TORTORA LYMPHATIC

• What is the primary role of the lymphatic system?

  To defend against disease-producing microbes and maintain homeostasis
• Why is it important to resist microbes in our environment?

  To prevent constant illness or death
• What are the two basic types of immunity?

  Innate and adaptive immunity
• What does innate immunity refer to?

  Defenses present at birth that act against all microbes in the same way
• What are the components of innate immunity?

  Physical and chemical barriers, antimicrobial substances, natural killer cells, phagocytes, inflammation, and fever
• How does adaptive immunity differ from innate immunity?

  Adaptive immunity involves specific recognition of a microbe after it breaches innate defenses
• What types of lymphocytes are involved in adaptive immunity?

  T lymphocytes (T cells) and B lymphocytes (B cells)
• What is the role of the lymphatic system in relation to the cardiovascular system?

  It assists in circulating body fluids and helps defend against disease-causing agents
• What are the primary functions of the lymphatic system?

  1. Drains excess interstitial fluid
  2. Transports dietary lipids
  3. Carries out immune responses
• What is lymph?

  Lymph is interstitial fluid that has entered lymphatic vessels
• How do lymphatic capillaries differ from blood capillaries?

  Lymphatic capillaries have greater permeability and can absorb larger molecules
• What is chyle?

  Chyle is lymph from the small intestine that appears creamy white due to dietary lipids
• What are lymph trunks?

  Lymph trunks are formed when lymphatic vessels exit lymph nodes and unite
• What are the principal lymph trunks?

  Lumbar, intestinal, bronchomediastinal, subclavian, and jugular trunks
• What is the cisterna chyli?

  The cisterna chyli is a dilation that receives lymph from lumbar and intestinal trunks
• How does lymph flow from the lymphatic system to the bloodstream?

  Lymph flows from lymphatic capillaries to lymphatic vessels, then to lymph trunks or ducts, and finally to the bloodstream
• What aids the return of lymph to the heart?

  The respiratory pump and skeletal muscle contractions
• What is the relationship between lymphatic vessels and blood capillaries?

  Lymphatic vessels drain interstitial fluid that filters from blood capillaries
• What tissues lack lymphatic capillaries?

  • Avascular tissues (e.g., cartilage, epidermis, cornea)
  • Portions of the spleen
  • Red bone marrow
• What is the main duct for the return of lymph to the blood on the left side of the body?

  The thoracic duct
• How does the pressure in lymphatic capillaries facilitate lymph flow?

  Higher pressure in interstitial fluid allows fluid to enter lymphatic capillaries
• What happens to lymphatic capillaries when excess interstitial fluid accumulates?

  Anchoring filaments are pulled, enlarging openings for more fluid to enter
• What is the function of valves in lymphatic vessels?


  To ensure one-way movement of lymph
• What is the significance of the lymphatic system in relation to the immune response?

  The lymphatic system initiates specific immune responses against particular microbes
• How does the lymphatic system contribute to homeostasis?

  By draining excess interstitial fluid and providing immune responses
• What do lymphatic vessels transport?


  Lymph
• Where do lymphatic trunks or ducts drain lymph?

  Into the junction of the internal jugular and subclavian veins
• How do the lymphatic and cardiovascular systems relate?

  Both systems form a very efficient circulatory system
• What maintains the flow of lymph?

  The same two pumps that aid the return of venous blood to the heart
• What is the role of the respiratory pump in lymph flow?

  It maintains lymph flow by pressure changes during inhalation
• During inhalation, where does lymph flow from and to?

  From the abdominal region to the thoracic region
• What happens to lymph flow when pressures reverse during exhalation?

  Valves in lymphatic vessels prevent backflow of lymph
• How much excess fluid drains into lymphatic vessels daily?

  About 3 liters per day
• What is the sequence of fluid flow from blood capillaries to the junction of the internal jugular and subclavian veins?

  Blood capillaries → interstitial spaces → lymphatic capillaries → lymphatic vessels → lymphatic trunks or ducts → junction of the internal jugular and subclavian veins
• What is the role of dendritic cells in the thymus?

  They assist in the maturation process of T cells
• What is positive selection in T cell maturation?

  It is the process where epithelial cells help educate pre-T cells
• What percentage of developing T cells survive in the cortex of the thymus?

  About 2%
• What happens to T cells that do not survive in the thymus?

  They die via apoptosis
• What is the appearance of the thymus in a living body?

  It has a reddish appearance due to its high content of lymphoid tissue
• How does the thymus change with age?

  Fatty infiltrations replace lymphoid tissue, giving it a yellowish color