Ch 9: The Immune and Lymphatic System

Lymphatic is mainly a _____ system, while immune is mainly a _____ system

structural, functional

Lymphatic System

consists of vessels that transport lymph from body tissues back to circular system

Immune System Cells

identify and inactivate pathogens trapped by lymphatic system

What structures make up the lymphatic system?

lymph (interstitial fluid), lymph vessels, lymph nodes, lymph glands, lymphoid tissues, lymphatic organs

What are the organs of the lymphatic system?

spleen, tonsils, vermiform appendix, thymus gland, right lymphatic duct, thoracic duct

Spleen

filters out old and inefficient RBCs, can store blood, produces lood cells when needed, activates WBCs when infection detected

Describe the size and location of the spleen

1 × 3 × 5 inches, in LUQ of abdomen, under diaphragm above stomach

Tonsils

protect body at entrance of respiratory and digestive systems by filtering out bacteria and viruses, produce WBCs and antibodies

Describe the size and location of the tonsils

pea-sized, can be lingual (on base of tongue, palatine (on lateral aspects of pharynx), and/or pharyngeal (also called adenoids, found i pharynx near opening of nasal cavity)

Vermiform Appendix

full purpose unknown, has bacteria that can be used to repopulate gut following illness, role in immune system

Describe the size and location of the vermiform appendix

thin tube about 4 inches long, pouch of the cecum

Thymus Gland

produces cells that mature into T cells

Describe the size and location of the thymus gland

large in infants, shrinks and turns to fat in adults, in mediastinum behind sternum and above heart

Peyer’s Patches

contain B and T cells of immune system

Describe the size and location of Peyer’s patches

bundles of lymph cells visible to naked eye and varying in sizes, in wall of ileum of small intestine

Right Lymphatic Duct

drains lymph from right upper limbs, right side of thorax, and right halves of head and neck, returns it to the circulatory system

Thoracic Duct

drains lymph from the rest of the body and returns it to the circulatory system

How is bone marrow important to the immune system?

WBCs are formed here

Leukocytes (WBCs)

secrete cytokines, which are chemical messengers that direct the immune response

What are the two types of leukocytes?

granulocytes and agranulocytes

Granulocytes

have granules in cytoplasm, segmented nuclei

Agranulocytes

no granules in cytoplasm, single nucleus

What are the types of granulocytes?

neutrophils, eosinophils, basophils

What are the types of agranulocytes?

lymphocytes, monocytes

Neutrophils

engulf and destroy invading microorganisms, most abundant type of WBC

Eosinophils

involved in counteracting histamine during allergic reaction and fighting parasites

Basophils

help fight infection, release histamine heparin

Lymphocytes

involved in antibody production, become either T or B cells, second-most abundant leukocyte

B Cells

produce antibodies

T Cells

help expose pathogens, allowing antibodies to inactivate and neutralize pathogens

Monocytes

can become macrophages, when they enter tissues then engulf and destroy pathogens

Where does most of the blood in capillary beds enter and exit?

most exit the arteriole and enter the venule ends

How much blood does not re-enter the venules? What happens to it?

~10% does not re-enter, becomes interstitial fluid, captured by lymphatic vessels and returned to circulatory system

How are lymphatic vessels similar to veins?

they also have one-way valves to prevent backflow

Describe the movement of lymph in the venous system

RUQ of body drains lymph into right subclavian vein, lymph from remaining quadrants collected in thoracic duct and drained into left subclavian vein

right and left subclavian veins dump blood and lymph into superior and inferior (respectively) venae cava

Describe the locations of lymph nodes and the movement of lymph through the lymphatic vessels

nodes are widely distributed along the lymphatic vessels, three main clusters (inguinal, axillary, cervical regions)

lymph is filtered as it flows toward the heart, lymph captured in loose collective tissue around blood capillaries and tissue fluid becomes lymph

Self

any molecule that belongs in the body and will not cause harm

Nonself Molecules

called antigens, recognized as foreign substances

Nonspecific Immunity

two layers, protects the body from all potentially harmful agents

Specific Immunity

one layer, selective to defend against certain agents, body’s immune response is faster and more efficient if antigen encountered again

What does the first line of defense consist of?

physical barriers, chemical barriers, reflexes

Physical Barriers

protects inside of body from outside pathogens

What is the most obvious and largest physical barrier?

integumentary system, also has openings lined with mucous membranes to trap pathogens (e.g. tonsils)

What are some examples of reflexes?

cough, sneeze, vomit, defecate

Chemical Barriers

fluids, pH differences to kill pathogens, discourage from entering or wash away pathogens

What are some examples of chemical barriers?

slightly acidic pH tears, saliva, and perspiration to discourage pathogens from entering body

low pH stomach acid to kill pathogens

What protection method is considered the second line of defense?

cellular and chemical barriers

Inflammation

chemical response that involves increased blood flow to area, results in increased number of present immune cells to fight pathogen

Pyrexia (Fever)

chemical response that stimulates phagocytic process and prohibits pathogen activity

Interferons (Protective Protein)

proteins formed as chemical response when cell exposed to virus, leaves infected cell and signals neighbor cells of danger

Complement (Protective Protein)

type of protein that punches holes in bacterial walls

Phagocytosis

cellular response “cell eating” where neutrophil/monocyte/macrophage encounters pathogen and engulfs it to destroy it

Natural Killer Cells

special type of lymphocyte that kills host cells infected by viruses/cancer

Memory

ability to recognize and wuickly respond to previously encountered antigen

What two factors are only present in specific immunity?

memory and specificity

Humoral Immunity/Antibody-Mediated Immunuty

based on B cell action

Describe the steps of the humoral immunity response

1. host binds with antigen: antigen engulfed and digested, small portions present to T cells which become sensitized to antigen

2. activation: T cells signal B cells, then produce antibodies

3. replication: B cells replicate and clone selves

4. Differentiation: some cloned B cells differentiate into plasma cells, which produce antibodies, remaining cells become memory cells

5. unique antibodies bind with antigens: plasma cells produce unique antibodies, which bind to antigens

What are the five classes of antibodies (immunoglobulins)

IgG, IgA, IgM, IgD, IgE

IgG

major antibody in primary and secondary immune responses, inactivates antigen, neutralizes toxins, responsible for Rh reactions

crosses plcenta to provide immunity for newborn

What is the prevalence of IgG? What is it found?

75-85% of total antibodies, in blood plasma

IgA

protects mucous membranes for body surfaces, provides immunity for newborn

What is the prevalence of IgA? Where is it found?

5-15% of total antibodies, in saliva, mucous, tears, breast milk

IgM

causes antigens to clump together, responsible for transfusion reactions in ABO blood typing system

What is the prevalence of IgM? Where is it found?

5-10% of total antibodies, attached to B cells, released into blood plasma during immune response

IgD

receptor sites for antigens on B cells, binding with antigen results in B cell activation

What is the prevalence of IgD? Where is it found?

0.2% of total antibodies, attached to B cells

IgE

binds to mast cells and basophils, causing histamine release, responsible for allergic reactions

What is the prevalence of IgE? Where is it found?

0.5% of total antibodies, produced by plasma cells in mucous membranes and tonsils

Cell-Mediated Immunity

specific immunity type where T cells mount a direct attack against antigens

Describe the steps of cell-mediated immunity

1. macrophage engulfs infected cell

2. macrophage presents it to T cell with has receptors for that antigen

3. activated T cell divides into clones

   1. killer T cells directly destroy infected cell

   2. helper T cells stimulate B cells to promote immune response

   3. suppressor T cells inhibit B cells and immune response

   4. memory T cells promote stronger and more efficient response if encountered again

Natural Immunity

body developed immunity through a natural response after encountering

Artificial Immunity

body developed immunity through deliberate action

Active Immunity

obtains when a person’s body produces B memory cells

slower, typically lasts lifetime

Passive Immunity

develops in another person and immunity transfered

short-term immunity

Active Natural

person naturally exposed to disease, body progresses through hormonal and cell-mediated immune processes to develop B cells, antibodies, and memory cells

Active Artificial

antigens injected or inhaled into body intentionally, body produces B cells, antibodies, and memory cells

Passive Natural

body obtains antibodies from another person, typically seen in mother producing milk for baby

Passive Artificial

immunoglobulins injected into body from another person

Vaccines/Immunizations

stimulate active immune response, consist of attenuated (weakened) microorganisms or their toxins, injected or inhaled by patient

stimulate antibody production

Boosters

any vaccination after the initial shot to help develop full immunity (only some cases)

Postexposure Prophylaxis (PEP)

instances where an individual is exposed to the pathogen and still has an opportunity to be vaccinated

Give an example of PEP

hepatitis B passive immune component works immediately while active immunity developed, admisistor prophylaxis vaccine within 24 hours for best results