ATI TEAS Immune System

Immune system

Body system that protects against pathogens and disease

Pathogen

Disease-causing organism such as bacteria or viruses

What is the main function of the immune system?

To defend the body against harmful invaders

Innate defense

Nonspecific, immediate immune response

Adaptive defense

Specific immune response with memory

Innate immune system

First and second lines of defense against pathogens

Adaptive immune system

Third line of defense that targets specific pathogens

What are the three lines of defense?

Barriers, internal defenses, and adaptive immunity

First line of defense

Physical and chemical barriers like skin and mucus

Second line of defense

Internal responses like inflammation and phagocytes

Third line of defense

Adaptive immune response using lymphocytes

Lymphocytes

White blood cells involved in adaptive immunity

B cells

Lymphocytes that produce antibodies

T cells

Lymphocytes that attack infected cells or coordinate response

What is the role of B cells?

To produce antibodies and memory cells

What is the role of T cells?

To kill infected cells or activate other immune cells

Phagocytes

Cells that engulf and destroy pathogens

Inflammatory response

Body's reaction to injury or infection causing redness, swelling, and heat

Histamine

Chemical that increases blood flow and immune cell activity

What happens during inflammation?

Increased blood flow and white blood cell activity

Interferons

Proteins that block virus replication

Natural killer (NK) cells

Cells that destroy infected or abnormal cells

Antimicrobial peptides

Molecules that destroy pathogens

What is the purpose of fever?

To speed up immune response and inhibit pathogens

Antigen

Molecule on a pathogen that triggers immune response

Antigen-presenting cell (APC)

Cell that displays antigens to activate T cells

Helper T cell

Cell that activates B cells and cytotoxic T cells

Cytotoxic T cell

Cell that destroys infected cells

Cytokines

Chemical signals that activate immune responses

What do helper T cells do?

Activate other immune cells using cytokines

Plasma cells

Activated B cells that produce antibodies

Antibody

Protein that binds to specific antigens

Memory cells

Cells that remember pathogens for faster future response

What is the benefit of memory cells?

Faster and stronger response upon reinfection

Humoral response

Immune response using antibodies in body fluids

Cellular response

Immune response that destroys infected cells

Active immunity

Protection developed by producing your own antibodies

Passive immunity

Protection from antibodies received from another source

What is a vaccine?

A weakened or dead antigen that stimulates immune memory

How do vaccines work?

They trigger antibody production without causing disease

What is an example of passive immunity?

Receiving antibodies for snakebite treatment

Autoimmune disease

Condition where immune system attacks the body

Allergy

Overreaction of immune system to harmless substances

What happens during an allergic reaction?

Excess antibodies trigger histamine release

What is AIDS?

Disease that weakens immune system by destroying helper T cells

How does HIV affect the immune system?

It prevents activation of adaptive immunity

What systems interact with the immune system?

Circulatory, lymphatic, integumentary, and skeletal

What is the role of the lymphatic system?

To transport and filter pathogens

What is the role of the circulatory system?

To transport immune cells

What is the role of bone marrow?

To produce white blood cells

What is the role of the integumentary system?

To act as a physical barrier

Where are B and T cells activated?

Lymph nodes

How do pathogens enter the body?

Through openings or breaks in the skin

What happens after a pathogen enters the body?

Innate response activates first, then adaptive

What happens if the immune system is weak?

Increased risk of infection

What happens if the immune system is overactive?

Allergies or autoimmune diseases occur

Why is the immune system essential?

It protects the body and maintains health