Lymphatic System Summary [Essential of Human Anatomy and Physiology]

TRABECULAE – divide the spleen into small,
LYMPHATIC SYSTEM interconnected compartments containing 2 specialized
FUNCTIONS: types of lymphatic tissue
1. Fluid Balance
WHITE PULP – surrounds the arteries within the spleen
2. Fat absorption
3. Defense RED PULP – associated with the veins

ANATOMY OF THE LYMPHATIC SYSTEM THYMUS
LYMPHATIC CAPILLARIES AND VESSELS Ø Bilobed gland roughly triangular in shape
LYMPHATIC CAPILLARIES – tiny, closed-ended Ø Site for maturation of lymphocytes
vessels consisting of simple squamous epithelium
CAPSULE – thin CT that surrounds each lobe
LYMPHATIC VESSELS – resemble small veins; formed
when lymphatic capillaries join together
TRABECULAE – divide each lobe into lobules
RIGHT LYMPHATIC DUCT – lymphatic vessels from
CORTEX – dark-staining areas where lymphocytes are
the right upper limb and the right half of the head, neck
numerous
and chest; empties into the right subclavian vein
MEDULLA – lighter-staining, central portion of the
THORACIC DUCT – lymphatic vessels from the rest of
lobules; has fewer lymphocytes
the body; empties into the left subclavian vein
OVERVIEW OF THE LYMPHATIC SYSTEM
LYMPHATIC ORGANS
LYMPHATIC TISSUE – consists of many lymphocytes Ø The lymphatic system removes fluid from tissues,
and other cells, such as macrophages; found within absorbs fats from the small intestine, and produces
lymphatic organs B cells and T cells, which are responsible for much
of immunity.
TONSILS
1. PALATINE TONSILS – located on each side of the IMMUNITY
posterior opening of the oral cavity Ø The ability to resist damage from foreign
Ø Usually referred to as “the tonsils” substances – such as microorganisms, harmful
2. PHARYNGEAL TONSILS – located near the chemicals, and internal threats
internal opening of the nasal cavity
Ø Adenoid – enlarged pharyngeal tonsil INNATE IMMUNITY – nonspecific resistance; the body
3. LINGUAL TONSIL – on the posterior surface of the recognizes and destroys certain foreign substances, but
the response to them is the same each time the body is
tongue
exposed.

LYMPH NODES ADAPTIVE IMMUNITY – specific immunity; the body
Ø Rounded structures, varying from the size of a small recognizes and destroys certain foreign substances, but
seed to that of a shelled almond the response to them improves each time the foreign
substance is encountered.
CAPSULE – dense CT that surrounds each lymph node Ø SPECIFICITY – ability of adaptive immunity to
recognize a particular substance
TRABECULAE – extensions of the capsule Ø MEMORY – ability of the adaptive immunity to
“remember” previous encounters with a particular
LYMPHATIC NODULES – dense aggregations of tissue substance
form from lymphocytes and other cells

LYMPHATIC SINUSES – spaces between the lymphatic INNATE IMMUNITY
tissues that contain macrophages on a network of fibers PHYSICAL BARRIERS
Ø Prevent microorganisms and chemicals from entering
GERMINAL CENTERS – lymphatic nodules containing the body in two ways:
the rapidly dividing lymphocytes 1. Skin and mucous membranes form barriers that
prevent their entry
SPLEEN
2. Tears, saliva, and urine wash these substances
Ø Roughly the size of a clenched fist and is located in
from body surfaces
the left, superior corner of the abdominal cavity
Ø Has an outer capsule of dense CT and a small
amount of smooth muscle




A c p s .