The immune System

What is the focus of Cam Clip 1 for A&P II, Session 6?

The immune system, specifically the relationship between the lymphatic and immune systems and their interaction with other body systems.

How is immunity defined?

Immunity is our resistance to the effects of disease-causing agents.

Why do we all have different immunity?

Because each person makes their own immunity, tailored to who they are.

Why is the immune system essential to life?

It protects us from potentially fatal disease processes, possibly some cancers, and generally keeps us alive by fighting pathogens.

How do we know if our immune system works?

We only know when it doesn’t work; its effectiveness is built-in and specific to defending against diseases.

What is meant by a “silent, portable army” in immunity?

After exposure to a pathogen (e.g., chickenpox), memory cells remain in the body for life, ready to attack the pathogen if it reappears.

What are the necessary components for a healthy immune system?

Lymphatics (filter and clean blood), skin and mucus membranes (mechanical barriers), interferons (proteins that interfere with viruses and tumors), enzymes in body fluids, leukocytes (white blood cells)

What is the first line of defense in the immune system?

Skin and mucus membranes, which act as mechanical barriers to bacteria and pathogens.

What are interferons, and what do they do?

Interferons are proteins that interfere with the proliferation or development of some viruses and tumors.

What is the role of enzymes in immunity?

They protect the body from disease and are present in various body fluids.

How many types of leukocytes are there, and which are phagocytic?

There are five types of leukocytes; neutrophils and monocytes are phagocytic.

What role do neutrophils play?

They act as short-term foot soldiers that increase during acute infections.

What happens to monocytes?

Monocytes mature into macrophages, which live throughout the body.

Where do macrophages reside, and what is their function?

Macrophages reside in lymph nodes, lungs, liver, and other tissues; they are aggressive phagocytes that clean blood and body fluids constantly.

Immunity

The body’s resistance to the effects of disease-causing agents, tailored individually, and essential for survival.

Silent, portable army

Memory cells that remain in the body after infection (e.g., chickenpox) to provide long-term immunity.

Lymphatics

Structures that filter and clean blood; essential for a healthy immune system.

First line of defense

Mechanical barriers like skin and mucus membranes that prevent pathogen entry.

Interferons

Proteins that interfere with the proliferation of some viruses and tumors, working quietly in the background.

Enzymes (immune-related)

Protective proteins in various body fluids that help fight disease.

Leukocytes

White blood cells; five types exist, including phagocytic neutrophils and monocytes.

Neutrophils

Short-term phagocytic leukocytes that increase during acute infection.

Monocytes

Phagocytic leukocytes that mature into macrophages.

Macrophages

Aggressive phagocytes located in lymph nodes, lungs, liver, and other tissues; clean blood and body fluids continuously.

Nonspecific defense mechanisms

General defenses that everyone has, such as inflammation, skin chemicals, and phagocytosis.

Specific defense mechanisms

Defenses tailored to an individual based on previous disease exposure or vaccinations; involve cells that remember and attack pathogens.

Humoral immunity

B cells and antibodies that target pathogens.

Cellular immunity

T cells that directly attack infected cells.

Antigen specific

Immunity designed to target specific pathogens.

Systemic

Immunity that recognizes pathogens anywhere in the body.

Memory

Immunity that remembers pathogens and responds faster upon re-exposure.

Histamine

An inflammatory chemical that increases capillary permeability, allowing fluid to escape into interstitial spaces.

Basophils

A type of leukocyte that releases histamine and heparin.

Mast cells

Connective tissue cells that release histamine during inflammation.

Keratin

Tough protein in epidermis that strengthens skin and makes it waterproof.

Mucous membranes

Line body cavities open to the outside and provide protective barriers.

Enzymes (immune-related)

Destroy pathogens in body fluids such as gastric juice, tears, and saliva.

Acidic pH

Helps inhibit bacterial growth on skin and in body fluids.

Inflammation

A protective process causing redness, swelling, heat, and pain, recruiting immune cells to injury or infection sites.

Neutrophils

Short-term phagocytic white blood cells that respond during acute inflammation.

Fibrinogen

A plasma protein/clotting factor that forms a mesh around pathogens or injury sites to contain them.

Reticuloendothelial system (RES)

Macrophages distributed throughout the body that phagocytize pathogens and debris.

Macrophages

Phagocytic cells in tissues that engulf and destroy pathogens; part of the RES.

Phagocytosis

Process by which a cell engulfs and breaks down pathogens or debris.

Interferons

Proteins that interfere with virus/tumor proliferation and stimulate tumor-fighting cells.

First line of defense

Mechanical and chemical barriers such as skin and mucous membranes.

Second line of defense

Nonspecific defenses like phagocytosis and inflammation.

Third line of defense

Specific defenses such as antibodies, T cells, and natural killer cells.

Where do all blood cells originate?

All blood cells originate from the bone marrow.

How many types of white blood cells are there?

There are five types of white blood cells.

What are the “phils” in white blood cells?

Eosinophils, neutrophils, and basophils.

What are the “cytes” in white blood cells?

Lymphocytes and monocytes.

What are the two categories of lymphocytes?

T cells and B cells.

Where do T cells mature?

T cells mature in the thymus.

What hormone is responsible for T cell maturation?

Thymosin.

What percentage of lymphocytes are T cells?

T cells make up about 70% to 80% of lymphocytes.

Where do T cells primarily reside?

Organs of the lymphatic system, such as the spleen and lymph nodes.

Where do B cells mature?

B cells mature in the bone marrow.

What percentage of lymphocytes are B cells?

B cells make up about 20% to 30% of lymphocytes.

Where do B cells reside after leaving the bone marrow?

In lymphatic organs, secretory glands, intestinal lining, and reticuloendothelial (RES) tissue.

What is the purpose of the body marking “self” before birth?

The body identifies which cells belong to it to prevent attacking its own tissues.

How do T cells and B cells work together?

They coordinate to mount a specific immune response against antigens.

What is the difference between self and non-self?

Self: belongs to the body and is recognized; Non-self: foreign substances that trigger an immune response.

What is an autoimmune disorder?

A condition where the immune system mistakenly attacks the body’s own cells.

What is an antigen?

Anything that triggers an immune response; typically considered a “bad guy” or non-self intruder.

Give examples of antigens.

Allergens like peanuts or ragweed, certain antibiotics, or other substances the body recognizes as non-self.

Where is the thymus gland located?

In the thoracic cavity, anterior chest, wrapped around the aorta, in the mediastinum (space between the lungs).

What happens to the thymus gland with age?

It atrophies and becomes less functional in old age.

What is the function of the thymus gland?

It develops T lymphocytes and helps them mature via thymosin.

Bone marrow

The origin of all blood cells.

White blood cells

Five types: eosinophils, neutrophils, basophils, lymphocytes, monocytes.

Phils

Eosinophils, neutrophils, basophils (types of WBCs).

Cytes

Lymphocytes and monocytes (types of WBCs).

Lymphocytes

White blood cells divided into T cells and B cells.

T cells

Lymphocytes that mature in the thymus, make up 70–80% of lymphocytes, reside in lymphatic organs.

B cells

Lymphocytes that mature in the bone marrow, make up 20–30% of lymphocytes, reside in lymphatic organs and RES tissue.

Thymus gland

Located in thoracic cavity, mediastinum; develops and matures T lymphocytes with thymosin.

Thymosin

Hormone responsible for T cell maturation in the thymus.

Self marker

Identification of body’s own cells to prevent immune attack.

Non-self

Foreign or invading substances that trigger an immune response.

Autoimmune disorder

Condition where the immune system attacks the body’s own cells.

Antigen

Any substance that triggers an immune response; considered a non-self intruder.

Examples of antigens

Allergens (peanuts, ragweed), antibiotics, other foreign substances.

Mediastinum

The space between the lungs where the thymus resides.

RES (Reticuloendothelial system)

Network of macrophages throughout the body that attack pathogens.

Where do all lymphocytes originate?

All lymphocytes originate in the bone marrow.

Where do B cells mature?

B cells mature in the bone marrow itself.

What is the primary function of B cells?

To develop antibodies that tag antigens and make them unusable.

How do antibodies work against antigens?

They bind to antigens, making them inactive and unable to harm the body.

Where do T cells mature?

T cells mature in the thymus gland.

What is the primary function of T cells?

They fight antigens directly and assist B cells in mounting an immune response.

How do T cells and B cells work together?

T cells coordinate attacks while B cells produce antibodies, working together to eliminate antigens.

What analogy is used to describe B cells and T cells?

Like two separate parts of a defense system, e.g., navy and army, with different roles but a common goal.

What are the three main types of T cells?

Killer T cells, Helper T cells, and Suppressor T cells.

What do Killer T cells do?

Directly attack and destroy antigens.

What do Helper T cells do?

Organize the immune response, help B cells become plasma cells, proliferate antibodies, and facilitate T cell and B cell interaction.

What do Suppressor T cells do?

Call off the immune response when the threat is eliminated, indicating the problem is cleared.

Lymphocytes

White blood cells that originate in the bone marrow and are critical for immune responses.

B cells

Lymphocytes that mature in the bone marrow and produce antibodies.

Antibodies

Proteins produced by B cells that bind to antigens, making them inactive and harmless.