01 Introduction to Immune System

Questions and Answers

What role do cytokines play in the adaptive immune response?

They directly kill pathogens in the bloodstream.

They facilitate the phagocytosis of bacteria by naive T cells.

They inhibit the differentiation of B cells into plasma cells.

They support the clonal expansion of CD4+ T cells. (correct)

Which statement about memory cells in the immune system is accurate?

Memory B cells are the first to respond to an infection.

They remain in the body for an extended period, ready for future infections. (correct)

Memory T cells differentiate into phagocytes during subsequent infections.

They are short-lived and only last for a few weeks.

How do CD8+ T cells respond to viral infections?

They release antibodies that tag viral particles.

They kill infected cells expressing viral antigens on MHC I. (correct)

They directly activate macrophages to eliminate all pathogens.

They phagocytose and present viral antigens to B cells.

What distinguishes the innate immune response from the adaptive immune response?

The innate response is immediate but non-specific and lacks memory. Signup and view all the answers

What happens to the majority of B and T cells after the pathogen is eliminated?

Most die of neglect, but some become memory cells. Signup and view all the answers

What is the primary disadvantage of the innate immune response?

It is non-specific and does not provide memory. Signup and view all the answers

Which of the following best describes the adaptive immune response?

It develops memory for specific pathogens and targets them specifically. Signup and view all the answers

How long does it typically take for an immune response to identify and eliminate a pathogen?

About 10 days. Signup and view all the answers

Which of the following components are part of the innate immune response?

Cilia in airways and low pH in the stomach. Signup and view all the answers

Which condition can arise if the immune system fails to properly distinguish between invaders and the body’s own tissues?

Chronic inflammation. Signup and view all the answers

What is a key function of the innate immune system?

To provide a rapid, non-specific defense mechanism. Signup and view all the answers

What is the result of the innate immune response's lack of memory?

It ensures the response to a pathogen is always the same. Signup and view all the answers

Which of the following statements is true regarding the immune system's response time?

The adaptive response is slower but develops memory. Signup and view all the answers

What is the role of dendritic cells in the activation of T cells?

They present antigens on MHC molecules to naive T cells. Signup and view all the answers

What is the main difference between B cells and T cells in terms of antigen recognition?

T cells require antigen presentation on MHC molecules, while B cells can bind directly. Signup and view all the answers

What triggers the activation of naive T cells?

Antigen presentation by antigen presenting cells. Signup and view all the answers

Which cells are specifically involved in targeting intracellular organisms and cancer cells?

Natural killer cells Signup and view all the answers

What is the role of CD4+ T cells during the immune response?

They secrete cytokines to coordinate the immune response. Signup and view all the answers

How do antibodies neutralize pathogens?

By tagging pathogens for destruction and enhancing phagocytosis. Signup and view all the answers

What is the primary function of cytotoxic T cells?

To directly kill target cells presenting specific antigens. Signup and view all the answers

Where do B cells complete their development?

In the bone marrow Signup and view all the answers

What type of immunity is characterized by the secretion of antibodies?

Humoral immunity Signup and view all the answers

What type of cytokines do activated macrophages secrete during inflammation?

All of the above Signup and view all the answers

Which cell type is primarily responsible for bridging the innate and adaptive immune responses?

Dendritic cells Signup and view all the answers

During a complete immune response, what happens after a pathogen is inhaled?

It penetrates the epithelium and induces a cytokine response. Signup and view all the answers

What distinguishes CD8 T cells from natural killer cells?

CD8 T cells are more specific and require MHC I for action. Signup and view all the answers

What is the primary role of memory cells in the adaptive immune response?

To mount a faster and stronger response upon re-exposure to the same pathogen Signup and view all the answers

Which process ensures that neutrophils can destroy pathogens after phagocytosis?

Oxidative burst Signup and view all the answers

What distinguishes basophils from the other white blood cells in their involvement in immune responses?

They have non-phagocytic roles and play a crucial role in initiating allergic responses Signup and view all the answers

During hematopoiesis, what type of cell do multipotent hematopoietic stem cells differentiate into for innate immunity?

Myeloid progenitor cells Signup and view all the answers

What happens to the majority of clonally expanded cells after a pathogen has been eliminated?

They undergo apoptosis Signup and view all the answers

How do eosinophils primarily combat helminthic parasites?

By releasing enzymes that penetrate their outer layers Signup and view all the answers

What are dendritic cells known for in the context of the immune response?

Presenting antigens to T cells Signup and view all the answers

What characterizes neutrophils as a specific type of white blood cell?

They have lobed nuclei and are involved in immediate responses to pathogens Signup and view all the answers

What is the main function of cytokines produced by monocytes, macrophages, and dendritic cells?

To attract other immune cells to the infection site Signup and view all the answers

What occurs during the oxidative burst in neutrophils?

Neutrophils produce reactive oxygen species to destroy ingested pathogens Signup and view all the answers

Which cells are primarily responsible for establishing immunologic memory?

Memory cells Signup and view all the answers

What role do granulocytes, such as eosinophils and basophils, play in the immune system?

They initiate and mediate inflammatory responses Signup and view all the answers

Where do monocytes mature into macrophages?

In tissues Signup and view all the answers

Why are dendritic cells referred to as prototypical antigen presenting cells?

They specialize in breaking down proteins into amino acids for presentation Signup and view all the answers

Study Notes

Immune System Overview

The immune system protects humans from harmful microorganisms, toxins, and cancer cells.
It consists of organs, tissues, cells, and molecules collaborating to generate immune responses.
The response can identify, attack, eliminate pathogens, and remember them for future encounters, typically within 10 days.

Immune Response Types

Innate Immune Response:
- Fast, non-specific response that operates within minutes to hours.
- Lacks memory; responds the same way to repeated exposure to pathogens.
- Composed of chemical barriers (e.g., lysozymes in tears, low stomach pH) and physical barriers (e.g., skin epithelium, airway cilia).
Adaptive Immune Response:
- Slower but highly specific to each pathogen.
- Utilizes unique pathogen parts called antigens to recognize threats.
- Develops immunologic memory, allowing for a stronger and faster response upon re-exposure.

Immunological Memory and Clonal Expansion

Upon initial exposure to a pathogen, adaptive immune cells undergo clonal expansion, proliferating extensively.
The majority die after the threat is eliminated, while some persist as memory cells for future defenses.

White Blood Cells (Leukocytes)

Hematopoiesis: Formation of blood cells, primarily in the bone marrow, starting from multipotent stem cells.
Two progenitor pathways: myeloid and lymphoid.

Myeloid Cells

Include neutrophils, eosinophils, basophils, mast cells, dendritic cells, macrophages, and monocytes.
Neutrophils utilize phagocytosis and oxidative bursts to eliminate pathogens.
Eosinophils combat large parasites and participate in allergic reactions, while basophils initiate allergic responses.

Monocytes, Macrophages, and Dendritic Cells

Monocytes circulate in blood; migrate to tissues to become macrophages.
Dendritic cells excel at antigen presentation, linking the innate and adaptive immune systems.
Antigen presentation occurs on Major Histocompatibility Complex (MHC) molecules.

T Cells and B Cells

T Cells (CD4+ and CD8+):
- CD4+ T cells assist in coordinating immune responses.
- CD8+ T cells kill infected or cancerous cells that display specific antigens.
B Cells:
- Capable of directly binding to antigens and presenting them to T cells.
- Differentiate into plasma cells that produce antibodies, contributing to humoral immunity.

Immune Response Process

Bacterial pathogens enter lungs, are tackled by macrophages and cytokines during the innate response.
Dendritic cells present processed antigens to T cells in lymph nodes, bridging innate and adaptive responses.
Activated T cells help B cells differentiate into plasma cells to produce antibodies, enhancing pathogen elimination.

Role of Natural Killer Cells

Part of the innate immune response, targeting and destroying virus-infected or cancerous cells using cytotoxic granules.

Summary of Immune System Functions

Innate response: Immediate, non-specific, no memory.
Adaptive response: Delayed but specific, with strong memory for quick future responses.

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Description

Explore the intricate mechanisms of the human immune system. This quiz delves into how various organs, tissues, and cells work together to protect us from harmful microorganisms and toxins. Test your understanding of immune responses and the vital role they play in maintaining our health.