Immunology Basics: Lymphatic and Thymus Cells

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Questions and Answers

Which of the following cells are responsible for producing antibodies?

Macrophages

B cells (correct)

Dendritic cells

T cells

What is the primary function of T cells?

Capture and transport antigens

Manage the immune response (correct)

Produce antibodies

Phagocytize foreign substances

Which of the following is NOT considered a primary lymphatic organ?

Lymph nodes (correct)

Thymus

Red bone marrow

Spleen

What is the role of reticular cells in lymphoid organs?

Produce a supporting network for other cells (A) Signup and view all the answers

Which of the following cells are similar to macrophages in their function?

Dendritic cells (A) Signup and view all the answers

Which of the following is NOT a characteristic of the thymus?

Functions primarily in B lymphocyte maturation (C) Signup and view all the answers

What is the purpose of the thymus's epithelial cells?

To secrete hormones that stimulate T cell maturation (B) Signup and view all the answers

Which of the following cells are NOT found in the cortex of the thymus?

B cells (A) Signup and view all the answers

What is the role of dendritic cells in the thymus?

To present antigens to T cells for immune recognition (A) Signup and view all the answers

What is the process called by which only about 25% of developing T cells survive in the thymus?

Positive selection (B) Signup and view all the answers

What is the primary function of the white pulp in the spleen?

Immune surveillance and response (D) Signup and view all the answers

Which of the following cell types are NOT found in the red pulp of the spleen?

Neurons (B) Signup and view all the answers

What is the role of macrophages in the red pulp of the spleen?

Removal of ruptured or worn-out blood cells (D) Signup and view all the answers

What is the significance of the spleen's ability to store up to 1/3 of the body's platelet supply?

To provide a reserve of platelets for blood clotting (D) Signup and view all the answers

Which of the following is NOT a function of the spleen?

Production of lymph fluid (D) Signup and view all the answers

Which of these events occurs during the early stages of inflammation, specifically related to neutrophils?

Neutrophils predominantly populate the site, but their lifespan is short. (B) Signup and view all the answers

What is the role of chemotaxis in inflammation?

It attracts neutrophils and other immune cells to the site of injury. (C) Signup and view all the answers

Which type of immunity is primarily involved in the destruction of intracellular pathogens such as viruses?

Cell-mediated Immunity (C) Signup and view all the answers

What is the main difference between innate immunity and adaptive immunity?

Adaptive immunity develops slowly after exposure to a pathogen, while innate immunity is immediate. (D) Signup and view all the answers

Which type of immune cell is responsible for the production of antibodies?

B cells (A) Signup and view all the answers

What is the primary function of helper T cells in the immune response?

Activating B cells and cytotoxic T cells. (C) Signup and view all the answers

Which of the following is NOT a characteristic of the adaptive immune system?

Rapid response to infection. (B) Signup and view all the answers

Which of the following is a characteristic of adaptive immunity?

The response is faster and more effective when previously exposed to the same antigen. (D), Specific to antigen (F) Signup and view all the answers

Which of the following statements accurately describes the role of helper T cells in the adaptive immune response?

Helper T cells activate both cytotoxic T cells and B cells by releasing interleukin-2 and other cytokines. (C) Signup and view all the answers

What is the defining characteristic that distinguishes exogenous antigens from endogenous antigens?

Exogenous antigens are found outside of body cells, while endogenous antigens are located within body cells. (D) Signup and view all the answers

Which type of cell is responsible for the production of antibodies?

Plasma cells (A) Signup and view all the answers

How do cytotoxic T cells eliminate infected cells?

By releasing cytotoxic substances, such as granzymes and perforin, which induce apoptosis or cytolysis. (D) Signup and view all the answers

Which of the following is NOT a characteristic of MHC-II molecules?

They are involved in activating cytotoxic T cells. (B) Signup and view all the answers

What is the primary function of memory cells in the adaptive immune response?

Memory cells quickly proliferate and differentiate into effector cells upon re-exposure to the same antigen. (D) Signup and view all the answers

What is the significance of the second signal in T cell activation?

The second signal ensures that T cells are only activated in response to a specific antigen and not by self-antigens. (C) Signup and view all the answers

Which of the following statements accurately describes the role of antibodies in the immune response?

Antibodies act as triggers for the activation of complement proteins, leading to the lysis of pathogens. (B) Signup and view all the answers

How do antibodies contribute to enhancing phagocytosis?

Antibodies bind to antigens on pathogens, marking them for destruction by phagocytes. (C) Signup and view all the answers

Which of the following is a primary function of dendritic cells in the immune response?

They serve as antigen-presenting cells, presenting antigens to T cells. (B) Signup and view all the answers

What is the main difference between cell-mediated immunity and antibody-mediated immunity?

Cell-mediated immunity primarily targets intracellular pathogens, while antibody-mediated immunity focuses on extracellular pathogens. (C) Signup and view all the answers

Which of the following accurately describes the process of antigen processing?

Antigen processing involves the breakdown of antigens into small peptide fragments and their association with MHC molecules. (A) Signup and view all the answers

Which of the following is a characteristic of the constant region of an antibody?

The constant region determines the antibody's class, such as IgG or IgM. (A) Signup and view all the answers

Which of the following is a key difference between cytotoxic T cells and natural killer cells?

Cytotoxic T cells are only activated by specific antigens, while natural killer cells can identify and destroy a wide variety of infected or cancerous cells. (D) Signup and view all the answers

What is the role of costimulatory molecules in T cell activation?

Costimulatory molecules provide the second signal necessary for full T cell activation. (C) Signup and view all the answers

Which of the following statements accurately describes the process of clonal selection in the adaptive immune response?

Clonal selection involves the proliferation and differentiation of specific lymphocytes that recognize a particular antigen. (D) Signup and view all the answers

Which of the following is not a function of the lymphatic system?

Producing red blood cells (B) Signup and view all the answers

What is the unique characteristic of lymphatic capillaries that allows interstitial fluid to enter but not exit?

They have anchoring filaments that pull openings wider as fluid accumulates. (A) Signup and view all the answers

What are lymph nodes?

Small, bean-shaped organs that filter lymph and contain lymphocytes. (B) Signup and view all the answers

What is the main difference between innate and adaptive immunity?

Both A and C. (C) Signup and view all the answers

How does the lymphatic system aid in the return of plasma proteins to the bloodstream?

By using the same mechanisms as venous return, such as the skeletal muscle pump and the respiratory pump. (B) Signup and view all the answers

What are the two main lymphatic ducts that drain lymph into the venous blood?

The right lymphatic duct and the thoracic duct. (A) Signup and view all the answers

Which of the following is not a major lymph trunk?

Splenic trunk (A) Signup and view all the answers

What is the relationship between the lymphatic system and the cardiovascular system?

The lymphatic system is a separate system that works closely with the cardiovascular system to maintain fluid balance and immunity. (B) Signup and view all the answers

Study Notes

Lymphatic System

The lymphatic system is a network of vessels, structures, and organs containing lymphatic tissue.
It also involves red bone marrow.
Its primary functions are:
- Draining excess interstitial fluid.
- Transporting dietary lipids.
- Carrying out immune responses.

Immunity or Resistance

Immunity is the body's ability to fight off damage or disease through its defenses.
There are two types of immunity:
- Innate (non-specific) immunity is present at birth and does not recognize invaders or have memory of them.
- Adaptive (specific) immunity specifically recognizes invaders and has memory of them.
- Innate immunity has 1st and 2nd lines of defense.

Lymphatic Vessels and Lymph Circulation

Lymphatic vessels start as capillaries, closed at one end.
They merge into larger vessels that resemble veins, having thinner walls and more valves.
Lymphatic vessels pass through lymph nodes and encapsulated vessels with B and T cells.

Lymphatic Capillaries

Lymphatic capillaries have larger diameters than blood capillaries.
They're exclusively one-way, allowing interstitial fluid to enter but not exit.
Anchoring filaments expand openings when fluid accumulates.

Lymph Trunks and Ducts

Lymphatic vessels merge to form trunks.
Principal trunks include lumbar, intestinal, bronchomediastinal, subclavian, and jugular.
Lymph trunks drain into two main channels (thoracic and right lymphatic ducts) that empty into venous blood.

Lymphoid Cells

Lymphocytes are the primary cells involved in the immune response.
The major varieties include T cells and B cells.

T cells and B cells

T cells and B cells protect the body against antigens.
Antigens are any substances the body perceives as foreign, including bacteria, toxins, viruses, and cancer cells.
T cells manage the immune response and attack foreign cells.
B cells produce plasma cells that secrete antibodies, immobilizing antigens.

Other Lymphoid Cells

Macrophages phagocytize foreign substances and help activate T cells.
Dendritic cells are spiny-like cells similar to macrophages that capture antigens and bring them back to lymph nodes.
Reticular cells are fibroblast-like cells that create a stroma supporting lymphoid cells in organs.

Lymphatic Tissues and Organs

Two groups based on function:
- Primary Lymphatic Organs
  - Sites for stem cell division and development of immunocompetence (red bone marrow and thymus).
- Secondary Lymphatic Organs
  - Sites for most immune responses (lymph nodes, spleen, lymphatic nodules).

Lymphoid Organs - Specific Examples

Thymus:
- Contains an outer cortex and an inner medulla.
- Cortex densely packs lymphocytes and macrophages; medulla has fewer lymphocytes and thymic corpuscles.
- Maintains T-cell maturation.
Lymph Nodes:
- Located along lymphatic vessels, scattered throughout the body.
- Contains stroma (capsule, fibers, and trabeculae) and parenchyma (cortex and medulla) involved in immune responses by filtering lymph and filtering antigens
- Lymph enters through afferent vessels and exits through efferent vessels. Two distinct regions exist cortex and medulla. Cortex contains follicles with germinal centers (dividing B cells); inner cortex houses T cells, and medulla houses B cells, plasma cells, and macrophages.
Spleen:
- Largest mass of lymphatic tissue.
- Stroma consists of capsule, trabeculae, reticular fibers, and fibroblasts.
Parenchyma:
Contains white pulp (lymphocytes, macrophages) and red pulp (blood-filled sinuses and splenic cords containing red blood cells, macrophages, lymphocytes, plasma cells, and granulocytes)
Lymph nodes and spleen filter lymph and blood, respectively.
Red pulp removes worn-out blood cells.
Spleen also serves as a blood reservoir and site of fetal blood cell production.

Lymphatic Nodules

Scattered throughout the lamina propria of mucous membranes.
Mucosa-associated lymphatic tissue (MALT) is in places like respiratory tract.
Some nodules, like tonsils, Peyer's patches, and the appendix, are larger.

Formation and Flow of Lymph

More fluid filters out of blood capillaries than is reabsorbed.
Excess fluid becomes lymph, about 3 liters per day, draining into lymphatic vessels.
Lymphatic vessels return lost plasma proteins to the bloodstream.
Lymphatic vessels have valves, aiding lymphatic return.
Skeletal muscle and respiratory pumps assist venous return.

Relationship of the Lymphatic System to the Cardiovascular System

Lymph vessels and lymph nodes connect to the cardiovascular system.
Lymph travels to venous circulation.

Overview of Innate Immunity

A first line of defense of the body against invaders consisting of physical and chemical barriers.
A second line of defense of the body against invaders consisting of cellular and molecular mechanisms which act internally. Ex. Inflammatory response, Natural killer cells and phagocytes.
Inflammation as a second line of defense in the body against cell damage

Adaptive Immunity

The adaptive defense mechanism acts against specific pathogens and produces cellular and molecular mechanisms.

Antigen Processing Pathways

B cells and T cells respond to antigens in distinct ways and utilize different antigen processing pathways based on whether the antigen is outside or inside the body's cells.

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Description

This quiz tests your knowledge of key concepts related to the immune system, focusing on lymphatic organs and their cellular components. Questions include the roles of various cells like T cells, macrophages, and dendritic cells, as well as the functions of the thymus and spleen. Challenge yourself to see how well you understand these essential aspects of immunology.