Week 2 - B - Lymphoid system - Primary and secondary lymphoid tissues, Lymph nodes and Spleen Flashcards
What are the central (aka primary) lympoid tissues?
These would be the bone marrow and thymus
What are the two main peripheral (secondary) lympoid tissues? name some other peripheral lympoid tissues as well
Lymph nodes and spleen - two main peripheral lymphoid tissues also Tonsils - waldeyers ring and Epithelio-lymphoid tissues
What is waldeyers ring?
What are the groups of tonsils in this ring?
Name two epithelio-lymphoid tissues?
Wlaldeyers ring - a ringed arrangement of lympoid tissues in the pharynx
- Have the adenoid (pharyngeal tonsils) Tubal, Palatine and Lingual tonsils
Epithelio-lymphoid tissues -lympoid tissue present in the alimentary tract (from mouth to anus) and the respiratory tract
Name the central lympoid tissues and the peripheral lymphoid tissues? Where do T and B cells mature?
Central lympoid tissues * Bone marrow (B-cells mature here) * Thymus (T-cells mature here) Peripheral lymphoid tissues * Lymph nodes and spleen as well as * Tonsils (Waldeyer’s ring - pharyngeal, tubal, palatine and lingual tonsils) * Epithelio-lympoid tissues - lympoid tissue present in the alimentary canal and respiratory tract
Lympoid tissue involved in: * Filtration of circulatory fluids * Location for cells of the immune system What are the lymphoid tissues that can be assessed on examination in the clinic? What is lymphadenopathy?
This would be the lymph nodes and the spleen Lymphadenopathy is abnormality of the lymph nodes be it in number, size or shape
What is the normal size and shape of lymph nodes? What is the function of the lymph nodes?
Normal size is up to 2.5 cm and they are small and oval/pea shaped They collect fluid from tissues (lymph) and identify it for any infection and then return the fluid into the normal circulation
Lymph (tissue fluid) filters through the lymph node How does the lymph enter the node? What are the spaces within the node through which the lymph flows? How does the lymph exit the node? Where do the arteries and veins supply the lymph node enter and exit the lymph node?
Afferent channels drain lymph through the capsule into the peripheral sinus The lymph then passes through the sinuses to drain out efferent vessels into the lymphatic system at the hilum of the node (concave end) The arteries and veins enter/exit the node at the hilum also
What makes up the left and right venous angle? What do the veins which make up the angles join to form?
Left venous angle - junction formed by the left subclavian & left internal jugular vein (IVC)
Right venous angle - junction formed by the right subclavian &right IVC
The two veins form the right &left brachiocephalic veins which drain into the superior vena cava
What large lymphatic vessel drains into the left venous angle? What large lymphatic vessel drains into the right venous angle? What is the beginning of the thoracic duct known as?
The thoracic duct drains lymph into the left venous angle - drains lymph from the left side & right side (below mid-abdomen) The right lymphatic duct drains lymph into the right venous angle - lymph from the right side (above mid-abdomen) Thoracic duct beginning = cisterna chyli
Lymph is filtered within the node parenchyma before return to the blood stream Why may lymphoedema occur post axillary surgery for breast cancer? What axillary nodes drain the arm? Where is there location? What axillary nodes drain the breast? Location?
Lymphoedema may occur as removal of the axillary nodes stops lymph from draining from the arm resulting in excessive fluid accumulation causing oedema Lateral axillary nodes (around axillary vein) drain the arm Anterior (inferolaterally to pec minor) drain breast
accumulation of lipid-rich lymph in the peritoneal cavity due to disruption of the lymphatic system secondary to traumatic injury or obstruction. What is this known as? Where does the fluid spill from? Can be due to trauma, malignancy, thoracic duct trauma, right sided heart failure
This is known as chylous ascites The fluid spills from the cisterna chyli
What are important functions of the lymph nodes?
They return lymph to the circulation - important function in fluid homeostastis and prevent excessive accumulation of fluid in tissues leading to oedema also They filter the lymph before it is returned therefore destroying any organsims
The lymphatic system is a very important defence system The antigen presenting cells of the innate immune system present to the lymph nodes and activate the cells of which immune sytem?
APCs present to the lymph nodes and activate the adaptive immune system - these would be the TandB cells and also the natural killer cells
What are the benefits of the adaptive immune response?
It is specific to the organism as memory is present It also enhances the immune reaction as there are preformed immune cells ready
What are the different types of cells present in the lymph nodes?
Lymphocytes * Bcells * Tcells - Thelper (CD4+) and Tcytotoxic cells (CD8+) * Natural killer cells * Mononuclear phagocytes and antigen presenting cells
What is the main T cell and B cell markers? What is the main stem cell marker? By marker - i mean what is the antigen to which an antibody would find in immunohistochemisty or immunophenotyping
Tcell marker - CD3 - protein (antigen) present on the cell B cell marker - CD20 - protein (antigen) present on the cell) Stem cell - CD34
When examining a patient with regional lymphadenopathy, where is it important to examine?
It is important to examine the territory that drains to the enlarged nodes - hence why you should be aware of lymphatic drainage of specific tissues
In cases of superficial infection may see red lines extending from an inflamed lesion What are these lines known as? What is the common bacterial cause of this condition?
Lympangitis - causes the lymph vessel to become inflamed The most common cause of lymphangitis in humans is Streptococcus pyogenes (Group A strep) Usually treat with antibitoics and painkillers
On blood films, does a lymphocytosis normally occur in response to bacterial or viral infections?
Lymphocytosis normally occurs in response to viral infections
What does the common hepatic artery give off before becoming the hepatic artery proper?
Gives off the gastroduodenal artery
The spleen contains two main types of tissue - white pulp and red pulp. Red pulp is made up of blood-filled cavities (venous sinuses) and splenic cords. What is the white pulp made up of?
White pulp is material which is part of the immune system (lymphatic tissue) mainly made up of white blood cells.
The trabecular arteries are the name of the branches of the splenic artery after it passes into the trabeculae of the spleen, where it branches What are the branches known as when they reach the white pulp of the spleen? What are the branches known as when they reach the red pulp of the spleen?
The trabecular arteries branching into the white pulp are known as central arteries The trabecular arteries branching into the red pulp are known as penicillary arteries
If people have a splenecotmy, what will commonly be seen on blood film? What are causes of hyposplenism?
Blood film post-splenecotmy - Howell-Jolly bodies, Pappenhiemer bodies, Target cells (Mexican hat cells)
Causes of hyposplenism - sickle cell anaemia and coeliacs disease
- Also seen in UC/crohns
