Human Anatomy - Chapter 22

What is a pathogen?

disease-causing microbes

What is immunity/resistance?

ability to ward off damage or disease via defenses​

What is susceptibility?

lack of resistance​

What are the different types of disease resistance?

1. non-specific (innate)
2. immunity (adaptive)

What is non-specific resistance/innate immunity?

present at birth and includes defense mechanisms that provide general protection against invasion by a wide range of pathogens

What is immunity resistance/adaptive immunity?

involves activation of specific lymphocytes that combat a particular pathogen or other foreign substance

What is one body system that carries out immune responses?

lymphatic system

What does the lymphatic system consist of?

1. lymph
2. lymphatic vessels
3. several structures and organs that contain lymphatic tissue (specialized reticular tissue)
4. bone marrow (site of lymphocyte production)

What is the major difference between lymph and interstital fluid?

location

What ar ethe functions of the lymphatic system?

1. drain excess interstitial fluid
2. return leaked plasma proteins to the blood
3. transport dietary lipids and lipid-soluble vitamins (A, K, E, D)
4. carry out immune responses

How do lymphatic vessels begin?

blind-ended lymphatic capillaries in tissue spaces between cells

Where are lymphatic capillaries not found?

1. avascular tissue
2. CNS
3. portions of the spleen
4. red bone marrow

What is the difference between lymphatic capillaries and blood capillaries?

1. lymphatic capillaries have a slightly larger diametre
2. lymphatic capillaries have overlapping endothelial cells which work as one-way valves for fluid to enter them

What are the different types of lymph vessels (from smallest to largest)?

1. lymph capillaries
2. lymph vessels
3. lymph nodes
4. lymph trunks
5. lymph ducts

What is a lacteal?

lymphatic capillary in the villus of the small intestine

What is a lacteal used for?

transport digested fats from the small intestines into the blood

What are the different lymph trunks?

1. lumbar
2. intestinal
3. bronchomediastinal
4. subclavin
5. jugular

What are the two lymph ducts?

1. thoracic duct
2. right lymphatic duct

Where does the thoracic duct drain lymph to?

venous blood via the left subclavin vein

Where does the right lymphatic duct drain lymph to?

venous blood via the right subclavin vein

What area does the right lymphatic duct drain?

anything from the upper right portions of the body

What area does the thoracic duct drain?

anything from the lower right, lower left, or upper left portions of the body

What is the route of drainage?

interstitial fluid → lymph capillaries → lymph vessels → lymph trunks → lymph ducts → subclavian veins

What do the lymph nodes do?

1. remove foreign substances through filtering lymph, phagocytosis, and immune reactions
2. proliferate plasma cells and t-cells

What are the two pumps of the lymphatic system?

1. respiratory pump
2. skeletal muscle pump

What do the lymphatic pumps do?

1. aid the return of venous blood to the heart whilst maintaining the flow of lymph
2. aided by lymphatic vessel valves that prevent backflow of lymph

What are the primary lymphatic organs?

1. red bone marrow (b cells)
2. thymus gland (t cells)

What do the primary lymphatic organs do?

where immune cells become immunocompetent

What does immunocompetent mean?

capable of mounting an immune response

Where is the thymus found?

medinastinum

What are the secondary lymphatic organs and tissues?

1. lymph nodes
2. spleen
3. lymphatic nodules

What do the secondary lymphatic organs and tissues do?

sites where most immune responses occur

What does lymph nodes contain?

1. t-cells
2. macrophages
3. follicular dentritic cells
4. b-cells

How does lymph flow through lymph nodes?

1. enters through afferent lymphatic vessels
2. exits through efferent lymphatic vessels

What functions as the filter in lymph nodes?

1. outer cortex
2. inner medulla

How are foreign substances filtered by the lymph nodes?

trapped by nodal reticular fibres

What is the route of lymph through a lymph node?

1. afferent lymphatic vessel
2. subcapsular sinus
3. trabecular sinus
4. medullary sinus
5. efferent lymphatic vessel

What two instances could occur after a foreign substances is trapped by a nodal reticular fibre?

1. macrophages destroy via phagocytosis
2. lymphocytes destroy via immune responses

Why is it important to know where the lymph nodes are?

important in the diagnosis and prognosis of the spread of cancer by metastasis

Where are some nodes?

1. submandibular
2. cervical
3. intestinal
4. inguinal
5. axillary

What is the spleen?

1. largest single mass of lymphatic tissue (encapsulated)
2. t-lymphocytes directly attack and destroy antigens in the blood (mainly via cytolysis)
3. b-lymphocytes develop into antibody producing plasma cells and the antibodies inactivate antigens in blood
4. stores blood platlets

Where is the spleen found?

left hypochondriac region between stomach and diaphragm

What are lymphatic nodules?

1. masses of lymphatic tissue that are not surrounded by a capsule
2. participate in immune responses by producing lymphocytes and antibodies

Where are lymphatic nodules found?

1. lamina propria of mucous membranes lining the gastrointestinal, urinary, and reproductive tract
2. respiratory airways

What is another name for lymphatic nodules?

mucosa-associated lymphatic tissue (MALT)

What are peyer’s pathches?

lymphatic nodules in the ileum of the small intestine

What are tonsils?

multiple aggregations of large lymphatic nodules embedded in a mucous membrane at the junction of the oral cavity and pharynx

What are the two lines of defense involved in innate immunity?

1. skin and mucous membranes
2. internal defenses

What are some mechanical defenses involved with the skin and mucous membranes?

1. intact epidermis layer of skin
2. mucous membranes
3. tears from the lacrimal apparatus
4. saliva
5. mucus
6. cilia in the respiratory tract
7. epiglottis
8. flow of urine
9. defecation and vomitting

What is the skin?

1. physical barrier
2. many layers
3. relatively low temp.

Where is chemical protection localized?

1. the skin
2. loose connective tissue
3. stomach
4. vagina

What chemical protection does the skin use?

sebum

What is sebum?

oil secreted by the skin with a low pH due to the presence of unsaturated fatty acids and lactic acids

What is lysozyme?

an enzyme compoonent of sweat that also has antimicrobial properties

What is gastric juice?

renders the stomach nearly sterile because its low pH (1.5-3.0) kills many bacteria and destroys most of their toxins

What are some second line (internal) defenses involved in innate immunity?

1. antimicrobial substances
2. phagocytes
3. natural killer cells
4. inflammation
5. fever

What are some antimicrobial substances involved in innate immunity?

1. interferons (IFNs)
2. complement system
3. iron-binding proteins
4. antimicrobial proteins (AMPs)

What are interferons?

1. a protein that lymphocytes and macrophages cells infected with viruses produce
2. protect uninfected host cells from viral infection

How do interferons work?

1. diffuses to uninfected neighbouring cells
2. binds to surface receptors
3. induce uninfected cells to synthesize antiviral proteins

What are complement systems?

1. a group of 30 proteins present in blood plasma and on cell membranes
2. when activated: proteins enhance certain immune, allergic, and inflammatory reactions

What do complement systems do?

1. causes cytolysis
2. promotes phagocytosis
3. contributes to inflammation
4. very important in protection from bacterial infections

What are iron-binding proteins?

inhibit growth of certain bacteria by reducing amount of available iron

What are antimicrobial proteins?

1. have broad-spectrum antimicrobial activites
2. attract dendritic cells and mast cells

How does a fever contribute to innate immunity?

1. intesifies effects of interferons
2. inhibits growth of some microbes
3. speeds up body reactions that aid repair

What are NK cells?

lymphocytes that lack the membrane molecules that identify t- and b-cells

How does a NK cell contribute to innate immunity?

1. kill infected target cells by releasing granules that contain perforin and granzymes
2. phagocytes kill released microbes

What are phagocytes?

1. process by which a cell ingests and disposes of foreign material
2. destruction of microorganisms and cellular debris

What are the major phagocytes?

1. neutrophils
2. macrophages

What are the steps of phagocytosis?

1. chemotaxis
2. adherence
3. ingestion
4. digestion
5. killing

What is chemotaxis?

chemically stimulated movement of phagocytes to site

What is adherence?

attachment of phagocyte to microbe

What is ingestion?

phagocyte engulfs microbe

What is digestion?

phagolysosome is formed

What is killing?

lysosome and lethal oxidants produces by the phagocyte quickly kill many types of microbes

What is an inflammatory response?

1. non-specific, defensive response to tissue damage
2. rapidly initiated
3. no memory cells

What causes inflammatory responses?

1. infection
2. mechanical damage
3. ischemia
4. nutrient deprivation
5. temperature extremes
6. radiation

What is PRISH?

signs or symptoms of inflammation

\
P: ain due to the release of certain chemicals

R: edness because more blood is rushed to the affected area

I: mmobility that results from some loss of function in severe inflammations

S: welling caused by an accumulation of fluids

H: eat due to more blood rushed to the affected area

What are the three stages of an inflammatory response?

1. vasodilation and increased permeability of blood vessels
2. emigration (movement) of phagocytes from the blood into interstitial fluid
3. tissue repair

What rea the vascular response of an inflammatory response?

1. increased blood flow to damaged area
2. histamine: vasodilation and increased permeability
3. kinins: vasodilation, increased permeability, and chemotaxis
4. prostaglandins: intensify histamine and kinins
5. leukotrienes: increased permeability, phagocytosis, and chemotaxis
6. complement: histmine, chemotaxis, and phagocytosis

What phagocytes emigrate in an inflammatory response?

1. neutrophils
2. leukocytosis
3. monocytes
4. macrophages
5. pus

What do neutrophils/polymorphonuclear neutrophils (PMNs) do in an inflammatory response?

1. predominate in early inflammatory responses
2. ingest bacteria, dead cells, and cellular debris
3. short lived and become components of the purulent exudate (pus)

What do monocytes and macrophages do in an inflammatory response?

1. predominate in late inflammation
2. monocytes become macrophages
3. macrophages are more active as phagocytes than neutrophils
4. engult damaged tissue, worn-out neutrophils, and invading microbes

What is pus in an inflammatory response?

1. a pocket of dead phagocytes, damaged tissue, and fluid
2. must drain out of the body or accumulates in a confined space
3. can cause abscesses
4. when tissue sloughs off, an ulcer forms

What is acute inflammation?

1. symptoms develop rapidly and usually last for a few days
2. usually mild and self-limiting
3. ex: sore throat, appendicitis, cold or flu, bacterial pneumonia, a scratch…

What is chronic inflammation?

1. symptoms develop more slowly and can last for up to several months or years
2. often severe and progressive
3. ex: mononuceosis, peptic ulcer disease, tuberculosis, rheumatoid arthritis, ulcerative colitis…

What are the two types of adaptive immunity?

1. cell-mediated
2. antibody-mediated

How do foreign antigens entire our body?

1. pathogens
2. noninfectious environmental agents
3. drugs
4. vaccines
5. transfusions
6. transplants

What type of lymphocytes does adaptive immunity rely on?

1. b-lymphocytes like plasma cells
2. t-lymphocytes


1. helper
2. cytotoxin

What is cell-mediated immunity?

1. destruction of antigens by t-cells
2. effective against intracellular pathogens (fungi, parasites, viruses…)
3. always involves cells attacking cells

What is antibody-mediated (humoral) immunity?

1. destruction of antigens by antibodies
2. effective against antigens dissolved in body fluids and extracellular pathogens (bacteria)

What is clonal selection?

1. process by which a lymphocyte proliferates (divides) and differentiates (becomes specialized) in response to a specific antigen
2. forms thousands of identical cells that can recognize the same specific antigen as the original lymphocyte

What are antigen-presenting cells (APCs)?

1. dendritic cells, macrophages, Langerhans cells and B cells
2. process and present antigens to immune cells (usually t-helper cells) to initate an immune response

What happens when t-helper cells and APCs interact?

differentiation of b-cells into active antibody-producing cells (plasma cells) and t-cells into effector cells

What are the two major types of cell results from clonal selection?

1. effector cells
2. memory cells

What are effector cells?

1. cells that actually do the work to destroy the antigen
2. include:


1. cytotoxic t-cells
2. helper t-cells
3. plasma cells (clone of b cells)

What are memory cells?

1. long life spans
2. provide faster second invasion response by proliferating and differentiating into effector cells

What are antigens?

1. chemical substances that are recognized as foreign by antigen receptors when introduced into the body
2. immunogenic and reactive
3. large, complex molecules

What is immunogenicity?

the ability to provoke an immune response by stimulating the production of specific antibodies or the proliferation of specific t-cells (or both)

What is reactivity?

the abiltiy of the antigen to react specifically with the antibodies or cells it provoked

What happens if an antigen gets past the non-specific (innate) defenses?

can get into lymphatic tissue by:


1. entering an injured blood vessel and being carried to the spleen
2. penetrating the skin and entering lymph vessels leading to lymph nodes
3. penetrating mucouis membranes and lodging into mucosa-associated lymphoid tissue