(7) Lymphatic System Flashcards
● Consists of lymphatic tissues and vessels
● This system returns protein-rich fluid to the blood circulation that escapes from the blood capillaries into tissue spaces
● Involved in lymphocyte and antibody production, phagocytosis of particulate matter, and movement of fats from the digestive system to the circulation
Lymphatic System
are not present in the brain, spinal cord or bone marrow
Lymph vessels
- Blind-ended tubes located throughout the body
- More permeable than blood capillaries, they “pick up” the excess interstitial fluid, which is then called lymph
Lymph capillaries
the larger vessels formed by the convergence of lymph capillaries
Lymphatic vessels
the ovoid or bean-shaped, encapsulated structures located along the course of the medium-sized lymphatic vessels
Lymph nodes
located in the lymph nodes, they differentiate into lymphocytes and/or plasma cells
Primitive cells
the phagocytic cells lining the walls of the sinuses
Macrophages
● Group of lymph nodes draining the same region of the body in all species
Lymphocenters
Trunks and ducts drain the lymphocenters back to the general circulation at the so-called?
venous angle
is where the ducts or trunks empty into the large veins in the thoracic inlet
venous angle
○ represents the parotid lymphocenter
○ It is located under the cranial edge of the parotid gland
○ It drains the dorsal part of the head, including the orbit and parotid gland, then the lymph continues to the retropharyngeal nodes
○ It is palpable in the dog and ox
Parotid lymph node
○ represents the mandibular lymphocenter and consists of
nodes located ventral to the angle of the jaw
○ They drain that part of the head not drained by the parotid gland to the medial retropharyngeal node
○ Present in all species, they are palpable in the dog, ox and horse
Mandibular lymph node
drains the deeper structures of the head and neck, including the pharynx and larynx
Retropharyngeal lymphocenter
the largest lymph node of the head and neck, present in all species
Medial retropharyngeal lymph node
usually absent in dog and palpable in the ox
Lateral retropharyngeal lymph node
○ represent the superficial cervical lymphocenter
○ Present in all species and palpable in dog, ox and horse
○ Located in front of the shoulder joint under the superficial neck muscles
○ Drain the superficial neck and dorsal thorax along with the proximal part of the forelimb
Superficial cervical lymph nodes
the chain of deep lymph nodes (cranial, middle and caudal) along the length of the trachea
Deep cervical lymph nodes
○ Traveling along the trachea, draining the
lymph nodes of the head and neck
○ Empty into the thoracic duct on the left
side, the right lymphatic duct, or the
vessels of the thoracic duct
Right and Left Tracheal (Jugular) Trunks
dorsal and ventral thoracic lymphocenters represented by the
intercostal and sternal lymph nodes
Parietal
mediastinal and bronchial lymphocenters
Visceral
consist of the cranial mediastinal lymph nodes in all species
Mediastinal lymphocenters
consists of nodes located around the tracheal bifurcation
Bronchial lymphocenters
○ constantly present in all species and palpable in dog
○ Located in the axilla, it drains the forelimb and the thoracic wall, including the first three pairs of mammary glands in the dog
Axillary lymph node (part of the axillary lymphocenter)
consist of lumbar lymph nodes located along the abdominal
aorta
Lumbar lymphocenters
a lymphatic structure found at the caudal end of the thoracic
duct that receives lymph draining from the abdominal and pelvic viscera and lower limbs
Cisterna chyli
● The major lymphatic vessel drawing the
entire body, except the right thoracic limb,
right cranial thorax, and the right side of
the neck
Thoracic Duct
○ masses of unencapsulated lymphoid tissue below mucous membranes (pharyngeal, palatine, and lingual)
○ The major ones protect the entrance to the larynx and esophagus from incoming pathogens
Tonsils
diffuse accumulation of lymphatic tissue in the wall of the ileum
Peyer’s patches
● The largest lymphoid organ in the body
● Flat, elongated structure interposed in the blood stream located next to the left abdominal wall
● In the fetus, it produces red blood cells
● In the adult, it stores red blood cells that can be squeezed back into circulation when needed
● Produces lymphocytes, stores iron, and destroys worn out red blood cells
Spleen
the area where vessels and nerves enter the spleen
Hilus
consist of splenic, gastric, hepatic and pancreaticoduodenal lymph nodes that drain associated structures to the cisterna chyli
Celiac lymphocenters
consist of jejunal, cecal, and colic lymph nodes
Cranial mesenteric lymphocenters
large node located in the root of the mesentery of the dog
Cranial mesenteric lymph nodes
represented by the caudal mesenteric lymph nodes draining the descending colon
Caudal mesenteric lymphocenters
