Lymphatic and Blood Vessels

Lymphatic and Blood Vessels

• Lymphatic vessels return interstitial fluids and leaked plasma proteins back into the blood via a series of vessels.
• They form a one-way system where lymph flows towards the heart
• Lymphatic capillaries are blind-ended vessels weaving between tissue and blood capillaries, except in bone, teeth, and bone marrow.
• Lymphatic capillaries are more permeable than blood capillaries
• Lymphatic capillaries allow proteins, cell debris, and cancer cells to pass through.
• Their functions include:
  • Collecting and returning fluid to the bloodstream
  • Carrying lymph
  • Filtering waste and abnormal cells
• Blood vessels carry oxygen and nutrients to tissues, consisting of RBCs, WBCs, and platelets.
• They span throughout the body with arteries and veins
• Blood vessels remove waste and carbon dioxide from tissues.

Lymphatic Organs: Anatomy and Function

• Primary lymphatic organs, where T and B cells mature, include the red bone marrow and thymus.
• Both T and B cells originate in the bone marrow.
• B cells mature in the red bone marrow, while T cells migrate to the thymus for maturation.
• The thymus stops growing during adolescence and atrophies throughout adulthood.
• The thymus functions as a lymphoid organ for T cell maturation, most active in childhood, slowing in mid-adolescence and decreasing with age
• The thymus produces immunocompetent cells, although at a slower rate with age.
• Vaccines are especially crucial for children's immune development. Older people cannot produce immunocompetent cells effectively and weakened immune responses due to declining T and B cell production
• The thymus lacks follicles and does not directly combat antigens, serving solely as a T lymphocyte maturation site.
• The blood thymus barrier isolates immature T lymphocytes from antigens to prevent premature activation.
• Secondary lymphatic organs activate mature lymphocytes upon encountering antigens. Including:
  • Lymph nodes
  • Spleen
  • MALT
  • Tissues
• Lymph nodes cleanse lymph and act as lymph filters.
• Macrophages consume microorganisms and debris in the lymph. Prevents unwanted substances from re-entering the bloodstream.
• Lymph nodes activate the immune system and are the location where lymphocytes are activated and prepare for attack
• Lymph nodes vary in shape and size, approximately an inch in size.

Mucosa-Associated Lymphoid Tissue (MALT)

• Lymphoid tissues in mucous membranes protect the body from pathogens.
• MALT is found in the mucosa of the respiratory, urinary, and digestive tracts.
• Tonsils are the largest collection of MALT, removing pathogens from food and air
• Palatine tonsils are the largest and most often infected.
• Lingual tonsils are lumpy follicle collections at the tongue's base.
• Pharyngeal tonsils are present
• Tubal tonsils surround auditory tube openings in the pharynx.
• Tonsillar crypts trap bacteria, allowing immune cells to destroy them

Peyer's Patches and Appendix Function

• Peyer's patches are lymphoid follicle clusters in the small intestine wall, similar to tonsils, that assist in storing bacteria for memory lymphocyte generation.
• The appendix contains lymphoid follicles. Its function is similar to tonsils, can become problematic if infected.

Main Lymphatic Organs

• Primary lymphoid organs:
• The red bone marrow is where B and T lymphocytes originate with B cells maturing here.
• The thymus matures T cells. It appears early in development and supports early immune system development
• Secondary lymphoid organs:
• Lymph nodes filter lymph, house lymphocytes, cleanse lymph, and activate immune response upon antigen encounter.
• The spleen filters blood, removes old red blood cells, and combats infections.
• Tonsils protect against pathogens entering through the mouth and nose.
• Peyer's patches monitor intestinal bacteria and prevent pathogenic bacteria growth.
• The appendix contains lymphoid tissue to destroy bacteria before breaching the intestinal wall.

Innate vs. Adaptive Immune Systems

• Focus on the differences between responses of the innate and adaptive immune systems.
• Innate Immunity is a non-specific defense system:
  • The first line of defense is the skin and mucosa which create protective chemicals that inhibit or destroy microorganisms or prevent their replication.
  • The second line of defense includes antimicrobial proteins, phagocytes, natural killer cells, inflammation, and fever.
  • Pattern recognition receptors tightly bind to microbial structures, disarming them.
    • Toll-like receptors (TLRs) trigger immune responses with 11 different types, each recognizing a different microbe class.
  • Innate Response also:
    • Inhibits pathogen spread
    • Activates specific pathways
    • Triggers an immediate response
    • Releases alert proteins
• Adaptive defense system - specific response
  • The third line of defense attacks specific foreign substances.
  • Requires longer to react than innate defenses because of antigen recognition and targeting before activation.
    • Humoral immunity: B cells that produce antibodies, and need help from the T cells to point out which antibody to make
    • Cellular immunity: T cells directly attack infected cells by targeting foreign invaders and acting as lymphocytes

Adaptive Immune System Details

• It provides a highly specific response to pathogens
• Foreign substances are identified through B and T lymphocytes.
• When a B cell encounters its specific antigen, it proliferates into a clone of cells.
• Some become plasma cells that produce antibodies, others become memory B cells.
• Antibody production involves plasma cells that secrete antibodies to neutralize pathogens.
• T cells undergo positive and negative selection in the thymus to ensure:
  • Recognition of self-MHC proteins and non-reaction to self-antigens.
  • Memory cell generation for faster and stronger responses upon re-exposure.
  • Full body protection
  • Enhances the inflammatory response and complement activation.

Involved Cells and Differentiation

• B lymphocytes originate and mature in the red bone marrow. Plasma and memory B cells are differentiated.
• T lymphocytes originate in the red bone marrow and mature in the thymus.
• Types:
  • Cytotoxic T cells (Tc) destroy virus-infected and cancerous cells.
  • Helper T cells (Th) activate B cells, other T cells, and macrophages.
  • Regulatory T cells (Treg) suppress immune responses to prevent autoimmunity.

Steps of Inflammation

• Understand how inflammation benefits the immune response.
• Benefits to the immune response:
• Confines damaging agents to a localized area, preventing spread.
• Removes cell debris and pathogens from the injury site.
• Alerts/prepares the adaptive immune system and tissues for repair.

Steps of Inflammation and Cardinal Signs

• Injured tissues and immune cells release histamine. This causes :

  • Vasodilation and increased blood vessel permeability.
  • Increased white blood cell production in the bone marrow.
  • Phagocytes cling to capillary walls.

• WBCs are guided to the injury site by chemical signals

• Cardinal signs of inflammation:

  • Redness: Increased blood flow.
  • Heat: Localized fever, increased metabolic rate.
  • Swelling: Increased blood flow and plasma in tissues.
  • Pain: Tells body to stop moving

Interferon

• Interferon is a family of immune modulating proteins, enhancing innate defenses.
• Interferon is small proteins the infected cells secrete to help nearby uninfected cells
• Alters surrounding tissues and cells that it is infected.
• Interferon binds to nearby uninfected cells and produces an antiviral protein that blocks vial replication, but is not virus specific
  • Types of interferon:
    • IFN-alpha and IFN-beta have antiviral effects and activate natural killer cells
    • IFN-gamma (immune interferon) secreted by lymphocytes, activates macrophages, mobilizes the immune system

Complement Activation Pathways

• Understand complement activation pathways (classical, lectin & alternative) and the effects
• There are 20 blood proteins that circulate the blood in an inactive form
• It's a major mechanism in destroying foreign substances, enhances innate and adaptive defenses.
• Activating these compliments enhance inflammation and directly destroy bacteria
• The three pathways are:

1. The Classical pathway: first antibodies bind to the invading organism and then bind to compliment components.

• Double binding = compliment fixation (Oreo)

2. The Lectin pathway: produced by the Innate system to recognize foreign invaders

• Bind to very specific sugars on the cell membrane of foreign invaders which helps to activate complement proteins, similarly to antibodies

3. The Alternative pathway: Involves spontaneous activation. Whenever complement factors bind directly to a foreign invader

• May be the lack of inhibitors on a microorganism surface that allow it to proceed or very specific types of pathogens

• Activation requires orderly protein activation. Pathway steps are catalyzed in orderly sequence. Each catalyzes the next step

• Self-cells have compliment activation inhibitors that inhibit compliment protein from attacking own cells under normal healthy circumstances

Behaviors of Antibodies

• Different behaviors of antibodies (neutralization, etc.) and the outcomes
• It enhances Phagocytosis:
  • Neutralization masks dangerous parts of bacteria viruses
  • Agglutination clumps cell-bound antigens together for easier removal
  • Preciptation - forms insoluble complexes with soluble antigens
  • Complement activation triggers a cascade leading to cell lysis and enhanced phagocytosis
• Five different antibody types:

1. IgM:
   • 1st produced in response to an infection
   • potent in agglutination and complement activation.
2. IgA:
   • found in saliva, tears, and breastmilk
   • prevents pathogen from adhering to epithelia surfaces.
3. IgD:
   • functions as a B cell receptor
   • found in limited amounts in plasma.
4. IgG
   • most abundant is plasma but found in blood, lymph, and intestine
   • enhances phagocytosis
   • protects fetus and newborns.
5. IgE:
   • binds to mast cells and basophils triggering histamine release
   • involved in allergic reactions and defense against parasitic infections

Immunological memory

• Understand what causes immunological memory and the difference between active and passive
• Immunological memory is a faster and more effective response upon the same antigen

1. Primary response: begins when B cells first encounter an antigen that activates and differentiates into plasma cell which produce antibodies - some B cells stay in the body as memory cells and ready to quickly respond to future encounters with the same antigen
2. Secondary response: - Re-exposure to same antigen B cells create a faster response - antibody levels are faster and higher for prolonged protection

• Active humoral immunity:
  • occurs when B cells encounter antigens and produce antibodies against them - Naturally acquired through infection/contact w/ pathogen
    • Artificially acquired through vaccines - B cells are activated, proliferate, and differentiate and create memory cells that provide long term immunity
• Passive humoral immunity: ready-made introduced into the body - Naturally acquired: antibodies pass from mother - Artificially passes through the placenta or breast mild - Artificially acquired: injection of some else's (exogenous) antibodies (gamma globulin) - Provides immediate short-term protection as B cells are not activated

Immune Cells

• Know cells include Cytotoxic T, helper T, NK cells, B, T cells
• Helper T cells activate B cells and other T cells
• Regulatory T cells moderate Immune response
• Cytotoxic T cells- destroy cells with foreign antigens inside the cell by inserting perforins into the target membrane
• Memory T cells cells that remember how to respond to the non-self antigen
• Leukocytosis induced by injured cells and factors from there will release neutrophiles from bone marrow in response
• Marginations - Diapedesis - neutrophiles flatten and squeeze between the endothelial cells of the capillary to move into interstitial spaces
• Be able to explain the role of both MHCs and MACs (membrane attack complex) in immune responses
• Class 1 MHCs
  • Recognized by CD8 cells and cytotoxic T cells
• Endogenous “I belong to self but have been invaded or became cancerous. Kill me”
• Class 2 MHC
  • Displayed by antigen presenting cells (APCs) like dendritic cells etc.
• Exogenous “I belong to self but have captured a invading for help to mount a defense against it”
• The three pathways involves complement system split into C3a and C3b: C3b activates by additional comp proteins
  • C5b will bind with C6, C7, and C9 to form MAC

Functions of the MAC

• Includes MAC inserts itself and can create pores in the target cell membrane, and these will disrupt cell membrane water causing and influx and cell lysis
• Targets bacteria and other foreign cells

Respiratory Anatomy

• Understand anatomical features of the respiratory system:

1. Nose: produces mucus, filters, warms incoming are.

• It's a resonance chamber and supported by bone and lined with mucosa

2. Paranasal: Lighten skill to help warm the inside, air-filled cavities in cranial bone
3. Pharynx: Passageway for for the air and food used to expose the inhaled antigens
4. the Larynx: air passageway to prevents food and produced voice, framework of cartilage contains dense connection tissue
5. Trachea: Air passageway which cleans and war air, flexible tube, contain C shaped cartilage
6. Bronchial tree: Is responsible for air passageway
7. Alveoli Main sites of gas exchange, special cells produce in surfaceterm.

Lungs & Conducting and Respiratory Zones

• Know differences between conducting and respiratory zones

1. Lungs
2. pleurae: produce lubrication fluid and compartmentalize the lungs, serous membrane

• Understand the difference between conducting and respiratory zones:
  • Conducting zone: involved in air movement
    • Trachea splits
  • Respiratory Zone: actual sight of gas exchange
    • Oxygen an CO2 are transported blood and air
    • composed of Bronchioles and alveoli

Function of Alveolar Features

• Know the function of alveolar features (pores, type I II etc.) Type 1 alveolar cells: provides thin barrier for gas exchange
• Type 2 and Elastic fibers: secrete surfactant and have pores
• Alveolar Immune cells crawl, consumes debris and bacteria and allows fibers a connection between both is
• Respiratory membrane: thin barrier of alveolar, capillary, with fused membranes facilitating oxygen/CO2 change
• Know all the different pressure to represent. There pressure to exert to the body.
• Alvopres rise's and fall's will
• Intrapulmonary pressure: and the alvi if
• Trans pulmonary pressure: maintains positive grade