Immune System Overview

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Questions and Answers

Which of the following is a strategy used by the innate immune system to respond to infection?

  • Antibody production
  • Pathogen adaptation
  • T-cell activation
  • Inflammation (correct)

Complement proteins can stimulate macrophages to engulf bacteria.

True (A)

What role do histamines play in the immune response?

Histamines cause vasodilation, increase vascular permeability, and attract immune cells.

Lysozymes are found in ______ and help to lyse microbial cells.

<p>tears</p> Signup and view all the answers

Match the following immune responses with their descriptions:

<p>Fever = Increased body temperature to enhance immune function Natural killer cells = Cells that provide rapid responses to virus-infected cells Non-specific phagocytosis = Engulfing and destroying pathogens regardless of type Complement = Proteins that aid in lysis and inflammation of pathogens</p> Signup and view all the answers

Which part of the immune system is present from birth and provides a non-specific fast response?

<p>Innate immune system (A)</p> Signup and view all the answers

The primary purpose of fever is to lower the body's temperature to inhibit pathogen growth.

<p>False (B)</p> Signup and view all the answers

What are the four cardinal signs of inflammation?

<p>Heat, Redness, Swelling, Pain</p> Signup and view all the answers

The __________ are important cells involved in non-specific phagocytosis during the innate immune response.

<p>macrophages</p> Signup and view all the answers

Match the following immune responses or cells to their descriptions:

<p>Natural Killer Cells = Destroy virus-infected cells Complement = Enhances the ability to clear microbes Histamine = Increases blood flow to an injury site Prostaglandins = Mediates fever response</p> Signup and view all the answers

What role do immunosuppressive medications play in organ transplants?

<p>Decrease the risk of organ rejection (A)</p> Signup and view all the answers

The mucociliary escalator functions to trap and remove pathogens from the lungs.

<p>True (A)</p> Signup and view all the answers

What chemical is responsible for resetting the body's temperature during fever?

<p>Prostaglandin-E2</p> Signup and view all the answers

Which of the following cells is primarily responsible for the humoral immune response?

<p>B lymphocytes (B)</p> Signup and view all the answers

The innate immune response is specific and has memory.

<p>False (B)</p> Signup and view all the answers

What is the primary function of interferon?

<p>To interfere with virus production and infection.</p> Signup and view all the answers

Kinins are polypeptides derived from plasma proteins that cause __________.

<p>vasodilation</p> Signup and view all the answers

Match the following immune components with their primary effects:

<p>Kinins = Increase vascular permeability Prostaglandins = Cause smooth muscle relaxation Complement = Promote phagocytosis Leukotrienes = Attract neutrophils</p> Signup and view all the answers

Which of the following statements correctly describes the cell-mediated response?

<p>Involves T lymphocytes and targets infected cells. (C)</p> Signup and view all the answers

Pyrogens stimulate the production of fever.

<p>True (A)</p> Signup and view all the answers

The primary origin of T lymphocytes is the __________.

<p>thymus</p> Signup and view all the answers

Which of the following is a benefit of fever?

<p>Leucocytes work better with increased temperature (B)</p> Signup and view all the answers

Natural killer cells are a type of specific immune response cell.

<p>False (B)</p> Signup and view all the answers

What do macrophages and neutrophils primarily do?

<p>Eliminate pathogens through phagocytosis.</p> Signup and view all the answers

Paracetamol reduces the amount of __________ produced, thus lowering fever.

<p>PGE2</p> Signup and view all the answers

Match the immune cells with their basic function:

<p>Macrophages = Phagocytosis of pathogens Natural Killer Cells = Targeting infected self-cells Neutrophils = Rapid response to infection Dendritic Cells = Antigen presentation to T cells</p> Signup and view all the answers

What initiates the process of phagocytosis in macrophages?

<p>Binding of PRRs to PAMPs (C)</p> Signup and view all the answers

All nucleated cells have MHC-2 receptors.

<p>False (B)</p> Signup and view all the answers

What types of molecules do natural killer cells produce to destroy target cells?

<p>Perforins and granzymes.</p> Signup and view all the answers

Flashcards

Complement Cascade

A series of reactions where each component activates the next, leading to destruction of pathogens.

Membrane Attack Complex (MAC)

Proteins that create holes in bacterial membranes, causing them to burst.

Histamine

Chemicals released by immune cells, causing blood vessels to widen and become more permeable, facilitating immune cell movement.

Lysozyme

Enzyme found in bodily fluids that breaks down bacterial cell walls.

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Mucus

A natural defense mechanism that helps trap and remove pathogens from the body.

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Innate Immunity

The immune system's first line of defense against pathogens. It includes physical barriers like skin and mucous membranes, as well as chemical defenses like sebum and sweat.

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Inflammatory Response

A complex process triggered by tissue damage or infection. It involves a series of steps to neutralize pathogens and repair damaged tissue.

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Phagocytes

Specialized white blood cells that engulf and destroy pathogens. They are a key component of the innate immune system.

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Natural Killer Cells

A type of lymphocyte that kills infected cells and tumor cells without needing prior exposure to a specific antigen. They are part of the innate immune system.

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Complement System

A cascade of proteins that can directly kill pathogens or enhance other immune responses. They are a key part of the innate immune system.

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Prostaglandins and Leukotrienes

A group of chemicals released during inflammation that cause pain and fever. They also contribute to immune cell recruitment.

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Pyrogens

A type of protein that induces fever by resetting the body's temperature set point in the hypothalamus.

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Fever: Benefits

Fever is a natural defense mechanism that raises body temperature to fight off infection. It increases the efficiency of leukocytes while hindering the growth of some bacteria.

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Fever: Costs

Fever can have negative consequences, including potential brain damage and general discomfort.

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Phagocytosis

Phagocytosis is a non-specific immune response where specialized cells engulf and destroy pathogens.

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Phagocytic Cells

Macrophages, neutrophils, and dendritic cells are types of phagocytic cells that eliminate pathogens by engulfing them.

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PRR and PAMP

Pattern Recognition Receptors (PRRs) are found on phagocytes and recognize Pathogen-Associated Molecular Patterns (PAMPs) on pathogens. This recognition triggers phagocytosis and the release of cytokines and cytotoxins.

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MHC (MHC-1 and MHC-2)

MHC (Major Histocompatibility Complex) is a group of genes that encode proteins found on the surface of cells. MHC-1 is present on most cells, with specific proteins unique to an individual. MHC-2 is primarily expressed on immune cells.

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What is complement?

A group of plasma proteins that enhance the inflammatory response by increasing vascular permeability, releasing histamine, activating kinins, lysing cells, promoting phagocytosis, and attracting immune cells.

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What are prostaglandins?

A group of lipids, produced by mast cells, that cause smooth muscle relaxation, vasodilation, increase vascular permeability, and stimulate pain receptors.

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What are leukotrienes?

A group of lipids, primarily produced by mast cells and basophils, that cause prolonged smooth muscle contraction, especially in the lungs, increase vascular permeability, and attract neutrophils and eosinophils.

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What are pyrogens?

Chemicals (like cytokines) released by neutrophils, monocytes, and other cells, that stimulate fever production.

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What is interferon?

A protein produced by cells in response to viral infection, interfering with viral replication and spreading.

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What is Humoral Immunity?

A type of adaptive immune response that involves the production of antibodies by B lymphocytes, targeting specific antigens.

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What is Cell-mediated Immunity?

A type of adaptive immune response that involves T lymphocytes directly attacking infected cells or cancer cells.

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What is the difference between innate and adaptive (acquired) immunity?

The adaptive immune response is a targeted, slower, but powerful type of immunity with memory. It is different from the innate response, which is non-specific and immediate.

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Study Notes

Immune System Overview

  • The immune system is a complex biological system that protects the body from harmful invaders
  • It has two parts, innate and acquired immunity

Innate Immunity

  • Present from birth
  • Fast-acting, non-specific response
  • First line of defense

Acquired/Adaptive Immunity

  • Develops over time
  • Specific to particular invaders
  • Slower response than innate immunity
  • Powerful, has memory

Defence Mechanisms of Skin and Epithelium

  • Skin and airways have physical barriers to infection
  • Skin contains sweat and sebaceous glands to secrete fatty acids inhibiting bacterial growth
  • These protective mechanisms are a first line of defense against infection

Mucociliary Escalator

  • Physical defense against pathogens entering the lungs
  • Mucus traps inhaled particles
  • Cilia move mucus towards the pharynx

Function of the Immune System

  • Immune system has crucial role in defending against pathogens
  • Key function is to identify and eliminate various pathogens (bacteria, viruses etc)

Autoimmune Diseases

  • Immune system mistakenly attacks the body's own tissues and organs
  • Examples include rheumatoid arthritis

Organ Transplants

  • Transplanted organs are at risk of rejection by the recipient's immune system
  • Immunosuppressive medications are needed to prevent organ rejection

Chemicals Involved in Innate Immunity

  • Surface chemicals (e.g. lysozyme, sebum, HCl) attack microbes or inhibit their growth
  • Histamine- causes vasodilation, increases vascular permeability, and stimulates gland secretions.
  • Kinins- causes vasodilation, increases vascular permeability, and stimulates pain receptors.
  • Interferons- interferes with virus production and infection
  • Complement- increases vascular permeability, stimulates the release of histamine, activates kinins, lysis cells, promotes phagocytosis, attracts neutrophils, monocytes, macrophages and eosinophils.
  • Prostaglandins- causes smooth muscle relaxation and vasodilation, increases vascular permeability, and stimulates pain receptors.
  • Leukotrienes- causes prolonged smooth muscle contraction, especially in lung bronchioles, increases vascular permeability, and attracts neutrophils and eosinophils.
  • Pyrogens- release by neutrophils, monocytes and other cells that stimulate fever production.

Inflammation

  • Four cardinal signs are heat, redness, swelling, and pain
  • Mechanism involves vasodilation, increased capillary permeability, attracting neutrophils/monocytes etc. and phagocytosis
  • Plays an important role in the overall immune response by removing microbes.

Fever

  • An elevated body temperature caused by pyrogens acting on the hypothalamus
  • The hypothalamus functions as a thermoregulatory center
  • Mediated by prostaglandin E2
  • Antipyretics can reduce fever

Benefits and Cost of Fever

  • Benefits include enhanced leukocyte activity and reduced bacterial growth
  • Costs might involve brain damage and general unwellness

Non-Specific Phagocytosis

  • Cells (e.g., macrophages, neutrophils, dendritic cells) eliminate pathogens via phagocytosis
  • These cells have receptors (PRRs) to bind to pathogen associated molecular pattern (PAMPs)

Natural Killer Cells

  • A type of lymphocyte, they are non-specific immune cells
  • Identify and destroy virus-infected or cancerous cells
  • Using perforins and granzymes for cell lysis

Complement

  • Series of 20 proteins circulating in the blood
  • Activated complement proteins create holes in bacterial membranes leading to cell lysis
  • Stimulate macrophages, attract immune cells and promote inflammation.

Acquired (Adaptive) Immunity

  • Specific immune response against a particular pathogen
  • Two major responses (Humoral and Cell Mediated) Two categories of adaptive immunity
  • Humoral (antibody-mediated)
  • Cell-mediated

Humoral Response

  • Involves B lymphocytes and antibody production
  • Antibodies bind to antigens, neutralizing them or marking them for destruction.

Cell-Mediated Response

  • Involves T lymphocytes targeting and destroying infected cells
  • T cells (e.g. helper T cells and cytotoxic T cells) are an essential component
  • T cells aid in the innate response, by attracting more immune cells to the site

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