Chapter 22.1-3 Immune System and the Body's Defense

What are organisms that cause damage, or possibly death, to the host organism that they invade?

What are organisms that cause damage, or possibly death, to the host organism that they invade?

infectious agents

What are infectious agents that cause harm to the host?

pathogenic

What are the five infectious agents?

Hint:

1. B

2. V

3. F

4. Pr

5. Pa

1. bacteria

2. viruses

3. fungi

4. protozoans

5. parasites

Which infectious agent is being described?

• Prokaryotic

• Size: 1-2 micrometers

• Features: intracellular and extracellular microbes; some have a sticky polysaccharide capsule and/or hairlike pili

• Diseases: strep, staph, tb, syphilis, diphtheria, tetanus, Lyme disease salmonella, anthrax

bacteria

Which infectious agent is being described?

• Not prokaryotic or eukaryotic, but rather DNA or RNA housed in a capsid protein

• 1/100 of a micrometer

• Features: obligate intracellular parasites; most enter a cell to replicate

• Diseases: common cold, influenza, polio, mumps, measles, hepatitis, rubella, chicken pox, ebola, herpes, and HIV (which leads to AIDS)

virus

Which infectious agent is being described?

• Eukaryotic

• 4-100 micrometers

• Features: produce spores; release proteolytic enzymes

• Diseases: ringworm, diaper rash, jock itch, athlete’s foot, yeast infection, histoplasmosis

fungi

Which infectious agent is being described?

• Eukaryotic

• 1-50 micrometers

• Features: intracellular and extracellular parasites that interfere with normal cellular functions

• Diseases: malaria, toxoplasmosis, giardiasis, amoebiasis, leishmaniasis, trichomonaisis, and African sleeping sickness

protozoan

Which infectious agent is being described?

• Eukaryotic

• Larger than a cm (not microscopic)

• Features: live within a host; grow in size with nutrients provided by the host

• Diseases: parasitic infection from tapeworms, lung, liver, and blood flukes, hookworms, Trichinella, Ascaris, whipworms, and pinworms

parasites

What are small fragments of infectious proteins that cause disease in nervous tissue?

prions

How do prions cause disease?

unknown

How are prions spread?

consumption of infected nervous tissue

Where are leukocytes made?

red bone marrow

What are the three types of granulocytes?

basophils, eosinophils, neutrophils

Basophils, eosinophils, and neutrophils are all types of what? :)

granulocytes

What do monocytes become?

macrophages or dendritic cells

What are the three types of lymphocytes?

T-lymphocytes, B-lymphocytes, and NK (natural killer) cells

Most leukocytes are found in ______rather than in the ________________.

body tissues; blood stream

What are the lymphatic tissues?

lymph nodes, spleen, tonsils, lymphatic nodules, and MALT

Macrophages are also found where?

select organs

What kinds of cells are being described?

• Cells that engulf pathogens in the skin and mucosal membranes then migrate to a lymph node through lymph vessels that drain the tissue

dendritic cells

Where are dendritic cells found?

skin and mucosal membranes

What relationship exists between CT and mast cells?

Mast cells are located within the CT throughout the body, primarily in close proximity to small blood vessels.

What is being described?

• Small, soluble proteins produced by cells of both the innate and adaptive immune system to regulate and facilitate immune system activity

• Serve as a means of communication between the cells, control the development and behavior of effector cells of immunity, regulate the inflammatory response of innate immunity, and can serve as weapons to destroy cells in some cases

• Can influence other non-immune cells like cells of the nervous system

cytokines

What are the four major classes of cytokines?

1. Interleukin (IL)

2. Tumor necrosis factor (TNF)

3. Colony-stimulating factor (CSF)

4. Interferon (IFN)

Which kind of immunity is being described?

• Non-specific

• We’re born with it

• Includes the barriers of the skin and mucosal membranes that prevent entry, as well as non-specific cellular and molecular internal defenses

• Provides an immediate response to many substances

innate immunity

Which kind of immunity is being described?

• Acquired immunity

• Produces a delayed response to specific antigens

• Gained through exposure to a foreign substance

• Involves specific T-lymphocytes and B-lymphocytes, which respond to different antigens

• Takes several days to be effective

adaptive immunity

Innate immunity includes all body processes that do one of two things. What are they?

1. Prevent entry of potentially harmful substances

2. Respond non-specifically to a wide range of potentially harmful substances following their entry into the body - that is, non-specific internal defenses

Internal innate defenses include what three things?

1. Activities of various types of cells including neutrophils, macrophages, and NK cells

2. Chemicals such as interferon and complement

3. Physiological processes that include inflammation and fever

What cells are involved in innate immunity?

granulocytes (basophils, eosinophils, and neutrophils), mast cells, NK cells, and macrophages

What cells are involved in adaptive immunity?

T-lymphocytes, B-lymphocytes, and plasma cells

How does the skin present a physical barrier?

If it’s in tact, the epithelial tissues of the epidermis and the CT of the dermis make a physical barrier that very few microbes can penetrate.

How does the skin present a chemical barrier?

Its cells release antimicrobial substances like IGA, lysozyme, sebum, and defensins. The skin also has normal flora living on it.

What is the ‘normal flora’? What is it’s purpose?

They are non-pathogenic microorganisms that live on the skin and help prevent the growth of pathogenic microorganisms.

List the structures in the body that use the process of ‘washing away microbes’ to prevent infection.

1. Sweat glands

2. Salivary glands

3. Lacrimal glands

What structures use a low pH to prevent infection?

1. Sebaceous (oil) glands

2. Stomach (hydrochloric acid

3. Vagina (lactic acid of urogenital tract)

What distinguishes neutrophils from macrophages?

Neutrophils

• most prevalent leukocyte in the blood

• first to arrive during inflammatory response

• “foot soldiers”

Macrophages

• less abundant

• arrive later after the inflammatory response begins

• stay longer than neutrophils

• “cleanup crew”

How do basophils differ from mast cells?

circulate in blood while mast cells reside in skin’s CT, mucosal linings, and various internal organs

How do NK cells accomplish the task of eliminating unwanted cells?

1. Patrol body for unhealthy cells (immune surveillance)

2. When they find unhealthy cells, they make physical contact with them and destroy them by releasing cytotoxic chemicals. Perforin, one of these chemicals, forms a transmembrane pore in the unwanted cells while granzymes enter the cell through this hole, which initiates apoptosis. The cell shrivels up and dies as a result.

What is being described?

• They are a class of cytokines released from a variety of cells, including leukocytes and fibroblasts.

• Serve as a non-specific defense mechanism against the spread of any viral infection

• When released, they bind to the receptors of neighboring cells to prevent them from becoming infected and trigger synthesis of enzymes that destroy viral RNA or DNA and inhibit synthesis of viral proteins

• Additionally stimulates macrophages and NK cells to destroy virus-infected cells when relased

interferon

What is being described?

• One of the most important antimicrobial groups of substances of innate immunity

• Made of at least 30 plasma proteins that make up approximately 10% of the serum proteins in the blood (collectively, these proteins are referred to as complement)

complement system

Which of the four means by which complement participates in innate immunity is being described?

• The binding of a protein to a portion of bacteria or other cell type that enhances phagocytosis

• Binding of complement makes it more likely that a substance is identified and engulfed by phagocytic cells

osonization

Which of the four means by which compleWhich of the four means by which complement participates in innate immunity is being described?

• By activating basophils and mast cells, as well as attracting neutrophils and macrophages, the complement increases the inflammatory response

inflammation

Which of the four means by which complement participates in innate immunity is being described?

• Various complement components trigger the direct killing of a target through the formation of a protein channel in the target cell’s plasma membrane.

• The membrane attack complex (channel) allows for fluid to rush into the cell and cause lysis of the cell

cytolysis

Which of the four means by which complement participates in innate immunity is being described?

• The complement links immune (antigen-antibody) complexes to erythrocytes so that they can be taken to the liver and spleen. The red blood cells have these complexes taken off by macrophages in these organs then continue to circulate in the blood.

elimination of immune complexes

Of what benefit is the inflammatory response?

It acts immediately and locally and is the major effector response of innate immunity. It’s successful in helping to get rid of most infectious agents and other unwanted substances from the body.

Summarize the four steps of the inflammatory response.

1. Damaged cells of injured tissues, basophils and mast cells, and infectious organisms release chemicals like histamine, leukotrienes, prostoglandins, and chemotactic factors.

2. Chemicals that were released cause vascular changes such as vasodilation, an increase in capillary permeability, and a display of CAMs (molecules for leukocyte adhesion).

3. Leukocytes go from the blood to the infected tissue through the process of margination, diapedesis, and chemotaxis.

4. Plasma proteins delivered to inflammation site

What are the cardinal signs of inflammation?

1. Redness

2. Heat

3. Swelling

4. Pain

5. Loss of function

In what ways does exudate assist in the body’s defense?

delivers cells and substances needed to eliminate the injurious agent and promotes healing

What is a fever?

abnormal elevation of body temp. (pyrexia) of at least 1.8 degrees F from the typically accepted body temp.

What does fever result from?

the pyrogens, toxins produced by infectious agents, or in response to trauma, drug reactions, and brain tumors

What are the stages of a fever?

1. Onset

2. Stadium

3. Defervescence

What are the benefits of a fever?

1. Inhibits reproduction of bacteria and viruses

2. Promotes interferon activity

3. Increases activity of adaptive immunity

4. Accelerates tissue repair

5. Can increase CAMs

6. Increase WBC activity

What are the risks of a fever?

1. Seizures

2. Irreversible brain damage

3. Death