Immunology-1 Lecture 2: Immune System Types

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Questions and Answers

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

To differentiate into memory cells

To produce antibody molecules (correct)

To secrete chemical messengers called cytokines

To bind to and kill infected cells

What role do memory B cells play in the immune system?

They bind to and destroy pathogens directly.

They produce antibodies immediately upon first exposure to an antigen.

They suppress the activation of other immune cells.

They provide long-lasting memory for future encounters with the same antigen. (correct)

What initiates the differentiation of B cells into plasma cells?

Presence of memory T cells in peripheral tissues

Clonal expansion in the lymphatic system

Binding to cytokines released by T cells (correct)

Detection of foreign antigens by receptors

Which type of T cell is responsible for killing infected cells and cancer cells?

Cytotoxic T cells Signup and view all the answers

What leads to the production of antibodies in the immune system?

Binding of antigens to lymphocyte receptors Signup and view all the answers

Which component of the immune system is primarily responsible for protecting the body from infection?

White blood cells Signup and view all the answers

Where do white blood cells originate?

Bone marrow Signup and view all the answers

Which type of white blood cells is involved in producing antibodies?

B cells Signup and view all the answers

What role do neutrophils play in the immune system?

They kill bacteria and fungi Signup and view all the answers

Which of the following is NOT a type of white blood cell?

Antibodies Signup and view all the answers

What is the primary function of the thymus gland in the immune system?

Help T cells mature Signup and view all the answers

Which structure is involved in the filtering of substances in the immune system?

Spleen Signup and view all the answers

What color do white blood cells appear when stained for microscopic examination?

Light purple to pink Signup and view all the answers

What is the primary role of eosinophils in the immune system?

To identify and destroy parasites and cancer cells Signup and view all the answers

What is the normal range of white blood cells per microliter of blood?

4,000 to 11,000 Signup and view all the answers

What triggers the body to initiate an immune response?

Antigens entering the bloodstream Signup and view all the answers

Which type of antigen is considered foreign to the body?

Heteroantigens Signup and view all the answers

Where do B cells and T cells originate?

Bone marrow Signup and view all the answers

What allows lymphocytes to bind to antigens?

Receptor molecules on their surfaces Signup and view all the answers

What is the typical lifespan of most lymphocytes?

A week to a few months Signup and view all the answers

What is immunologic memory primarily due to?

Long-lived T and B cells Signup and view all the answers

Study Notes

Immunology-1 Lecture 2: Types of Immune System

The immune system is composed of many organs and cells that work together to maintain health.
White blood cells (WBCs) are crucial components of the immune system.
WBCs, also known as leukocytes, protect the body from infection.
WBCs circulate in the bloodstream and tissues, identifying and responding to infection sites.

White Blood Cells (WBCs) - Characteristics

WBCs are colorless, but can appear light purple or pink when stained and viewed under a microscope.
They have a round shape with a distinct central membrane, or nucleus.
WBCs represent approximately 1% of total blood volume; red blood cells are more prevalent.

WBC Formation

WBCs originate from cells that develop into other cells, specifically stem cells, found within the bone marrow.
White blood cell development also occurs in the soft tissue inside bones (bone marrow).
Different types of white blood cells, such as lymphocytes (including B cells and T cells), develop in different locations (thymus, lymph nodes, and spleen).

WBC Types

Five types of white blood cells:
- Neutrophils: Protect the body by killing bacteria, fungi, and foreign debris.
- Lymphocytes: Include T cells, natural killer cells, and B cells; protect against viral infections and produce antibodies.
- Eosinophils: Destroy parasites, cancer cells, and play a role in allergic responses.
- Basophils: Trigger allergic reactions, such as coughing, sneezing, or a runny nose.
- Monocytes: Defend against infection by cleaning up damaged cells.

WBC Normal Count

A normal count of white blood cells ranges between 4,000 and 11,000 cells per microliter of blood.
Approximately 100 billion WBCs are produced daily.

Antigens & Antibodies

Antigens: Substances or toxins in the blood that trigger the immune system's response.
- Antigens are primarily bacteria or viruses, but can also include other foreign substances.
- The immune system's response to antigens is called an immune response.
Antibodies: Proteins that protect the body from invaders by binding to and destroying them.

Heteroantigens and Autoantigens

Heteroantigens: Foreign substances to the body, including viruses, bacteria, protozoa, blood/red blood cells from others, snake venom, and allergens (like pollen) or food proteins.
Autoantigens: Proteins made by the body to fight the body's own cells; often a sign of autoimmune diseases.

Lymphocytes

Lymphocytes (a type of WBC) are crucial for determining the specificity of the immune response to infections and foreign substances.
- B cells and T cells originate in bone marrow and in some cases mature in the thymus.
- Most lymphocytes have a short lifespan — a few weeks to a few months.
- However, some lymphocytes have longer lifespans to maintain long-term immune responses and memory.
Lymphocytes are able to respond rapidly to subsequent encounters with the same antigen.
Lymphocytes recognize foreign antigens (non-self) to help remove them from the body.
Each lymphocyte has receptors that bind to a specific antigen.

Lymphocyte Activation

Lymphocytes multiply and differentiate upon stimulation by a foreign antigen, including bacteria or viruses.
Activated lymphocytes differentiate into other cell types with specific functions.
- B cells differentiate into plasma cells to produce antibodies that bind to the antigen.
- Helper T cells secrete cytokines that activate other white cells to help destroy and eliminate the antigen.
- Some lymphocytes become memory cells to create a rapid response if the same antigen is encountered again.
Cytotoxic T cells destroy infected cells.
Regulatory T cells control immune reactions.

Types of Lymphocytes

Innate lymphocytes (ILCs) and adaptive lymphocytes (B cells and T cells) are two main classes.
- ILCs are innate lymphocytes that do not have T-cell receptors.
- Adaptive lymphocytes use T-cell or B-cell receptors.

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Description

Dive into the second lecture of Immunology-1, focusing on the various types of the immune system and the essential role of white blood cells (WBCs). Learn about their characteristics, formation, and how they protect the body from infections. Enhance your understanding of immunology through this informative session.