 'humoral immunity' refer to?

The physical barriers like skin and mucus membranes.

The immune response mediated by T cells.

The production of antibodies in the blood. (correct)

The action of natural killer cells.

Which of the following is a key difference between the innate and adaptive immune systems?

Innate immunity is non-specific while adaptive immunity is specific. Signup and view all the answers

What is the primary function of antibodies in the immune system?

To neutralize antigens Signup and view all the answers

What is an antigen?

A substance that triggers an immune response Signup and view all the answers

What kind of immunity is primarily enacted by T cells?

Cell-mediated immunity Signup and view all the answers

Which type of white blood cells are classified as granular leukocytes?

Neutrophils Signup and view all the answers

What does the term 'epitope' refer to in immunology?

A specific sub-region of an antigen Signup and view all the answers

Which of the following best describes the role of antibodies?

They are proteins produced in response to antigens. Signup and view all the answers

Which cells are known as agranular leukocytes?

Lymphocytes and monocytes Signup and view all the answers

Why is understanding the immune system important for physical therapy?

It is crucial for managing inflammation and immune-mediated diseases. Signup and view all the answers

What is the role of macrophages in the immune system?

To clear cellular debris Signup and view all the answers

Which of the following diseases is NOT classified as an immune-mediated or autoimmune disease?

Osteoarthritis Signup and view all the answers

What can be considered a common substance for an antigen?

Polysaccharides found on foreign invaders Signup and view all the answers

What is the final product of the initial phases of the adaptive immune response?

Effector T cells Signup and view all the answers

Which cell type is primarily responsible for presenting antigens in the immune response?

Antigen presenting cells Signup and view all the answers

Where do lymphocyte stem cells mature into immunocompetent T cells?

Thymus Signup and view all the answers

What distinguishes a mature immunocompetent T cell from other cells?

It is capable of an immune response. Signup and view all the answers

What is the role of helper T cells in the immune response?

They help turn on the inflammatory response. Signup and view all the answers

What is the primary function of lymphokines?

To activate and attract other white blood cells Signup and view all the answers

Which type of T cell is primarily responsible for turning off the immune response?

Suppressor T cells Signup and view all the answers

What is the main role of plasma cells?

To secrete immunoglobulins or antibodies Signup and view all the answers

How do memory B cells function in the immune response?

They circulate and trigger rapid antibody production upon re-encounter with an antigen. Signup and view all the answers

What does the term 'humoral immunity' refer to?

The specific response of antibodies produced by B cells Signup and view all the answers

What is the main characteristic of innate immunity?

It operates quickly and non-specifically. Signup and view all the answers

How does the adaptive immune response primarily function?

It responds specifically to recognized foreign pathogens. Signup and view all the answers

What role do B lymphocytes play in the immune response?

They produce antibodies against specific microbes. Signup and view all the answers

What is the relationship between T cells and macrophages in the adaptive immunity?

Macrophages present antigens to T cells. Signup and view all the answers

How long does it generally take for the adaptive immune system to respond to a pathogen?

Days Signup and view all the answers

Study Notes

Understanding the Immune System

The immune system is complex, involving various cells and chemicals essential for managing inflammation in physical therapy.
Key understanding of the immune system aids in the management of immune-mediated diseases such as rheumatoid arthritis, myasthenia gravis, and Guillain-Barre syndrome.

Key Terminology

Antigen: A substance that triggers an immune response, typically proteins or polysaccharides found on foreign invaders.
Antibody: A protein produced by the immune system in response to an antigen, functioning to neutralize or inhibit the antigen's negative effects.
Epitope: A specific sub-region of an antigen that antibodies bind to.
Pathogen: A microorganism that causes infectious diseases, characterized by various antigens with associated epitopes.

Immune System Cells

Leukocytes (white blood cells): Main players in the immune response, classified into granular and agranular types.
- Granular leukocytes:
  - Eosinophils: 2-4% of white blood cells, stain red.
  - Basophils: 0.5-1%, stain blue/purple.
  - Neutrophils: 60-70%, neutral staining, dominant white blood cell type.
Agranular leukocytes:
- Lymphocytes: Include B-cells and T-cells, essential for adaptive immunity.
- Monocytes: Larger cells that differentiate into macrophages, which engulf cellular debris and pathogens.

Immune System Branches

Innate Immune System:
- Non-specific, includes physical barriers like skin and mucus membranes.
- Components like phagocytes (e.g., macrophages, neutrophils) respond rapidly (within hours) to any perceived threat without discrimination between harmful and harmless substances.
Acquired (Adaptive) Immune System:
- Specific immunity involving lymphocytes, particularly B-cells (produce antibodies) and T-cells (mediators of cell-mediated immunity).
- Takes days to mount a response, recognizing and targeting specific pathogens, often after an innate response.

Functions of Immune Cells

B-cells: Produce antibodies that circulate and bind to specific antigens on pathogens.
T-cells: Help coordinate immune responses; may kill infected host cells and support B-cell antibody production.

Immune Response Dynamics

Innate immunity acts quickly upon exposure to pathogens, while adaptive immunity has a delayed but targeted response.
Adaptive immunity involves:
- B-cell activation: Upon recognizing an antigen, B-cells proliferate and differentiate into antibody-producing plasma cells.
- T-cell activation: T-cells become activated through interactions with antigen-presenting cells (e.g., macrophages), leading to proliferation and targeted immune actions.

Summary of Immunity Types

Cell-mediated Immunity: Primarily refers to the functions of T-cells.
Humoral Immunity: Relates to B-cells and the antibodies produced in response to antigens.

Overall Structure

The immune system is organized into specific branches (innate and adaptive), with distinct roles and collaborative interactions to effectively combat infections.### Adaptive Immune Response
Effector T cells are the final outcomes of the initial phases of the adaptive immune response, taking days to develop.
Antigen presenting cells (APCs), primarily macrophages, collect cellular debris and antigens to activate immune responses by other immune cells.

Antigen Presenting Cells

Macrophages function like "garbage bags," engulfing and presenting antigens from various sources, including bacteria and innocuous materials.
Antigens presented by APCs interact with lymphocytes to determine whether an immune response is necessary.
Cytokines released during the interaction between APCs and lymphocytes trigger either an inflammatory response or halt the immune reaction.

T Cells Development

T cells originate from pluripotent hematopoietic stem cells in the bone marrow and mature in the thymus.
Mature immunocompetent T cells can differentiate into:
- Helper T cells: Activate other white blood cells and enhance the inflammatory response.
- Regulator T cells: Control and suppress the immune response to prevent overactivation.

Effector and Memory T Cells

Cytotoxic T cells: Primarily kill virus-infected and pathogenic cells.
Memory T cells: Provide long-term immunity by rapidly responding to previously encountered antigens.

B Cells Development

B cells mature in the bone marrow and are vital for producing antibodies.
They differentiate into:
- Plasma cells: Secrete immunoglobulins (antibodies) to target specific pathogens.
- Memory B cells: Retain information about encountered antigens for quicker responses in the future.

Humoral Immunity

Humoral immunity is facilitated by B cells, primarily targeting extracellular microbes.
B cells produce antibodies that bind to specific antigens, neutralizing pathogens or marking them for destruction by phagocytosis.
Antibodies can inhibit pathogen function, recruit complement proteins, or facilitate engulfment by neutrophils and macrophages.

Cell-Mediated Immunity

Cell-mediated immunity involves T cells responding to intracellular pathogens, such as viruses.
Helper T cells, upon recognizing antigens presented by APCs, release cytokines that promote T cell proliferation and activation.
Activated cytotoxic T cells destroy infected host cells through direct apoptosis or other mechanisms.

Summary of Lymphocyte Functions

B lymphocytes: Key for antibody production, neutralization of pathogens, and tag pathogens for destruction by phagocytes.
Helper T lymphocytes: Interact with APCs to activate macrophages, B cells, and further T cell proliferation, initiating inflammatory responses.
Cytotoxic T lymphocytes: Identify and eliminate infected cells through antigen recognition and subsequent activation.

Key Terms

Cell Mediated Immunity: T cell response.
Humoral Immunity: B cell response, primarily targeting blood and extracellular fluids.
Immunocompetent: Capability to respond to antigens.
Cytokines: Signaling molecules that mediate immune responses.### Immune Cell Functions
Cytotoxic T lymphocytes (CTLs) destroy infected cells, acting as the immune system's executioners.
Regulatory T lymphocytes (Tregs) regulate and suppress the immune response to prevent overactivity.
Natural killer (NK) cells inherently target and kill antigen-presenting cells without prior activation.

Role of Dendritic Cells in Immune Activation

Dendritic cells, a type of macrophage, transport antigens to lymph nodes via lymphatic vessels.
Naive T and B cells, which have not encountered antigens, are activated in the lymph nodes when presented with antigens by dendritic cells.
Activation leads to the proliferation and differentiation of T and B cells into effector or memory cells.

T Cell Activation and Response

Effector T cells exit lymph nodes into circulation to perform immune functions, including assisting phagocytes and causing inflammatory responses.
Helper T cells have a critical role in activating B cells, boosting antibody production through signals.

B Cell Immunity

B cells produce antibodies, which bind specifically to epitopes on antigens.
Initial antibody production starts with Immunoglobulin M (IgM), followed by class switching to produce more specific Immunoglobulin G (IgG) antibodies.
Memory B cells are formed for long-term immunity after the initial exposure to pathogens.

Antibodies Overview

Antibodies (or immunoglobulins) are proteins produced by B cells that bind antigens.
There are five main types of antibodies:
- IgG: Most abundant, found in body fluids, protects against bacteria and viruses.
- IgA: Located on mucous membranes, such as in the eyes.
- IgM: First antibody produced during an infection; present in blood and lymph.
- IgE: Involved in allergic reactions.
- IgD: Found in small amounts in blood; its function is not well understood.

Active vs Passive Immunity

Active immunity results from exposure to antigens and the body producing its own antibodies.
Passive immunity provides antibodies directly, without prior exposure; occurs naturally (e.g., maternal transfer) or artificially (e.g., convalescent plasma therapy).
Maternal antibodies (like IgG and IgA) transfer to the fetus through the placenta or breast milk, offering protection during early life.
Convalescent plasma therapy involves transferring antibodies from recovered patients to help newly infected individuals, such as those with COVID-19.

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Explore the complexities of the immune system in this quiz. Learn about the various cells and chemicals that play crucial roles in immune function. This quiz will help demystify the intricate workings of our body's defense mechanisms.

Human Physiology Week 2b - Immune System

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