– Lymph is the fluid
– Lymphatics nodes
– Structures & organs
- Functions:
– Return tissue fluid to the bloodstream.
– Transport fats from the digestive tract to the bloodstream.
– Surveillance & defense.
Lymphatics:
- Originate as lymph capillaries
- Capillaries unite to form larger vessels
– Resemble veins in structure
– Connect to lymph nodes at various intervals
- Lymphatics ultimately deliver lymph into 2 main channels:
– Right lymphatic duct:
- Drains the right side of head & neck, right arm, right thorax
- Empties into the right subclavian vein
– Thoracic duct:
- Drains the rest of the body
- Empties into the left subclavian vein.
Main channels of lymphatics:
Lymphatic tissues:
- 3 types:
– Diffuse lymphatic tissue:
- No capsule present.
- Found in the connective tissue of almost all organs.
– Lymphatic nodules:
- No capsule presents.
- Oval-shaped masses.
- Found singly or in clusters.
– Lymphatic organs:
- Capsule present.
- Lymph nodes, spleen, thymus gland.
Lymph nodes:
- Oval structures located along lymphatics.
- Enclosed by a fibrous capsule.
- Cortex: outer portion
– Germinal centers produce lymphocytes
- Medulla: the inner portion
Medullary cords:
- Lymph enters nodes through afferent lymphatics, flows through sinuses, exits through efferent lymphatic.
Tonsils:
- Multiple groups of large lymphatic nodules.
- Location: mucous membrane of the oral and pharyngeal cavities
- Palatine tonsils:
– Posterior-lateral walls of the oropharynx
- Pharyngeal tonsil:
– The posterior wall of the nasopharynx
- Lingual tonsils:
– Base of tongue
Spleen:
- Largest lymphatic organ
- Located between the stomach & diaphragm
- A structure like a node:
– Capsule present
– But no afferent vessels or sinuses
- Histology:
– The red pulp contains all the components of circulating blood
– White pulp is like lymphatic nodules
- Functions:
– Filters blood
– Stores blood
Thymus gland:
- Location: behind the sternum in the mediastinum
- The capsule divides it into 2 lobes
- Development
– Infant: conspicuous
– Puberty: the maximum size
– Maturity: decreases in size
- Function
– Differentiation and maturation of t cells
The function of the lymphatic system:
- Defense against harmful organisms and chemicals
- 2 types of defense:
– Nonspecific
– Specific
- Specific defense: immunity:
– Humoral immunity involves b cells that become plasma cells that produce antibodies that bind with specific antigens.