Module 3 Flashcards
Lymphatic system actually consists of two semi-independent parts:
1) a meandering network of lymphatic vessels
2) various lymphoid tissues and organs scattered throughout the body
What do the lymphatic vessels do?
The lymphatic vessels transport fluids that have escaped from the blood vascular system back to the blood.
The lymphoid organs house ______ ______ and ________, which play essential roles in _____ ____ and ________ __ ________.
Phagocytic cells and lymphocytes, body defence and resistance to disease.
The function of the lymphatic vessels is to:
Pick up this excess tissue fluid, now called lymph (lymph = clear water), and return it to the blood stream.
Harmful materials that enter lymph vessels:
Bacteria, viruses, cancer cells, cell debris
How does lymph move?
It has no pumping system, its a milking action of skeletal muscle. Rhythmic contractions of smooth muscle in vessel walls and breathing.
Medial iliac lymph nodes:
These are located at the point where the aorta splits in the pelvic region. They drain the pelvic viscera and pelvic limbs
Lateral iliac lymph nodes:
Not always present, located at the bifurcation of the deep circumflex iliac artery
Internal iliac lymph nodes:
Located adjacent to the internal iliac artery, drain adjacent regions
Sacral lymph nodes:
Located ventral to the sacrum, drains the adjacent region
Anorectal lymph nodes:
Located lateral to the rectum, drains the adjacent region
Iliofemoral lymph centre
Located along the course of the femoral continuation of the external iliac artery.
Ischial lymph centre
Located on the lateral aspect of the sacrosciatic ligament, adjacent to the ischial tuberosity
Popliteal lymph center
Located caudal to the stifle and drains the distal limb
Elastin makes up 40% of equine lymphatic vessel walls, assisting them to stretch and contract while on the other hand having fewer smooth muscle cells than those of people. True or False
True
All lymph vessels follow the pattern of the main veins, eventually discharging into a venous vessel - the lumbar duct. True or False
False. Thoracic duct
More closely related to the immune system, what do the lymph nodes do?
They help protect the body by removing foreign material such as bacteria and tumor cells from the lymphatic stream and by producing lymphocytes that function in the immune response.
Explain macrophages.
They engulf and destroy bacteria, viruses, and other foreign substances in the lymph before it is returned to the blood.
Why is the flow of lymph through the node very slow?
Allows time for the lymphocytes and macrophages to perform their protective function.
What happens to a lymph node once it is destroyed?
Nothing since they do not come back.
What are lymphoid organs?
Tonsils, thymus, spleen, peyer’s patches and bone marrow
Spleen:
Located on the left side of the abdomen, filters blood, destroys worn out cells, forms blood cells in the fetus, acts as a blood resevoir
Thymus:
Located low in throat, overlying the heart, functions at peak levels only during childhood, produces hormones to program lymphocytes
Tonsils:
Small masses of lymphoid tissue around the pharynx, trap and remove bacteria and other foreign materials, tonsillitis is caused by congestion of bacteria