Week 7 Lymph Part 5 Flashcards
Describe thymic or hassall’s corpuscles?
1) Isolated masses of closely packed ER cells
2) Contain keratinohyalin granules (secret A LOT of keratin)
3) Extensive keratinization near the center
4) These are distinguishing features of the thymus
Lymphocytes reaching the thymic cortex are prevented from contact with antigens by?
A physical barrier of blood-thymus barrier
What does the blood-thymus barrier do?
Protects developing lymphocytes from exposure to antigens; want to prevent blood from directly contacting developing lymphocytes
Endothelium lines?
Capillary walls
Epitheliorticular cells have what type of junction?
Tight junctions
Epithelioreticular cell layer does what?
Covers entire thymus and houses tight junctions
What is a spleen?
Bag of immune cells in abdomen with lots of blood flow
How big is the spleen? Where is it found?
Roughly the size of your fist. Found in the upper left quadrant of abdominal cavity
The spleen is rich in ______ supply?
Blood
The spleen has a large number of?
Lymphocytes, macrophages, and dendritic cells
The spleen is comprised of a meshwork of?
Reticular cells and reticular fibers (secreted by fibroblasts)
What is the function of the spleen?
Filters blood and reacts immunologically to blood borne pathogens
What are the two important things the spleen does when it filters blood?
1) Removal of old RBCs, recaputes iron
2) Converts hemoglobin to bilirubin and iron
Just like the thymus and lymph nodes, the spleen anatomy consists of?
Enclosed in a dense connective tissue capsule with trabeculae extending into the parenchyma
What type of pulp is found in the spleen?
Red and white; NOT based on color
Majority of the spleen is made of what type of pulp?
Red
White pulp?
Is mostly lymphocytes. Splenic nodules sitting in a sea of red pulp
White pulp is considered basophilic so it stains?
With hematoxylin (more purple); red pulp is more pink
White pulp is made up of what two things?
Periarterial lymphatic sheth (PALS) and Splenic nodules (lymph nodules)
Periarterial lymphatic sheath (PALS)
Diffuse lymphoid tissue associated with and surrounding the central artery
Splenic nodules (lymph nodes of spleen)
Dense lymphoid tissue, may contain germinal centers, usually located eccentrically to the central artery
Periarterial lymphatic sheath is located?
Around arteries
Red pulp contains large numbers of?
RBCs that are filtered and degraded, fresh tissue appears red
Red pulp is made of?
Splenic sinuses and splenic cords
What are splecnic cords composed of?
Loose meshwork of reticular cells and reticular fibers containing: RBCs, macrophages, lymphocytes, dendritic cells, plasma cells, and granulocytes
Finustrated?
Like a filter, endothelial cells are an example
Arteries branch along?
Trabeculae
Splenic nodules are mainly white or red pulp?
White
Circulation within the red pulp in the spleen allows macrophages to screen _____ in the blood
Antigens
The spleen can have what type of circulation?
Open or closed
Open circulation: blood enters the central artery of spleen and branches to the penicillar arterioles before?
Entering the sheathed capillaries which empty directly into reticular network of splenic cords
Spleen has an extra layer of tissue that allows it to?
Have open circulation (as well as closed)
