How can we help?

You can also find more resources in our Help Center.

78 terms

micro chapter 14 Host defenses

micro chapter 14 Host defenses
STUDY
PLAY
lysozyme
in tears and saliva break apart peptidoglycan cell wall
immunology
the study of all features of the body's second and third lines of defense
Immune defenses: Body compartments
Intracellular - digesting
Extracellular
Lymphatic
Cerebrospinal
Circulatory
Body Compartments that Participate in Immune Function
1. Reticuloendothelial system (RES)
****Provides a passageway within and between tissues and organs
2. Spaces containing extracellular fluid (ECF)
3. Bloodstream
4. Lymphatic system
plasma
1. hundreds of different chemicals
2. Components = water (92%), albumin, globulins, immunochemicals (antibodies), fibrinogen, hormones, nutrients, dissolved gases and waste products
hematopoesis
production of blood cells
pluripotential stem cells
primary precursor of new blood cells
nonspecific chemical defenses
1. Sebaceous secretions and specialized glands- antimicrobial
2. Lysozyme in tears and saliva (break apart peptido)
3. Lactic acid and electrolyte concentrations of sweat
4. Skin's acidic pH and fatty acid content
5. HCl in the stomach
6. Digestive juices and bile in the intestine
7. Semen- antimicrobial chemical
8. Acidic pH in the vagina
immune system is responsible for:
1. Surveillance of the body
2. Recognition of foreign material
3. Destruction of entities deemed to be foreign
4. White blood cells must distinguish self from nonself cells
5. Evaluates cells by examining markers (proteins/sugars) on their surfaces
Origin, Composition, and Functions of the Blood
Circulatory system
- Circulatory system proper
- Lymphatic system
Mast cells
secrete histamine causing vasodilation, and openings occur in capillaries
antigen
anti = antibody
gen = generator
Erythrocytes
1. Develop from stem cells in the bone marrow
2. Lose their nucleus just prior to entering circulation
3. Transport oxygen and carbon dioxide to and from the tissues
Platelets
1. Formed elements in circulating blood
2. Not whole cells
3. Function primarily in hemostasis and in releasing chemicals for blood clotting and inflammation
Neutrophils
Granulocyte
phagocytosis
starts inflammation
Eosinophils
Granulocyte
Attack and destroy large eukaryotic pathogens
Also involved in inflammation and allergic reactions
Basophils
Granulocyte
Parallel eosinophils in many actions
Monocytes
Agranulocyte
1. Discharged by bone marrow into bloodstream, live as phagocytes for a few days, then differentiate into macrophage
2. "Fixed" (lungs, liver, bronchii) and wandering
3. Responsible for
- Many specific and nonspecific phagocytic and killing functions
- Processing foreign molecules and presenting them to lymphocytes
- Secreting biologically active compounds that assist, mediate, attract, and inhibit immune cells and reactions

Dendritic cells (we'll learn more in specific immunity)
Lymphocytes
1. Key cells in the third line of defense and the specific immune response (notice nonself)
2. When stimulated by antigens, transform into activated cells that neutralize and destroy that foreign substance
3. B cells
- Humoral immunity: protective molecules carried in the fluids of the body
- Produce specialized plasma cells which produce antibodies/immunoglobulins
4. T cells
- cell-mediated immunity: T cells modulate immune functions and kill foreign cells (confirm infection & allow start of response
Humoral immunity
protective molecules carried in the fluids of the body
B cells
cell-mediated immunity
T cells modulate immune functions and kill foreign cells (confirm infection & allow start of response
Lymphatic System
1. Compartmentalized network of vessels, cells, and specialized accessory organs
2. Transports lymph through a system of vessels and lymph nodes
3. Major functions
- Provide an auxiliary route for the return of extracellular fluid to the circulatory system proper
- Act as a drain-off system for the inflammatory response
- Render surveillance, recognition, and protection against foreign materials
Lymphatic Fluid
1. Lymph
2. Plasma-like liquid formed when certain blood components move out of blood vessels into the extracellular spaces and diffuse or migrate into the lymphatic capillaries
3. Composition parallels that of plasma, but without red blood cells
Lymphatic Vessels
1. Along the lines of blood vessels
2. Similar to thin-walled veins
3. High numbers in hands, feet, and around the areola of the breast
4. Flow of lymph is in one direction only- from extremities toward the heart
5. Lymph is moved through the contraction of skeletal muscles through which the lymphatic ducts wend their way
Lymphoid Organs and Tissues
1. Lymph nodes
2. Thymus
3. Spleen
4. Gut-associated lymphoid tissue (GALT)
5. Tonsils
6. Loose connective tissue framework that houses aggregations of lymphocytes
Lymph Nodes
1. Small, encapsulated, bean-shaped organs
2. Usually found in clusters along lymphatic channels and large blood vessels of the thoracic and abdominal cavities
3. Major aggregations: axillary nodes, inguinal nodes, cervical nodes
Spleen
1. Similar to a lymph node except it filters blood instead of lymph
2. Filters pathogens from the blood
Thymus
1. Site of T-cell Maturation
2. Thymus originates in the embryo
3. High rates of activity and growth until puberty
4. Shrinks gradually through adulthood
5. Thymic hormones help thymocytes develop specificity to be released as mature T cells
Miscellaneous Lymphoid Tissue
1. Bundles of lymphocytes lie at many sites on or just beneath the mucosa of the gastrointestinal and respiratory tracts
2. Tonsils
3. Breasts of pregnant and lactating women
4. GALT in the intestinal tract
- Appendix
- Peyer's patches
5. Mucosal-associated lymphoid tissue (MALT)
6. Skin-associated lymphoid tissue (SALT)
7. Bronchial-associated lymphoid tissue (BALT)
GALT
in the intestinal tract
- Appendix
- Peyer's patches
MALT
Mucosal-associated lymphoid tissue
SALT
Skin-associated lymphoid tissue
BALT
Bronchial-associated lymphoid tissue
Second Line of Defense
1. generally nonspecific but supports & interacts w/specific immune response
Inflammation
Phagocytosis
Interferon
Complement
The Inflammatory Response
1. Cascade of events
2. injured tissues release chemicals (chemotactic)
3. selectins appera on endothelial capillaries (stickey surface)
4. integrins on neutrophils help them attach to endothelial integrins receptors. this is called margination.
5. mast cells release histamine
6. histamine causes vasodilation, and openings occur in capillaries
7. neutrophils change shape and squeeze thru capillaries. this is call extravastion/diapedesis
8. neutrophils & others are attracted to site by chemotactic
9. ingest & destroy invading bacteria
chemotactic
injured tissues release chemicals
margination
integrins on neutrophils help them attach to endothelial integrins receptors
extravastion/diapedesis
WBC/neutrophils change shape and squeeze thru capillaries
The Inflammatory Response: A Complex Concert of Reactions to Injury
1. Reaction to any traumatic event in the tissues
2. Classic signs and symptoms
Rubor (redness)
Calor (warmth)
Tumor (swelling)
Dolor (pain)
3. Fifth symptom has been added: loss of function
Rubor
redness
Calor
warmth
Tumor
swelling
Dolor
pain
Chief Functions of Inflammation
1. mobilize & attract immune components to site of injury
2. set in motion mechanisms to repair tissue damage & localize & clear away harmful substances
3. detroy microbes & block further invasion
Vascular Changes: Early Inflammatory Events
1. Controlled by nervous stimulation, chemical mediators, and cytokines (released when damage to tissue) released by blood cells, tissue cells, and platelets in the injured area
2. Vasoactive mediators affect the endothelial cells and smooth muscle cells of blood vessels.
3. Chemotactic factors (chemokines) affect white blood cells
4. Cause fever, stimulate lymphocytes, prevent virus spread, and cause allergic symptoms
5. Arterioles constricted at first but quickly vasodilation takes place
Vasoactive mediators
affect the endothelial cells and smooth muscle cells of blood vessels.
Chemotactic factors
chemical mediators that stimulate the movement of WBC(chemokines) affect white blood cells
Chemicals Released by Damaged Cells:
Histamine
Produced by mast cells
Vasodilation, increased permeability of blood vessels (allows cells to escape ex. monocytes)
Chemicals Released by Damaged Cells:
kinins
are the chemicals
Vasodilation, increased permeability of blood vessels
Play a role in chemotaxis by attracting phagocytic neutrophils
Chemicals Released by Damaged Cells:
prostaglandins
Intensify histamine and kinin effect
Powerful stimulants of inflammation of pain
Chemicals Released by Damaged Cells:
leukotrienes
Increased permeability of blood vessels, phagocytic attachment
Stimulate contraction of smooth muscle
Edema
1. Exudates: the fluid that escapes through gaps in the walls of postcapillary venules
2. Contains plasma proteins, blood cells, and cellular debris
3. May be clear (serous) or may contain red blood cells or pus (accumulated phagocytes, cellular debris, and pyogenic bacteria)
4. Diapedesis: how WBCs leave the blood vessels and into tissue spaces
5. chemotaxis: the tendency of WBCs to migrate in response to a specific chemical stimulus
Exudates
the fluid that escapes through gaps in the walls of postcapillary venules
Diapedesis
how WBCs leave the blood vessels and into tissue spaces
aka extravasation
chemotaxis
the tendency of WBCs to migrate in response to a specific chemical stimulus (gradient)
Benefits of Edema and Chemotaxis
Dilutes toxic substances
Fibrin clot can trap microbes and prevent further spreading
Phagocytosis occurs immediately (not dependent on antigen signal)
pyogenic bacteria
ability to make pus
Late Reactions of Inflammation
1. Long-lived inflammation attracts a collection of monocytes, lymphocytes, and macrophages to the reaction site
2. Macrophages clear pus, cellular debris, dead neutrophils, and damaged tissue
3. B lymphocytes produce antibodies/immunoglobulins
4. T lymphocytes kill intruders directly
5. Late in the process the tissue is repaired or replaced by connective tissue (scar)
Fever
1. An abnormally elevated body temperature
2. FUO: cause of fever is unknown
3. Initiation of fever
- pyrogen sets the hypothalamic "thermostat" to a higher setting
a. Muscles increase heat production
b. Peripheral arterioles decrease heat loss through vasoconstriction
- Pyrogens can be exogenous or endogenous
- Macrophages release two potent pyrogens :
1. interleukin 1 - communication btw wbc (endogenous)
2. tumor necrosis factor (TNF)
pyrogen
a substance that causes a rise in body temperature
endogenous
originating or produced within an organism or one of its parts (GN bacteria lipopolysaccharide layer is the causative agent)
exogenous
originating outside the body
exotoxin
a toxin that is secreted and acts upon a specific cellular target
are released by bacteria
endotoxin
a bacterial toxin that is not ordinarily released. endotoxin is composed of a lipopolysaccharide complex of GN bacteria
- are exogenous pyrogens
ex. E. coli
benefits of fever
1. inhibits multiplication of temp.sensitive MO
2. impedes the nutrition of bacteria by reducing the availibility of iron
3. increases your metabolism & stimulates immune reactions & naturally protective physiological processes
Phagocytosis: Cornerstone of Inflammation and Specific Immunity
1. General activities of phagocytes
- Survey the tissue compartments and discover microbes, particulate matter, and injured or dead cells
- Ingest and eliminate these materials
- Extract immunogenic information (antigens) from foreign matter
Three main types of phagocytes
1. neutrophils
2. monocytes
3. macrophages
Histiocytes:
specialized macrophages that migrate to a certain tissue and remain there during their life span
phagocytosis
1. something on surface that triggers attachment
2. phagosome
3. lysosome - organelle containing lysozyme
4. lysozyme - breaks apart peptidoglycan
5. protease - break apart proteins
Interferon
Antiviral Cytokines and Immune Stimulants
1. Interferon (IFN): involved against viruses, other microbes, in immune regulation and intercommunication
2. Three major types: alpha, beta & gamma
3. All three classes produced in response to viruses, RNA, immune products, and various antigens
4. Bind to cell surfaces and induce changes in genetic expression (can tell cell what to transcribe & translate)
5. Can inhibit the expression of cancer genes and have tumor suppressor effects
Complement
1. Over 30 blood proteins that work in concert to destroy bacteria and certain viruses
**Cascade reaction AKA as domino effect

2. Three different pathways that all yield similar end results
Classical pathway
Lectin pathway
Alternative pathway
classical pathway
activated by antibody.
C3 cleaved,
results in
1. opsonization =ability to phagosize (like putting handles on a capsule)
2. inflammation = (mast cell releases histamine)
3. cytolysis = ring of proteins inserted one at a time, causing a hole and lysis occurs
Lectin pathway
activated by mannose on surface
results in
1. opsonization =ability to phagosize (like putting handles on a capsule)
2. inflammation = (mast cell releases histamine)
3. cytolysis = ring of proteins inserted one at a time, causing a hole and lysis occurs
Alternative pathway
activated by factors BDP (recognize a complex on microbes
results in
1. opsonization =ability to phagosize (like putting handles on a capsule)
2. inflammation = (mast cell releases histamine)
3. cytolysis = ring of proteins inserted one at a time, causing a hole and lysis occurs
Complement Cascade
1. Initiation - this is the variation
2. Amplification and cascade
3. Polymerization
4. Opsonization, Inflammation and formation of Membrane attack complex (MAC) (many different proteins. ring, hollow center, makes a hole, things leak out and cell lyses). Purpose for each of these? (36)
Membrane attack complex (MAC)
cytolysis
many different proteins. ring, hollow center, makes a hole, things leak out and cell lyses
chemokine
chemical mediators (cytokines) that stimulate the movement of SBC
cytokine
chemical substance produced by WBCs and tissue cells that regulate development, inflammation & immunity