Chapter 14: Lymphatic System and Immunity

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Chapter 14 Lymphatic System and Immunity

• Anatomy and Physiology
• 12th Grade

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Immunity

• Ability of the body to protect itself from
  disease causing invaders called pathogens.
• From the Latin word immunis--exempt

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Immune System

• Consists of lymphoid tissues of the body, the
  immune cells, and chemicals that coordinate and
  execute the immune functions

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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)

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Pathogens

• Include bacteria, viruses, fungii, one-celled
  protozoans, multicellular parasites (i.e.
  hookworm)
• Bacteria and viruses are the most common
  pathogens.

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Bacteria Vs. Viruses

• Know the diagram from the board!!

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Anatomy of the Immune System

• Primary lymphatic tissuesthymus gland, bone
  marrow where cells involved in the immune
  response grow mature
• Secondary lymphatic tissuestwo types
• Encapsulated
• Unencapsulated

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Encapsulated Tissues

• Lymph nodeslocated along the pathway of
  lymphatic circulation filters lymph.
• They grab invaders that enter the lymph system by
  breaks in the skin or mucous membranes

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Encapsulated contin

• Spleentraps and removes aging red blood cells
  with the help of phagocytes contains immune
  cells to capture foreign invaders

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Unencapsulated Tissues

• Tonsilslocated 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

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Lymphatic System

• Lymph is a clear fluid that is driven through
  hydrostatic pressure from the interstitial spaces
  into the lymphatic capillaries
• Muscular activitymajor driving force of lymph
  through the lymphatic vessels

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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.

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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)

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Collecting Ducts

• Lymphatic trunks join one of two
• Thoracic duct
• Right lymphatic duct

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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

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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

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Edema

• Anything that interferes with the flow of lymph
  can cause a back-up of interstitial fluid in an
  area.
• This causes swellingaka. 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
  flowlymphedema

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Lymph Nodes

• Vary in size and shapeon average are bean-shaped
  and approx. 2.5 cm
• Lymphatic sinusspace 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)

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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.

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Lymphocytes and Macrophages

• Lymphocytesattack invaders that enter the lymph
  node
• Macrophages--engulf and destroy foreign
  substances, damaged cells, and cellular debris

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Thymus

• Located posterior to the upper sternum (breast
  bone) upper chest
• Large during infancy and childhood
• Shrinks after puberty
• In elderlytissue is gradually replaced by
  adipose (fat) and connective tissues
• By 70 yearsit is one-tenth the size that it was
  when a person is 10!!

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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.

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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

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Spleen

• Has two types of tissue
• White pulplike splattered islands around the
  space contains many lymphocytes
• Red pulpContains many red blood cells, plus
  lymphocytes and macrophages

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Spleen

• Splenectomyremoval of the spleen
• Splenitisinflammation of the spleen

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Immunity

• Your body has two ways to defend against
  infection
• Innate (nonspecific) defense
• Adaptive (specific) defense

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Innate (Nonspecific) Defense

• There are six basic types of innate defense
• Species Resistance
• Mechanical Barriers
• Chemical Barriers
• Fever
• Inflammation
• Phagocytosis

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Innate (Nonspecific) Defense

• Species resistancea 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

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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.

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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

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Chemical Barriers

• Interferonhormone-like peptides made by
  lymphocytes and fibroblasts in response to cells
  with viral infection or tumor cells
• Interferonbinds to receptors on the outside of
  healthy cells?cells synthesize proteins that
  block the replication of viruses
• Interferonstimulates phagocytosis, also helps
  resist infection and kill tumor cells

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Fever

• Feverelevated 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!!

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Fever

• High body temperature also increases the activity
  of phagocytes.
• Low-grade fever is actually a healthy response by
  the body?dont medicate unless you have a high
  fever!!!

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Inflammation

• Inflammationtissue 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

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Phagocytosis

• Phagocytic cells include
• Neutrophils
• Monocytes
• These cells can leave the blood by squeezing
  between the cells of blood vessel
  wallsdiapedesis
• Chemicals from injured tissues attract these
  cells (chemotaxis)

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Adaptive (Specific) Defenses

• Adaptive (Specific) DefensesImmunity
• It is our third line of defense
• Is what our bodies develop in response to a
  particular pathogen

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Antigens

• On the surface of all cells
• Can be a protein, a polysaccharide, glycoprotein,
  or glycolipid

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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

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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

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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 bodys lymphocytes

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Lymphocytes

• Are the cells primarily responsible for the
  immune response
• Two types
• T-lymphocytesT-cells
• B-lymphocytesB-cells

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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

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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

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Cell Mediated.

• Helper T-cellsrelease cytokines to call other
  cells to the area to help and/or ingest the
  infected cell
• Cytotoxic T-cellsform protein channel (hole)
  called perforin in cell membrane of infected
  cell. It then injects granzymes ?
  apoptosis(death) of cell

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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

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Humoral.

• The receptor on B-cell attaches to the antigen.
• The antibody goes to work.
• Antibodies
• 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

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Complement Proteins

• Complement has a variety of functions
• Enhancing phagocytosis
• 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 cant work

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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.

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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

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Primary/Secondary Response

• Humoral Responseprimary response and secondary
  response
• Primary responsethe initial response that occurs
  with infection (by effector B-cells)
• Secondary responsethe lasting immunity provided
  by long lasting memory B-cells (live a long time
  and wait to see if pathogen)

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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.