Immune Organs Flashcards
What is the difference between Primary/Central Lymphoid Tissue and Secondary/Peripheral Lymphoid Tissue?
Primary/Central Lymphoid Tissue — where stem cells differentiate and mature into lymphocytes
Secondary/Peripheral — where the actual immune response occurs
T/F: T-cells derive from bone marrow
TRUE; all cells in immune system derive from bone marrow (RBC, WBC, and platelets)
Thymus: is _____ (smaller/larger) in children.
LARGER
increases in size/most active during childhood, but stops growing in adolescence and gradually atrophies
T/F: when the thymus atrophies, it loses its function
FALSE; it maintains its function
What is the thymus’s primary function?
Where T-cells “mature” (gain self-tolerance)
What is self-tolerance?
Cell’s ability to differentiate between functional cell and pathogens (prevents autoimmunity)
Describe the path of a T-cell from immature to mature…
From red marrow, immature t-cell enters thymus cortex, proliferates/matures, enters thymus medulla, then enters lymph circulation
Where can you find Hassall’s Corpuscles?
What is their function?
Thymus (specifically medulla); help regulate t-cell development
Where are lymphocytes more tightly packed in the thymus? (Outer cortex or inner medulla)
OUTER CORTEX;
This is where t-lymphocytes proliferate
Medulla moves them out into the lymph circulation
Where is the thymus’s located?
Inferior neck, within mediastinum, overlies heart
Describe how T-cells differentiate into CD8 and CD4 T-cells.
Initially, T-cells are DN (double negative), which means they are immature and not differentiated. Then, they become DP (double positive), positive for both CD8 and CD 4 markers; as they mature, they differentiate into SP (single positive) — either CD4+ or CD8+
What occurs to B-cells within the lymph node that are activated?
Proliferate and remain in the node, differentiate into plasma cells, and create antibodies
What occurs to B-cells within the lymph node that are inactivated?
Return to general circulation
Where is the spleen located?
- Quadrant
- Behind which ribs
- Which Abdomen Region
Upper Left Quadrant
Behind Ribs 9-11
Left Hypochondriac Region
Spleen Blood Supply
Large splenic a. & short gastric aa.
Splenic veins drain into…
The portal vein
Spleen is innervated by…
The celiac plexus nerves
T/F: the thymus is the largest lymphoid organ in the body
FALSE;
The spleen is the largest lymphoid organ
Spleen is mostly made up of ______ (white/red) pulp
RED — 85%
White — 5-20%
In what way is the spleen said to have a CLOSED circulation?
Parts of the spleen has arterioles that branch into capillaries and are continuous with the venous sinus of red pulp
In what way is the spleen said to have a OPEN circulation?
Parts of the spleen has capillaries that drain freely into the interstitia and flow through the red pulp, eventually entering venous sinuses via fenetrations
What are the functions of the Spleen? (8)
- Filtering
- Immunity
- Culling
- Iron Reutilization
- Reservoir
- Hematopoiesis
- Pitting
- Pooling
Where are Peyer’s Patches located?
Small intestine
What is Waldeyer’s Ring?
Multiple structures of MALT (diffuse lymph tissue) — tonsils and adenoids
What is EALT?
What does it include?
Eye-Associated Lymphoid Tissue:
CALT (Conj) and LDALT (Lacrimal Drainage)
Regarding Immune Privilege, what is sequestration?
Isolate the pathogen to avoid spread without eliciting an immune response
What are some mechanisms by which the eye has immune privilege? (4)
- Lack of lymphatic vessels
- BAB/BRB
- Immune suppressing molecules (MIF, α-MSH, VIP, SOM, cytokine TGF-ß2 ) and surface expression of FasL (induces apoptosis of T-cells)
- Anterior Chamber-Associated Immune Deviation
