L48-49: Lymphatic system I & II Flashcards
What does the lymphatic system collect? (3)
Interstitial fluids, absorbed fats, leaked proteins
What makes the largest % of lymph (out of all the ones that it collects)?
Interstitial fluid
Where does the lymph system return to?
Venous system
Where does the lymph system NOT exist in? (everywhere EXCEPT what places) (4)
Cartilage, cornea, CNS, epidermis
What does the lymph system not have?
Central pump
Where is the lymph system open-ended? Close-ended?
Open-ended: periphery Close-ended: proximally
Origin of lymph is from the ________
Interstitial fluid
What are 3 features of the lymph capillaries?
- Cells overlap 2. Very thin walls (same wall layers as other vessles but one endothelial cell think) 3. No tight junctions
What makes sure the lymph vessles “stay in place”?
Anchoring filament
What are 4 features of the lymphatic collecting vessels?
- Thicker walls 2. Presence of valves 3. Superficial: travel with larger veins 4. Deep: travel with larger arteries
What do the valves on the lymphatic collecting vessles do?
Prevent backflow*
What happens to antigens if they are present in the body?
Removed
What “type” of lymph is going in from the periphery? What “type” is going out of the hilum?
“dirty” lymph in from periphery “Clean” lymph out from hilum
Lymph from intersitial spaces travels to —> 3 things
Lymphatic capillaries
Lymphatic coll. vessles
At least one lymph node
Gathering of lymph nodes flow to what 3 things?
Lymphatic trunks Lymphatic ducts Venous system
Immunity is the response of cells and tissues to ______
Antigens
There are two types of immune reactions- what are they?
Innate response Adaptive response
What are 3 features of the innate response type of immune reactions?
- No requirement for previous exposure 2. Non-specific response 3. Immediate and rapid response
What are 3 features of the adaptive response type of immune reactions?
- Requires previous exposure 2. Recognition of diverse antigens 3. Delayed response
The innate immune response provides the “ _____”
First line of defense
The innate immune response consists of cells that __, _____, or present ____.
Recruit, phagocytose, or present antigens
What are the two antigen-presenting cells (APCs)? What do they do?
Macrophages and dendritic cells - Trigger adaptive immune resonse
What is this a structure of?
Lymph capillaries
The lymph moves in one direction in the lymphatic collecting vessels- which direction is this?
Left to right
Name these innate immune response cells from left to right- also which two are APCs?
Mast cells, granulocytes, macrophages, dendritic cells
The macrophages and dendritic cells are antigen-presenting cells
In adaptive immune response, what are the main cells involved?
Lymphocytes
What are the two types of lympocytes?
B and T lymphocytes
What is the type of immune response of B lymphocytes and what are they activated by?
Humoral (antibody) immune response
Activated by: “externalized” antigens
What type of immune response will T lymphocytes have? What are they activated by?
Cell-mediated immune response
Activated by “internalized” antigens APCs needed
What are the two effectors B lympthocytes?
- Plasma cells
- B memory cells
What are the 3 effectors of T lymphocytes?
- Cytotoxic
- Helper
- Regulatory (suppressor)
What is this image of and what does it do?
Parenchyma- working cells
Packed lymphocytes that produce antigens
What is this image of and what does it do?
Stroma
retciular tissue- except in thymus
Specialized collegen found in places that filter (lymph nodes)
What are high endothelial venule (HEVs)?
Specialized post-capillary venule
Where are HEVs found?
Most lymphoid organs except spleen
What is diapedesis?
WBCs move in and out of capillaries
What structure is shown and what type of tissue is seen? What do we see that they are trying to do?
Simple cuboidal epithelium- therefore High endothelial venule (HEV) in lymphoid organ
WBC is trying to sneak out
Where are the lymphocytes “educated”?
Primary lymphoid organs
Origin of lymphocytes?
Bone marrow
Where are B-cells made in?
Bone marrow
T-cells are made in _____ but educated in the ______
Made in bone marrow and moves to THYMUS to get educated
What are secondary lymphoid organs? (3)
B and T lymphocytes work together to FIGHT antigen
Site of action!
-Diffuse lymphoid tissues, lymph nodes, spleen
The bone marrow is?
Primary lymphoid organ
Functions of bone marrow? (2)
Form “generic” lymphocytes
“Educate” B lymphocytes
In bone marrow, ___ is reticular tissue. ____ is hematopoetic cells.
Stroma is reticular tissue
Parenchyma is hemotapoetic cells
What is the primary lymphoid organ?
Thymus
Diff btwn primary and secondary lymphoid organ?*
Primary: where cells are educated
SEcondary: where they fight
Thymus gets relatively smaller with ___
Age
What is this? and what is it and what is it NOT (tissue)?
Unique strma of thymus- this is NOT reticular tissue but it is EPITHELIAL TISSUE (b/c of its function..BTB/ gatekeepers)
Why are thymus epithelial tissue?*
Policing, need to be highly regulated!!*
Thymus creates a _____ for education
Mcroenvironment
What are the arrow and the dots and blue circles indicating in the thymus?
Arrow: CT Capsule- keeps maturing T cells in and antigens out
… : CT trabecula- divdies thymus into incomplete lobules
Blue dot: lobules are still connected at bases
What is each color representing in the thymus?
Purple: cortex
Yellow: medulla
Green: Corticomedullary junction
What is storedi n the coricomedullary junciton?*
HEVs! High endothelial venules
What is this structure? (simple labeling) in the thymus- also what is happening at this area regarding lymphocytes?*
HEVs location
Lymphocytes exit and enter blood here! this is after exiting the capillary bed!!!
What is indicated? What is it a visual clue of?
Thymic (Hassall’s) corpuscles made up of old epithelial reticular cells - indicates you are in thymus
What is going on here? Explain.
Pre T lymphocytes get to thymus via blood stream thru HEVs
Here is an artery in red arrow –> leads to capillary bed in yellow arrow –> pre T comes from bone arrow comes via arterial system and enters thymus
What are 2 things we need during the education of T lymphocytes?
- Clean evnironemtn
- Barries to isolate pre T cells from unwanted antigens
What is the blood-thymus barrier?
Btwn blood vessel lumen and pre T cells
What do each arrow represent?
REd: Blood vessel and endotehlium
Balack: Basal lamina (endo)
Blue (macrophages)
Black 2 : Basal lamina (epithelial reticular cells)
Yellow: Epithelial reticular cells
Pre T cells descend thru ___ as they are selectted for immunocempetance
Cortex
Only ___ % of pre T cells become immunocompetant T cells
2%
There are 2 classifications of llymphoid organs?
- No nodlules
- Nodules
Which lymphoid organ has no nodules?
Primary lymphoid organs
(bone marrow: makes all B and T and educates B, Thymus educates T cells)
Which lymphoid organ has nodules?
Secondary lymphoid organs
(lmyphoid tissue, lymph nodes, spleen = battle ground of work)
What are lymphoid nodules?
Temporary reaction of T and B lymphocytes to a specific antigen
What type of arrangment is this in lymphoid nodules?
Unchallenged: diffuse arrangement
What type of arrangment is this in lymphoid nodules? what do the red dotted lines indicate? What do the yellow dotted lines indicate?
Challenged: nodular arrangement
Red dotted lines: secondary nodules
Yellowe dotted lines: primary nodules
What are the secondary lymphoid odules?
Indicates B lymphocyte activation and proliferation
Inside the secondary lymphoid nodule, what is the green dots indicating? what about hte black dots? What about the yellow arrows?
Green: Germinal center (“generation” area, plasma c, B memory c)
Black: Corona (exiting effector/memory cells, “unchallenged” B lymphocytes)
Yellow arrows: Helper T lymphocytes surround nodules- help activate B lymphocytes
What are the 3 secondary lymphoid organs and what do each do?
- Diffuse lymphoid tissue and tonsils (survey epithelial barriers)
- _Lymph nodes (_filter (survey) lymph)
- Spleen (filter (survey) blood)
What is the diffuse lymphoid tissue also known as?
MALT
Mucosa-Associated Lymphoid Tissue
What is this structure? What are 5 functions?
Tonsil that is a diffuse lymphoid tissue
- Found under epith linings
- No cortex, medulla
- Not surrounded by CT capsule
- Randomyl packed lymphocytes
- Nodules form when challenged
What is the function of MALT?
Protect epithelial barrier
Is this primary or secondary? Education or battle? What do each arrow indicate? What is its significance?**
Secondary, battle
Red: “drity” lymph enters thru several AFFERENT lymph vessels
Green: “cleaner” lymph enters thru 1-2 EFFERENT lymph vessels
*Significance: only organ that filters lymph
Label the colors on this lymph node
Blue: Capsule
Yellow: Cortex
Green: Medulla
Red: Hilum
The hilum on the lymph node is a fissure where ____ enter and exit . It is also where ________ vessels exit
Blood vessels enter
Efferent lymph vessels
What is this structure a closeup of? What does it support and what does it do?
Reticular tissue
Sieve-like mesh supports parenchema
Mechanical filtering
What is this a picture of?
Superficial cortex
What is the deep cortex under? What do they not have?
Under the nodular cortex, there are no nodules in the deep cortex
What is located in the deep cortex?
HEVs
Most lymphocytes enter nodes here
What does the superficial cortex contain? What do those contain?
Nodules
Nodules containe B lymphocytes
What is the superficial cortex a site of?
B cell activation and proliferation
Most lymphocytes enter the node here and exit _____
Diapedesis
What does the parenchyma form in the lymph node?
Medullary cords
What does the medulla of the lymph node contain?
Contain B cells, macrophages, and plasma cells
The cords in the medulla are seaparted by ?
Medullary sinuses
Plasma cells secrete antibodes into ?
Sinuses
What are these areas in the lymph node indicated? (name)
Sinuses
Sinuses are lined with _____, carry _____
Lined with endothelium, carry lymph
What is this structure of lymph node sinus? What 2 things does it do?
Lumina spanned by reticular fibers
Slows down flow
Allows APCs to filter antigens
General flow of lymph?
Afferent lymph vessel –> lymph goes thru the sbucapsular, trabecular, medullar sinuses–> efferent lymph vessels
What is the spleen/
Largest single lymphoid organ in the body
Fetal vs adult funcions of spleen?
Fetal: hematopoiesis (creating new cells in body)
Adult: 1. Filter blood of antigens, 2. Remove aged RBCs
What is this structure? What do arrow indicate?
Spleen
White: CT Capsule
Yellow? Lymphoid nodules (secondary lymphoid organ)
The spleen does not have ________ or _____ and cannot _______
Does not have cortex or medulla (nodules randomly scattered)
Cannot filter lymph (no afferent lymph vessels)
In spleen? what is red pulp vs white pulp?
Red pulp: removed aged RBCs (acidophilic)
White pulp: adaptive immune response (strongly basophilic)
The splenic artery brings blood to?
Spleen
Splenic artery divdes as trabeular arteries into _______ and then branches to _______and then dump blood into red pulp, which is not directly conected to veins- this allows for “open circulation”
Central arterioles
Penicillar arterioles
What activates white pulp?
APCs
In spleen are there always nodules?
Yes- constantly fighting antigens
White pump conists of ____ around central artierole
T and B cells
What can be seen from this structure? Yellow arrow and white dotted line?
White pulp structure
Yellow arrow: T cells surround central arteriole
Periarterial lymphoid sheath (PALS)- T cells
