Lymphatic System Flashcards
Lymphatic is open circulation system. What does that mean?
It allows transfer of matter in or out of system
Lymph moves in one direction:
How to does lymph move?
Towards the neck
By muscle contractions
2 main functions of lymphatic system
Transport WBCs through body and provide environment for immune function to occur
- Lymphatic system derives from what germline?
2. What week does it begin to develop?
- Mesoderm
2. 5th week of embryonic development (2 weeks after cardiovascular system)
What part of lymph system is developing at each time and where do the capillary plexuses spread to?
- 5 weeks
- 6 weeks
- 9 weeks
- Jugular lymph sacs - thorax, UE, neck, head
- Retroperitoneal: abdominal viscera and diaphragm; posterior (iliac) lymph sac (abdominal wall, pelvic region, LE) and cisterna chyli
- R and L thoracic duct
During development, cisterna chyli drains into ____ which develop into?
2 thoracic lymph ducts which develop further and drain into internal jugular and subclavian veins
Cisterna chyli serves as a connecting sac for lymph going through ducts during beginning of development
How do those lymph sacs get converted into secondary lymphatic organs?
Exception?
They become invaded by mesenchymal cells
Exception- cisterna chyli
Name a secondary lymphatic organ and what it develops from?
Spleen = develops from mesenchymal cells between layers of dorsal mesentery of stomach
Why is thymus considered a primary lymphatic organ?
Is arises from two basic germ layers (endoderm and mesoderm)
- Right shoulder/ UE/ thorax/ head and neck region drain into what vein?
- Path of parts of body below abdomen?
- Right subclavian; rest of body drains into left
2. Cisternae chyli- thoracic duct - left subclavian vein
Name the draining trunk of the following part of body:
- Right thoracic cavity drains via?
- Right arm?
- Right side of head and neck
- Right bronchomediastinal trunk to right lymph duct
- Subclavian trunk to right lymph duct
- Jugular trunk to right lymph duct
~ look at slide 13 and name this lymph nodes
!!
3 primary lymphoid organs?
2 secondary?
Primary= thymus, bone marrow, and fetal liver
Secondary= lymph nodes and spleen
What is MALT?
Name the 5 cells of MALT
Role of MALT?
MALT is mucosa associated lymphatic tissue (diffuse lymphatic tissue)
T lymphocytes, B cells, plasma cells, macrophages, and microfold cells (GI tract)
Encounter antigens passing through the mucosal epithelium
Lymph nodules are more ___ than lymph tissue
Definition of lymph nodule
Organized
Lymph tissue localized in regions that are most frequently exposed to microorganisms
Name some ways that lymph nodules differ from lymph nodes
Most importantly: lymph nodules are not located along the lymphatic vessel - no filtration. Also, nodules are much smaller and do not have a well defined capsule boundary
How does a lymph nodule differ from diffuse lymphatic tissue?
Nodules have germinal centers (which are located in the middle of a follicle)
What happens at germinal center?
Site of B cell proliferation and differentiation into plasma cells in response to an antigen
Two groups of lymphatic nodules. One has 4 subsections.. what are they?
Primary lymphatic nodules (esophagus) and aggregated lymphatic nodules
Aggregated= peyers patches (small intestine), white pulp (spleen), tonsils and vermiform appendix
All tonsils in the body are considered ___; aka NALT which stands for?
Name the 4 tonsils
Waldeyers ring
Nasopharynx associated lymphoid tissue
Palatine (x2), tubal (x2), lingual, and pharyngeal tonsil-adenoid
Where are lymph nodes located?
Function of lymph nodes?
Function of the following:
- Dendritic cells
- Follicular dendritic cells
Along the pathway of lymphatic vessels
Filter lymph and maintain and produce several types of immune cells
- Present antigens to T and B lymphocytes
- (Non migratory) Capture antigen and retain for further presentation to B cells
What is contained in each part of the lymph nodes structure:
- Cortex-
- Follicle germinal centers-
- Paracortex-
- Medulla-
- Contains B and T cells
- Site of B cell activation
- Contains T and DC cells
- Contains densely packed B and T cells, macrophages, and plasma cells
What are high endothelial venules (HEVs)?
Present in what organs?
Where lymphocytes enter the lymph node from blood
Present in all secondary lymphoid organs except the spleen
Functions of the spleen? (3)
Filters blood from senescent blood cells (removes pathogens from blood)
Supplies immunocompetent B and T lymphocytes
Major site for antibody production
The spleen is the ___ lymphatic organ
Tissue of spleen is divided into two regions:
Largest
Red pulp and white pulp
Significance of splenic cords in the red pulp of the spleen?
Splenic cords contain half of the body’s monocytes as a reserve so that after tissue injury they can aid locally sourced monocytes in wound healing
- White pulp of spleen consists of what?
2. 3 cells contained in the white pulp?
- Lymphocytes surrounding splenic artery referred to as PALS (periarteriolar sheaths)
- T cells, B cells, and follicular dendritic cells
Splenic circulation:
Once it gets to central arteries what happens?
Arterial splenic blood supply from celiac trunk to spleen artery to trabecular arteries to central arteries.
Once it gets to central arteries, it branches to radial arteries for the white pulp and penicillar arteries for red pulp. Penicillar arteries branch end at splenic sinusoids (closed circulation) and empty into the red pulp (open circulation)
Two ways that the spleen filters the blood
Mechanical - as blood passes through spleen, endothelium will trap defective RBCs and prevent their reentry to the blood
Biological - macrophages remove non functional RBCs from circulation by phagocytosis
- Spleen derives from?
2. Primary follicles assembly ___ weeks of gestation
- Mesenchymal cells (mesoderm germline)
2. ~23
Thymus a ___ lymphoid organ
Thymus is site of?
Primary
T cell maturation (learning to differentiate between self and non-self antigens)
Difference between a primary lymphoid organ and secondary?
Primary develops first and is the site of maturation of lymphocytes
Secondary are sites of action of immunological activity of T or B cells
What are thymocytes?
Thymic epithelial cells are derived from what germ layer?
What is the precursor for a thymocyte?
Future T cells (located in the thymus; mature into T cells that identify non-self antigens)
Endoderm (all epithelial tissue is from endoderm) of third pharyngeal pouch
Thymic hematopoietic bone marrow (mesoderm)
During what time in your life is thymus most active?
Cortex of thymus is inhabited by what kind of cells?
Medulla of thymus is inhabited by what kind of cells?
Fetal and neonatal period (starts to disappear during puberty)
Thymocytes (immature form)
T cells (mature form)
Hassall’s corpuscles are always found where?
Shape?
What kind of cells are these?
Always found in the medulla of the thymus
Concentric
Epithelial reticular cells
Purpose of blood thymus barrier
What kind of capillary is the blood thymus barrier made of?
Protects developing T lymphocytes from pathogens;
Blood thymus barrier prevents antigens from reaching the T cells
Non fenestrated (so things cant permeate through); macrophages are also present just in case something does end up getting through
Thymus has no lymphatic drainage vessels (to help protect developing T cells from unwanted exposures) but it does have its own 3 lymph nodes. Name?
Internal mammary-parasternal
Tracheobronchial-hilar
Mediastinal-brachiocephalic
developmental conditions:
What is congenital asplenia?
Brief description of the 2 types:
- Syndromic asplenia
- Isolated congenital asplenia
When a child is born without a spleen
- Child dies very early on - spleen produces immunoglobulins so child is unable to fight infections without one
- Same disease but if child is not exposed to anything it can live until about 5-6 years
developmental condition:
What is thymus hypoplasia (DiGeorge syndrome)
Underdeveloped thymus and deficiency in mature T cells (diminished adaptive immunity)
What is lymphoid hyperplasia?
Broad category
This is a symptom, not a disease: Abnormal proliferation of one or more components of the lymphatic system (ex: enlarged lymph nodes) can be present in tonsilitis, strep throat, etc.
Follicular hyperplasia?
Paracortical hyperplasia?
Abnormal proliferation of secondary follicles (B cells)
Abnormal expansion of the interfollicular zones (T cells) can be cancerous (if they overgrow the capsule) or non cancerous (if they stay confined in the capsule)
Sinus hyperplasia
Preferential stimulation of the macrophages within a lymph node
Appendicitis
Type of lymphoid hyperplasia as well.
Obstruction of appendiceal lumen, filling of appendix with mucous, increase of internal pressure, inflammation, necrosis
Reasons why you may need a splenectomy?
Effect splenectomy has on body?
Trauma mostly, but also sickle cell anemia
When spleen is removed, it causes diminished levels of antibodies and susceptibility to infections (will need different vaccinations if you dont have a spleen)
