Structural and Functional Organization of the Lymphatic and Immune Systems Flashcards
What type of tissue is lymphatic tissue?
A specialized form of reticular connective tissue that contains large numbers of lymphocytes.
What is the main difference of interstitial fluid and lymph compared to blood plasma?
They contain less protein than blood plasma because most plasma protein molecules are too large to filter through capillary walls.
How many liters of fluid filter from blood into tissue spaces each day?
20 liters.
How many liters of fluid is filtered from the arterial end of blood capillaries?
17 liters of the initial 20. This fluid returns to the blood directly by reabsorption at the venous end of capillaries.
How many liters per day passes into the lymphatic vessels to be returned to the blood?
3 liters out of the original 20.
What are the three primary functions of the lymphatic system?
1) Drains excess interstitial fluid.
- This helps to maintain fluid balance in the body and prevents the depletion of plasma.
2) Transports dietary lipids.
- Lymphatic vessels transport lipids and lipid-soluble vitamins (ADEK) absorbed by the GI tract into the blood.
3) Carries out immune response.
- Lymphatic tissue initiates highly specific responses against particular microbes or abnormal cells.
How are lymphatic capillaries different to blood capillaries?
They are slightly larger and are structured to let interstitial fluid to flow into them, but not back out.
Describe how interstitial fluid enters the lymphatic capillaries.
When pressure is greater in interstitial fluid (outside) than in lymph, the cells separate slightly and interstitial fluid enters the lymphatic capillary (via the one-way valve).
When pressure is greater in the lymphatic capillary, the cells adhere more closely and lymph cannot escape back into the interstitial fluid.
What are located at intervals along lymphatic vessels?
Lymph nodes, which are masses of B and T cells surrounded by a capsule.
What two main channels does lymph pass into?
The thoracic duct and the right lymphatic duct.
The thoracic duct is the main duct.
What areas of the body does the thoracic duct receive lymph from?
Left side of the head, neck, and chest
Left upper limb
Entire body below the ribs
What areas of the body does the right lymphatic duct receive lymph from?
Upper right side of the body
Where do the thoracic and right lymphatic ducts ultimately drain into?
Thoracic:
Junction of the left internal jugular and left subclavian veins
Right lymphatic:
Junction of the right internal jugular and right subclavian veins
What two pumps maintain the flow of lymph?
Skeletal muscle pump
-“Milking action” of skeletal muscle contractions compresses lymphatic vessels and forces lymph toward the subclavians.
Respiratory pump
- During inhalation, lymph flows from the abdominal region (higher pressure), toward the thoracic region (lower pressure).
- When the pressure reverses during exhalation, the valves prevent back flow of lymph.
What are the two primary lymphatic organs where stem cells divide and develop into mature B and T cells?
Red bone marrow - flat bones and the ends of long bones of adults.
*Stem cells create mature B cells and immature T cells.
Thymus - two lobed organ located posterior to the sternum.
*Immature T cells migrate to the thymus where they mature into functional T cells.
What are the secondary lymphatic organs?
Lymph nodes
Spleen
Lymphatic nodules
Describe lymph nodes
“Bouncers”
Heavily concentrated near the mammary glands, axillae, and groin.
Contain mature B cells, plasma cells, T cells, dendritic cells, and macrophages.
They filter lymph and trap foreign substances.
Describe the spleen
It is the largest single mass of lymphatic tissue in the body.
It is located between the stomach and diaphragm and covered by a capsule of dense connective tissue.
It contains two types of tissue:
-White pulp, which is lymphatic tissue where B and T cells carry out immune responses.
-Red pulp, which are blood filled sinuses where worn out blood cells and platelets are removed (like the graveyard).
Describe lymphatic nodules
Egg shaped masses of lymphatic tissue not surrounded by a capsule.
They are plentiful in the connective tissue of mucous membranes lining the GI, urinary, and reproductive tracts as well as the respiratory airways.
Which type of immunity is non-specific?
Innate Immunity
This includes barriers provided by the skin and mucous membranes (First Line Defense) as well as various internal defenses (Second Line Defense) such as:
Antimicrobial substances NKCs Phagocytes Inflammation Fever
What type of immunity involves lymphocytes?
Adaptive Immunity
It involves lymphocytes called B and T cells.
There are two types of adaptive immunity:
- Cell-Mediated Immunity
- Antibody-Mediated Immunity
What type of immunity are we born with?
Innate Immunity