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Lecture 16. Lymphatic System and Immune Response Anatomy and Physiology JPHubbard Hartnell College – Bio11. Drain excess interstitial fluid & plasma proteins from tissue spaces Transport dietary lipids & vitamins from GI tract to the blood Produce, maintain and distribute lymphocytes.

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lecture 16

Lecture 16

Lymphatic System and Immune Response

Anatomy and Physiology

JPHubbard

Hartnell College – Bio11

slide2
Drain excess interstitial fluid & plasma proteins from tissue spaces
  • Transport dietary lipids & vitamins from GI tract to the blood
  • Produce, maintain and distribute lymphocytes
slide3
Components of Lymphatic System
  • Lymph
    • similar to interstitial fluid
  • Vessels
    • Blind ended
  • Organs
    • red bone marrow
    • thymus
    • spleen
    • lymph nodes
  • Diffuse Tissues
    • tonsils, adenoids & peyers patches
slide4
Lymphatic Vessels
  • Capillaries – similar to veins
    • Specialized to gather tissue fluid
    • In GI tract, known as lacteals -- contain chyle
  • Drain through series of trunks to 2 ducts:
    • Right lymphatic duct: right side head, arm & chest (above diaphragm)
    • Thoracic duct: Rest of body
slide7
Lymph Nodes
  • Fibrous connective covering = capsule
  • Fibrous partitions = Trabecula
  • Hilus: point of entry of blood vessels, efferent lymphatic vessel
  • Afferent vessels enters opposite hilus through cortex
  • Cortex and Medulla harbor various sorts of immune cells – site of development of specific immune response
  • Concentrated in different regions
slide9
Distribution of Lymph Nodes – major areas
  • Cervical – head/neck
  • Axillary – upper limbs, mammary in F.
  • Popliteal – thigh and leg
  • Inguinal – from lower limbs
  • Thoracic – lungs, resp. and mediastinal strs.
  • Also - Nodules: Associations with digestive tract/pharynx
slide10
Lymphatic Nodules
  • scattered throughout connective tissue of mucous membranes = mucosa-associated lymphoid tissue (MALT)
  • Peyer’s patches in the ileum of the small intestine
  • Appendix
  • Tonsils form ring at top of throat
    • adenoids (pharyngeal tonsil)
    • palatine tonsils (on each side wall)
    • lingual tonsil in the back of the tongue
slide12
Other Lymphatic Organs
  • Spleen
    • Lateral to stomach
    • Site of
      • exposure of blood to populations of immune cells
      • Destruction of erythrocytes
  • Thymus
    • superior to heart in mediastenum
    • Site of maturation and production of hormones which stimulate maturation of T-lymphocytes
    • Decreases in mass after adolescence
slide13
Spleen
  • Largest lymphoid organ in body
  • The spleen serves two major functions in the body:
  • 1. It is responsible for the destruction of old red blood cells (RBC)
  • 2. It is a major site for mounting the immune response. The spleen behaves similarly to a lymph node but instead of filtering the lymphatic fluid it filters the blood.
slide14
Disease and Immunity
  • Pathogenesis: Process by which a pathogen causes disease
    • Virus: Invade and subvert host cell metabolic processes, damage cells
    • Bacteria, Fungi, Protozoans: Produce toxins, direct tissue damage (enzymes)
    • Worms: release toxins, feed off blood, compete with host for food
    • Prions: misfolding of host proteins
  • Resistance: 2 levels
    • Innate/nonspecific
    • Adaptive/specific
slide15
Innate Defenses
  • Passive:
    • Mechanical barriers
    • Chemical barriers
  • Active:
    • Interferons – hormone-like produced in response to virus infection
    • Fever
    • Inflammation
    • Defense cells
      • Phagocytes
        • Neutrophils, monocytes – become active in tissues
        • Macrophages: fixed in certain organs
      • Natural killer cells
slide19
Complement proteins (~ 20 different ones)
  • Stimulation
    • Non-specific – by presence of foreign invader
    • Specifically – by interaction with antigen specific antibodies
  • Functions:
    • Stimulate histamine release
    • Promote phagocytosis
    • Kill bacteria through formation of membrane attack complex
    • Enhance inflammation
slide21
Pathogen Specific Active Responses
  • Two Important Characteristics:
    • Specific
      • Response to specific antigen or hapten
    • Memory
      • Basis for immunization
  • Development of two cell lines
    • B-cell line
    • T-cell line
slide22
Two Cell Lines – Specific Response
  • T-cells: produced bone marrow, mature in thymus
    • produce specific cytotoxic cells
    • like natural killer cells – but specific
    • Cell mediated response
  • B-cells: produced/mature in bone marrow
    • specific antibodies (immunoglobulins)
    • Humoral response
slide23
Specificity

Body reacts to:

  • Antigens – a foreign substance
    • Protein, Glycoprotein, smaller molecules (hapten) bound to larger molecules
      • Toxins (poisons)
      • Molecules unique to microorganisms that are not associated with human cells
      • Altered major histo-compatibility proteins (MHC protein) identify self (‘Flag’ – friend/foe recognition)
    • 10 million  1 billion different antigens may be recognized
  • See: http://www.cat.cc.md.us/courses/bio141/lecguide/unit1/prostruct/toll/toll.html
slide24
How the specific response is developed:
  • Antigen digested by macrophages / binds Virgin B cell
  • Macrophage
    • Acts as antigen presenting cell
    • Sends chemical signals which stimulate Helper T-cells division
  • Helper T cells + antigen (or antigen-MHC complex) activates multiplication of:

T cell line  cytotoxic T cells

B cell line  plasma cell

production of Memory B and T cell lines

fig 14 13
Fig. 14.13

P371-372

slide26
Clonal Selection Theory
  • Diverse B lymphocytes produced during fetal development
    • Body harbors diverse population of capable of producing specific antibody w/o ever being exposed to particular antigen
  • Encounter with antigen stimulates multiplication of specific cell line; a clone from ancestral cell
    • All descendents produce same antibody
slide27
Role of T cells in defending the body
  • Act like natural killer cells – but they are specific
  • Act primarily on cells
  • Kill
    • virus infected cells
    • Cancer cells
    • bacteria
slide29
Role of B cells in Defending Body
  • Produce antibodies – humoral response
  • Antibodies bind to foreign antigen
    • either free or on cell surface
    • Binding may destroy antigen directly, make it a better target for phagocytes
  • Examples:
    • Toxins produced by pathogens
    • Bind bacteria, fungi, protozoan pathogens
antibodies
Antibodies
  • 5 types –
  • IgG – main type of antibody involved in response to disease –
  • Other types:
  • IgM – involved in activation of complement
  • IgA – certain secretions, protection of digestive and resp. epith.
  • IgD – found on surface of virgin B cells
  • IgE – association with mast cells – allergic response and certain parasites
slide31
How your immune system ‘remembers’:
  • Two memory cell lines are produced:
    • Memory T cells
    • Memory B cells
  • Long lived – ready to stimulate immune system to respond rapidly if the same pathogen shows up again
    • Produce effector B and T cell lines
slide33
Induced Immunity – Active vs. Passive
  • Passive Immunity – occurs when individual given antibodies formed in another organism
  • Active Immunity – results in activation of body to produce its own antibodies – B and T cell lines
    • Primary immune response –
      • results in lower and transient titre
      • Important in elicitation of secondary response
allergies immune system out of control
Allergies - Immune System out of Control?
  • Excess IgE antibodies produced
  • IgE antibodies bind to mast cells –
  • IgE antibodies interact with allergen and release histamine
  • Histamine causes swelling of blood vessels, fluid leakage
  • Type of response depends on where reactions occur and degree of reaction
slide36
The End.

http://marie.guibert.chez.tiscali.fr/html/illsc.html

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