Immune System Flashcards
The defence mechanisms of the immune system are classified as ___ and ___.
nonspecific / specific
Protects the body against many different types of foreign agents where the body need not recognize the specific foreign agent.
Nonspecific immunity
Hones in on a specific substance.
Specific immunity
Also called innate immunity.
Nonspecific immunity
Contains certain defence mechanisms that do not require prior exposure to a pathogen or foreign agent.
Nonspecific immunity
Nonspecific immunity can be divided into ___ lines of defence.
2
Includes mechanical barriers, chemical barriers, and reflexes.
Nonspecific - 1st line of defence
Includes phagocytosis, inflammation, fever, protective proteins (interferons and complement proteins), and natural killer (NK) cells.
Nonspecific - 2nd line of defence
Work against all foreign agents or types of injury; no recognition of a specific agent or injury is necessary.
Nonspecific defence mechanisms
Intact skin and mucous membranes serve as this (pathogens cannot cross these structures and enter the body).
Mechanical barrier
Assists the skin and mucous membranes with their mechanical defensive functions.
Chemical secretions
The secretion of the sebaceous and sweat glands of the skin forming an acid coating (acid mantle) that inhibits bacterial growth is an example of this.
Chemical secretion (chemical barrier)
The external layer of the skin continuously sloughing off, thereby shedding microorganisms from the skin surface is an example of this.
Mechanical barrier
Stomach secretions, saliva, sweat, and enzymes such as lysozyme.
Chemical barriers
Perspiration, tears, and saliva containing lysozyme, an enzyme that discourages the growth of pathogens are examples of this.
Chemical barrier
Includes mechanical barriers, chemical barriers, and reflexes.
1st line of defence (nonspecific)
The acid and digestive enzymes secreted by the cells of the stomach killing most of the microorganisms that are swallowed is an example of this.
Chemical barrier
Destruction of mechanical barriers is an invitation to microbial invasion and subsequent ___.
infection
Other secretions make the environment sticky and so provide another type of barrier. The mucus secreted by the mucous membranes of the respiratory tract ___ inhaled foreign material. Then the ___, which line most of the respiratory structures, sweep the entrapped material toward the throat, so that the material can eventually be coughed up or swallowed.
traps / cilia
In addition to the mechanical and chemical barriers, ___ assist in the removal of pathogens.
reflexes
Sneezing and coughing that help remove pathogens from the respiratory tract are examples of this.
Reflexes
Vomiting and diarrhea helping to remove pathogens from the digestive tract are examples of this.
Reflexes
Includes phagocytosis, inflammation, fever, protective proteins, and NK cells.
2nd line of defence
Ingest and digest pathogens and other foreign substances by phagocytosis.
Leukocytes
Two important phagocytes are the n___ and m___.
n - eutrophils / m - onocytes
Small and motile, they travel to the site of infection quickly.
Netrophils
At infection they engage the pathogen aggressively and most die in battle, becoming part of the cellular debris and pus.
Netrophils
Active in the absence of infection; they constantly wander throughout the connective tissue, killing bacteria before they have a chance to grow and multiply.
Neutrophils
This secretes and surrounds itself within a cloud of bactericidal chemicals prompted to phagocytose, thus feasting away in a phagocyte-friendly chemical killing zone.
Neutrophil
Some circulate within the blood and are described as free and motile, while others leave the blood, developing into macrophages and becoming fixed in lymphatic tissue throughout the body.
Monocytes
When they become fixed in specific organs they are stationary or nonmotile but can divide and reproduce in their fixed sites.
Macrophages
The macrophages that become fixed in an organ often take on a variety of names for instance, the ___ cells.
kupffer (coop-fer)
Reside in the liver and are fixed to the walls of the large capillaries called sinusoids.
Kupffer (coop-fer)
As blood flows through the ___, pathogens and other foreign substances are removed from the blood and phagocytosed.
sinusoids
The liver, spleen, lungs, and lymph nodes have a particularly rich supply of these.
Phagocytes (fa-guh-site)
Some fixed macrophages in the lungs are called “___ cells” because they phagocytose inhaled solid particles.
dust
Macrophages function as ___ or “big eaters,” as their name implies.
phagocytes
Help the lymphocytes, as antigen-presenting cells, to mount an immune response.
Macrophages
As they travel through the blood to the site of infection, the neutrophils and monocytes can squeeze through the tiny gaps between the endothelial cells of the ___ walls and enter the tissue spaces at the site of infection.
capillary
The process of neutrophils and monocytes squeezing through the tiny gaps.
Diapedesis (dye-ah-peh-dee-sis)
Chemicals released by injured cells attracting neutrophils and monocytes to the injured site.
Chemotaxis (kee-moh-tak-sis)
This process is like a bloodhound tracking a scent; the hound picks up the signal (odor), which identifies its source.
Chemotaxis (kee-moh-tak-sis)
Engulfs or eats particles or pathogens much like an ameba does.
Phagocyte
The ___ plasma membrane sends out pseudopods (“false feet”) that surround the pathogen. The surfaces of the pseudopods then fuse, thereby enclosing the pathogen within it. The trapped pathogen encounters a lysosome; the lysosomal membrane fuses with the pathogen, releasing potent ___ that destroy the pathogen.
phagocyte’s (fa-guh-site) / enzymes
The process can be summarized as “ingested (eaten) and digested.”
Phagocytosis
Refers to the body’s responses to being confronted by an irritant.
Inflammation
Can be almost anything; pathogens, friction, excessive heat or cold, radiation, injuries, and chemicals.
Irritant
If an irritant is caused by a pathogen, the inflammation is called this.
Infection
Characterized by redness, heat, swelling, and pain.
Inflammation
When the tissues are injured or irritated, injured cells release ___ and other chemicals. These chemicals cause the blood vessels in the injured tissue to ___ and the ___ blood vessels bring more blood to the area. The increased blood flow, called hyperemia, causes redness and heat.
histamine / dilate /dilated
Causes the blood vessel walls to leak fluid and dissolved substances into the tissue spaces, causing swelling.
Histamine
Fluid and irritating chemicals accumulating at the injured site also stimulate pain ___; therefore the person experiences pain.
receptors
Redness, heat, swelling, and pain are the classic signs of ___.
inflammation
Also known as pyrexia (pye-rek-see-ah).
Fever
An abnormal elevation in body temperature.
Fever
As phagocytes perform their duty, they release fever-producing substances called ___ (from the Latin word for “fire”).
pyrogens
Stimulate the hypothalamus in the brain to reset the body’s temperature, producing a fever.
Pyrogens
Stimulates phagocytosis and decreases the ability of certain pathogens to multiply.
Fever (elevation in temperature)
Two groups of protective proteins that act nonspecifically to protect the body.
Interferons (in-ter-feer-ons) and complement
A group of proteins secreted by cells infected by a virus.
Interferons (in-ter-feer-ons)
Diffuse to surrounding cells, where they prevent viral replication, thereby protecting neighbouring cells.
Interferons (in-ter-feer-ons)
Researchers first found these cells infected by the influenza virus and named them accordingly because they interfered with viral replication.
Interferons (in-ter-feer-ons)
Activate NK cells and macrophages, thus boosting the immune system.
Interferons (in-ter-feer-ons)
Circulate in the blood in their inactive form and swarm over bacterium when they are activated against it.
Complement proteins
Attaches to the bacterium’s outer membrane and punches holes in it. The holes in the membrane allow fluid and electrolytes to flow into the bacterium, causing it to burst and die.
Complement protein
When activated, these proteins also perform other functions that enhance phagocytosis and the inflammatory response.
Complement
A small population of a special type of lymphocyte that acts nonspecifically to kill a variety of cells.
Natural killer (NK)
Effective against many microbes and certain cancer cells.
Natural killer (NK) cells
Cooperate with the specific defence mechanisms to mount the most effective defence possible.
Natural killer (NK) cells
Also called adaptive immunity because the immune cells can respond or adapt to newly encountered pathogens or foreign agents.
Specific immunity
Cell-Mediated Immunity. Steps in cytotoxic T-cell activation and production of a clone of cytotoxic T cells and memory T cells.
Antibody-mediated Immunity.Steps in B-cell activation and production of a clone of antibody-secreting plasma cells and memory B cells.
Types of Immunity.
