Lecture 10 - Lymphatic System Flashcards
Lymphatic System
Network of tissues , vessels & organs that work together to move lymph back into circulatory system
Transport excess fluid back to blood circulation
Lymphatic System - Characteristics
- Thin walled vessels that transport fluid throughout the body resembling veins ( but thinner walls and more valves)
- From lymphatic capillaries which unite to form larger lymphatic vessels
- Lympathic vessels drain into the THORACIC DUCT or the RIGHT LYMPATHIC DUCT ( schema )
Lymphatic System - Functions
- Tissue drainage Return proteins , lipids & water from interstitial fluid to blood
- Immunity against harmful organism
- Absorption
Lymphatic System Constitution
- Lymph fluid
- Lymph vessels : fluid moves through
- Lymph nodes : filtering station
- Lymph organs : spleen & thymus
- Lymphoid tissue ( tonsils ) : MALT / GALT
- Bone Marrow : WBC production
Lymph Fluid
Watery fluid similar to blood plasma but less plasma proteins & same composition as interstitial fluid
Contains :
- Water
-Leukocytes
-Plasma proteins ( sepped out of capillaries )
-Fats( absorbed from small intestines )
- Bacteria & cell debris from damage tissue
Lymphatic vessels - Capillaries
- Located in spaces between cells
- One -way structure - blind-end tubes
Lymphatic vessels - Larger lymph vessels
- 3 layers like veins
- Numerous valves
- Vessels unite to form lymph trunk
Lymphatic vs Cardiovascular system
Cardiovascular : Circular & closed system
Lymphatic : Linear
Lymphatic fluid transports it back to vascular system
Lymphatic Nodes - Overview
- Filter Lymph & remove foreign matter such as microbes , cell debris & tumor cells
- Lymph passes through many lymph nodes before returning to blood ( 600 beans structures )
- Same route as vein
- Filled with immune cells (lymphocytes & phagocytes)
Lymphatic Nodes - How does it works
1.Lymph enters via afferent vessels
2. Foreign substances trapped by reticular fibres
3.Macrophages destroy foreign substances by phagocytosis
4. If needed Lymphocytes will destroy remainder
5. Filtered Lymph leaves via efferent vessels
Many afferent vessels few efferent => Allows immune cells time to remove foreign matter
Lymph Nodes - Location
5 locations contain many :
- Cervical
- Axillary
- Inguinal
- vertebral column
- Mesenteric ( intestinal )
Lymph Nodes - Growth
Develops during childhood & atrophy begins in adolescence
Lymph Nodes - Infection
Early stage of infection -> Incomplete phagocytosis of microbes => Lymphadenopathy ( swelling )
Spleen - Overview
- Largest Lymph organ ( like heart )
- Between stomach & diaphragm on the left
- Similar in shape & structure to lymph node
- Contains White & Red pulp :
- White pulp :lymphocyte + Macrophages
- red pulp : components of circulating blood
Spleen - Functions
- Hematopoiesis in foetus
- Blood reservoir (adult ) -> RBC graveyard ( where they are broken down )
- Phagocytosis of worn out / defectives erythrocytes
- Immunity : T&B-lymphocytes.
Spleen Rupture
- Can occur following trauma can cause haemorrhage & shock
- Need to remove to prevent death
- Liver & red bone marrow take over some function but immune function compromised
Thymus - Overview
- Bi lobed organ that plays important role in immune development and antibody production in early life
- Contains epithelial cells , T-lymphocytes & macrophages
- Atrophy begins in puberty declining through life - tissue replaced by fat
Thymus - Function
- Maturation of T-Lymphocytes : Epithelial cells produce thymosin
Cells are taught ot recognize difference between self & non-self (1/5% pass test -> rest apoptosis( cell suicide) - T-cells that leave the thymus via blood to migrate to lymph nodes & other lymphatic tissue ( Galt / Malt ) where they colonize
MALT : Mucosa Associated Lymphoid Tissue
Small aggregations of lymphoid tissue found in areas of the body exposed to the external environment - FIRST LINE OF IMMUNE DEFENCE
- Malt can be found in :
- Adenoids
- tonsils
- Small intestine & Large intestine : - Malt in GIT -> GALT
Note : Allow IS to sample digestive system & find out info about what’s coming from our environment => Expose children to bacteria
Lymphatic System Functions - Tissue Drainage
1.Blood arrives at the tissue at high pressure -> some fluid and nutrients forced out of capillaries to interstitial fluid
2.Remaining cells & Plasma proteins in blood create osmotic pressure which maintains Blood Volume
3.90% returns to circulation via veins
Symptom lymphatic system not working : Oedema
Lymphatic System - Circulation
Assisted by :
- Lymphatic pump : Mild , rythmical contractions of the lymphatic vessels
- Skeletal muscle pump : Movement / exercise drains fluid ( especially calf )
- Respiratory pump : During inhalation air pressure drops in thoracic region - Lymph moves from high to low pressure
Lymphatic System Functions - Absorption
- Lacteals absorb fat soluble substances from small intestines to the body :
- dietary fats
- Fat soluble vitamins ( A,D,E & K)
Lymphatic System Functions - Immunity
Production & Maturation of lymphocytes - Lymph nodes - Spleen - Thymus & bone Marrow Lymphocyte made in bone marrow , mature in spleen & thymus , hang out in spleen & lymph node to sample lymph seeing if they need to launch immune response
Pathologies - Lymphangitis
- Inflammation of Lymph vessels => Bacterial infection ( usually streptococcus )
- Swelling , painful red lines below skin along lymph vessel course => Infection may spread into blood causing septicaemia => medical emergency
