Exam 3: Lymphatic System Flashcards
Capillary Level
-fluids pushed out of vessels and into tissues
Interstitial Fluid
- fluid within tissues
- venules pick up most, but not all of this fluid
Lymph
-interstitial fluid picked up by lymphatic system
Lymphatic System (consists of)
-consists of lymph vessels and lymphatic tissues and organs
Functions of Lymphatic System
- absorbs dietary lipids and fat-soluble vitamins (A, D, E, K)
- returns interstitial fluid back into blood stream (done by lymph vessels)
- initiates an immune response when mecessary (done by lymphatic tissues/organs)
Lymph Vessels (system)
-low pressure system
Lymphatic Capillaries
- smallest lymph vessel
- wall composed of endothelium (simple squamous)
- walls have 1-way flaps which allow lymph to enter but not escape
Lacteals
- lymphatic capillaries in small intestine
- function absorb dietary fats
Lymphatic Vessels (characteristics)
- like veins, have 3 tunics
- have valves which prevent backflow
- take lymph to and from lymph nodes
Lymphatic Trunks
- formed from merging lymphatic vessels
- drain into lymphatic ducts
Lymphatic ducts
- Right Lymphatic Duct
- Thoracic Duct
Right Lymphatic Duct
- receives lymph from right side of head, neck and thorax, right upper limb
- drains into right subclavian vein
Thoracic Duct
- receives lymph from left side of head, neck, thorax, left upper limb, entire abdomen, left and right lower limbs
- drains into left subclavian vein
Lymphedema
- buildup of interstitial fluid due to lymph vessel damage
- causes: surgery that removes lymph vessels (eg for breast cancer), cancer spread, infection from parasitic worms (filarial worms)
Pathway of Lymph
-lymphatic capillaries–>lymphatic vessels–>lymphatic trunks–>lymphatic ducts–>venous circulation
Lymphatic Cells
-start and produce immune response when exposed to antigens
Antigens
-anything perceived as foreign in the body
Lymphocytes
- T-lymphocytes (T-cells)
- B-lymphocytes (B-cells)
T-Lymphocytes
- mature in thymus
- functions: some of these cells manage/direct an immune response, while others directly attack cells
- general/soldiers
B-Lymphocytes
- mature in red bone marrow
- function: many secrete antibodies which attach to antigens and immobilize them until another cell destroys antigen
- handcuffs
Macrophages
- monocytes that migrated from bloodstream into other tissues
- function: phagocytize foreign substances
Lymphatic Structures
- not organs
- consists of connective tissue containing lots of lymphatic cells
- not surrounded by CT capsule
Lymphatic Nodules
- main type of lymphatic structures
- clumps of lymphatic cells within other organs
- ex: tonsils in pharynx, MALT (Mucosa Associated Lymphatic Tissue) in walls of GI and respiratory tract
- both respond to antigens
Lymphatic Organs
-lymphatic structures surrounded by connective tissue capsule
Thymus
- behind sternum
- function: T-lymphocytes mature and differentiate here. this happens prior to adult hood
- adult thymus is non functional
Lymph Nodes
- tiny oval organs
- hundreds
- found in clusters
- connect with lymphatic vessels
- functions: filter lymph, activate immune response if antigens found in lymph
- infection: lymph nodes become swollen and tender
Cancer Spread and Lymph Nodes
- cancer can spread through lymph vessels and lymph nodes
- cancerous lymph nodes tend to be hard and nontender
Spleen
- largest lymphatic organ in body
- located in upper left abdomen, behind and lateral to stomach
- red pulp and white pulp
- functions: does NOT filter lymph, it filters blood
Red Pulp
- splenic sinusoids (large capillaries) and splenic cords
- contains erythrocytes, platelets and macrophages
- function: removes old erythrocytes and platelets
- graveyard for erythrocytes
White Pulp
- lymphocytes
- will start an immune response if antigens found in blood
