Lymph and the Lymphatic System

• Lymph is lymphatic fluid that plays a large role in the immune system.

Composition of Lymph

• White blood cells, primarily lymphocytes, attack bacteria.
• Minerals and Nutrients, such as protein, fat, glucose, and vitamins.
• Damaged cells and Cancer cells.
• Microbes, including bacteria and viruses, and Drained fluid from capillaries.
• Lymph is derived from the Latin word lympha meaning "pure or clear water."
• Lymph presents as either a clear or white fluid within the body.

Lymphatic System

• The lymphatic system is a network of organs, tissues, and vessels.
• It shuttles lymph from the blood to tissues and back.
• It helps fight infections and maintain fluid balances within tissues and organs.
• The lymphatic system consists of Lymph, Lymphatic vessels, Lymph nodes, Lymphatic tissues and Organs.

Lymphatic Vessels

• Contain and move lymph much like blood vessels contain and move blood.

Lymph Nodes

• Collect and cleanse lymph by releasing antibodies.
• They also fight infections, detect and destroy cancer cells, and kill bacteria.

Lymphatic Tissues:

• Peyer's patches kill bacteria in the small intestine.
• Bone marrow makes white blood cells, red blood cells, and platelets.

Organs

• Spleen filters blood, stores blood, and makes white blood cells.
• Thymus makes T cells, a specific type of lymphocyte.
• Tonsils and adenoids serve as the first line of defense against inhaled and consumed infectious agents.
• Appendix destroys pathogens and possibly repopulates "good" bacteria in the gut.
• Tonsils contain lymph nodes to fight infections entering through the mouth.

Functions of Lymph

• Transports nutrients.
• Returns protein to the blood.
• Drains excess fluid from tissues.

Transportation of Nutrients

• Lymph from the small intestine contains fat and fat-soluble vitamins.
• Fat serves as a high-yield energy source, storing vitamins A, D, E, and K.
• The lymphatic system absorbs a portion of nutrients and redistributes them to other tissues.

Returns Protein to Blood

• Lymph returns proteins absorbed from tissue back to the blood.
• Proteins reenter the bloodstream and redistribute.
• Globulins are a major protein group; immunoglobulins (antibodies) fight infections and help blood clot.

Drains Excess Fluids from Body Tissues

• Excess fluid could drown tissue cells.
• Interstitial fluid exists between tissue spaces.
• Fluid flows from high to low pressure.
• Removing fluid from tissues removes pressure and creates space for the blood to provide cells with "fresh" fluid, oxygen, and nutrients.
• Lymph washes away waste and pathogens from cells.
• Lymph reconstitutes blood volume by returning fluid.
• Lymph is derived from blood plasma and interstitial fluid, but does not normally contain red blood cells.

Composition of Lymph

• Composition varies based on body part.
• Lymph from the gastrointestinal tract contains high amounts of fat.
• Lymph from extremities maintains a composition closer to blood plasma.
• Plasma contains more protein than lymph.
• Chyle is a specialized version of lymph containing a high amount of fat.

White Blood Cells

• Macrophages engulf and kill microorganisms and dead cells, also activating other white blood cells.
• Lymphocytes include:
  • B cells which make antibodies to fight infections (made in bone marrow).
  • T cells which attack bacteria, viruses, fungi, and parasites (made in the thymus).
  • Natural killer cells which kill abnormal cells like virus-infected or cancer cells.

Chyle

• It is a specialized version of lymph.
• Milky-white fluid contains Fat and Chylomicrons, Protein, Electrolytes, Glucose, Urea, and Lymphocytes.
• Produced in the small intestine, flowing through the lymphatic system to liver and adipose cells.
• White color is from high-fat content.
• Chyle is bacteriostatic and prevents bacteria from reproducing.
• Fatty acid molecules leave the intestine and enter lacteals.
• Chyle flows into the cisterna chyli and into the thoracic duct, then enters the bloodstream.

Formation of Lymph

• Lymph is formed from fluid leaving blood capillaries to nourish tissues.
• Fluid then leaves tissues to enter lymphatic vessels.
• Lymphatic vessels maintain different sizes and have a hierarchy of flow.
• Fluid that becomes lymph enters lymphatic capillaries, then flows into larger lymphatic vessels.
• The thoracic duct receives lymph from the lower body, gut, internal organs, and the left side of the upper body.
• The right lymphatic duct receives lymph from the right side of the upper body.

Location of Lymph

• Lymph is found throughout the body in lymphatic vessels and lymph nodes.
• Lymph is concentrated in lymph nodes for cleansing.
• Lymphocytes release antibodies.
• Cancer cells are detected and destroyed.
• Macrophages destroy bacteria.
• Lymph travels via valves, preventing backflow.
• Lymph converges into the thoracic duct and right lymphatic duct, then enters the subclavian veins to return to the bloodstream.