The lymphatic system Flashcards
functions of the circulatory system
- returns excess fluid that has leaked from capillaries
- filter pathogens
- produce and mature lymphocytes which produce antibodies
- Transport the products of fat digestion via the lacteals
what is lymph?
Lymph fluid is similar to plasma but without the larger plasma proteins
fluid that has leaked from capillaries
it contains more lymphocytes than circulating blood
Lymphatic system
- made up of lymphatic vessels and lymphoid tissue
- they are found all over the body with the exception of nervous tissue and bone marrow
Lymphatic Capillaries
- excess fluid is collected the interstitial space by small lymphatic vessels - the lymphatic capillaries
the capillaries are thin walled, delicate tubes which form a network within the tissues
Lymphatic vessels
- lymphatic capillaries then form larger vessels that have a similar structure to veins
they have small valves within them to only allow lymph to flow one way
lymph flow is passive
Lymphatic Ducts
- the lymphatic vessels then enter a larger lymphatic duct
- these then drain into the blood vessels leading to the heart and then return circulation
Right Lymphatic Duct
drains lymph from the right side of the head, neck, thorax and right forelimb
tracheal ducts
drain lymph from the left side of the head and neck
Thoracic duct
this is the main lymphatic duct. it collects lymph from the rest of he body
lower portion of the thoracic duct is called the cisterna chyli
Thoracic Duct
it receives lymph from
-left side of the upper body
-left forelimb
-abdomen
the thoracic duct then empties into the jugular vein or cranial vena cava
Interstitial fluid
odema is caused by an excess of fluid in this compartment
where is lymph nodes on the body
neck
underarm
chest
abdomen
groin
Lymphatic nodes
- Each node is surrounded by fibrous connective tissue - capsule
nodes are divided into two regions
cortex
medulla
cortex and medulla
cortex - contains lymph nodules that produce lymphocytes
medulla - reticular framework containing phagocyte cells
Lymphatic tissue
spleen
thymus
tonsils
spleen
largest of the lymphoid organs
stores new blood cells
destroys worn out red blood cells
acts as a filter for foreign materials
produces lymphocytes
where is the spleen located
located in the cranial abdomen just behind the stomach
Thymus
Important in young animals
it is located in the cranial thorax
it is active in late foetal and early postnatal life and is responsible for production of T - lymphocytes
Tonsils
form a ring of lymphoid tissue around the junction of the pharynx with the oral cavity
they are the first line of defence against microorganisms that enter the mouth physical barrier
What 3 layers of immunity does the body have?
Physical barrier - integument, tear production etc
Innate immunity - next stage, once gets past first barrier - immediate WBC response
Acquired immunity
the immune system
the bodies defence system to protect against disease by detecting and resisting microbial parasitic or neoplastic invasion
the immune system must distinguish between these and the bodies own healthy cells and tissue
Leucocytes
Innate -
Neutrophils
monocytes
eosinophils
Basophils
Acquired
Lymphocytes
