Chapter 12 -The Lymphatic and Immune System Flashcards
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
Lymphedema
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
Thymus
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
Spleen
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)
Tonsils
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
Phagocytosis
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
Inflammation
Innate (Nonspecific) Defenses
Inflammation
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
Antigens
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
Antibodies
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
Autograft
From the person’s own body
Isograft
From an identical twin
Allograft
From someone other than the individual or an identical twin
Xenograft
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
Mononucleosis
Highly contagious viral infection
Spread through the saliva of the infected person
Caused by either the Epstein-Barr virus or the cytomegalovirus
Symptoms
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.
HIV/AIDS
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
