Sistema Linfatico e Funzioni

General Structure and Function

• The lymphatic system is a network of vessels, tissues, and organs that transport lymph, a fluid containing immune cells, throughout the body.
• It plays a crucial role in maintaining fluid balance, absorbing fats, and mounting immune responses.
• The lymphatic system is a one-way system, carrying lymph towards the heart.
• It lacks a central pump, relying on skeletal muscle contractions and pressure changes for lymph movement.

Lymphatic Vessels

• Lymphatic capillaries are small, thin-walled vessels that begin as blind-ended sacs in tissues.
• They are more permeable than blood capillaries, allowing larger molecules and cellular debris to enter.
• Lymph vessels progressively get larger and merge to form larger lymphatic vessels.
• These vessels contain valves to prevent backflow, ensuring unidirectional lymph flow.
• Lymph eventually flows into collecting ducts.

Lymph Nodes

• Lymph nodes are small, bean-shaped structures located along lymphatic vessels throughout the body.
• They act as filters for lymph, trapping pathogens and cellular debris.
• Lymph nodes contain lymphocytes (a type of white blood cell) that mount an immune response.
• They are crucial in the body's immune defense mechanisms.

Lymphatic Organs

• Spleen: Filters blood, removing aged or damaged red blood cells, playing a role in immune responses against blood-borne pathogens.
• Thymus: Crucial for the maturation of T lymphocytes (a type of white blood cell), essential for adaptive immunity.
• Tonsils and adenoids: Located in the throat, helping defend against inhaled pathogens.
• Peyer's patches: Located in the small intestine, helping defend against ingested pathogens.

Lymph Composition

• Lymph is a clear, slightly yellowish fluid similar to plasma, with a lower protein concentration.
• It contains water, dissolved salts, proteins, fats, and various cellular components, including lymphocytes (white blood cells), macrophages, and other immune cells.
• Lymphocytes play a major role in the immune response, identifying "self" from "non-self."

Lymph Circulation

• Lymph circulates throughout the lymphatic system via the contraction of skeletal muscles and the pressure changes in the surrounding tissues during breathing.
• This flow is unidirectional due to the valves in the lymphatic vessels.
• Lymph eventually drains into the circulatory system at the junction of the subclavian veins with the internal jugular veins.

Immune Function

• The lymphatic system is essential for the immune response, playing a critical role in the recognition and elimination of pathogens.
• Lymphatic organs and tissues are densely populated with lymphocytes, crucial for the adaptive immune response.

Lymphatic System Disorders

• Lymphedema: Swelling due to lymphatic fluid buildup.
• Lymphoma: Cancer of the lymphatic system's cells.
• Tonsillitis: Inflammation of the tonsils.
• Splenomegaly: Enlargement of the spleen.

Relationship to the Circulatory System

• Lymph originates from interstitial fluid around cells.
• Lymphatic vessels closely interact with blood vessels.
• The lymphatic system returns excess interstitial fluid to the bloodstream, maintaining blood volume and pressure.

Fluid Balance in Tissues

• The lymphatic system helps maintain interstitial fluid volume by collecting and returning excess interstitial fluid to the bloodstream, preventing tissue swelling.