Ch 16 Innate Host Defenses

Question 1

Adaptive defenses

Answer 1

Respond to particular agents called antigens. Adaptive defenses respond to these antigens by producing protein antibodies. Adaptive responses also involve the activation of the lymphocytes.

Question 2

Antigens

Answer 2

molecules found in or on viruses and pathogenic bacteria that the body uses to identify them

Question 3

Antibodies

Answer 3

Protein molecules created by the body to combat infection

Question 4

Innate Defenses

Answer 4

Defenses of the body that act against any invading agent, not just a specific one. These defenses usually perform their function before the bodies adaptive defense mechanisms are activated. Innate defenses are however necessary to the activation of the adaptive defenses.

Question 5

6 types of Innate immunity

Answer 5

• Physical Barriers
• Chemical Barriers
• Cellular defenses
• Inflammation
• Fever
• Molecular defenses

Question 6

Physical Barriers

Answer 6

includes the skin, mucous membranes, and the chemicals that they secrete

Question 7

Chemical Barriers

Answer 7

includes antimicrobial substances in body fluids such as saliva, mucus, gastric juices, and the iron limitation mechanisms

Question 8

Cellular Defenses

Answer 8

consists of certain cells that engulf invading microorganisms (phagocytes)

Question 9

Inflammation

Answer 9

the reddening, swelling, and temperature increases in tissues at sites of infection

Question 10

Fever

Answer 10

the elevation of body temperature to kill invading agents and/or inactivate their toxic products

Question 11

Molecular Defenses

Answer 11

interferon and complement, which destroy or impede invading microbes

Question 12

Myeloid Stem Cells mature into

Answer 12

basophils, eosinophils, neutrophils, dendritic cells, and monocytes

Question 13

Lymphoid Stem Cells mature into

Answer 13

B lymphocytes, T lymphocytes, and Natural Killer Cells

Question 14

Granulocytes

Answer 14

have granular cytoplasm and an irregularly shaped, lobed nucleus. Include Basophis, Neutrophils, and eosinophils

Question 15

Agranulocytes

Answer 15

Lack granular cytoplasm and have a round nucleus, Includes monocytes and lymphocytes

Question 16

The process of Phagocytosis (4 steps)

Answer 16

Find (chemotaxis), adhere to, ingest, and digest

Question 17

Phagocytosis: Chemotaxis (finding the cell)

Answer 17

In order to recognize invading microorganisms, Phagocytes use toll-like receptors (TLRs) that recognize molecular patterns unique to the pathogen, such as pepdidoglycan, lipopolysaccharide, flagellin, proteins, zymosan from yeast, and many other pathogen specific molecules. They are able to distinguish between gram + and gram - as well as bacterial and viral in order to tailor the response. During this process cytokines are released, which cause the attraction of more macrophages (chemokinees) and even inflammation.

Question 18

Phagocytosis: Adherence

Answer 18

The ability of the phagocyte cell membrane to bind to specific molecules on the surface of the microbe, During this process the microbe can be coated with antibodies or with proteins of the complement system in order to make adherence much easier

Question 19

Phagocytosis: Ingestion

Answer 19

here, the phagocyte forms fingerlike extensions called pseudophilia, that surround the microbe. These extensions then fuse and engulf the microbe within a cytoplasmic vacuole called a phagosome

Question 20

Phagocytosis: Digestion

Answer 20

Phagocytic cells can digest microbes through several different methods. The first involves the lysosomes found within the phagocyte’s cytoplasm. These organelles fuse with the phagosome membrane creating a phagolysome. Digestive enzymes and densins are then released into the phagolysome and break down the microbe. Macrophages also can use other metabolic products to destroy ingested microbes. These include hydrogen peroxide, nitric acid, superoxide ions, and hypochloritic ions. Once the microbes are destroyed, indigestible material is left in the phagolysome, now called a resifual body, and transported into the plasma membrane where it is excreted.

Question 21

Microbe Defence Mechanisms Against Digestion

Answer 21

• Interfering with chemotaxis
• antiphagocytic capsules
  which make adherence
  diffucult
• Capsules that are invulnerable
  to destruction by
  macrophages, this allows the
  microbe to reproduce within
  the phagocyte
• Some mirobes are just
  naturally resistant to digestion
  (mycobacterum & protozoa)
• Other microbes produce
  toxins that kill phagocytes
  (leukocidins & streptolysin)

Question 22

The lymphatic system

Answer 22

Provides many of the adaptive and innate defense mechanisms against infectious agents, collects excess fluid from the spaces between body cells, and transports digested fats to the cardiovascular system. Includes the lymph fluid, lymph nodes, and lymph vessels

Question 23

B cells

Answer 23

mature in the bone marrow

Question 24

T cells

Answer 24

mature in the thymus

Question 25

The acute inflammatory process

Answer 25

Functions to (1) kill invading microbes (2) clear away tissue debris, and (3) repair injured tissue. Includes the use of histamine, vasodilation, edema, bradykinin, diapedesis, pus, fibroblasts, and granulation tissue

Question 26

Histamine

Answer 26

When cells are damage, this is released from basophils and mast cells. It diffuses into nearby capillaries, causing the walls of these vessels to dilate and become more permeable.

Question 27

Vasodilation

Answer 27

When the walls of vessels dilate and become more permeable. This increases the amount of blood flowing to the damaged area, which causes the skin around wounds to become red and warm to the touch.

Question 28

Edema

Answer 28

Swelling. Because of vasodilation, the vessel walls are more permeable, fluids leave the blood and accumulate around the injured cells, causing edema

Question 29

Bradykinin

Answer 29

Pain associated with tissue injury is thought to be due to the release of bradykinin, a small peptide, at the injured site. Cellular regulators called prostaglandins seem to intensify the effects.

Question 30

Diapedesis

Answer 30

neutorphils pass out of the blood by squeezing between endothelial cells lining the vessel walls. This process allows neutrophils to congregate in tissue fluids at the injured regions.

Question 31

Pus

Answer 31

The accumulation of dead phagocytes, injured or damaged cells, the remains of ingested organisms, and other tissue debris forms this white or yellow fluid

Question 32

Fibroblasts

Answer 32

connective tissue cells that replace the destroyed tissue as a clot dissolves.

Question 33

Granulation Tissue

Answer 33

new connective tissue and tiny blood vessels that form on the surfaces of a wound during the healing process.

Question 34

Granulomatous Inflammation

Answer 34

Results in granulomas

Question 35

Granuloma

Answer 35

a pocket of tissue that surrounds and walls off the inflammatory tissue. Helps to limit the spread of the infectious agent

Question 36

Fever involves

Answer 36

exogenous and endogenous pyrogens

Question 37

Exogenous Pyrogens

Answer 37

include exotoxins and endotoxins from infectious agents. These toxins cause fever by stimulating the release of an endogenous pyrogen from macrophages

Question 38

Endogenous Pyrogens

Answer 38

a cytokine called interleukin-1 that circulates via the blood to the hypothalamus, where it causes certain neurons to secrete prostaglandins which reset the hypothalamus thermostat at a higher temp, causing the body temp to begin rising.

Question 39

Beneficial roles of Fever

Answer 39

(1) raises body temp above optimum temp for growth of many pathogens
(2) At the higher temps of fever some microbial enzymes or toxins may be inactivated
(3) Fever can heighten the level of immune responses by increasing the rate of chemical reactions in the body.
(4) Phagocytosis is enhanced
(5) Production of antiviral interferon is increased
(6) Breakdown of lysosomes is heightened, causing death of infected cells and the microbes inside of them
(7) Causes the patient to feel ill, making it more likely that the patient rest, preventing any further damage and focusing energy on fighting the infection

Question 40

Interferon

Answer 40

A small soluble protein that interferes with virus replication. There are three kinds that include alpha, beta, and gamma interferons.

Question 41

Alpha & Beta Interferons

Answer 41

Seeing as the two are very similar, they have been placed together as type 1 interferons. The synthesis of these two interferons occurs after a virus infects a cell. They do not interfere directly with viral replication, but rather after viral infection, where the cell synthesizes and secretes minute amounts of interferon. They then diffuse to adjacent, uninfected cells and bind to their surfaces. This binding stimulates the production of certain mRNA that are transcribed into many new proteins. These are called Antiviral Proteins (AVPs). These proteins then interfere with viral replication once the virus infects the adjacent cells.

Question 42

Gamma Interferons

Answer 42

Classified as type 2 interferons, these can also block virus replication via AVP synthesis, however they can be produced before viral infection in lymphocytes an NK cells that are sensitive to specific foreign antigens present in the body, Enhances activities of lymphocytes, NK cells, and macrophages. Also enhancces adaptive immunity by increasing antigen presentation. Also helps infected macrophages rid themselves of pathogens.

Question 43

The complement System and Opsonization

Answer 43

Opsonization counteracts microbe defenses that prevent phagocytes from adhering to them. This starts when special antibodies called opsonins bind to and coat the surface of the microbe. The complement cascade is then initiated ultimately resulting in C3b binding to the surface of the microbe. Complement receptors on the plasma membrane of phagocytes recognize the C3b and this stimulates phagocytosis

Question 44

The Complement System and Inflammation

Answer 44

C3a, C4a, and C5a enhance the acute inflammatory reaction by stimulating chemotaxis and thus phagocytosis. They also adhere to the membranes of basophils and mast cells causing them to release histamine

Question 45

The Complement System and Membrane Attack Complexes

Answer 45

Another defense triggered by C3b is cell lysis. By a process called immune cytolysis, complement proteins produce lesions in cell membranes of microorganisms and other types of cells. These lesions cause cellular content to leak out The pore that is formed constitutes the Membrane Attack Complex (MAC) which is composed of the c5b, C6, C7, C8, and C9 proteins

Question 46

Acute Phase Proteins

Answer 46

C-Reactive Protein and Mannose Binding Protein are produced during acute illness. These proteins can bind to the infectious agent and activate the complement cascade, as well as attract macrophages.