Fundamentals of Anatomy and Physiology

The Lymphatic Circulatory System 367

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Summary Outline
Introduction

1. The lymphatic system transports a fluid called
   lymph through lymphatic capillaries and vessels

called lymphatics.^

2. The system controls body fluids and destroys harm-ful

microorganisms.^

3. The system consists of lymph, lymph vessels, lymph
   nodes, the tonsils, the spleen, the thymus gland, and
   Peyer’s patches in the intestine.

The Functions of The System
and The Structure and Functions
of The Lymphatic Vessels

1. The functions of the system are to drain interstitial
   fluid from tissue spaces, to transport fats from the
   digestive tract to the blood, to develop immunities,

and to produce lymphocytes.^

2. Some blood plasma gets forced through the blood
   capillary walls into spaces between tissue cells. This is

called interstitial fluid.^

3. Lymphatic capillaries drain interstitial fluid, which is
   now called lymph, and pass this fluid on to lymph
   vessels called lymphatics.
   4. In the villi of the small intestine, special lymphatics
   called lacteals pick up fats and transport them to the
   blood.^


4. Lymph in lacteals looks milky due to the fats and is
   called chyle.

Lymphatic Vessels

1. Lymphatic vessels originate singly or in plexuses as
   blind-end tubes called lymphatic capillaries be-tween
   cells in most parts of the body.^


2. Lymphatic capillaries unite to form larger vessels
   called lymphatics, which resemble veins but are
   thinner and have more valves. Valves ensure a one-
   way flow of lymph.^


3. Eventually, all lymphatics converge into two
   main channels: the thoracic duct and the right
   lymphatic duct.

Lymph Nodes

1. Lymph nodes, also called lymph glands, are found
   along the lengths of lymphatics. Groupings of lymph
   nodes are present in the groin, armpit, and neck region.


2. Efferent lymphatics exit the lymph node at the hi-
   lum, a slight depression on one side. Blood vessels
   and nerves also exit and enter at the hilum.