Chapter 12 -The Lymphatic and Immune System Flashcards Preview

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Functions of the immune system

Responsible for protecting humans against bacteria, viruses, fungi, toxins, parasites, and cancer

Works with the organs of the lymphatic system to clear the body of these disease-causing agents
Thymus, spleen, lymphatic vessels, lymph nodes, and lymphoid tissue


Lymphatic System Components and Functions

Network of connecting vessels that collects the interstitial (or tissue) fluid found between cells

Lymphatic vessels then return this fluid, now called lymph, to the bloodstream

Also picks up lipids and fat-soluble vitamins from the digestive tract and transports them to the bloodstream

Protects the body against disease-causing agents


Interstitial Fluid and Lymph Fluid

Fluid constantly leaks out of blood capillaries into the spaces between cells
Increased tissue hydrostatic pressure moves interstitial fluid into the lymphatic vessels
Fluid is destined to become lymph


Lymphatic Capillaries

Similar in structure to blood capillaries
Larger in diameter

Thin, very permeable walls
Lined by a single layer of squamous epithelial cells called endothelium

Epithelial cells overlap
Create flaplike valves that allow fluid to enter the capillary, but do not allow fluid to exit under normal conditions

Lymph can leak out of the vessels, causing edema or fluid buildup in the interstitial spaces


Lymphatic Trunks

Named after the region in which they are found
Jugular trunks - Head and neck region
Lumbar trunk - Lower extremities
Subclavian trunk - Upper limbs
Bronchomediastinal trunk - Thorax


Right lymphatic duct

Receives lymph from the upper right side of the body
Empties its contents into the right internal jugular and right subclavian veins
Return the lymph to the right atrium by way of the superior vena cava


Thoracic duct

Drains lymph from all parts of the body that are not drained by the right lymphatic duct
Begins at the level of the second lumbar vertebra and has a dilated sac or channel called the cisterna chyli
Empties into the junction of the left internal jugular and left subclavian veins


Lymphatic Movement

Lymph is moved along towards the heart


Skeletal muscle pump

Utilizes skeletal muscle contractions to move the lymph


Respiratory pump

Utilizes pressure changes in the thorax to assist circulation


Lymphatic Pathway

Lymphatic Capillary >Afferent Lymphatic vessel> lymph node> Efferent Lymphatic vessel >Lymphatic trunk>collecting duct >Subclavian trunk



Blockage of lymphatic vessels

Caused by genetics, parasitic infections, trauma to the vessels, tumors, radiation therapy, cellulitis, and surgeries (mastectomies and biopsies).
Tissue swelling that lasts longer than a few days or increases over time
compression stockings . maintain good nutrition . keep skin clean


Lymph Nodes

Very small, glandular structures
Located along the paths of larger lymphatic vessels
Spread throughout the body

Indented side is called the hilum- Nerves and blood vessels enter
Afferent lymphatic vessels -Carry lymph to the node
Efferent lymphatic vessels - Carry lymph out of a node are called efferent vessels
Lymph tends to concentrate in the node.- Pressure builds up that assists in filtration
Surrounded by a fibrous capsule of connective tissue
Medulla- Inner portion
Cortex- Outer portion


Macrophages and lymphocytes

Together these form the lymph nodules
Lymph nodules are found in the cortex.
Macrophages digest unwanted pathogens in the lymph.
Lymphocytes are part of the immune response against the pathogen.


Viral or bacterial infection, causes lymphadenitis

Inflammation of the lymph nodes
Any disease of the lymph nodes is called lymphadenopathy
Terms lymphadenitis and lymphadenopathy are often used interchangeably



Soft, bilobed organ
Located behind the sternum, just below the thyroid gland and above the heart
Large in the infant
Maximum size, 1 to 2 ounces, when the child is about two years of age
After adolescence, atrophies or involutes
In older adults, tiny or almost nonexistent

Produces the hormone thymosin
Stimulates the production of mature lymphocytes


Cortex of thymus

Outer portion
Where T lymphocytes (T cells) that have been produced in the bone marrow proliferate


Medulla of thymus

Inner portion
T cells move to and mature



Located in the upper-left quadrant of the abdominal cavity
Below the diaphragm and behind the stomach
Protected by the rib cage
Divided into lobules with two types of tissues
White pulp is concentrated with lymphocytes.
Red pulp has an abundance of red blood cells, lymphocytes, and macrophages.

Filters blood and removes worn-out red blood cells from the bloodstream
Splenomegaly- Injured or becomes enlarged due to disease
Splenectomy- Removed to prevent rupture


Lymphatic Nodules

Masses of lymphatic tissue not surrounded by a capsule
Often referred to as mucosa-associated lymphoid tissue (MALT)



Lymphatic Nodules
Tonsils are three sets of lymphoid tissue
Form a ring known as the Ring of Waldeyer
Pharyngeal tonsils or adenoids
Junction of the mouth and oropharynx
Palatine tonsils
Junction of the nasal cavity and nasopharynx
Lingual tonsils
Located at the base of the tongue


Appendix, or vermiform appendix

Lymphatic Nodules
Located in the lower-right quadrant at the junction of the large and small intestines
Once thought to have no function
Part of the immune system

Peyer’s patches
Located in the small intestine


Disease Defenses

Immunity, also known as resistance
Divided into innate and acquired immunity
We are born with innate or nonspecific immunity.
Acquired or specific immunity takes place over a period of time after exposure to an antigen.
Disease may take the form of injury, infection, or malignancy.
Infection is the presence of a pathogen in or on the body.
Pathogen is a disease-causing agent such as a bacterium, virus, toxin, fungus, or protozoan.


Zoonotic disease

Disease that is transmissible from an animal to humans



Innate (Nonspecific) Defenses
Neutrophils and monocytes have phagocytic characteristics
Monocytes are transformed into macrophages.
Very large and active phagocytes capable of ingesting very large particles
Neutrophils, monocytes, and macrophages make up what is called the mononuclear phagocytic system or the reticuloendothelial system


Physical barriers

Skin and the mucosa that line the digestive tract, oral cavity, and other areas
First line of defens


Chemical barriers

Chemicals and enzymes in body fluids provide barriers that destroy pathogens
Along with the remaining nonspecific mechanisms, form the second line of defense


Natural killer (NK) cells

Innate (Nonspecific) Defenses
Natural killer (NK) cells
Type of lymphocyte which primarily targets cancer cells
Like cytotoxic T cells, NK cells kill harmful cells on contact
Secrete chemicals called perforins that punch holes in the membranes of harmful cells
Unlike B and T cells, NK cells do not have to rely on memory to recognize a specific antigen to start destroying pathogens



Innate (Nonspecific) Defenses
Injury or infection cause this vascular response
Cardinal signs
Heat, swelling, erythema, pain, and loss of function
Blood vessels in the injured area first constrict then dilate
Also become more permeable or “leaky”

Neutrophils and monocytes
Leave the blood vessels to fight the infection
Clean up the area


Acquired (Specific) Defenses

Another name for immunity, the third line of defense
Classified as cellular or humoral immunity



Defined as foreign substances in the body
Pathogens have many antigens on their surfaces
Haptens - Combine with larger proteins in the blood to make them capable of eliciting an immune response


B cells

Do not attack antigens directly
Respond to antigens - Becoming plasma cells or memory B cells


Plasma cells

Make antibodies that are directed against a specific antigen
Antibodies attach to the antigens in the humors (fluids) of the body.
Humoral immunity or antibody-mediated response


Memory B cells

Recognize the antigen the next time exposure to the same antigen occurs
Stronger and more immediate response results


T cells

Go to the thymus to mature or be processed
Bind to antigens on cells and attack them directly
Called a cell-mediated response, or cellular immunity
Respond to antigens by secreting cytokines called lymphokines


T cell activation

Macrophage ingests and digests a pathogen that has antigens on it
Takes some of the antigens from the pathogen and puts them on its cell membrane next to a large protein complex called a major histocompatibility complex (MHC)
Another name is human leukocyte antigens (HLAs).
T cell that has a receptor for the antigen recognizes and binds to the antigen and the MHC on the surface of the macrophage
T cell is now activated and begins to divide to form other types of T cells


Cytotoxic T cells

Protecting the body against viruses and cancer cells


Helper T cells

Increase antibody formation, memory cell formation, B-cell formation, and phagocytosis


Memory T cells

“Remember” the pathogen that activated the original T cell


Compare origin of undifferentiated T cell vs b cells

Both in red bone marrow


Compare site of differentiation T cell vs b cells

Tcells - Thymus
Bcells- Red bone Marrow


Compare primary locations of T cell vs b cells

T and Bcells - lymphatic tissues - circulating lymphocytes in blood


Compare primary fuctions of T cell vs b cells

Tcell - provide cellular immune response where t cells interact directly with the antigens or antigen bearing agents to destroy them

Bcells- provide humoral immune response where b cells interact directly producing antibodies that destroys the antigens or antigen bearing agents



Called immunoglobulins (Ig)
Proteins produced by plasma cells

Antibodies bind to antigens, they take one of the following three actions
-Allow phagocytes to recognize and destroy antigens
-Make antigens clump together, causing them to be -destroyed by macrophages
-Cover the toxic portions of antigens to make them harmless


Primary immune system response

First time a person is exposed to an antigen
Slow and takes several weeks to occur
Memory cells are produced


Secondary immune system response

Next time a person is exposed to the same antigen
Very quick and usually prevents a person from developing a disease
Memory cells carry out this response


Naturally Acquired Active Immunity

Naturally exposed to an antigen
Make antibodies and memory cells
Long lasting


Artificially Acquired Active Immunity

Injected with a pathogen
Make antibodies and memory cells
Long lasting


Transplantation and Tissue Rejection

Tissues and organs that are transplanted
Cornea, kidney, lung, pancreas, bone marrow, skin, liver, and heart
Transplanted tissue may actually cause harm to the host’s tissues
Graft-versus-host disease (GVHD)
MHC of the host or recipient and the possible donor are examined for a match



From the person’s own body



From an identical twin



From someone other than the individual or an identical twin



From another species, such as a pig or other primate


Immunosuppressive drugs

Given to help reduce the risk of Transplantation and Tissue Rejection
Serious side effects such as infection, kidney damage, and even cancer


Allergic reaction

Excessive immune response to a stimulus
Substances that trigger allergic responses are called allergens
Allergic reactions involve IgE antibodies and mast cells
IgE antibodies bind to allergens, they cause mast cells to release histamine and heparin


Autoimmune Disease

Failure of self-recognition
Body does not recognize a part of itself
Considers it “foreign” and attacks its own antigens
Much more common in women
First lines of treatment
Corticosteroids to control the inflammatory response



Highly contagious viral infection
Spread through the saliva of the infected person
Caused by either the Epstein-Barr virus or the cytomegalovirus

Unexplained fever, extreme fatigue, sore throat, weakness, headache, and swollen, tender lymph nodes

Rest, proper nutrition, and antibiotics to prevent secondary infections usually result in recovery from acute symptoms.



AIDS is caused by HIV, and is spread in three ways:
-Sexual contact with someone who is HIV-positive
-Sharing needles with someone who is HIV-positive
-Mother to fetus or infant through the placenta during the birth process or through breast milk

HIV attacks specific lymphocytes called T lymphocytes
Places the individual at risk of contracting many other potentially fatal diseases
T-cell counts below 200;
No cure for AIDS