Lymphatic System Flashcards
What is the lymphatic system
Series of lymphatic vessels → lymphatics
Lymph- clear fluid which flows through lymphatics
Lymphatic tissue → specialised reticular connective tissue, containing large numbers of
Lymphocytes
What are the functions of the lymphatic system?
Drains tissue spaces of excess interstitial fluid
Transports dietary fats (lipids and lipid soluble vitamins absorbed by the gl tract)
Defends the body against invasion of micro-organisms such as bacteria and abnormal cells such as malignant cells
How is lymph formed?
Permeability of lymphatic vessels allows large molecular weight substances to enter the lymph such as protein molecules. Large molecules could be toxic to tissue if they remain in interstitial spaces. Reabsorption is important to maintain homeostasis
What are lymphatics
They commence as closed end vessels and are located in the spaces between cells. At this level they are known as lymphatic capillaries
What are the sites where no lymphatic capillaries are found?
Avascular tissues (eg the cornea)
Central nervous system
Bone marrow
What is the structure of lymphatic capillaries?
As capillaries unite to form larger lymph vessels their structure becomes similar to veins though they have:
Thinner walls
More valves
Larger diameter
lymphatic capillaries
Unique vessel wall structure allows for interstitial fluid to flow into capillary but not out
What does interstitial fluid pressure equal
Fluid flows into lymphatic capillary
What does lymphatic pressure equal
Cell junctions become tighter to stop lymph leaving the vessel
What are anchoring filaments
Attach lymphatic vessels to surrounding tissues (to which they’re perpendicular)
Anchoring filaments → what to do in the event of excess fluid
Odematous issues pull on the filaments causing them to pull the endothelial cells of the vessel walls apart, allowing interstitial fluid to flow into them more rapidly
What are lacteals?
Specialised lymphatic capillaries found in the villi of the small intestine
What are lacteals functions?
To transport recently absorbed lipids away from the digestive tract into the lymphatic vessels and into the blood.
What is the creamy white lymph in lacteals called?
Chyle
Lymph movement
Lymph passes from lymphatic capillaries to lymphatic vessels and through lymph nodes.
Lymphatic vessels exiting lymph nodes pass lymph towards another node of the same group or another group of nodes
From the most proximal group of each chain of nodes the vessels white to form lymphatic trunks
What are lymph nodes?
Are found along the length of lymphatic vessels
There are 600 - 700 lymph nodes throughout the body
Act as fillers for lymph
Storage site for white blood cells
What are the lymphatic trunks
Lumbar trunk( RT & LT) → lower limbs,abdominal wall & kidneys
Intestinal trunk (LT only) → stomach, intestines & spleen
Branchomediastinal trunk (RT & LT) → lung & heart
Subclavian trunk (RT & LT) → upper limbs
Jugular trunk (RT & LT) → head & neck
What are lymphatic ducts?
Lymph flows slowly along the primary lymphatics.it empties into progressively larger lymphatic vessels which ultimately converge to form the thoracic duct and right lymphatic duct
What is the function of the right lymphatic duct?
To empty at the junction of right internal jugular and right subclavian veins
What is the function of the thoracic duct?
To empty into junction of left internal jugular and left subclavian veins
Thoracic duct
Is ~ 38 - 45 cm long arises anterior to the second lumbar vertebra as an enlarged sac called the cisterna chyli
What is the cisterna chyli?
A sac like lymphatic mass collecting lymph from right and left lumbar trunks and intestinal trunks
How do the thoracic duct receive lymph?
The left and right side of the head and neck
The left upper limb
The thorax and left side of the heart
Both sides of the body below the ribs
The smooth muscle → aids the flow of lymph
How does the cisterna chyli receive lymph ?
Left and right lumbar trunks drain lymph from:
Lower limbs
Walls and viscera of pelvis
Kidneys
Adrenal glands
Deep lymphatics from abdominal wall
Intestinal trunk drains lymph from:
Stomach
Intestines
Pancreas
Spleen
Liver
Right lymphatic duct
Approximately 1.25cm long
Drains the upper night limb, right thorax and right side of the head
A summary of lymphatics
A slow flowing low pressure drainage system
Collects small portion of the interstitial fluid from throughout the body
Returns interstitial fluid and nutrients to the bloodstream
