Lymphatic and Immune system• Chapter 17

Lymphatic System

• System consists of– Lymph fluid– Lymphatic vessels– Structures and organs consisting of lymphatic tissue

– Red bone marrow– Lymphocytes

TortoraPages 454-455

Functions of Lymphatic System

• Draining interstitial fluid

• Transporting lipids and lipid soluble vitamins A,D, E, and K

• Carries out immune responses

TortoraPage 456

Lymphatic and Interstitial fluid

• Same fluid - different areas.– Interstitial fluid bathes cells.– Lymphatic fluid is I.F. in lymphatic vessels.

• Contains same materials as plasma except no proteins

Lymphatic capillaries

– Lie between cells– Open– Collect interstitial fluid.

– Fluid moves due to pressure.

– Flaps open, allow fluid in, then close

Tortora 456

Lymphatic Vessels

• Lymphatic vessels– Carry lymph fluid– Similar structure as veins with

– Thinner walls & more

valves.– Skeletal and muscular pumps move it towards the heart.

Tortora pg 457

Return to veins

• Lymphatic fluid is returned to circulatory system via the jugular & subclavian veins

• 20 L of plasma become IF every day

• 17 L goes back to heart via the veins

• 3 L becomes lymph

Tortora456-457

Lymph Nodes

– Located along lymphatic vessels.

– Arranged in groups.

– Afferent vessel leads to node.

– Efferent leads away.

– Valves do not let lymph fluid move backwards.

Tortora pg 458-459

Lymphatic nodes

– 600 located in the body

– Concentrated at axillae, mammary glands, throat and groin

– Foreign materials are filtered and destroyed in nodes.

– Macrophages destroy by phagocytosis

– Lymphocytes destroy by a variety of immune responses

Tortora pg 458

Macrophages

Two cross sections of a lymph node: macrophages, which appear as red in the top image, are sticky cells that act like flypaper, trapping viruses and bacteria when they enter the lymph node. Green and blue show other structural elements of the node. In the bottom picture, B cells are red and the structural elements of the node are in green and blue

Swollen lymph nodes

Tonsils & spleen

• Tonsils:– Large nodules grouped together.

– Contains T and B lymphocytes.

• Spleen– Largest mass of lymphatic tissue.

– Stores blood.– Stores 1/3rd of the body’s platelets

– Destroys broken RBCs & platelets.

Thymus gland– Contains T cells, dendritic cells, and macrophages.

– Immature T cells arrive here from the red bone marrow.

– 2% “graduate” to be mature T cells.

– Mature T cells leave the thymus via the blood, are carried to the lymph nodes, spleen, and other lymphatic tissues.

Tortora 458

Lymph Circulation

• Fluid from plasma of blood.

• Interstitial fluid.• Lymph Vessels and nodes– Lymphatic capillaries

– Lymphatic vessels.– Lymph nodes.

• Back to plasma.

Thursday 5/8/03Pages 383-388

Lymph Circulation

• Lymph fluid is moved by;– Skeletal muscles

compressing vessels.– Valves insure one way

flow.

• Edema– Fluid gain in the

interstitial spaces.– Can be due to blocked

lymphatic vessels or nodes.

Thursday 5/8/03Pages 383-388

Innate Resistance to Disease

• Pathogens are disease causing organisms.

• Pathogens produce toxins or toxic waste products.

• Your ability to ward off pathogens is resistance.

• Lack of resistance is susceptibility.

Skin & Mucous Membranes

• Skin is 1st defense against pathogens.

• Mechanical factors– Many layers of epithelial cells.

– Role of keratin.– Role of Mucus membranes.

– Mucus– Cilia– Role of lacrimal apparatus

– Role of Saliva

Skin & Mucous Membranes

• Chemical Factors in skin and mucous membranes:

– Oil glands secrete sebum.

– Perspiration– Lysozymes– Gastric juice– Vaginal Secretions.

Defenses Against Microbes

• Second line of defense:– Interferon

• Proteins produced by cells infected by viruses.

• Bind to receptor sites of other cells.

– Complement• Group of about 20 proteins.

• Found in the plasma of blood.

• Inhance immune system.

Monday 5/12/03Pages 388-388

Defenses Against Microbes

• Natural killer cells– Type of lymphocyte.– Ability to kill microbes and some cancer cells.

– Located in spleen, lymph nodes, bone marrow, and blood.

• Phagocytes– Macrophages are monocytes that morph.

• Wandering and fixed.– Neutrophils

• Hi

Monday 5/12/03Pages 388-388

Phagocytosis• Chemotaxis

– Phagocytes move towards higher concentration of chemicals.

• Adherence– Phagocytes attach to

microbe.– Role of complement.

• Ingestion– Pseudopod surrounds

microbe.– Phagocytic vesicle is

formed.– Vesicle fuses to

lysosome.– Microbe is digested.– Wastes are released by

exocytosis.

Inflammation

• Caused by pathogens, abrasions, chemical irritations.

• Symptoms– Redness– Pain– Heat– Swelling

Inflammation• Stages of inflammation– Vasodilation & increased permeability of blood vessels.

– Phagocyte migration.• Usually within an hour.

• Chemotaxis & emigration

• Repair

Fever

• The hypothalamic thermostat resets to raise body temp.

• Reason: higher temps inhibit antigen replication, but speeds up interferon and body repair

Innate and Adaptive Immunity

• Innate immunity is a generalized response

• Adaptive immunity refers to “specific” response to certain pathogens.

• An antigen is any substance that triggers an immune response.

• The immune system carries out immune responses to antigens

• Self-tolerance is when a body does not attack its own tissues and chemicals. Lack of self tolerance results in autoimmune diseases.

2 forms of adaptive immunity

– Cell mediated immunity:• Cells directly attack a specific

antigen (pathogens)

– Antibody mediated immunity:• Antibodies are produced to attack

specific antigen.

– Both use mature T and B cells– 2 types work together to remove

infection

T Cells and Cell Mediated Immunity

• Recognizing self from nonself :MHCs– Major

histocompatibility complex proteins recognize non-self antigens

– Role of MHCs in transplants

• T Cells destroy antigens:– Macrophages present

antigen to T cells.– T cells sensitize.– T cells clone.– Lyse infected cells

Antibodies and antigens

Antigens can be – Whole pathogens– Toxins– Parts of pathogens

• Antigens + interleukin-2 induce plasma cells to secrete proteins called antibodies (immunoglobulins)

• Shaped like a “Y”• One arm is always the

same.• Other 2 arms are

specifically shaped to antigen.

TortoraPages 465-467

Antibody action

• Antibodies travel to the infection site, bind to the antigen, and inactivate it.

How Antibodies affect antigens

• Neutralize the antigen toxins

• Immobilize bacteria.

• Agglutination- antigens are stuck together

Memory cells– Converted B

lymphocytes– B lymphocytes

were shown the antigen by macrophages.

– B cells now recognize antigen.

– Some B cells become memory cells

B Cells and Antibody-Mediated immunity• Long-lasting

antibodies and lymphocytes “remember” the invading antigen

• If the body is ever re-exposed, it will launch a swift attack

• Primary response– Slower to develop

• Secondary response– Much faster and

stronger.

TortoraPages 428-437

Primary and secondary response

Vaccines and immunological memory

• Vaccines contain weakened, killed microbes or parts of microbes.

• Without getting sick, your body launches an immune response, activating B and T cells

• If you are ever exposed, your body will quickly remove the antigen.

• Some vaccines need “booster shots” to remain effective

• ( tetanus)

Types of Immunity

1. Naturally acquired active immunity.• Response to pathogens in every day life.

2. Naturally acquired passive immunity.

• Natural transfer of resistance. Nursing baby.

3. Artificially acquired active immunity.

• Acquired through vaccinations.

4. Artificially acquired passive immunity.

• Intravenous injection of antibodies.