Week 6 – Lymphatic System & Immunity

Instructor Information

Dr. Amany Abdelkader
Email: a.abdelkader@federation.edu.au
Phone: 5122 6014
Location: Berwick Campus, Building 901, Office 120

Learning Objectives

This week, students will gain a comprehensive understanding of the lymphatic system and immunity through the following learning objectives:

Name and locate the components of the immune system.
Describe the formation and composition of lymph.
Explain how lymph is transported through the lymphatic vessels back into the circulation.
Discuss the role of the lymphatic system in body defenses.
Describe the immune response.
Differentiating between B-cells and T-cells in the immune response.
Differentiating between antigens and antibodies.

The Lymphatic System

The lymphatic system serves two major roles in bodily function:

Transportation of Lymph: It transports tissue fluid, known as lymph, that accumulates due to the leakage of blood vessels back into the circulatory system.
Protection Against Infections: It plays a crucial role in the immune functions of the body, collectively referred to as immunity.

Additionally, it is essential to understand the following concepts:

Interstitial Fluid: This is the fluid that surrounds the cells in tissues, providing essential nutrients and maintaining the balance of fluids in the body.
Oedema: Oedema refers to the swelling caused by an excessive accumulation of interstitial fluid, often occurring when the lymphatic system is unable to adequately drain the fluid.

Lymphatic Capillaries & Vessels

Lymphatic capillaries and vessels play a pivotal role in lymphatic drainage, including returning lymph to the bloodstream.

Key Structures of the Lymphatic System

Several key components contribute to the immune functions of the lymphatic system:

Palatine Tonsils: These lymphoid tissues help protect against infections entering through the oral cavity.
Spleen: The spleen filters blood and helps produce immune responses. It is significant to note that a person can survive without a spleen, though its absence can lead to increased susceptibility to infections.
Thymus: This organ is essential for the maturation of T-cells, which are critical to the immune response.

Body Defenses Against Antigens

The body has multiple defenses against antigens:

Physical Barriers: Skin and mucous membranes serve as primary barriers to prevent invasion.
Chemical Barriers: The body produces acidic secretions that deter pathogens.
Phagocytes: These cells engulf and destroy invading pathogens.
Immune Surveillance: Continuous monitoring and elimination of potentially harmful cells.
Inflammation and Fever: These are systemic responses that aid in fighting infections.

Specific Immune Responses

The immune response can be categorized into two main types:

Humoral (Antibody-Mediated) Immunity

This form of immunity involves the production of antibodies by B-cells. It targets pathogens primarily found in body fluids.

Cell-Mediated Immunity

Cell-mediated immunity involves the direct destruction of cells containing antigens, mainly carried out by T-cells. This includes:

Direct Contact: T-cells bind to and immobilize infected cells.
Toxic Chemicals: Cytotoxic T-cells release substances that destroy infected cells.

Blood Typing and ABO Blood Groups

Understanding blood types, such as ABO blood groups, is essential for safe blood transfusions and matching donors to recipients.

This concludes the overview of the lymphatic system and immunity. A solid grasp of these concepts is crucial for further studies in health and wellbeing.

Comprehensive Overview of the Lymphatic System and Immunity

Comprehensive Overview of the Lymphatic System and Immunity