Lymphatic System Flashcards
What are the 4 types of lymphatic vessels, from smallest to largest?
Lymphatic capillaries
Lymphatic collecting vessels
Lymphatic trunks
Lymphatic ducts
What are the 9 lymphatic trunks, and which one is unpaired?
8 paired:
- jugular
- subclavian
- bronchomediastinal
- lumbar
1 unpaired:
- intestinal
What are the 2 types of lymph organs, and their components?
2 primary organs: red blood marrow and thymus
5 secondary organs: lymph nodes, tonsils, appendix, spleen, intestinal follicle (Peyer’s patches)
What are the 2 types of lymphoid tissue?
Diffuse
- loose arrangement of lymphoid cells and reticular fibres
- in most organs of the body (ie: lamina propria in GIT)
Lymphoid follicles
- solid spherical bodies made of tightly packed lymphoid cells and reticular fibres
- have germinal centres of proliferating B lymphocytes
- make up part of lymphoid organs
What are the 2 functions of the lymph system?
Immunity:
- lymphocytes are activated by immune responses
- some lymphoid organs have macrophages
Circulatory:
- transports interstitial fluid back into venous system
What are the 2 lymphatic ducts, and which areas of the body do they drain?
Right lymphatic - drains right upper quadrant of the body
Thoracic - drains the rest of the body (left upper quadrant, lower body)
What is the direction of lymph flow through the lymphatic and circulatory systems?
- interstitial fluid (blood)
- lymphatic capillaries (lymph)
- lymphatic collecting ducts
- lymphatic nodes
- lymphatic trunks
- lymphatic ducts
- subclavian veins into circulatory system
How is lymphatic fluid absorbed from interstitial fluid into lymphatic capillaries?
Lymphatic capillaries are made up of overlapping endothelial cells that are anchored to surrounding structures by collagen filaments
When interstitial pressure is higher than intercapillary pressure, gaps (mini-valves) open between endothelial cells and allow flow of lymph into lymphatic capillaries
Where do lymphatic collecting ducts run?
Cutaneous lymphatic collecting ducts run alongside superficial veins (before draining into deep collecting ducts)
Deep collecting ducts run alongside deep arteries
Where do the lymphatic ducts drain into the venous system?
At the junction of the internal jugular and subclavian veins (right lymphatic duct into right veins, thoracic duct into left veins)
What is the cisterna chylli?
An enlarged area of the thoracic duct, formed by the convergence of the lumbar and intestinal trunks (anterior to L1-2 vertebrae)
Describe the course of the thoracic duct
- 38-45cm long
- formed by the union of the lumbar and intestinal trunks at L1-2 spinal levels
- in 50% of people, a cisterna chylli exists (enlargement)
- ascends through aortic hiatus of diaphragm (T12)
- ascends through posterior mediastinum
- drains into junction of left internal jugular and subvlavian veins
Which trunks drain into the right lymphatic duct?
The right jugular, right subclavian, and right bronchomediastinal
Which trunks drain into the thoracic duct?
Left jugular, left subclavian, left bronchomediastinal, intestinal, right and left lumbar
Which 4 factors enable the flow of lymphatic fluid towards the venous system?
- rhythmic contractions of smooth m in lymphatic vessels
- pulsations of nearby arteries
- intermittent pressure on lymphatic vessels from skeletal m contractions and visceral movements
- respiratory pump and changes in thoracic cavity pressure
What are the 3 types of lymphoid cells, and their subtypes?
- lymphocytes
- T cells
- B cells
- natural killer cells - Auxillary cells
- macrophages
- dendritic cells - Supporting cells
- reticular cells
What are 3 types of lymphocytes, and their functions?
T cells:
- cell mediated adaptive immunity
- cytotoxic T cells produce granules that kill damaged or infected cells
- helper T cells produce cytokines that mediate inflammatory response
- regulatory T cells modulate immune system and prevent auto-immune disease
B cells:
- humoral adaptive immunity
- plasma cells: produce antibodies that stick to antigens on the surface of pathogens
- memory cells: remember pathogen for future immunity
Natural killer cells:
- innate non-specific immunity
- induce apoptosis of virus or cancer infected cells
What are the sub-types of T cell lymphocytes and their functions?
Cytotoxic T cells:
- produce cytotoxic granules that kill damaged or infected cells
Helper T cells:
- produce cytokines that mediate immune response
Regulatory T cells:
- modulate immune system and prevent auto-immune disease
What are the 2 types of B cell lymphocytes, and their function?
Plasma cells - produce antibodies that stick to the surface of specific antigens
Memory cells - remember antigens for future immune response
What are the 2 types of auxillary immune cells, and their functions?
Macrophages:
- distributed throughout lymphoid organs
- phagocytosis
- enhance inflammatory response
- present antigens to T cells
Dendritic cells:
- have wispy cellular extensions that capture antigens
- migrate to lymph nodes and present antigens to naive lymphocytes
Where are B and T cell lymphocytes produced?
Up to adolescence:
- thymus and red bone marrow
All:
- red bone marrow
What are the 2 functions of secondary lymph organs?
- lymph filtration (lymph nodes only)
- where mature lymphocytes first encounter antigens and become activated
What are the 3 functions of lymph nodes?
- house lymphocytes and macrophages
- site of immune system activation
- lymph filtration (lymph nodes only)
What is the direction of lymph flow through lymph nodes?
- enter via afferent lymph vessels
- through subscapular sinus
- through medullary sinuses
- exits via efferent lymph vessels in hilum
What are the 4 major anatomical components of a lymph node?
- dense fibrous outer capsule
- cortex: contains germinal centres of proliferating B cells, T cells in transit, and dendritic cells
- medulla: medullary cords are thin inward extensions from cortex containing numerous T and B cells
- lymph sinuses: subscapular sinus underlying outer fibrous capsule, and medullary sinus draining lymph towards efferent vessels
