The Lymphatic and Immune Systems (Q3,P7) Flashcards
Main structures of the lymphatic system
Lymphatic vessels
Main components of the immune system
- Lymphocytes
- Lymphoid tissue
- Lymphoid organs
Lymphatic vessels
- collect lymph from loose connective tissue
- Carry fluid to great veins in the neck
- Fluid flows only toward the heart
Orders of Lymphatic Vessels (Smallest to Largest)
- Lymph Capillaries
- Lymphatic Collecting Vessels
- Lymph Nodes
- Lymph Trunks
- Lymph Ducts
Lymph capillaries
- smallest lymphatic vessel
- first receive lymph
Lymphatic collecting vessels
collect from lymph capillaries
Lymph nodes
scattered along collecting vessels
Lymph trunks
collect lymph from collecting vessels
Lymph ducts
empty into veins of the neck
Functions of Lymphatic Vessels
- Collect excess tissue fluid and blood proteins
- Return tissue fluid and blood proteins to bloodstream
Lymph Capillaries
- Located near blood capillaries
- Receive tissue fluid from connective tissue
- Increased volume of tissue fluid
- Minivalve flaps open and allow fluid to enter
- Highly permeability allows:
Uptake of tissue fluid and the entrance of bacteria, viruses, and cancer cells
Lacteals
- specialized lymphatic capillaries
- Only in the small intestines;
- that receive a fatty lymph called “chyle
Lymphatic Collecting Vessels
- Accompany blood vessels
- Composed of the same three tunics as blood vessels
- Contain more valves:Helps direct the flow of blood
- Lymph is propelled by:Bulging of skeletal muscles, Pulsing of nearby arteries, and Tunica media of the lymph vessels
Lymph Nodes
- Cleanse the lymph of pathogens
- Human body contains approximately 500
- Lymph nodes are organized in clusters
- Located along lymphatic vessels
Lymph Trunks
- Lymphatic collecting vessels converge
- Five major lymph trunks: Lumbar trunks, Intestinal trunk, Bronchomediastinal trunks, Subclavian trunks, Jugular trunks
Lumbar trunks
- Type of Lymph Trunk
- receives lymph from lower limbs
Intestinal Trunk
- Type of Lymph Trunk
- receives chyle from digestive organs
Bronchomediastinal Trunks
- Type of Lymph Trunk
- collects lymph from thoracic viscera
Subclavian Trunks
- Type of Lymph Trunk
- receive lymph from upper limbs and thoracic wall
Jugular Trunks
- Type of Lymph Trunk
- drain lymph from the head and neck
Cisterna chyli
- Type of Lymph Duct
- located at the union of lumbar and intestinal trunks
Thoracic Duct
- Type of Lymph Duct
- ascends along vertebral bodies
- Empties into venous circulation
- Junction of left internal jugular and left subclavian veins
- Drains three quarters of the body (all but upper right)
Right Lymphatic Duct
- Type of Lymph Duct
- Empties into right internal jugular and subclavian veins
The Immune System
- Recognizes specific foreign molecules
- Destroys pathogens effectively
- Key cells in the immune system: lymphocytes
- Also includes lymphoid tissue and lymphoid organs
Lymphocytes
A type of immune cell that is made in the bone marrow and is found in the blood and in lymph tissue
- Macrophages are released, then lymphocytes
- 2 Types: B Lymphocytes and Cytotoxic T Lymphocytes
B lymphocytes
- become plasma cells
- Secrete antibodies (apart of blood plasma and lymphatic system)
Cytotoxic T lymphocytes
Destroy antigen-bearing cells
Lymphocyte Activation
- Lymphocytes originate in red bone marrow
- Some travel to the thymus gland and mature in the thymus gland (endocrine gland), and become T lymphocytes
- Some stay in bone marrow and mature in the bone marrow
B lymphocytes
How are T and B Cells activated
Able to recognize a unique antigen – B and T cells are activated by an antigenic encounter
What do T and B Cells Produce
- Effector Lymphocytes
- Memory Lymphocytes
Effector lymphocytes
short-lived, attack immediately. (first responders)
Memory lymphocytes
- wait until body encounters their antigen again. (attack later if needed)
- Basis of acquired immunity
Memory lymphocytes
- wait until body encounters their antigen again. (attack later if needed)
- Basis of acquired immunity
Lymphoid Tissue
- Most important tissue of the immune system
- Two general locations:
1. Mucous membranes of Digestive, urinary, respiratory, and reproductive tracts (Mucosa-associated lymphoid tissue (MALT))
- Lymphoid organs
Lymphoid Organs
- Designed to gather and destroy infectious microorganisms
- Thymus, Lymph Nodes, Spleen, Tonsils
Thymus
- Immature lymphocytes develop into T lymphocytes
- Secretes thymic hormones
Lymph Nodes
- Most antigenic challenges occur in lymph nodes (where b and t lymphocytes go)
Destroy Antigens – and activate B and T lymphocytes
Spleen
- Largest lymphoid organ
- Two main blood-cleansing functions: 1. Removal of blood-borne antigens 2. Removal and destruction of old/defective blood cells
- Site of hematopoiesis (blood cell formation) in the fetus (because babies don’t have enough bone marrow to make blood)
Tonsils
- Simplest lymphoid organs
- Four groups of tonsils: Palatine, lingual, pharyngeal, and tubal tonsils
- Arranged in a ring to gather and remove pathogens
- Underlying lamina propria consists of MALT
- Palatine tonsils are the largest and most often infected in childhood
Aggregated Lymphoid Nodules and the Appendix
- MALT – abundant in walls of intestines
- Fight invading bacteria
- Generate a wide variety of memory lymphocytes: Peyer’s Patches, Appendix
Peyer’s patches
- Aggregated lymphoid nodules
- Located in the distal part of the small intestine
- Generate a wide variety of memory lymphocytes
Appendix
- tubular offshoot of the cecum
- Generate a wide variety of memory lymphocytes
