Lymphatic system notes PPT/PDF


Lymphatic system


·         Lymph is the clear, nearly colorless, alkaline fluid that occupies the space between all cells of the body.

·         The term for this is ‘interstitial fluid’, and it is similar to blood plasma. 

·         It is 95% water. It seeps in and out through the walls of very small vessels called capillaries.

·         Carries the nutrients, oxygen and hormones to cells

·         Carries waste back to capillaries

Lymph is mostly fluid from blood plasma.

Lymphatic system

       The lymphatic system is connected to the circulatory system. 

       It consists of capillaries, vessels, ducts, and nodes. This system transports lymph one-way…back to the blood stream.

There is no pump, but the lymph moves via skeletal muscle action, respiratory movement, and contraction of smooth muscle in vessel walls.

Structures of the lymphatic system

       Lymph fluid

       Lymph vessels

       Lymph nodes

       Lymph glands

Lymph vessels

·         Transport excess lymph fluid back to circulatory system.

·         Located in almost all tissues and organs

·         Closely parallel veins

·         Since the lymphatic system has no pump, skeletal muscle contractions moves lymph through the vessels

       Valves prevent backward flow

       Only move in one directions (from body towards heart)

       Lymph vessels parallel to blood vessels


       Specialized lymph vessels in the small intestines that absorbs digested fat

       Lymph vessels join together to form larger lymph vessels à

       Large lymph vessels join together to form lymphatics à

       Two main lymphatics:

1.       Thoracic duct

§  Also called the left lymphatic duct

§  Receives lymph from the left side of chest, head, arm and neck, the entire abdominal area and entire lower body

§  Dumps back into left subclavian à SVC

2.       Right lymphatic duct

§  Receives lymph from the right side of the chest, head, arm and neck

§  Dumps back into right subclavian à SVC

Lymph nodes

·         Tiny, oval-shaped structures!

·         Range in size from a pinhead to an almond

·         Site of lymphocyte formation and filter for screening out harmful substances (ex: bacteria, cancer)

·         If substances can’t be destroyed, node becomes inflamed


Masses of lymphatic tissue that produce lymphocytes and filter bacteria

·         3 pairs

1.       Palatine tonsils: sides of throat

2.       Adenoids / Pharyngeal tonsils: upper throat

3.       Lingual tonsils: back of tongue


·         Sac-like mass of lymphatic tissue

·         LARGEST lymphatic structure

·         Located in the LUQ – just below diaphragm

·         Forms lymphocytes and monocytes

·         Filters blood

·         Stores large amounts of RBCs – contracts during vigorous exercise or loss of blood to release RBCs

·         Destroys or removes old or fragile RBCs – preserves hemoglobin

Thymus gland

·         Located in the upper, anterior thorax (chest), above the heart

·         Produces T lymphocytes

·         Also an endocrine gland because also secretes hormones

Functions of the lymphatic system

The lymphatic system has 3 primary functions: 

1.  Transports proteins and fluids, lost by capillary seepage, back to the bloodstream.

2. Participates in the body’s immune response.

3.  The pathway for the absorption of fats from the small intestine into the bloodstream.

Lymph nodes are filters, slowing down and cleaning the lymph before returning it to the blood.

Lymph nodes trap and sometimes become swollen with bacteria that has invaded the body AND the white blood cells that fight that bacteria.

The lymphatic system and cancer

       The lymphatic system plays an important role in the development or spread of cancer.

       Cancer that starts in the lymph nodes is called a lymphoma.

       When cancer cells break off a tumor and spread into the lymph nodes, it is known as metastatic cancer.

Lymphatic system notes PDF

Lymphatic system notes PPT

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