Lymphatic System Flashcards
Define lymphatic system
a system of specialised vessels and organs that regulate amount of fluid in body and defend it against infections
lymphatic system functions:
- fluid balance regulation by returning excess fluid (lymph) and proteins into bloodstream
- immune surveillance and filtering pathogens from blood
- transport of large molecules
What is lymph?
a clear, yellowish fluid present in most tissues of the body, created as a result of filtration of the plasma
What is interstitial fluid?
How does interstitial fluid turn into lymph?
the blood left in tissue (10%) after nutrients in blood get delivered to tissues and fluid gets reabsorbed into blood.
when interstitial fluid gets reabsorbed into lymphatic capillaries, it becomes lymph
How does lymph flow?
lymph flows thanks to the:
- movements of the body,
- pulsation of the arteries and
- contractions of skeletal muscles.
The lymphatic vessels have valves that prevent the lymph flowing backwards
Tissues and organs lacking the lymphatic vessels:
epidermis, cartilage, bone marrow, the structures of the eye
two main systems of lymph vessels – superficial and deep:
Superficial vessels – arise in the subcutaneous tissue, and tends to accompany venous flow. They eventually drain into deep vessels.
Deep vessels – drain the deeper structures of the body, such as the internal organs. They tend to accompany deep arteries.
Flow of lymph
starts in tissue as interstitial fluid –>
gets absorbed into lymphatic capillaries as lymph –>
lymphatic collecting vessels ( with valves) –>
lymph nodes –>
Lymph trunk –>
right lymphatic duct and left thoracic duct
role of right lymphatic duct and left thoracic duct
how do the 2 ducts empty into venous circulation
- right lymphatic duct drains the lymph from the upper right quadrant of the body (includes the right side of the head and neck, the right side of the thorax and the right upper limb)
- left thoracic duct is much larger and drains lymph from the rest of the body.
These two ducts then empty into the venous circulation at the subclavian veins, via the right and left venous angles
lymph organs and their functions
Spleen – Functions mainly as a blood filter, removing old red blood cells. It also plays a role in the immune response.
Thymus – Responsible for the development and maturation of T lymphocyte cells.
Red bone marrow – Responsible for maturation of immature lymphocytes
Where is lymphatic tissue located?
in the tonsils, appendix, and in the walls of the gastrointestinal tract
primary and secondary lymphoid organs
- primary lymphoid organs serve as a nursery for the formation and development of the lymphocytes
- 2 primary lymphoid organs; the bone marrow and the thymus
- secondary lymphoid organs are the spleen, tonsils, vermiform appendix, lymph nodes, and specialized lymphoid tissue of the mucosae (MALT)
spleen location and function (with detail)
- spleen is located in the upper left quadrant of the abdomen, under cover of the diaphragm and the ribcage
- slightly oval shape. It is covered by a weak capsule that protects the organ whilst allowing it to expand in size
- intraperitoneal organ, entirely surrounded by peritoneum (except at the splenic hilum).
- functions mainly as a blood filter, removing old red blood cells. It also plays a role in cell-mediated and humoral immune responses
outer surface of the spleen can be anatomically divided into two
enlargement of the spleen movements
Diaphragmatic surface – in contact with diaphragm and ribcage.
Visceral surface – in contact with the other abdominal viscera.
In enlargement of the spleen (known as splenomegaly), the superior border moves inferomedially, and its notches can be palpated.
thymus gland
- pink, lobulated lymphoid organ, located in the thoracic cavity and neck
- In adolescents, it is involved in the development of the immune system. After puberty, it decreases in size and is slowly replaced by fat
- The gland is mainly located within the thoracic superior mediastinum, posterior to the manubrium of the sternum
