Lymphatic System Flashcards
What is the lymphatic system
Thin-walled vessels responsible for the transporting of excess tissue fluid throughout the body which drain into the thoracic duct or right lymphatic duct back into the blood stream
90% returns to circulation via veins
Main functions of the lymphatic system
Return proteins, lipids & water from the interstitial fluid to the blood
Immunity against harmful organisms - lymph organs contribute to maturation of immune cells
What part of the body does the thoracic duct drain
Almost entire body, pelvic & abdominal cavities and left hand side of the thorax, head & neck & left arm into the subclavian veins at the root of the neck
What part of the body does the lymphatic duct drain
Right side of the body, arm upwards into the right subclavian vein at root of the neck
What different parts does the lymph system consist of
🍑lymph FLUID 🍑lymph VESSELS 🍑lymph NODES 🍑lymph ORGANS (spleen & thymus) 🍑lymphoid TISSUE (eg tonsils, MALT & GALT) 🍑 bone marrow (lymphocyte production)
What is ‘lymph’ & what it contains
A watery fluid similar to blood plasma but with less plasma protein
Same composition of interstitial fluid just called lymph when found in lymph system, contributes to the nourishment of tissues
Contains:
Water
Leukocytes
Leaked out of capillaries, plasma proteins
Fats absorbed from small intestine
Bacteria & cell debris from damaged tissue
What are blind-end tubes
A one way structure, like an open drain
What is the lacteal
A blind ended lymph vessel in the small intestine
Where are lymph capillaries located
In space between cells, veins & arteries
What is the structure of lymph vessels
3 layers like veins
Numerous cup shaped valves
Vessels unite to form lymph trunks
What is the function of lymph nodes
Filter lymph & remove foreign matter such as microbes, cell debris & tumour cells
Formed of reticular cells & lymphatic tussue
They are filled with immune cells, mainly phagocytes & lymphocytes
Lymph passes through many nodes before returning to the blood, around 600 located in groups along lymph vessels throughout the body
Generally follow same route as veins
What vessels do lymph enter via
Afferent, prolific in body
As many as 4-5 afferent lymph vessels can enter a node
What vessels do filtered lymph leave via
Efferent, few in body
Only one efferent vessel carries lymph away from the node
Where are the 5 main locations of lymph nodes
- Cervical (neck)
- Axillary (armpit area)
- Inguinal (groin)
- Vertebral column
- Mesenteric (intestinal) - MALT & GALT dont have afferent lymphatics so not exposed to lymph diseases
What can cause lymphadenopathy
During early stages of infection, incomplete phagocytosis of microbes can cause swelling of the lymph nodes, as material filters by passing from node to node
What is the white and red pulp of splenic pulp
White pulp contains lymphocytes & macrophages
Red pulp contains all the components of circulating blood
What are the main functions of the spleen as a giant lymph node
- During foetal development - haematopoesis
- Blood reservoir in adults
- Phagocytosis of worn out/defective erythrocytes & breakdown products eg bilirubin & iron are transported to liver via portal vein
- Immunity: T & B lymphocyte maturation
Spleen has no afferent lypmhatics entering so is not exposed to diseases spread by lymph
How does the thymus work as another big lymph node
Imprtant role in immune development & antibody production in early life
It contains epithelial cells, T lymphocytes & macrophages
Epithelial cells produce ‘thymosin’ which promotes the maturation of T lymphocytes (produced in red bone marrow)
Atrophy begins in puberty, declining throughout life & replaced with fat
What do the lymphatic system rely on for assistance of drainage
🍒mild, rhythmical contractions of the lymph vessels (lymphatic pump) & one-way system
🍒skeletal muscle pump - movement/exercise, especially calves
🍒respiratory pump - during inhalation air pressure drops in the thoracic region, lymph moves from high to low pressure
How does the lymphatic system absorb substances
Lacteals (found in the villi of small intestines) absorb fat-soluble substances/nutrients such as dietary fats & fat-soluble vitamins (A, D, E & K)
What is the structure of lymph capillaries
Originate as blind-ended tubes in interstitial spaces, same structure as blood capillaries ie single layer of endothelial cells but far more permeable
They join up to form larger lymph vessels
What are the three types of tonsil
Palatine - ones visible on wall at back of the mouth
Pharyngeal (adenoids) - lie at back of nasal cavity
Lingual - collections of lymphoid tissue at back & sides of tongue
