LYMPHOID SYSTEM Flashcards
what is the lymphoid system?
a sort of ‘overflow’ system that provides for the drainage of surplus tissue fluid and leaked plasma proteins to the bloodstream, as well as for the removal of debris from cellular deposition and infection
what is the order of lymphatic drainage?
lymphatic capillaries —> lymph vessels —(lymph nodes)—> lymph trunks —> thoracic duct/right lymphatic duct —> venous angle
what is the venous angle?
junction between the subclavian and internal jugular veins
what trunk do the head and neck drain to?
jugular trunk
what trunk does the upper limb drain to?
subclavian trunk
what trunk do the lungs, heart, trachea, and mediastinum drain to?
bronchomediastinal trunk
what trunk do the lower limbs, pelvis, and kidneys drain to?
lumbar trunk
what trunk do the intestines drain to?
intestinal trunk
what is a lymphatic plexus?
a network of lymphatic capillaries that originates blindly in the extra cellular (intracellular) spaces of most tissues
what allows plasma proteins, bacteria, cellular debris, and even whole cells (esp. lymphocytes) to readily enter lymphatic capillaries?
lymphatic capillaries are formed of a highly attenuated endothelium lacking a basement membrane, along with a surplus of tissue fluid
describe lymphatic vessels
= thin-walled vessels with abundant lymphatic valves that compromise a nearly body-wide network to drain lymph from the lymphatic capillaries
what gives lymphatics a beaded appearance?
the vessels bulge where each of the closely spaced valves occur giving it a beaded appearance
what are lymphatic trunks?
large collecting vessels that receive lymph from multiple lymphatic vessels
where are lymphatic vessels and capillaries NOT found?
teeth, bone, bone marrow, the CNS
where does tissue fluid from the CNS drain into?
cerebrospinal fluid
what is lymph?
the tissue fluid that enters lymph capillaries and is conveyed by lymphatic vessels. usually clear, watery and slightly yellow. has a similar composition to blood plasma
what are lymph nodes?
small masses of lymphatic tissue located along the course of lymphatic vessel. where lymph is filtered on its way to the venous system
what are lymphoid organs?
parts of the body that produce lymphocytes
what traverses lymph nodes?
deep and superficial lymphatic vessels as they course proximally. become larger was they merge with vessels drinking adjacent regions
right lymphatic duct
- drains lymph from the body’s right upper quadrant (right side of head, neck and throat plus the right upper limb)
- at the root of the neck, it enters the right venous angle
what is the right venous angel?
the junction of the right internal jugular and right subclavian veins
thoracic duct
drains lymph from the rest of the body. the lymphatic trucks draining the lower half of the body merge in the abdomen, sometimes forming a dilated collecting sac, the cisterna chyli —> from this sac (if present), or from the merger of the trunks, the thoracic duct ascends into and then through the thorax to enter the left venous angle
what is the left venous angle?
the junction of the left internal jugular and left subclavian veins
name 2 additional functions of the lymphoid system
- absorption and transport of dietary fat
2. formation of a defence mechanism for the body
name 8 lymph node groups
- cervical (neck)
- mesenteric
- axillary (armpit)
- cubital
- iliac
- inguinal (groin)
- lumbar
- popliteal
what is primary lymphoid tissue?
red bone marrow + the thymus gland
primary lymphoid tissue functions
- where lymphocytes are formed and mature
- provide an environment for stem cells to divide into B and T cells
- both B and T cells are ‘born’ in bone marrow
- B cells mature in bone marrow whereas T cells mature in the thymus
secondary lymphoid tissues
lymph nodes, tonsils, Peyer’s patches, musosa associated lymphoid tissue (MALT)
functions of secondary lymphoid tissues
- a series of filters monitoring the contents of the extracellular fluids (ie. lymph, tissue fluid, blood)
- where lymphocytes are activated
what are Peyer’s patches?
large masses of confluent lymphoid follicles found in the walls of the ileum.
