Ch 21

1. Fluid Recovery - Reabsorbs fluid lost from capillaries

2. Immunity - Picks up foreign cells and chemicals, passes through lymph nodes to activate immune responses.

3. Lipid Absorption - Lacteals in the small intestine absorb dietary lipids not absorbed by blood capillaries.

What are the three primary functions of the lymphatic system?

transport lymph, a recovered fluid, through a network that includes lymph nodes, trunks, and ducts, ultimately returning it to the bloodstream.

What are lymphatic vessels and their function?

Jugular, subclavian, bronchomediastinal, intercostal, intestinal (unpaired), and lumbar trunks.

What are the six major lymphatic trunks?

moves through vessel contractions, skeletal muscle pumps, arterial pulsations, the thoracic pump, and one-way valves that prevent backflow.

How does lymph move through the body

1. Natural Killer (NK) Cells - Attack bacteria, transplanted cells, virus-infected cells, and cancerous cells.

2. T Lymphocytes (T Cells) - Responsible for cell-mediated immunity.

3. B Lymphocytes (B Cells) - Differentiate into plasma cells that produce antibodies.

4. Macrophages - Phagocytic cells that process and present antigens to T cells.

5. Dendritic Cells - Antigen-presenting cells that alert the immune system.

6. Reticular Cells - Contribute to the structural framework of lymphatic organs.

What are the primary types of lymphatic cells and their functions?

Red bone marrow and thymus (where T and B cells become immunocompetent).

What are the primary lymphatic organs?

houses developing T cells, secretes hormones (thymosin, thymopoietin), and forms the blood-thymus barrier to protect immature T cells from premature activation.

What is the function of the thymus?

1. Filter lymph and remove harmful substances.

2. Site for T and B cell activation.

What are the two primary functions of lymph nodes?

Cancer cells can enter lymphatic vessels, lodge in lymph nodes, multiply, and spread to other tissues.

How do lymph nodes contribute to cancer metastasis?

Specific responses, involves memory, includes T and B cells that recognize and attack specific pathogens.

What is adaptive immunity?

The skin is tough (keratin), dry, nutrient-poor, and secretes antimicrobial substances like dermicidin, defensins, and cathelicidins.

How does the skin protect against infection?

They line body passages, secrete mucus to trap microbes, and contain lysozyme, an enzyme that destroys bacterial cell walls.

How do mucous membranes contribute to immunity?

Neutrophils, eosinophils, basophils, monocytes, and lymphocytes.

What are the five types of leukocytes involved in immunity?

patrol the body and destroy infected, cancerous, or foreign cells using perforins and granzymes to induce apoptosis.

What is the function of natural killer (NK) cells?

Proteins secreted by virus-infected cells to warn neighboring cells, activate NK cells, and enhance macrophage activity.

What are interferons?

A group of 30+ plasma proteins that enhance immunity by triggering inflammation, immune clearance, phagocytosis, and cytolysis.

What is the complement system, and how does it destroy pathogens?

Fever increases metabolic rate, accelerates tissue repair, promotes interferon activity, and inhibits microbial reproduction.

How does fever help fight infection?

Redness, swelling, heat, and pain.

What are the four cardinal signs of inflammation?

1. Born in bone marrow.

2. Mature in the thymus (selection process).

3. Deployed to lymphatic tissues.

What are the three stages of T cell development?

Cytotoxic T cells (attack infected cells)

Helper T cells (coordinate immunity)

Regulatory T cells (prevent overreaction)

Memory T cells (provide long-term immunity).

What are the four classes of T cells?

recognize antigens, proliferate into plasma cells, and produce antibodies that neutralize or tag pathogens for destruction.

How do B cells function in humoral immunity?

IgG: Most abundant, crosses placenta, secondary response.

IgA: Found in secretions (tears, saliva, breast milk).

IgM: First produced in infection, pentamer structure.

IgE: Involved in allergic reactions and parasite defense.

IgD: Functions in B cell activation.

What are the five classes of antibodies (immunoglobulins)?

Antibodies are transferred (natural: mother to baby; artificial: antibody injection).

What is passive immunity?

Lymphatic tissue and red bone marrow decline, fewer immune cells are produced, and responses to infections and cancer become weaker.

How does aging affect immunity?

Attack bacteria, transplanted cells, virus-infected cells, and cancerous cells.

Natural Killer (NK) Cells

Responsible for cell-mediated immunity.

T Lymphocytes (T Cells)

Differentiate into plasma cells that produce antibodies.

B Lymphocytes (B Cells)

Phagocytic cells that process and present antigens to T cells.

Macrophages

Dendritic Cells

Antigen-presenting cells that alert the immune system

Reticular Cells

Contribute to the structural framework of lymphatic organs.

Neutrophils

Primarily responsible for phagocytosis (engulfing and digesting pathogens like bacteria). They are the first responders to infection

eosinophils

Combat parasitic infections and play a role in allergic reactions by releasing enzymes that break down parasites and allergens.

basophils

Release histamine and other chemicals that promote inflammation during allergic reactions and help fight infections

monocytes

Develop into macrophages or dendritic cells that ingest and digest pathogens, dead cells, and debris, and help activate the immune system.

lymphocytes

Include T-cells (which kill infected cells or help other immune cells) and B-cells (which produce antibodies to fight infections). They are central to adaptive immunity.

Cytotoxic T cells

attack infected cells

Helper T cells

coordinate immunity

Regulatory T cells

prevent overreaction

Memory T cells

provide long-term immunity

IgG

Most abundant, crosses placenta, secondary response.

IgA

Found in secretions (tears, saliva, breast milk).

IgM: First produced in infection, pentamer structure.

IgE: Involved in allergic reactions and parasite defense.

IgD: Functions in B cell activation.

IgM

First produced in infection, pentamer structure.

IgE

Involved in allergic reactions and parasite defense.

IgD

Functions in B cell activation.