Anatomy - Lymphatic System Flashcards
What are 3 functions of the lymphatic system?
- Returning excess interstitial fluid to the bloodstream
- Transporting dietary lipids
- Immune responses
How does interstitial fluid re-enter the circulation?
By entering:
1. Capillaries at venous ends
2. Lymphatic capillaries
What is lymph?
Tissue fluid which enters lymphatics
What % of tissue fluid is returned to the blood by the lymphatics?
10-20%
Why can bacteria, viruses and cancer cells enter the lymphatic system?
Lymph capillaries have a very high permeability.
What feature of lymph capillaries allows tissue fluid to enter?
Very permeable walls.
List the lymphatic vessels in order of size.
Lymph capillaries < lymphatics < lymph trunk < lymph duct
What is the function of lymphatics?
To collect lymph from the lymph capillaries
Where do lymphatics lie in the body?
They accompany the blood vessels
Do lymphatics travel without coming into contact with other lymphatics?
No. They have frequent interconnections and many are arranged as networks
How is the back flow of lymph prevented?
Valves. Lymphatics have more valves that veins
Where are lymph nodes found? (in general)
Scattered along lymphatics
Where are lymph capillaries found?
Nearly all tissues in the body.
Where are lymph capillaries absent from?
- CNS
- Bone marrrow
- Avascular tissues e.g cartilage, nails, epidermis, cornea, hair
How does the lymphatic system take in dietary lipids
Through lacteals which are located in villi of the small intestine
What is fatty lymph called?
Chyle
Name some of the main groups of regional lymph nodes
- cervical nodes
- axillary nodes
- inguinal nodes
- aortic nodes
- iliac nodes
How do the lymphatics of the skin work?
They run independently of blood vessels.
They drain into nodes where limbs attach to the trunk
Where are lymph nodes found?
Scattered along lymphatics
What surrounds lymph nodes?
A fibrous capsule
How does lymph enter LNs?
Through afferent lymph vessels
Through what structure does lymph leave LNs?
Through efferent lymph vessels
What is the function of a LN? (2)
- lymph percolates through LNs
- antigens are destroyed and B/T cells are activated
Lymph from which part of the body don’t pass through a series of lymph nodes?
- Lymph from paired viscera on abdominal wall (ovaries, kidneys, testis)
- Lymph from thyroid gland
Where does lymph from paired viscera drain into?
Para-aortic LNs.
Where does lymph from the thyroid gland drain into?
Directly into the neck veins, doesn’t pass through any lymph nodes
What are the 3 main lymph trunks?
- Right and left JUGULAR TRUNKS
- right and left SUBCLAVIAN TRUNKS
- Right and left BRONCHIOMEDIASTINAL TRUNKS
What do the jugular trunks drain?
Head and neck
What do the subclavian trunks drain ?
Upper limbs
What do the bronchiomediastinal trunks drain?
Much of the thoracic cavity
What are the 2 lymphatic ducts in the body?
- Thoracic duct
- Right lymphatic duct
What does the right lymphatic duct drain?
Right side of head
Right UL
Right side of thorax
Are the two lymphatic duct always present?
No. Right lymphatic duct is only present in 20% of population
What forms the right lymphatic duct?
Right subclavian trunk
Right bronchomediastinal trunk
Right jugular trunk
What does the thoracic duct drain?
Entire body except the part drained by right lymphatic duct (or the structure that form it in 80% of population)
Where does the thoracic duct begin?
As the cisterna chyli in abdomen
Where does the thoracic duct lie in the thoracic cavity ?
Along vertebral bodies
Where does the thoracic duct empty back into the veins?
At junction of left IJV and left subclavian vein
Where does the right lymphatic duct drain into?
Junction of Right IJV and right subclavian vein
How does lymph return to the blood from the ride side of the body if there is no right lymphatic duct?
The trunks (jugular, subclavian, bronchomediastinal) drain directly into right IJV and subclavian
How is lymph moved along the lymphatic system?
- contraction of skeletal muscle
-pulse in adjacent arteries
VALVES PREVENT BACKFLOW
What tissue are lymphatic organs made up of?
Lymphatic tissue
What do lymphatic organs do?
Filter the lymph to scan for pathogens
Are lymph organs encapsulated?
Some are.
Name 3 encapsulated lymphatic organs.
-lymph nodes
-spleen
-thymus
Where is the thymus located
Superior mediastinum
What is the function of the thymus gland?
Matures T lymphocytes
Is the thymus a secondary or primary lymphoid organ?
Primary
Describe the growth of the thymus gland
It grows rapidly during the first year of life
It stays the same size in adulthood
In gets smaller after 60 years old
What are the simplest lymphoid organs?
The tonsils
What are the 3 groups of tonsils?
- Palatine tonsils (i.e ‘the tonsils’)
- Pharyngeal tonsils (i.e ‘the adenoids’)
- Lingual tonsils
Where are the lingual tonsils?
On back of toungue
Wher are the palatine tonsils?
They are the main tonsils that you see when you open your mouth - sides of the throat
Where are the pharyngeal tonsils?
Roof of throat
What is the function of the tonsils?
They form a ring around the border between the oral cavity and the pharynx
They gather and remove pathogens
Where is the spleen located?
Left side of abdomen
When and how is the spleen commonly injured?
In road traffic accidents
Since it is located behind the ribs, when ribs break they damage the spleen
What are the functions of the spleen (3)?
-detects and responds to foreign substances
- destroy defective RBCs
-act as a limited reservoir for blood
Why can the spleen act as a reservoir for blood?
It has a very rich blood supply
What are 2 lymphoid organs in the latter end of the GIT?
-Peyer’s patches
- Appendix
What is MALT?
Mucous associated lymphoid tissue
Where is MALT found?
Walls of intestine
What is the function of MALT?
Fight invading bacteria in intestines
Where are Peyer’s patches located?
Distal part of small intestine
Where is the Appendix found?
It is a tubular offshoot from the caecum
What is chylothorax?
Leakage of fatty lymph into thorax
What is mononucleosis?
- A viral disease caused by Epstein-Barr virus (glandular fever)
- attacks B lymphocytes
What is lymphangitis?
Inflammation of the lymph vessel
How can you recognise lymphangitis?
The overlying skin shows inflammation in superficial lymph vessels. Appears as tender, reddened streaks.
What happens to the draining lymph nodes when you have an acute infection?
They become enlarged, tender and painful.
What is Hodgkin’s disease?
A malignancy of the LNs (cancer)
- lymphocytes grow out of control
What is Non-Hodgkins Lymphoma?
Uncontrolled multiplication and metastasis of undifferentiated lymphocytes.
What is the difference between Hodgkin’s and Non-Hodgkin’s lymphoma
Main difference = the type of WBC that are affected
What % of breast lymph drains into the axillary LNs?
75%
Where else should you examine if you find a breast lump?
The axillary
What are metastases?
This is when cancer cells spread from a tissue into the through lymphatic system and grow and multiply in LNs
What do the lymph nodes feel like when there are metastases?
The LNs are enlarged, but they aren’t tender
What would happen if the lymphatic vessels were blocked
Edema- swelling of tissues due to excess tissue fluid
