Human Immunology and Lymphatic System Quiz

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Questions and Answers

What is the primary function of the thymus?

Storage of red blood cells

Maturation of T lymphocytes (correct)

Activation of B cells

Production of antibodies

Which component is NOT found in the stroma of the thymus?

Dendritic cells

Star-shaped epithelial cells

Macrophages

Reticular fibers (correct)

What happens to the size of the thymus as a person ages?

It remains the same size

It becomes entirely non-functional

It shrinks significantly (correct)

It increases in size

How do immature T cells begin their maturation process?

By proliferating in the outer cortex of the thymus Signup and view all the answers

What percentage of T cells typically survive the positive selection process in the thymus?

25% Signup and view all the answers

What is one of the primary functions of the lymphatic system?

Drain excess interstitial fluid Signup and view all the answers

What distinguishes innate immunity from adaptive immunity?

Innate immunity does not have a memory component. Signup and view all the answers

What are lymphatic capillaries primarily designed to do?

Allow interstitial fluid flow in but not out. Signup and view all the answers

What is the primary functional component of the lymph node called?

Parenchyma Signup and view all the answers

Which structure is involved in carrying out immune responses within the lymphatic system?

Lymph nodes Signup and view all the answers

What is true about lymphatic nodules?

They are not surrounded by a capsule and are scattered throughout mucous membranes. Signup and view all the answers

What type of cells predominantly populate the inner cortex of a lymph node?

T cells Signup and view all the answers

What is the composition of lymph in relation to plasma?

Lymph contains lost plasma proteins. Signup and view all the answers

Which type of vessels do lymphatic vessels resemble?

Veins Signup and view all the answers

What are Peyer’s patches and appendix classified as?

Lymphatic nodules Signup and view all the answers

Which structure is responsible for filtering lymph as it passes through a lymph node?

Sinuses Signup and view all the answers

How much excess fluid is drained into lymphatic vessels daily?

3L Signup and view all the answers

Which of the following is NOT a physical barrier in the first line of defense of innate immunity?

Sebaceous secretions Signup and view all the answers

What is formed primarily in the outer cortex of lymph nodes?

Memory B cells and plasma cells Signup and view all the answers

Which of the following fluids serves to cleanse the urinary system?

Urine Signup and view all the answers

What aids in the movement of lymph through lymphatic vessels?

Respiratory pump and skeletal muscle pump Signup and view all the answers

In which direction does lymph flow through a lymph node?

One direction only Signup and view all the answers

What role do interferons play in innate immunity?

They prevent the replication of viruses in neighboring cells. Signup and view all the answers

What role do macrophages play in lymph nodes?

Destroy microorganisms and debris Signup and view all the answers

Which component helps physically trap microbes in the upper respiratory tract?

Mucus Signup and view all the answers

What is the role of dendritic cells in the outer cortex of the lymph node?

Encapsulate lymphatic nodules Signup and view all the answers

Which component of the lymph node divides it into compartments?

Trabeculae Signup and view all the answers

Which of the following is a chemical barrier that discourages bacterial growth?

Gastric juice's acidity Signup and view all the answers

What type of tissue is referred to as mucosa-associated lymphatic tissue (MALT)?

Scattered lymphatic nodules in mucous membranes Signup and view all the answers

What is the primary purpose of clonal selection in lymphocytes?

To increase the proliferation and differentiation of lymphocytes in response to a specific antigen Signup and view all the answers

Which type of cell is produced during clonal selection that is responsible for inactivating the antigen?

Effector cell Signup and view all the answers

What characteristic allows an antigen to provoke an immune response?

Immunogenicity Signup and view all the answers

What do memory cells do during a second invasion by an antigen?

They proliferate and differentiate into more effector and memory cells Signup and view all the answers

Which of the following components is primarily responsible for helping T cells recognize foreign or self-antigens?

Major Histocompatibility Complex Antigens (MHC) Signup and view all the answers

What is an epitope in the context of an antigen?

The small part of an antigen that is recognized by the immune system Signup and view all the answers

What typically results from the swelling of lymph nodes and tonsils during an immune response?

Proliferation of lymphocytes Signup and view all the answers

What is reactivity in the context of antigens?

The ability of an antigen to react specifically with the antibodies it provoked Signup and view all the answers

What defines the role of antigen-presenting cells (APCs)?

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

How do endogenous antigens differ from exogenous antigens?

Endogenous antigens are found inside body cells. Signup and view all the answers

What is the initial activation step for T cells?

T-cell receptors recognizing antigen-MHC complexes. Signup and view all the answers

What role does interleukin-2 serve in the immune response?

It acts as a costimulator for all immune responses. Signup and view all the answers

What ultimately happens to activated B cells?

They undergo clonal selection and produce plasma cells. Signup and view all the answers

Which statement is true regarding cytotoxic T cells?

They require helper T cells for maximal activation. Signup and view all the answers

Which structure is characteristic of antibodies?

T-shaped or Y-shaped due to the hinge region. Signup and view all the answers

Which process occurs when antibodies neutralize an antigen?

Antibodies prevent viruses from attaching to body cells. Signup and view all the answers

What primary function do memory helper T cells serve?

They rapidly proliferate if the antigen reappears. Signup and view all the answers

How do cytotoxic T cells eliminate infected cells?

By releasing perforin and granzymes. Signup and view all the answers

What does the constant region of an antibody determine?

The class or type of antibody reaction. Signup and view all the answers

What is the function of costimulation in the immune response?

To prevent accidental immune responses and provide a second signal. Signup and view all the answers

How are plasma cells related to B cells?

Plasma cells secrete antibodies and originate from activated B cells. Signup and view all the answers

What defines the fate of activated T cells?

Activated T cells can proliferate and differentiate into effector cells or memory cells. Signup and view all the answers

Study Notes

Lymphatic System

The lymphatic system is a network of vessels, tissues, and organs that helps maintain fluid balance in the body and plays a crucial role in the immune system.
The system consists of lymph, lymphatic vessels, structures, and organs containing lymphatic tissue, and red bone marrow.
The lymphatic system performs three key functions:
- Draining excess interstitial fluid
- Transporting dietary lipids
- Carrying out immune responses

Immunity or Resistance

Immunity is the ability to ward off damage or disease through defenses.
There are two main types of immunity:
- Innate (non-specific) immunity – present at birth, with no specific recognition of invaders and no memory component. It includes the first and second lines of defense.
- Adaptive (specific) immunity - involves specific recognition of invaders and has a memory component.

Lymphatic Vessels and Lymph Circulation

Lymphatic vessels begin as lymphatic capillaries, which are closed at one end.
They unite to form larger lymphatic vessels, that resemble veins in structure but have thinner walls and more valves.
These vessels pass through lymph nodes and encapsulated organs with masses of B and T cells.

Lymphatic Capillaries

Lymphatic capillaries are slightly larger in diameter than blood capillaries.
They have a unique one-way structure.
Anchoring filaments pull openings wider when interstitial fluid accumulates.

Lymph Trunks and Ducts

Lymphatic vessels unite to form lymph trunks.
Principal trunks include lumbar, intestinal, bronchomediastinal, subclavian, and jugular trunks.
Lymph from these trunks flows into two main channels: thoracic and right lymphatic ducts.
These ducts drain into venous blood.

Lymphoid Cells

Lymphocytes are the main cells involved in the immune response.
There are two main types:
- T cells which manage the immune response and attack and destroy foreign cells.
- B cells which produce plasma cells that secrete antibodies to immobilize antigens.
Other lymphoid cells include macrophages, which phagocytize foreign substances and help activate T cells, and dendritic cells, which capture antigens and bring them to lymph nodes.

Lymphoid Tissues and Organs

Lymphoid tissues and organs are grouped into two categories based on function:
- Primary lymphatic organs: sites where stem cells divide and become immunocompetent (capable of mounting an immune response). Examples include red bone marrow and the thymus.
- Secondary lymphatic organs: sites where most of the immune response occurs. Examples include lymph nodes, spleen, and lymphatic nodules.

Thymus

The thymus's internal anatomy includes the outer cortex and inner medulla. The cortex contains densely packed lymphocytes and scattered macrophages, while the medulla primarily contains fewer lymphocytes.
The thymus plays a crucial role in the maturation of T lymphocytes
The stroma of the thymus consists of star-shaped epithelial cells.
Thymocytes secrete hormones that stimulate lymphocytes to become immunocompetent

Lymph Nodes

Lymph nodes are located along lymphatic vessels and throughout the body.
They are encapsulated with a fibrous capsule, trabeculae extending inward, reticular fibers, and fibroblasts.
The parenchyma of a lymph node is divided into outer and inner cortex as well as medulla.
The outer cortex contains follicles and nodules, which are areas of B cells.
The inner cortex primarily houses T cells and dendritic cells, while the medulla contains B cells, plasma cells, and macrophages.
lymph flows through the node in one direction.
Lymph nodes function as a filter, and pathogens here are destroyed by macrophages.

Spleen

The spleen is the largest single mass of lymphatic tissue in the body.
The stroma comprises a capsule, trabeculae, reticular fibers, and fibroblasts.
The parenchyma is composed of white pulp, which contains lymphocytes and macrophages for immune responses, and red pulp, which consists of blood-filled venous sinuses and splenic cords for filtering blood and removing defective blood cells.

Lymphatic Nodules

Lymphatic nodules are scattered throughout the lamina propria of mucous membranes lining the gastrointestinal, urinary, and reproductive tracts, and the respiratory system.
Some lymphatic nodules are larger and include tonsils, Peyer's patches, and the appendix.

Antigen Processing

B cells can bind to antigens in lymph, interstitial fluid, or blood plasma.
T cells only recognize antigen fragments.
An antigen-presenting cell (APC) processes and presents the antigen.
Exogenous antigens are present in the body fluids; APCs ingest these antigens, process, and display them attached to MHC-II molecules.
Endogenous antigens are present inside the cells, so infected cells display them next to MHC-I molecules.

Cell-Mediated Immunity

Cytotoxic T cells directly attack invading antigens, making them particularly effective against intracellular pathogens.
The major function is for T cells to attack cells by releasing cytotoxic chemicals after binding to the infected cells.
These T cells also have helper T cells, which play a part in the process.

Antibody-Mediated Immunity

B cells turn into plasma cells and generate antibodies that combat pathogens outside cells.
Antibodies bind to antigens and mark them for destruction by other immune cells or macrophages.
Memory B cells are long-lived and provide immunological memory, enabling rapid and effective responses upon subsequent encounters with the same antigen.
There are different classes of antibodies, each with distinct functions in the immune response.
Immunological memory is the ability of the adaptive system to quickly respond to previous antigens and mounts a quicker and stronger resposne when an antigen reemerges.

Self-Recognition and Self-Tolerance

T cells must recognize self-MHC proteins and be tolerant of their own proteins.
Pre-T cells in the thymus undergo positive selection where they learn to recognize self-MHC proteins. Those that cannot are eliminated.
Negative selection occurs in the thymus to further eliminate T cells that could possibly target self-antigens.
Anergy maintains unresponsiveness among mature lymphocytes in the secondary lymphoid tissues.

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Description

Test your knowledge on the thymus, T cell maturation, and the lymphatic system in this comprehensive quiz. Explore the vital roles of lymph nodes, lymphatic capillaries, and innate versus adaptive immunity. Challenge yourself with questions about the functions and structures of the immune system.