Lymphatic system

innate, adaptive

What are the two parts of the immune system

Immunity

Ability to resist infection and disease

Adaptive Defense

Responds to:

• Environmental pathogens

• Toxins and Foreign proteins

• Abnormal body cells including cancers

Includes lymphocytes (primary cells of the immune response)

Innate Defense

Block or attack any potential infectious organism

• Cannot distinguish one attack from another

Lymphatic vessels

Carry lymph from peripheral tissues to the venous system

Lymph

A fluid similar to plasma but has a lower amount of plasma proteins

Red Bone Marrow and thymus

What are the lymphoid organs (lymphocytes are produced here)

Produce, maintain, and distribute lymphocytes to provide defense against infection and transport lymphocytes through the body; circulation of fluids

Functions of the lymphatic system

Lymphatic capillaries

Differ from blood capillaries

• start as pockets rather than tubes

• Larger diameters but thinner walls

• basement membrane is incomplete or absent

• endothelial cells loosely bound together overlapping edges forming mini-valves

Absent in areas of the body with poor blood supply

Mini valves

One way valves attached by collagen fibers to the surrounding tissues

• allows fluids, solutes, viruses, bacteria, and cellular debris to enter

  • prevents return to intercellular space

Lacteals

special lymphatic capillaries in the small intestine

• transport lipids from digestive tract

Lymphatic tissue

travels from lymphatic capillaries to larger lymphatic vessels through one-way valves

• similar to valves in the venous system, but they are closer together

• Larger vessels are called collecting lymphatic vessels

Superficial lymphatics

Located in the subcutaneous layers of the skin, respiratory, urinary, and reproductive tracts

• Also within the areolar tissue of the digestive lining, pleural, pericardial and peritoneal cavities

Deep lymphatics

Larger vessels that accompany arteries and veins

• within skeletal muscle, organs of the neck, limbs, trunk, and walls of visceral organs

trunk

Superficial and deep lymphatics unite to form ____ to drain large areas of the body

right lymphatic duct, thoracic duct

Trunks empty into what two major collecting vessels

Right lymphatic duct

Collects lymph from right jugular trunk, right subclavian trunk, right bronchomediastinal trunk

• empties into the right subclavian vein

Thoracic duct

collects lymph from the left side of the body and every region inferior to the diaphragm

• empties into the left subclavian vein

cisterna chyli

Thoracic duct expands into a sac-like structure called:

right and left lumbar trunks, intestinal trunk

Where does cisterna chyli receive lymph from

Cytotoxic T cells

Attack cells infected by viruses

• produce cell-mediated immunity

Memory T Cells

Respond to foreign substance

• remain in body to give immunity

Helper T Cells

Stimulate function of T and B cells

Suppressor T Cells

Inhibit function of T and B cells

Regulatory T Cells

Are helper and suppressor T cells

• Control immune response

B cells

Make up 10-15% of circulating lymphocytes

• differentiate into plasma cells which produce and secrete antibodies

T and B cells

What protects the body from antigens by producing antibodies

Antigens

Act as targets that identify any pathogen or foreign compound

Antibodies

Bind to specific target antigen, initiating antibody-mediated immunity

Antibody mediated immunity

A chain of events that destroys the target compound or organism

Natural killer cells

Make up 5-10% of circulating lymphocytes

Responsible for immunological surveillance

• attack foreign cells, virus-infected cells, and cancer cells

• Identify and attach to abnormal cell due to abnormal plasma membrane components

• Golgi apparatus in this cell forms perforin vesicles and release them through exocytosis

Macrophages

Phagocytize foreign substances

• activate T cells

Dendritic cells

capture antigens and bring them back to lymph ndoes

Reticular cells

Act like fibroblasts creating reticular tissue that will support lymphoid organs and tissues

Reticular connective tissue

Dominates most lymphoid organs except the thymus

• macrophages reside in the reticular fibers

• starting place for lymphocytes to transfer between lymphatic and blood vessels

  • Allowing for constant surveillance

Diffuse lymphoid tissue

Loose arrangement of lymphoid cells and reticular fibers

• found in almost every body organ

Lymphoid nodules

Areolar tissue with densely packed lymphocytes

• Germinal center contains dividing lymphocytes

  • found in larger lymphoid organs, lymph nodes, spleen, tonsils, along digestive, urinary, and reproductive tracts

Purifies lymph before return to venous circulation, removing debris, pathogens and 99% antigens

Lymph node functions

Afferent lymphatics

What carries lymph from peripheral tissues

Capsule

Dense connective tissue covering lymph node

• bundles of collagen fibers extend from capsule into interior of lymph node making up the trabeculae

Cortex

Inside capsule containing many germinal centers

• deeper in the cortex houses T cells in transit

Medulla

Deep to the cortex

• contains B cells and plasma cells linked into medullary cords

Lymph sinuses

Houses macrophages as they monitor lymph

Efferent lymphatics

What carries lymph to venous circulation

spleen

What is found below the diaphragm, lateral to kidney and posterior to the stomach

removal of abnormal blood cells and other components by phagocytosis, storage of iron recycled from RBCs, initiation of immune responses by B and T cells, storage of platelets and monocytes for emergencies

Functions of spleen

Thymus

Located in mediastinum

• superior to the heart

  • divided into two lobes

Cortex (thymic lobe)

Lymphocytes divide here

• Epithelial cells surround lymphocytes maintaining blood-thymus barrier

  • Keep T cells from activating early

    • Secrete thymic hormones that stimulate stem cell divisions and T cell differentiation

Medulla (thymic lobe)

T cells migrate into this

• Thymic epithelial cells form concentric layers known as thymic corpuscles

  • Has no blood-thymus barrier

  • Mature T cells leave thymus by medullary blood vessels

Mucosa-associated lymphoid tissue

Associated with digestive, respiratory, urinary, and reproductive systems

Tonsils

Forms a ring of lymphoid tissue around the throat

• gather and remove pathogens as they enter the pharynx or throat

Pever’s patches and appendix

Used for destroying intestinal bacteria, and creating lymphocyte memories for long term immunity

Appendix

What contains a mass of fused lymphoid nodules

Innate (nonspecific) Immunity

Type of defense:

• Always works the same way against any type of invading agent

  • Nonspecific resistance

Adaptive (specific) Immunity

Type of defense:

• protects against specific pathogens

• Depends on activities of lymphocytes

• Specific resistance

  • Develops after exposure to environmental hazards

Responds to specific antigens with coordinated action of T and B cells

Physical barriers

Component of innate immunity:

• Outer layer of skin and hair

• Epithelial layers of internal passageways (mucous membranes)

• Physical obstruction

• Produce protective chemicals

  • Secretions that flush away unwanted materials

    • Sweat glands, mucus, and urine

  • Secretions that kill or inhibit microorganisms

    • Enzymes, antibodies, and acids

Phagocytes

Component of Innate Immunity Internal defenses:

• Attacks and removes dangerous microorganisms pathogens and cellular debris

  • Chemotaxis

• Has 2 classes

• Responds to pathogens in several ways

  • Engulf pathogen and destroy it with lysosomal enzymes

  • Bind to pathogens so other cells can destroy it

  • Destroy pathogen by releasing toxic chemicals into interstitial fluid

    • Hydrogen peroxide, nitric oxide, and tumor necrosis factor

Chemotaxis

The release of chemicals in surrounding fluids may attract or repel phagocytes

microphages, macrophages

What are the two classes of phagocytes

Microphages

Type of phagocyte:

• Neutrophils and eosinophils

  • Leave the bloodstream and enter peripheral tissues to fight infections

Macrogphages

Type of phagocyte:

• Large phagocytic cells derived from monocytes

  • Distributed throughout body tissues

Perforins

What splits or lyse abnormal cells, cancer cells and cells infected with viruses

Tumor-specific antigens

How do NK cells identify cancer cells as abnormal

abnormal proteins on plasma membranes

What allows NK cells to identify and destroy infected cells to stop the spread of disease

Cytokines

Released by activated lymphocytes, macrophages, and infected tissue cells

• chemical messengers released by tissue cells

  • To coordinate local activities

  • Can act as hormones to affect whole body if necessary

Interferons

Bind to adjacent cells, triggering the release of antiviral proteins

• Antiviral proteins do not kill viruses, but block replication within adjacent cells

Alpha, beta, gamma

What are the three types of interferons

Alpha

Type of interferon:

• Produced by leukocytes and infected cells

  • Stimulate NK cells

Beta

Type of interferon:

• Secreted by fibroblasts

  • Slow inflammation

Gamma

Type of interferons:

• secreted by T cells and NK cells

  • Stimulates macrophage activity

Complements

Helps with antibody action within the body through a series of cascade reactions

• plasma proteins that circulate in the blood in an inactive state

• Has two pathways that can be activated:

  • Classical and Alternative

Both pathways ends with the conversion of inactive protein C3 to active form C3b

Classical pathway

Pathway of activating complement system:

• Protein CI binds to antibody molecules attached to antigen of foreign microorganism

• Bound protein acts as enzyme speeding up the chain reaction

Alternative pathway

Pathway of activating complement system:

• Factor P, Factor B, and Factor D interact in plasma after exposure to surface antigen of a microorganism

enhancement ease of phagocytosis by signaling macrophages, releases histamine to increase the degree of local inflammation and blood flow, destruction of target plasma membranes

Effects of complement activation

Inflammatory response

Part of innate immunity internal defenses:

• Localized, tissue-level response that attempts to limit the spread of injury or infection

• Triggered by any stimulus that kills cells or injures tissue

  • Intense heat, physical trauma, irritating chemicals and infections

• Cardinal signs or symptoms

  • Swelling, redness, heat, pain and occasionally lost function

Temporary repair and barrier against pathogens, slows spread of pathogens into surrounding areas, mobilization of local and systemic defenses, facilitation of tissue repair

Effects of inflammation

injury or immune cells

What are inflammatory chemicals released by

Mast cells

What will release histamine, heparin and other chemicals

• stimulate neurons signaling pain in an area

• speed up blood flow through the area

  • clotting factors and antibodies will permeate the area

necrosis, pus, abscess

What are the products of inflammation

Necrosis

Local tissue destruction in area of injury

Pus

Mixture of debris and necrotic tissue

Abcess

Pus accumulated in an enclosed space

37.2 Celsius (99 F)

Above what body temperature is considered a fever

Pyrogens

Cause hypothalamus to raise body temperature

• Circulating pathogens, toxins, or antibody complexes created by macrophages

Increases body metabolism, accelerate defenses by moving cells along faster, inhibits some viruses and bacteria

Benefits of fevers

T cells

provides cell-mediated immunity

• Defend against abnormal cells and pathogens inside cells

B cells

Provide antibody-mediated immunity

• Defend against antigens and pathogens in body fluids

• Attack antigens by producing specific antibodies

• Millions of populations, each with different antibody molecules

specific, systemic, versatile, memory, tolerance

Properties of adaptive immunity:

Specific

Property of adaptive immunity:

• T or B cell responds only to a specific antigen and ignores all others

Systemic

Property of adaptive immunity:

• Immunity is not restricted to the initial infection site

Versatile

Property of adaptive immunity:

• The body produces many types of lymphocytes and antibodies

  • Each fights a different type of antigen

Memory

Property of adaptive immunity:

• Provides immunity against new exposure

  • Memory cells stay in circulation after initial exposure

Tolerance

Property of adaptive immunity:

• Immune system ignores antigens produced by the body

Antigens

Any substance that can create or mobilize an immune response

• a contraction for “Antibody Generating”

  • Has 2 properties: immunogenicity and reactivity

Immunogenicity

Property of antigens:

• Stimulates specific lymphocyte to multiply

  • Antigenic determinants allow lymphocytes to recognize the antigen

Reactivity

Property of antigen:

• Reacts to activated lymphocytes and antibodies

intruders

As far as the body is concerned, any not body generated antigens are _____

Haptens

Smaller molecules/incomplete antigens that must attach to proteins

• Immune system recognizes the combination as foreign

Red bone marrow

Where are lymphocytes created

Bone marrow

Where do B cells mature