Lymphatic System Flashcards
The lymphatic system
Two semi-independent parts
A network of lymphatic vessels; lymphoid tissue and organs scattered throughout the body
Houses phagocytes and lymphocyte essential for body’s defense
The lymphatic system’s job
Return interstitial fluid and leaked plasma proteins back to the blood
What is Lymph?
Interstitial fluid once it has entered lymphatic vessels
What is the order in which lymph travels?
A one-way system, lymph flows towards the heart
lymphatic collecting vessels with valves -> lymph nodes -> lymph trunks -> lymph ducts.
How lymph vessels similar to capillaries?
Very permeable
loosely joined endothelial minivalves
withstand interstitial pressure and remain open
Minivalves function as one way gates
During inflammation lymph vessels open and absorb
Cell debris
pathogens
cancer cells
Lacteals
Specialized lymph capillaries present in intestinal mucosa
Lymph from digestive viscera has a milky color
Lacteals Function
Absorbs digested fat and deliver this chyle (juice) to the blood
Lymphangitis
When vessels are inflamed the vasa vasorum becomes congested with blood and red streaks; can be seen under the skin
Right lymphatic duct
Drains the right upper arm and the right side of the head and thorax
Thoracic duct
Arises from the cisterna chyli and intestinal trunk and drains the rest of the body
Cisterna chyli
Collect lymph from the two lumbar trunks that drain the lower limbs
Intestinal trunk
Collect lymph from digestive organs
Lymphatic trunks
Are formed by the union of the largest collecting vessels
major trunks include:
Paired lumbar, bronchomediastinal, subclavian and jugular trunks
a single intestinal trunk
How is lymph transported?
Same method As veins, milking action of skeletal muscles pressure changes in thorax pulsations of nearby arteries contractions of smooth muscle in the wall of the lymphatics
How much lymph is transported each day?
Approximately 3 L of lymph enters the bloodstream every 24 hours
Antigen
Anything the body perceives as foreign
bacteria and toxins; viruses
mismatches RBCs or cancer cells
T-Cell
T = thymus
manages the immune response
Attacks and destroys foreign cells
( helper and cytotoxic)
B cell
Produce plasma cells, which secrete antibodies
antibodies immobilize antigens until they can be destroyed
Macrophages
Phagocytize foreign substances and help activate T cells
Dendritic cells
Spiny-looking cells with functions similar to macrophages
Reticular cells
Fibroblast-like cells that produce a stroma or network, that supports other cell types in lymphoid organs
Lymph nodes
Principal lymphoid organ of the body
Embedded in connective tissue and clustered along lymphatic vessels
Aggregations of these nodes occur near the body surface inguinal, axillary, and cervical regions of the body
Lymph nodes two basic functions
Filtration
immune system activation
Filtration
Lymph is filtered, Then macrophages destroy any microorganisms and debris
Immune system activation
Lymphocytes in the nodes monitor for antigens and mount an attack against them
Nodes have what two distinct regions
A cortex and a medulla
Why are there more afferent than efferent vessels
It gives lymphocyte and Macrophages in the efferent vessels time to carry out protective functions
Bubonic plague
“black death” lymph nodes overwhelmed by bacteria, large amounts of bacteria are trapped in the nodes, become swollen, inflamed, painful, infected nodes are called buboes
Spleen
Largest lymphoid organ, located on the left side of the abdominal cavity beneath the diaphragm
It is served by the splenic artery and vein which enter and exit at the hilus
Spleen function
Site of lymphocyte proliferation Immune surveillance and response cleanses the blood stores breakdown products of RBCs for later reuse Stores blood platelets Site of fetal erythrocyte production
Spleen white pulp
Containing mostly lymphocyte suspended on reticular fibers and involved in immune functions
Spleen red pulp
Remaining splenic tissues concerned with disposing of worn-out RBCs and blood-borne pathogen
Thymus gland
A bilobed organ That secretes hormones that cause T lymphocytes to become immunocompetent
(Train T lymphocytes) responsible for lymphocyte maturation
Size varies with age
Does not directly fight antigen
Tonsils
Simplest lymphoid organ
Palatine, lingual, Pharyngeal, tubal
Tonsil crypt
Traps and destroys bacteria and particulate matter
Peyers patch
Isolated clusters of lymphoid tissue similar to tonsils
destroy bacteria preventing them from breaching the intestinal wall
Generate memory lymphocytes for long-term immunity
MALT mucosa associated Lymphatic tissue
Peyers Patch, tonsils and the appendix
Lymphoid nodules in the walls of the bronchi
protect the digestive and respiratory systems from foreign matter
Lymphoma
Any neoplasm (tumor) of the lymphoid tissue
Hodgkin’s disease
Malignancy of lymphoid tissue with swollen, nonpainful nodes, fatigue, intermittent fever. characterized by giant malignantly transformed B cells
Non-Hodgkin’s lymphoma
All cancers of lymphoid tissue except Hodgkin’s disease
Mononucleosis
Viral disease common in young people. Epstein-Barr virus attacks the B cells. T cells attack the virus-laden B cells. characterize by large numbers of enlarged T cells in the blood. these were mistaken for monocytes thus the erroneous name
“the kissing disease”
Elephantiasis
Lymphatics become clogged with parasitic roundworms, swelling from edema
