Chapter 20: Lympthatic System Flashcards
The lymphatic system consists of 3 parts:
Network of lymphatic parts
Lymph- fluid in vessels
Lymph nodes- cleanse lymph
Lymphatic system:
Returns excess fluid that leaked from blood vessels back to blood.
Lymphoid organs and tissues do what?
▪️provide structural basis of mine system
▪️house phagocytosis and lymphocytes
▪️structures include spleen, thymus, tonsils, lymph nodes, other lymphoid tissue
Lymphatic vessels:
▪️return interstitial fluid and leaked plasma proteins back into blood
▪️~ 3 L /day
▪️once interstitial fluid enters lymphatics, called lymph
Lymphatic vessels: distribution and structure:
▪️one- way system; flows toward heart ▪️lymphatic vessels include: -Lymphatic capillaries -Collecting lymphatic vessels -Lymphatic trunks and ducts
Lymphatic capillaries:
Similar to blood capillaries EXCEPT:
▪️very permeable (take up proteins, cell debris, pathogens, and cancer cells)
- endothelial cells overlap loosely to form one-way mini valves
▪️pathogens travel throughout body via lymphatics
Lymphatic capillaries are absent from what?
Bones, teeth, bone marrow, and CNS
Lacteals:
Specialized lymph capillaries present in intestinal mucosa
-absorb digested fat and deliver fatty lymph (chyle) to the blood
Lymphatic collecting vessels:
Similar to veins EXCEPT:
Have thinner walls, with more internal valves
-anastomose more frequently
▪️collecting vessels in skin travel with superficial veins
▪️deep vessels travel with arteries
▪️nitrients supplied from branching vasa vasorum
Lymphatic trunks:
◾️paired lumbar ◾️paired bronchomediastinal ◾️paired subclavian ◾️paired jugular trunks ◾️single intestinal trunk
Lymphatic ducts:
Lymph delivers into one of two large ducts:
Right lymphatic duct drains right upper arm and right side of thorax
Thoracic duct arises as cisterna chyli ; drains rest of body
Each empires lymph into venous circulation at junction of internal jugular and subclavian veins on its own side of body
Lymph transport:
Lymph propelled by :
▪️milking action of skeletal muscle
▪️pressure changes in thorax during breathing
▪️valves to prevent backflow
▪️pulsation of nearby arteries
▪️contractions of smooth muscle in walls of lymphatics
Lymphocytes:
Main warriors of immune system
Where do lymphocytes arise from?
Red bone marrow
Lymphocytes mature into with two varieties ?
T cells( T lymphocytes ) B cells (B lymphocytes )
Specific immunity involves which cells?
T cells
B cells
Neutrophils
T and B cells protect against what?
Antigens !
Bacteria, bacterial toxins, viruses , cancer cells
T cells:
▪️manage immune response
▪️attack and destroy infected cells
B cells:
- produce plasma cells which secrete antibodies
- antibodies mark antigens for destruction by phagocytosis or other means
Do T or B cells product antibodies?
B cells produce antibodies
Macrophages:
Phagocytize foreign substances, help activate T cells
Dendritic cells:
Capture antigens and deliver them to lymph nodes; activate T cells (antigen presenting cells)
Reticular cells:
Produce reticular fiber
Stroma:
Supports other cells in lymphoid organs
Lymphoid tissue:
Houses, provides proliferation site for, lymphocytes
Lymphoid is largely what kind of tissue?
Reticular connective tissue (loose connective tissue )
Two main types of lymphoid tissue:
Diffuse lymphoid tissue
Lymphoid follicles
Where are Peyers Patches located ?
Small intestine
Lymph nodes:
▪️principal lymphoid organs of body
▪️embedded on connective tissue in clusters along lymphatic vessels
▪️near body surface in inguinal, axillary, cervical regions of body
What are the 2 functions of lymph nodes?
- Filter lymph - macrophages destroy microorganisms and debris
- Immune system activation - lymphocytes activated and mount attack against antigens
Circulation in the lymph node:
Enters convex side via agreement lymphatic vessels; travel through large sub capsular sinus and smaller sinuses to medullary sinuses ; exists concave side at Hilum via efferent vessels
Spleen:
▪️Largest lymphoid organ
▪️served by splenic artery and vein which entree and exit at the Hilum
▪️functions:
-sit of lump cute proliferation andime surveillance and response
-cleases boos of aged cells and platelets , macrophages, remove debris
-
Which organ is responsible for breakdown products of RBC?
Spleen
White pulp:
Most lymphocytes on reticular fibers involved with immune functions
Red pulp:
In venous sinuses.
Rich in RBC and macrophages for disposal of worn out RBC and blood borne pathogens
-composed of splenic cords and sinusoids
Thymus:
Important functions early on life.
▪️increases in size and most active during childhood
▪️stops growing during adolescence then gradually atrophies
▪️still produces incompetent ces but slowly
Most thymus cells are lymphocytes: true or false?
True
- cortex constrains rapidly dividing lymphocytes and thymus corpuscles involved in regulatory T cell development
The thymus differs from other lymphoid organs in important ways:
▪️has no follicles because it lacks B cells
▪️functions strictly in T lymphocyte maturation. Keeps isolated with blood thymus barrier
Stroma:
Provide environment in which T lymphocytes become immunocompetent
4 types of lymphoid tonsils?
Palatine
Linguinal
Pharyngeal
Tubal
To solar crypts:
Trap and destroy bacteria and particulate matter
-allow immune cells to bu memory for pathogens
