H2 Lymphatic System Flashcards
List major functions of lymphatic system:
- Drain excess interstitial fluid
- Provide alternative transportation (hormones, nutrients, waste)
- Immune response (lymphocytes)
Lymphatic vessels begin as networks of ____ capillaries in microcapillary beds.
Lymphatic capillaries form network within _____ tissues
Blind-ended
Loose connective
Endothelial tubes lacking continuous basal lamina resulting in high permeability.
Lymphatic Capillaries
The lymphatic system has no central pump, but relies on ____ for movement. Lymphatic vessels posses ____ to prevent backflow.
Skeletal muscle compression
Valves
B Lymphocytes were first recognized in _____ of birds.
Membrane-bound B-cell receptor is known as _____.
Bursa of Fabricius
Immunoglobulin
Activated B cells are known as ____. They secrete non-membrane bound form of immunoglobulins known as ____.
Plasma Cells
Antibodies
B cells = ____ immunity
T cells = ____ immunity
NK cells = ____ immunity
Humoral
Cell-mediated
Innate
Accumulations of lymphatic tissue found within alimentary canal, respiratory passages, and genitourinary tract. Not surrounded by a connective tissue capsule. Mostly lymphocytes.
Diffuse Lymphatic Tissue
Discrete concentrations of lymphocytes contained in meshwork of reticular cells. Found in walls of alimentary canal, respiratory passages, genitourinary tract.
Lymphatic Nodules (follicles)
A Lymphatic nodule consisting primarily of small lymphocytes is known as _____.
A lymphatic nodule containing light staining germinal center and outer mantle zone is known as ____.
Primary Nodule
Secondary Nodule
A Morphological indication of response to antigen; develops when lymphocytes binds antigen, returns to primary nodule, and proliferates. Light staining; folllicular dendritic cells present.
Germinal Center
Darker outer ring of small lymphocytes that encircle the germinal center
Mantle Zone (corona)
Lymphatic nodules are disperse randomly by themselves, but aggregations of lymphatic nodules are found in specific locations:
- Tonsils
- Peyer’s Patches
- Vermiform Appendix
Located within the ileum of small intestine; consists of numerous aggregations of lymphatic nodules containing T and B lymphocytes.
Peyer’s Patches
Accumulations of lymphocytes associated with different mucosal areas
MALT (Mucosa-Associated Lymphatic Tissue)
Types of MALTs:
GALT (Gut-Associated Lymphatic Tissue)
BALT (Bronchus-Associated Lymphatic Tissue)
Small, bean shaped encapsulated lymphatic organs interposed along pathway of lymphatic vessels. Filter lymph.
Lymph Nodes
_____ lymphatic vessels convey lymph towards the node; enter at convex surface of capsule.
____ lymphatic vessels convey lymph away from the node; leave at hilum (concave)
Afferent
Efferent
____ = Dense connective tissue surrounding node
____ = Dense connective tissue extending from capsule
____ = Reticulare cells and reticular fibers that form fine supporting meshwork
Capsule
Trabeculae
Reticular Tissue
These cells synthesize/secrete reticular fibers (type III collagen) and ground substance. Elongated cytoplasmic process. Supporting role in expressing surface molecules and producing substances that attract T/B cells and dendritic cells.
Reticular Cells
Bone marrow-derived antigen presenting cells. Monitor environment for antigens (present to T cells). Localized to T cell-abundant areas.
Dendritic Cells
Act as both phagocytes and antigen presenting cells
Macrophages
These cells have multiple, thin, hairlike branching cytoplasmic processes that interdigitate between B cells in germinal centers. No APCs, but similar to Macrophages.
Follicular Dendritic Cells (FDCs)
_____ of lymph node is divided into cortex and medulla.
Parenchyma
Forms outer portion of lymph nodes (except at hilum).
Cortex
____ cortex continues germinal centers. Mainly B cells.
____ cortex contains majority of T cells.
Medulla contains mainly ____ cells.
Superficial Cortex (nodular cortex)
Deep Cortex (paracortex)
B
The medulla consists of cords of lymphatic tissue (____) that contain lymphocytes, macrophages, dendritic cells, plasma cells and are separated by lymphatic sinuses (____) which converge near hilum to drain into efferent lymphatic vessels.
Medullary cords
Medullary Sinuses
____ sinus is beneath capsule of lymph node (afferents drain here), it drains into ____ sinuses (extend into cortex along trabeculae) which then drain into ____ sinuses to finally drain into efferent lymph vessels.
Subcapsular (cortical)
Trabecular
Medullary
Lymphocytes conveyed in lymph enter nodes via afferent lymph vessels.
However, 90 percent of lymphocytes are conveyed in blood; enter lymph node thru _____ in ____ cortex.
High Endothelial Venules (HEVs)
Deep
Flow of lymphocytes from blood through lymph node:
HEV -> Deep Cortex -> Superficial Cortex -> Medulla -> Efferent Lymph Vessel
Bilobed organ located in superior mediastium, anterior to heart and great vessels.
Thymus
Thymus persists as large organ until puberty when _____ is reduce and lymphatic tissue is replaced with ____ tissue.
T cell differentiation and proliferation
Adipose
Thymus Capsule is made of thin _____
Trabeculae establish domains called ____ -> cortical caps over portions of convoluted and continuous medullary tissue
Connective tissue
Thymus Lobules
In the Thymus cortex, developing lymphocytes (____) occupy spaces within extensive meshwork of ____ cells.
Thymocytes
Epithelioreticular
____ cells form the most characteristic feature of the thymus medulla known as ____.
Type VI Epithelioreticular cells
Thymic (Hassall’s) Corpuscles
These cells provide framework for developing T cells. Serve as supporting storma.
Epithelioreticular cells
Isolated masses of closely-packed concentrically arranged Type VI epithelioreticular cells with flattened nuclei. Possess keratohyalin granules.
Thymic (Hassall’s) Corpuscles
Largest lymphatic organ; located in upper left quadrant of abdominal cavity. Filters blood. Enclosed in dense connective tissue capsule from which trabeculae extend into parenchyma.
Spleen
Primary role of red pulp of the spleen is ____.
It consists of blood-filled sinuses (splenic sinuses) separated by loose meshwork of reticular cells and fibers (splenic cords).
Blood Filtration
White pulp consists of ____ tissue, mostly ____.
Branches of splenic artery course through and enter white pulp.
_____ -> branch of splenic artery initially in central position within white pulp
____ -> aggregates of lymphocytes around artery.
Lymphatic
Lymphocytes
Central Artery
PALS (Periarterial Lymphatic Sheath)
Lymphatic nodules displace central artery to ____ position
Eccentric
This Sinuses wall has lattice-like structure. Prominent intercellular spaces between endothelial cells (allow blood passage; macrophage processes extend into and monitor)
Splenic Sinuses
