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.