Chapter 14: Lymphatic System and Immunity : Chapter 14: Lymphatic System and Immunity Anatomy and Physiology
12th Grade Immunity : Immunity Ability of the body to protect itself from disease causing invaders called pathogens.
From the Latin word “immunis”--exempt Immune System : Immune System Consists of lymphoid tissues of the body, the immune cells, and chemicals that coordinate and execute the immune functions Functions of the Immune System : Functions of the Immune System Immune System has 3 main functions:
Protect the body from pathogens
Remove dead or damaged tissue and cells
Recognize and remove abnormal cells that have abnormal cell growth and development (i.e. cancer cells) Pathogens : Pathogens Include bacteria, viruses, fungii, one-celled protozoans, multicellular parasites (i.e. hookworm)
Bacteria and viruses are the most common pathogens. Bacteria Vs. Viruses : Bacteria Vs. Viruses Know the diagram from the board!! Anatomy of the Immune System : Anatomy of the Immune System Primary lymphatic tissues—thymus gland, bone marrow; where cells involved in the immune response grow & mature
Secondary lymphatic tissues—two types:
Unencapsulated Encapsulated Tissues : Encapsulated Tissues Lymph nodes—located along the pathway of lymphatic circulation; filters lymph.
They grab invaders that enter the lymph system by breaks in the skin or mucous membranes Encapsulated contin… : Encapsulated contin… Spleen—traps and removes aging red blood cells with the help of phagocytes; contains immune cells to capture foreign invaders Unencapsulated Tissues : Unencapsulated Tissues Tonsils—located in your posterior nasopharynx
Gut Associated Lymphoid Tissue (GALT)—lies under the mucosa of the esophagus and intestines
Clusters of lymphoid tissue in respiratory tract and skin Lymphatic System : Lymphatic System Lymph is a clear fluid that is driven through hydrostatic pressure from the interstitial spaces into the lymphatic capillaries
Muscular activity—major driving force of lymph through the lymphatic vessels Flow of Lymph : Flow of Lymph Once lymph enters a lymphatic vessel, valves prevent lymph from flowing backward (back toward the interstitial space)
Lymph can only move toward a collecting duct thanks to these valves!
As it moves through vessels, it is filtered periodically by lymph nodes. Lymphatic PathwayFigure 14.5 : Lymphatic PathwayFigure 14.5 Fluid in interstitial space?Lymphatic vessel?Lymph node?Lymphatic vessel?Lymphatic trunk?Collecting Duct?Subclavian Vein (where it re-enters the bloodstream) Collecting Ducts : Collecting Ducts Lymphatic trunks join one of two:
Right lymphatic duct Thoracic Duct : Thoracic Duct Larger and longer collecting duct
Receives lymph from lower limbs, abdominal regions, left upper limb, left side of head, thorax, neck
Empties into the left subclavian vein near the junction of the left jugular vein Right Lymphatic Duct : Right Lymphatic Duct Collects lymph from right side of head and neck, right upper limb, right thorax
Empties into the right subclavian vein near the junction of the jugular vein Edema : Edema Anything that interferes with the flow of lymph can cause a back-up of interstitial fluid in an area.
This causes swelling—aka. Edema
This can happen from something (like position or turnicate) obstructing the flow of lymph or from surgical removal of lymph nodes.
Swelling due to malfunction of lymph flow=lymphedema Lymph Nodes : Lymph Nodes Vary in size and shape—on average are bean-shaped and approx. 2.5 cm
Lymphatic sinus—space inside the node
Lymphatic sinus contains many macrophages (highly concentrated here)
Are located everywhere on the body except the CENTRAL NERVOUS SYSTEM (brain and spinal cord) Lymph Node Physiology : Lymph Node Physiology Lymph nodes have two main functions:
Filtering harmful particles from lymph before it returns to the bloodstream
Immune surveillance by lymphocytes and macrophages
Also, they produce lymphocytes along w/ the red bone marrow. Lymphocytes and Macrophages : Lymphocytes and Macrophages Lymphocytes—attack invaders that enter the lymph node
Macrophages--engulf and destroy foreign substances, damaged cells, and cellular debris Thymus : Thymus Located posterior to the upper sternum (breast bone); upper chest
Large during infancy and childhood
Shrinks after puberty
In elderly—tissue is gradually replaced by adipose (fat) and connective tissues
By 70 years—it is one-tenth the size that it was when a person is 10!! Thymus Physiology : Thymus Physiology Thymus contains immature cells called thymocytes.
These can be inactive. However, when needed they can mature into T-cells (T-lymphocytes)
T-cells are important in immunity
Thymus epithelial cells also secrete hormones called thymosins, stimulate T-cells to mature as they migrate to other tissues. Spleen : Spleen Largest lymphatic organ
Located in the upper abdomen to the left of the stomach (on left side)
Sort of like a large lymph node except instead of inner space having lymph, it has blood Spleen : Spleen Has two types of tissue:
White pulp—like splattered islands around the space; contains many lymphocytes
Red pulp—Contains many red blood cells, plus lymphocytes and macrophages Spleen : Spleen Splenectomy—removal of the spleen
Splenitis—inflammation of the spleen Immunity : Immunity Your body has two ways to defend against infection:
Innate (nonspecific) defense
Adaptive (specific) defense Innate (Nonspecific) Defense : Innate (Nonspecific) Defense There are six basic types of innate defense:
Phagocytosis Innate (Nonspecific) Defense : Innate (Nonspecific) Defense Species resistance—a given organism develops a set of diseases that is unique to it but it will be resistant to other disease because the conditions in our body are not ideal for every pathogen
Ex. Other animal species do not get measles, mumps, gonorrhea, syphilis Mechanical Barriers : Mechanical Barriers The skin and the mucous membranes of the respiratory, digestive, urinary, and reproductive systems create mechanical barriers that prevent the entry of pathogens
These barriers are a “first line of defense.” Chemical Barriers : Chemical Barriers Enzymes in body fluids are chemicals that provide a chemical resistance, or barrier, to pathogens.
Ex. Protein-splitting enzyme pepsin in the stomach; enzyme, lysozyme, in tears; salt (from sweat) on the skin Chemical Barriers : Chemical Barriers Interferon—hormone-like peptides made by lymphocytes and fibroblasts in response to cells with viral infection or tumor cells
Interferon—binds to receptors on the outside of healthy cells?cells synthesize proteins that block the replication of viruses
Interferon—stimulates phagocytosis, also; helps resist infection and kill tumor cells Fever : Fever Fever—elevated body temperature\
Bacteria and fungii require iron as temperature rises.
High body temperature stimulates liver and spleen to hoard iron so it is out of the blood.
It slows the growth of bacteria and fungii!! Fever : Fever High body temperature also increases the activity of phagocytes.
Low-grade fever is actually a healthy response by the body?don’t medicate unless you have a high fever!!! Inflammation : Inflammation Inflammation—tissue response to injury or infection categorized by localized redness, swelling, heat, and pain.
Causes the site of the problem to be “walled” off or isolated so that it cannot spread Phagocytosis : Phagocytosis Phagocytic cells include:
These cells can leave the blood by squeezing between the cells of blood vessel walls=diapedesis
Chemicals from injured tissues attract these cells (chemotaxis) Adaptive (Specific) Defenses : Adaptive (Specific) Defenses Adaptive (Specific) Defenses=Immunity
It is our “third line of defense”
Is what our bodies develop in response to a particular pathogen Antigens : Antigens On the surface of all cells
Can be a protein, a polysaccharide, glycoprotein, or glycolipid Recognizing “Self” : Recognizing “Self” Before birth, cells go around to body cells & “take inventory”
This is how your body determines which cells are “self”
Then as your immune system develops after birth, it recognizes any other type of cell as “foreign or non-self” Recognizing “Nonself” : Recognizing “Nonself” After birth, the body really begins developing its immune system
It produces lymphocytes that go around to the cells of the body and recognize the foreign antigens as “nonself” Major Histiocompatibility Complex : Major Histiocompatibility Complex AKA, MHC
Cell membrane proteins that are coded by certain genes
The MHC on the outside of your cells is recognized by your body’s lymphocytes Lymphocytes : Lymphocytes Are the cells primarily responsible for the immune response
B-lymphocytes—B-cells Cell Mediated Immunity : Cell Mediated Immunity AKA, Cellular Immune Response
T-cells are primarily responsible for this immune action
In cell mediated, the t-cells attach to foreign antigen cells and interact directly by cell to cell contact Cell Mediated Immunity : Cell Mediated Immunity Cell ingests or is infected with pathogen.
The pathogen breaks up inside the cell and pieces of it bind to the MHC on the cell membrane. “Presents the antigen”
T-cells then bind to the antigen presenting cell Cell Mediated…. : Cell Mediated…. Helper T-cells—release cytokines to call other cells to the area to help and/or ingest the infected cell
Cytotoxic T-cells—form protein channel (hole) called perforin in cell membrane of infected cell. It then injects granzymes ? apoptosis(death) of cell Humoral Immune Response : Humoral Immune Response AKA, Antibody Mediated Immune Response
Led by the B-cells
B-cells secrete antibodies.
Antibodies bind to pathogen and target them for destruction
Mature B-cells insert antibodies into their cell membrane to form receptor Humoral…. : Humoral…. The receptor on B-cell attaches to the antigen.
The antibody goes to work.
Make it easier for phagocytic cells to eat infected or antigen bearing molecules
Covering antigen-presenting cell or molecule in “envelope” and inactivating the antigen.
Activating complement proteins Complement Proteins : Complement Proteins Complement has a variety of functions:
Attracting macrophages and neutrophils
Rupturing cell membranes of foreign cells
Causing antigen-bearing agents to “clump” making it easier to get them out
Altering the molecular structure of viruses so that they can’t work 5 Types of Antibodies : 5 Types of Antibodies Immunoglobulin G (IgG)—in plasma and tissue fluids; effective against virus, bacteria, & toxins; activate complement; babies get from mom through cord ?lasts 6 months to 1 yr
Immunoglobulin A (IgA)—in exocrine gland secretions (sweat glands); breast milk, tears, nasal fluid, bile, urine, etc. 5 Types Antibodies…. : 5 Types Antibodies…. Immunoglobulin M (IgM)—develops in response to foods or bacteria
Immunoglobulin D (IgD)—found on surfaces of B-cells; important to B-cell activation
Immunoglobulin E (IgE)—in exocrine secretions along w IgA; ASSOCIATED WITH ALLERGIC REACTIONS Primary/Secondary Response : Primary/Secondary Response Humoral Response—primary response and secondary response
Primary response—the initial response that occurs with infection (by effector B-cells)
Secondary response—the lasting immunity provided by long lasting memory B-cells (live a long time and wait to see if pathogen) Vaccine : Vaccine When you get an infection, your body develops resistance the natural way. (Naturally Acquired Immunity)
A vaccine gives you resistance artificially. (Artificially Acquired Immunity)
It is made of live/weakened or dead pathogen and creates an immune response that prevents infection without causing illness.