Ch.21- The Lymphatic and Immune System

• Active immunity


  Vaccination

  
• Passive immunity


  Breast feeding

  
• Where are blood cells produced?

  Bone Marrow
• What does an increase in white blood cells mean?

  Infection
• Macrophages


  Responds to foreign substances
• T lymphocytes


  Attacks viruses
• B lymphocytes


  Specific bacteria
• What is the lymphatic system?


  Carries excess interstitial fluid from tissue back to cardiovascular circulation and provides locations for immune cells to monitor the body
• How does the lymphatic system work?


  Take in fluids from the extracellular space and carry them through lymph nodes, where immune cells scan the fluids for foreign particles
• Why does the lymphatic system exist?


  Fluids must be returned to circulation via lymphatics to maintain cardiovascular function, and lymph nodes are necessary to monitor the body for infections
• The Lymphatic system consists of two parts:


  1. lymphatic vessels and

  2. lymphoid tissues and organs
• What are the functions of the lymphatic system?


  -Transports escaped fluids from cardiovascular system back to the blood

  -Plays essential role in body defense and resistance to disease
• Lymphatic vessels consists of:

  Excess tissue fluid and plasma proteins
• If fluids are not picked up


  edema occurs as fluid accumulates in tissues
• Lymphatic vessels(lymphatics) pick up


  excess fluid(lymph) and return it to the blood
• Lymphatic vessels (lymphatics) functions


  -Forms a one-way system

  -Lymph flows only towards the heart
• lymph capillaries weave between


  tissue cells and blood capillaries
• lymph capillaries walls overlap to form

  flaplike minivalves
• what leaks into lymph capillaries?

  fluid
• Lymph capillaries are anchored to the

  connective tissue by filaments
• High pressure on the inside results in

  closing minivalves
• What role does lymphatic collecting vessels play in?


  -Collect lymph from lymph capillaries

  -Return fluid to circulatory veins near the heart
• What is the role of the right lymphatic duct?


  Drains the lymph from the right arm and the right side of the head and thorax
• Where does the thoracic duct drain the lymph from?

  rest of the body
• Lymphatic vessels are similar to veins of the cardiovascular system because they are


  -Thin-walled

  -Larger vessels that have valves

  -Low-pressure, pumpless system
• Lymph transport is aided by:


  - Milking action of skeletal muscles

  - Pressure changes in thorax during breathing

  - Smooth muscle in walls of lymphatics
• Lymph nodes filter lymph before it is returned to the

  blood
• Harmful materials that are filtered include:

  bacteria, viruses, cancer cells, foreign substances
• What are the 2 defense cells within the lymph nodes?

  Macrophages and Lymphocytes
• Macrophages


  engulf and destroy bacteria, viruses, and other foreign substances in lymph
• Lymphocytes


  Respond to foreign substances in lymph
• Most lymph nodes are

  kidney shaped and less than 1 inch long that is buried in the connective tissue
• lymph nodes location


  - Surrounded by a capsule

  - Divided into compartments by trabeculae
• The cortex is located where in the lymph node?

  Outer part
• Cortex(Outer part of lymph node)


  - Contains follicles-collections of lymphocytes

  - Germinal centers enlarge when antibodies are released by plasma cells
• The medulla is located where in the lymph nodes?

  Inner part
• Medulla(Inner part of the lymph node)

  Contains phagocytic macrophages
• Flow of lymph through nodes


  1. Lymph enters the convex side through afferent lymphatic vessels

  2. Lymph flows through a number of sinuses inside the node

  3. Lymph exits through efferent lymphatic vessels

  4. Fewer efferent than afferent vessels causes flow to be slowed
• Other lymphoid organs contribute to lymphatic function which is the:


  -Spleen

  -Thymus

  -Tonsils

  -Peyer's patches

  -Appendix
• Lymphoid Organ: Spleen


  -Located on the left side of the abdomen

  -Filters and cleans blood of bacteria, viruses, debris

  -Provides a site for lymphocyte proliferation and immune surveillance

  - Destroys worn-out red blood cells

  - Stores platelets and acts as a blood reservoir