Immune System Flashcards
Name the two systems explored in this chapter.
The lymphatic system and the lymphoid organs and tissues.
What is the function of the lymphatic system?
To return fluids that have leaked from the vascular system back to the blood.
What are the three parts of the lymphatic system?
Lymphatic vessels, lymph nodes, and MALT (mucosa-associated lymphoid tissue).
What is the anatomical basis for the body’s defenses?
Lymphoid organs and tissues.
What are some examples of lymphoid organs and tissues?
Lymph nodes, spleen, thymus, and MALT.
What is the function of lymph nodes?
To filter lymph and remove foreign substances, such as bacteria and cancer cells.
What is the function of the spleen?
To filter blood and remove old or damaged red blood cells.
What is MALT?
Mucosa-associated lymphoid tissue, which protects mucous membranes from pathogens.
What is the relationship between the lymphatic system and the immune system?
The lymphatic system supports the immune system by returning leaked fluids and providing a site for immune cell activation and proliferation.
What is the purpose of exploring the developmental aspects of the lymphatic system and lymphoid organs and tissues?
To understand how these systems develop and mature over time, and how they may be affected by disease or injury.
List the functions of the lymphatic vessels.
The lymphatic vessels collect excess protein-containing interstitial fluid and return it to the bloodstream, and also transport lymph, a clear water fluid, which contains immune cells and waste products.
Describe the structure and distribution of lymphatic vessels.
Lymphatic vessels form a one-way system in which lymph flows only toward the heart. The transport of lymph begins in microscopic blind-ended lymphatic capillaries that weave between the tissue cells and blood capillaries in the loose connective tissues of the body. Lymphatic capillaries are widespread, but they are absent from bones (including bone marrow) and teeth.
Describe the source of lymph and mechanism(s) of lymph transport.
Lymph is formed from the excess interstitial fluid that is collected by the lymphatic capillaries. The lymphatic vessels have valves that prevent backflow of lymph, and they are also aided by the contraction of surrounding skeletal muscles and respiratory movements to propel lymph towards the heart.
What is the function of the minivalves in lymphatic capillaries?
To allow fluid to enter the lymphatic capillary when fluid pressure in the interstitial space is greater than the pressure in the lymphatic capillary.
What happens when the pressure is greater inside the lymphatic capillary?
The endothelial minivalve flaps shut, preventing lymph from leaking back out as the pressure moves it along the vessel.
What kind of particles can enter lymphatic capillaries easily?
Proteins in the interstitial space and larger particles such as cell debris, pathogens, and cancer cells when tissues become inflamed.
What happens to the particles that enter lymphatic capillaries?
They travel with the lymph to the lymph nodes, where they are removed by cells of the immune system.
Why is the process of pathogens meeting up with immune cells in lymph nodes critical?
Because it allows for the removal of disease-causing microorganisms such as bacteria and viruses.
Where are lymphatic capillaries present in the central nervous system?
They are present but restricted to limited locations in the meninges, where they help drain the extracellular fluids in the brain.
What are the two unique structural modifications that make lymphatic capillaries permeable?
Loosely overlapping edges of adjacent endothelial cells forming easily opened, flaplike minivalves and collagen filaments anchoring the endothelial cells to surrounding structures.
What is the function of the thoracic duct?
To drain lymph from the rest of the body and empty it into the blood at the junction of the left internal jugular and subclavian veins.
What is the function of the right lymphatic duct?
To drain lymph from the right upper limb and the right side of the head and thorax, and empty it into the blood at the junction of the right internal jugular and subclavian veins.
What are the mechanisms that promote lymph flow in the lymphatic vessels?
The milking action of active skeletal muscles, pressure changes in the thorax during breathing, and valves to prevent backflow.
What is the function of smooth muscle in the walls of lymphatic vessels?
To contract rhythmically and help pump lymph along.