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Lymphatic System
I). General Function
A). Fluid Balance
B). Fat Absorption
C). Defense
II). Lymphatic Vessels and the
Cardiac System
A). Associated with cardiovascular
system
B). There is no pump and lymphatic pressure
is very low.
C). One way system
D). Lymph is moved by:
III). Structure of the Lymphatic Vessels
A). Lymphatic Capillaries
1). blind-ended’ lymphatic capillaries found
between the interstitial tissues and the cardiovascular system
2).
Lymphatic capillaries
are
i. Not found in the bones, teeth, and central
nervous system.
3). Specialized
capillaries called “lacteals”
drain fat from the intestine in fatty lymph called “chyle”
B). Lymphatic Collecting Vessels
1). Three distinct tunics
 | tunica interna |
| tunica media |
| tunica externa |
2). Valves to prevent backflow.
C). Lymphatic Trunks
|
1). Intestinal Trunk
2). Lumbar Trunk
3). Bronchmediastinal Trunk
4). Subclavian Trunk
5). Jugular Trunks
|
 |
D). Lymphatic Ducts
|
Major ducts:
1). Thoracic duct:
2). Right lymphatic duct
|
 |
Cisterna chyli:
An enlarged
abdominal sac
IV). Lymphoid Cells
A). Macrophages (monocytes)
B). Lymphocytes
:
- Responsible for immunocompetence response. The
ability of the to recognize specific antigens.
Types of Lymphocytes
i). T lymphocytes (T cells)
Acts directly against virus infected cells and tumor
cells.
ii). B lymphocytes (B cells)
Produces antibodies (immunoglobulins)
C). Dendritic cells:
D). Reticular cells:
The lymphoid organs are encapsulated collections of diffuse
lymphatic tissue that is made up of reticular
connective tissue.
V). Lymphatic Follicles
A). Lymphatic follicles or nodules
B). Germinal centers (that stain
lighter)
C). Aggregates of Lymphatic Follicles
1). Peyer’s patches
2). Mucosa-Associated Lymphatic
Tissues
3). Appendix
VI). Lymphoid Organs
A). Lymph Nodes
1). Location:
| i. cervical nodes ii. axillary nodes
iii. inguinal nodes
iv. pelvic nodes
v. abdominal nodes
vi. thoracic nodes
vii supratonchlear nodes |
 |
2). Function:
i). Filter the lymph.
ii). Activate the immune system.
3). Structure of Lymph Nodes
i). Capsule
ii). Regions:
a). Cortex:
compartments with lymphatic follicles or
nodules with germinal centers
b) Medulla:
iii). Afferent lymphatic vessels
iv). Efferent lymphatic vessels
B). Spleen
1). Location
2). Functions
i). salvages the breakdown products of red blood cells
ii). Stores platelets
iii). lymphocyte proliferation
3). Structure
i). Blood vessels
- splenic artery
- splenic vein
ii). Regions
C). Thymus
1). Location
2). Function
3). Structure (histology)
i). thymic lobules
ii). Hassall’s corpuscles
D). Tonsils
1). Location
2). Named by location
i). Palatine tonsils
ii). Lingual tonsils
iii). Pharyngeal tonsils
iv). Tubal tonsils
3). Structures (histology)
Not completely encapsulated with blind end structures that
are called crypts that trap bacteria.
