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Questions and Answers

What is the main function of the thymus in the lymphatic system?

Storage of immune cells

Production of red blood cells

Filtration of lymphatic fluid

Maturation of T cells and elimination of self-reacting cells (correct)

What is the primary role of the spleen in the lymphatic system?

Transporting lymphatic fluid

Breakdown of old red blood cells (correct)

Immune response activation

Storage of B lymphocytes

Lymphatic nodules are distinguished from lymph nodes by their lack of what structure?

Lymphocytes

Fibrous capsule (correct)

Macrophages

Adipose tissue

Which type of tonsil is also known as adenoids?

Pharyngeal tonsils Signup and view all the answers

What are Peyer's patches primarily associated with?

Digestive system Signup and view all the answers

What is contained in the red pulp of the spleen?

Macrophages and recycled iron Signup and view all the answers

What is the primary role of lymphatic fluid?

Transporting immune cells and waste products Signup and view all the answers

What condition describes the accumulation of fluid in interstitial spaces?

Edema Signup and view all the answers

What is interstitial fluid called once it enters the lymphatic vessels?

Lymph Signup and view all the answers

What prevents the backflow of lymph in the lymphatic vessels?

Valves Signup and view all the answers

What is the primary function of lymph nodes in the lymphatic system?

Filter lymph and house immune cells Signup and view all the answers

Where are lymph nodes most often found in larger numbers?

In the digestive tract Signup and view all the answers

How does fluid movement through the lymphatic vessels primarily occur?

Through peristalsis and skeletal pump action Signup and view all the answers

What type of substances can lymphatic vessels take up that blood vessels cannot?

Proteins and debris Signup and view all the answers

What role do immune cells in the lymph nodes play?

Recognize and fight pathogens Signup and view all the answers

What causes the slow and low pressure movement of lymph in the lymphatic vessels?

Presence of valves and lack of a central pump Signup and view all the answers

What role do interferon (INF) molecules play when released by infected cells?

They target surrounding healthy cells to produce antiviral proteins. Signup and view all the answers

What is one of the functions of complement proteins during an infection?

They stimulate mast cells to produce histamine. Signup and view all the answers

What distinguishes acute inflammation from chronic inflammation?

Acute inflammation is a healthy response, while chronic inflammation results in sustained damage. Signup and view all the answers

Which statement about the inflammatory response is true?

Chronic inflammation can be triggered by diet or stress. Signup and view all the answers

What initiates the process of acute inflammation?

Activation of macrophages by foreign pathogens. Signup and view all the answers

What is the effect of histamine during the inflammatory response?

It increases the permeability of blood vessels. Signup and view all the answers

How do neutrophils respond during the inflammatory process?

They migrate to the infection site through chemotaxis. Signup and view all the answers

Which condition is associated with chronic inflammation?

Cancer and heart disease. Signup and view all the answers

What is the primary purpose of toxoid vaccines?

To stimulate the immune system to produce antigens Signup and view all the answers

How long does immunity from toxoid vaccines typically last before a booster is needed?

Approximately 10 years Signup and view all the answers

Which of the following is NOT a structure of the lymphatic system?

Kidneys Signup and view all the answers

What component of the body does lymph return to after traveling through the lymphatic system?

Bloodstream Signup and view all the answers

What is one function of the immune system?

To maintain homeostasis by protecting against pathogens Signup and view all the answers

What is primarily required for T cell activation?

Encounters with antigen-presenting cells Signup and view all the answers

Which type of T cell is responsible for destroying virus-infected cells?

Cytotoxic T cells Signup and view all the answers

What role do antigen-presenting cells (APCs) play in the adaptive immune response?

They activate Helper T cells through antigen display Signup and view all the answers

What function do Memory T cells serve after initial exposure to an antigen?

They proliferate upon future exposure to the same antigen Signup and view all the answers

What occurs during the cellular immune response involving T cells?

T cells bind directly to antigen-bearing cells Signup and view all the answers

What is the consequence of perforin release by Cytotoxic T cells?

Induction of apoptosis in the target cell Signup and view all the answers

Which of the following is NOT a function of Helper T cells?

Directly killing virus-infected cells Signup and view all the answers

What happens when an undifferentiated Helper T cell matches its receptors with a displayed antigen?

It becomes activated and proliferates Signup and view all the answers

What is the role of activated Cytotoxic T cells in the immune response?

To release perforin and destroy infected cells Signup and view all the answers

Which cell type requires Helper T cells for activation after encountering an antigen?

B cells Signup and view all the answers

What is the primary function of plasma cells in the immune response?

To secrete antibodies that bind to antigens Signup and view all the answers

What happens to B cells after they are activated by encountering an antigen?

They proliferate and can become either plasma cells or memory B cells Signup and view all the answers

Which of the following describes the purpose of Memory B cells?

They respond quickly to future encounters with the same pathogen Signup and view all the answers

How do antibodies facilitate the humoral immune response?

By binding to antigens and marking them for destruction Signup and view all the answers

What is one consequence of opsonization in the immune response?

It enhances phagocytosis of pathogens by immune cells Signup and view all the answers

Which sequence best represents the order of events from B cell activation to antibody production?

B cell binding → Helper T cell activation → Plasma cell formation → Antibody secretion Signup and view all the answers

Study Notes

Unit 13: The Lymphatic System and Immunity (Chapter 23)

Chapter covers the lymphatic system and immunity, specifically focusing on Chapter 18, pages 401-403.
Edited by Claudia Schubert, Ph.D., OCT; Lauren Brown, MSc, WWHP; Jessie Carviel, Ph.D., B.Ed.
Prepared by Wendi Roscoe, Fanshawe College.
Published in 2016 by Nelson Education Ltd.

Lecture Outcomes

13.1: Description of lymph formation and functions.
13.2: Explanation of lymph node, thymus, tonsils, and spleen functions.
13.3: Tracing the path of lymph back to venous circulation.
13.4: Description of the lymphatic system's role in immunity and cardiovascular support.
13.5: Description of vaccine production and function in individual immunity.
13.6: Discussion of vaccines' role in disease transmission and public health.

Functions of the Immune System

Drains excess interstitial fluid.
Transports dietary fats and fat-soluble vitamins.
Recognizes and destroys infectious organisms (bacteria, viruses, fungi, parasites).
Tolerates our own cells and non-harmful foreign molecules (like food).
Produces immunological memory cells to prevent future infections.

Structure of the Immune System (Diagram)

Shows major lymphatic structures (lymph nodes, thymus, spleen, tonsils, etc.) within the body.
Highlighting connections to the venous system (e.g., right and left subclavian vein).

Refresh: Anatomy of the Blood Vessels (and the role of the lymph vessels)

The cardiovascular system is described as leaky.
Approximately 4 liters of fluid are lost daily due to capillary exchange.
The lymphatic system functions in collecting and recycling this fluid.
Interstitial fluid is the fluid between cells.
Lymph is interstitial fluid that enters lymphatic vessels.
Lymph re-enters the bloodstream.

Blood & Lymphatic Vessels (Diagram)

Illustrates the relationship between blood vessels (arterioles, venules, capillaries) and lymphatic vessels.
Shows how lymph is collected from interstitial fluid.

Lymphatic Vessels (Diagram)

Shows the structure of a lymph vessel including:
- Smooth muscle cells
- Basement membrane
- Epithelial cells
- Valves
- Direction of lymph flow

Movement of Lymph

Peristalsis: Smooth muscle in lymphatic vessel walls moves lymph slowly.
Valves: Prevent backflow of lymph.
Skeletal pump: Lymph vessels use valves similar to veins to assist in movement.
Flow: Slow and low pressure in the lymphatic system.
Function: Lymph nodes clean and examine lymph for pathogens.

Lymphatic Ducts (Diagram)

Illustration of important lymphatic ducts and nodes in the body (such as cervical, axillary, and spleen).
Shows connections to the circulatory system (superior vena cava, subclavian veins).

Structures of the Lymphatic System

Lymph nodes contain immune cells to recognize and fight infections.
Lymph nodes are plentiful in areas where microorganisms can enter the body (ears, mouth, lungs, urogenital tract, mammary glands).

Anatomy of a Lymph Node (Diagram)

Shows the structures of a lymph node, including:
- Capsule
- Afferent lymphatic vessels
- Reticular fiber
- Lymphocytes
- Lymphoid follicle
- Efferent lymphatic vessels
- Hilum

Anatomy of the Lymphatic System - Bone Marrow

Hematopoietic stem cells in bone marrow differentiate into red and white blood cells, and platelets (B cells also mature).

Anatomy of the Lymphatic System - Thymus

Thymus contains thymocytes, which undergo maturation to eliminate "self" antigen recognizing cells.

Anatomy of the Lymphatic System - Spleen (Diagram)

Red pulp: Contains macrophages, red blood cells, and platelets (old red blood cell breakdown).
White pulp: Contains lymphocytes, macrophages, and dendritic cells (involved in adaptive immune responses).

Anatomy of the Lymphatic System - Lymphatic Nodules

Similar to lymph nodes, but lack a capsule.
Examples: tonsils, appendix, adenoids, Peyer's patches (located around small intestines).
Also called gut-associated lymphoid tissue (GALT).

Anatomy of the Lymphatic System - Tonsils (Diagram)

Show types of tonsils (pharyngeal, palatine, lingual) and their tonsillar crypts to trap unwanted materials from the digestive and respiratory systems.

Edema

Fluid accumulation in interstitial fluid leads to swelling (edema).
Causes of fluid buildup include high capillary hydrostatic pressure, kidney dysfunction, venous valve failure, lack of muscle contraction, decreased plasma proteins, and blocked lymphatic vessels.

Innate Immune Response

First line of defense: Skin, hair, cilia, mucus, antimicrobial agents in tears, saliva, sweat, and stomach acid/gut bacteria.
Second line of defense:
- Neutrophils: arrive first, secrete cytokines, attract other immune cells, phagocytose.
- Monocytes: differentiate into macrophages and dendritic cells, phagocytosis.
- Natural killer cells: puncture virus-infected cells (perforin).
Interferon (INF): a molecule released by viruses-infected cells to target surrounding healthy cells to inhibit viral replication.
Complement proteins: produced by the liver and activated by infection (bind to microbes), and stimulate phagocytosis, and form the membrane attack complex (MAC).

Inflammatory Response

Triggered by tissue injury.
Chronic: sustained injury from long-term exposure to cytokines. Linked to chronic diseases like cancer, diabetes, and heart disease.
Acute: a healthy response to injury or infection that promotes regrowth of healthy tissue.

Acute Inflammation

Foreign pathogen invades the body.
Macrophages are activated and release cytokines/chemokines.
Mast cells release histamine.
Histamine and cytokines increase vasculature permeability.
Neutrophils migrate to the site, engulf pathogens and destroy them.

Adaptive Immune System

Body's third line of defense (learned response).
Lymphocytes like T cells and B cells.
Works with innate immune system.
Reacts to antigens of foreign cells/pathogens.
APCs (Antigen Presenting Cells): Engulf foreign cells (macrophages and dendritic cells) and present antigens to adaptive immune system cells.

T Cells and the Cellular Immune Response

T cells are activated by encountering antigen-presenting cells.
Recognition leads to activation.
Activated T cells interact directly with antigen-bearing cells (cellular immune response).

Types of T Cells

Helper T cells: stimulate B cells to produce antibodies.
Cytotoxic T cells: monitor and eliminate infected and cancer cells via perforin.
Memory T cells: provide a quick response to subsequent encounters with the same antigen.

T Cell Activities: Summary

Foreign pathogen enters tissues, antigen-bearing agent phagocytic cells.
Accessory cell displays pathogen antigens on the cell membrane.
Undifferentiated Helper T cell becomes activated if its antigen receptors bind to displayed antigens.

T Cell Activities: Summary- Helper T cells

Activated Helper T cells proliferate.
Interact with cytotoxic T cells and release cytokines to activate cytotoxic T cells.
Interact with B cells to release cytokines activating B cells, starting the humoral response.
Memory T cells: from activated Helper T cells.

B Cells and the Humoral Immune Response

B cell activation occurs when it encounters and binds to a foreign antigen.
Most need Helper T cell activation to fully activate.
Activated B cell divides (creating clones):
- Plasma cells: produce antibodies.
- Memory B cells: form for future defense.

B Cell Activities: Summary

Antigen-bearing pathogens enter tissues.
B cell encounters an antigen.
B cell proliferates and differentiates into plasma cells.
Plasma cells produce antibodies.
Some B cells differentiate into memory B cells, for future encounters.

Functions of Antibodies

Antibodies produced by plasma cells circulate and bind to the infecting organism, known as opsonization.
Opsonization increases phagocytosis (eating) by macrophages and dendritic cells and killing by complement proteins.
Microbes are neutralized via antibodies.
Bacteria are immobilized by antibody-induced clumping (agglutination).

Adaptive Immune Response Summary (Diagram)

Illustrates the different components working together in the adaptive immune response, including antibodies, phagocytosis, and cytotoxicity.

Vaccines

Vaccination introduces a dead or inactive pathogen or its components to stimulate the immune system.
Artificial Active Immunity: The vaccine triggers an immune response. This helps the body build immunity without infection.
Types of Vaccines:
- Live attenuated vaccines use weakened versions of a virus, typically preventing smallpox, measles, mumps, and rubella.
- Inactivated (killed) vaccines use killed pathogens, such as influenza and cholera
- Toxoids are inactivated bacterial toxins; examples include tetanus, diphtheria, and pertussis (DPT).

Summary

Functions of the immune and lymphatic systems (homeostasis, pathogen defense, and fluid handling).
Includes descriptions of structures of the systems and their roles.

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