Lymphatic/ Immune System Evelin Morales Period 5 (T cells and the…
Lymphatic/ Immune System
Major functions of the Lymphatic System
Drain excess fluid from tissue.
Play an essential role in body defenses and resistance to diseases.
Return clean fluids and leaked proteins back to the blood.
Functions as the body's defense against infectious pathogens.
Keeps pathogens out and attacks those that do enter the body.
Adaptive (specific) Defenses
the response mounted by the body against specific recognized foreign molecules.
A.k.a. Immunity (acquired immunity).
Body's 3rd line of defense.
Anatomy of the lymphatic system
Comprised of a network of vessels that assist in the circulation of body fluids.
Lymphatic vessels collect and carry away (one way) excess fluid from interstitial spaces and special vessels called lacteals transport facts to the circulatory system.
contain lymphocytes and macrophages.
these contain both lymphacytes and macrophages which clean the lymph as it flows through the nodes.
located along lymphatic vessels
Lobules contain lymphocytes, some of which mature into T lymphocytes (T cells) that leave the thymus to provide immunity.
The thymus secretes hormones called thymosins, which regulates of T lymphocyte development.
Located behind the sternum, above the heart; it shrinks in size during the lifetime (large in children, microscopic in the elderly.
It is composed of white pulp and red pulp.
The spleen resembles a large lymph node except that it contains blood instead of lymph.
lies in the upper left abdominal cavity and is the body's largest lymphatic organ.
The spleen filters the blood and removes damaged blood cells and bacteria.
Innate (nonspecific) Defenses
Mechanical Barriers= body's 1st Line of Defense.The rest of the innate defenses are part of the 2nd line of defense.Unbroken skin mad mucous membranes of the body create mechanical physical barriers.
chemical barriers= Interferons, and stimulation of inflammation, attraction pf phagocytes and enhances phagocytosis.
Species Resistance= a species is resistant to diseases that affect other species.
Natural Killer(NK) cells= a type of lymphocyte thatdefend the body against various viruses and cancer cells and secrets cytolytic substances called perforins.
Inflammation= characterized by reness, swelling, heat, and pain. INVASION OF WHITE BLOOD CELLS INTO THE AFFECTED AREA; BLOOD CLOTTING.
Phagocytosis= the most active phagocytes are neutrophils and monocytes; these leave the bloodstream at areas of injury.Neutrophils engulf smaller particles; monocytes attack larger ones. Removes foreign particles from the lymph.
Pathogens= Disease- causing agents that can produce infections within the body.
2 lines of defense against pathogens:
Innate (non- specific) defense
"born with it"
respond rapidly .
Adaptive (specific) defenses
"body learns" this during its lifetime.
carried out by lymphocytes that recognize a specific invader.
develop slowly (takes time)..
Carried by body fluids, capable of binding specifically to antigens.
There are 5 major types of antibodies.
Soluble protein secreted by plasma cells (that are derived from B cells).
T cells and the cellular immune response
T cells activation requires the presence of an antigen- presenting cell, such as B cell or macrophage, that has already encountered the antigen.
In order for a T cell to become activated, it must first encounter a macrophage displaying the antigen on its major histocompatibility complex (MHC).
Activated T cells interact directly with antigen- bearing cells and such cell- to- cell contact is called cellular immune response or cell- mediated immunity.
Cytotoxic T cells continually monitor the body's cells, recognizing and eliminating tumor cells and virus- infected cells.
A helper T cell stimulates B cells to produce antibodies for the displayed antigen.
T cells also synthesize and secrete cytokins that will enhance cellular responses to antigens.
Memory T cells provide a no- delay response to any future exposure tot the same antigen.
B cells and the Humoral Immune system Response
plasma cells, producing antibodies.
The helper T cell releases cytokins that activate the B cell.
A B CELL MAY BECOME ACTIVATED AND PRODUCE A CLONE OF CELLS WHEN ITS ANTIGEN RECEPTOR ENCOUNTERS ITS MATCHING ANTIGEN, BUT MOST B CELLS EED HELPER T CELLS FOR ACTIVATION.