Anatomy _amp; Physiology by yurtgc548


									Anatomy & Physiology

Lymphatic System
    Ch. 20
  Overview of The Lymphatic System
A. Importance of the lymphatic system:
     1. Two most importance functions—maintain fluid balance in
        the internal environment & immunity

     2. Lymph vessels act as “drains” to collect excess tissue fluid &
        return it to the venous blood just before it returns to the heart.

     3. Lymphatic System—specialized component of the circulatory
        system; is made up of:
           Lymph
           Lymphatic Vessels
           Lymph nodes
           Isolated nodules of lymphatic tissue
           Tonsils
           Thymus
           Spleen
You’ll need to
be able to ID
organs for
your TEST!
       Lymph & Interstitial Fluid
A. Lymph-
     1. Clear, water-appearing fluid found in the lymphatic
        vessels; closely resembles blood plasma in composition
        but has a lower percentage of protein; isotonic.
     2. Elevated protein concentration in thoracic duct lymph
        due to protein-rich lymph from the liver and small
B. Interstitial fluid-
     1. Complex, organized fluid that fills the spaces between
        the cells; resembles blood plasma in composition with a
        lower percentage of protein.
     2. Along with blood plasma, constitutes the extra cellular
              Lymphatic Vessels
A. Distribution of lymphatic vessels-
     1. Lymphatic capillaries-microscopic blind-end vessels where
         lymphatic vessels originate, wall consists of a single layer of
         flattened endothelial cells; networks branch and *anastomose
         freely.*Anastomosis is the connection of two structures. It refers to
         connections between blood vessels.

     2. Lymphatic capillaries merge to form larger lymphatic and eventually
         form the main lymphatic trunks the right lymphatic ducts and the
         thoracic duct.

     3. Lymph from upper right quadrant empties into right lymphatic duct &
         then into right subclavian vein.

     4. Lymph from rest of the body empties into the thoracic duct, which then
         drains into the left subclavian vein.
We’ll talk about this in a bit…..
Cont of Lymphatic Vessels…

B. Structure of lymphatic vessels-
   1. Similar to veins except lymphatic vessels have
       thinner walls, have more valves and contain lymph
   2. Lymphatic capillary wall is formed by a single layer of
       thin, flat endothelial cells

C. Functions of the lymphatic vessels-
  1. Remove high-molecular-weight substances and even
      particular matter from interstitial spaces.
  2. Lacteals absorb fats & other nutrients from the small
        Circulation of Lymph
A. The Lymphatic pump
     1. Lymph moves through the system in the right
     direction due to the large number of valves.

     2. Breathing movements & skeletal muscle
     contractions establish a lymph pressure
     gradient, as they do with venous blood.

     3. Lymphokinetic actions—activities that result
     in a central flow of lymph.
                        Lymph Nodes

A. Structure of Lymph nodes
   1. Lymph nodes are oval-shaped structures enclosed by a fibrous capsule.
   2. Nodes are similar to biological filter
   3. Once lymph enters a node, it moves slowly through sinuses to drain in
      to efferent exit vessel

B. Location of Lymph nodes
     1. Most lymph nodes occur in groups
     2. Location of groups with greatest clinical importance are
        submental & submaxillary groups & superficial cervical,
        superficial cubital, axillary, and inguinal lymph nodes
     3. Preauricular lymphs nodes located in front of the ear drain
         superficial tissues and skin on the lateral side of the head and face.

                 -needle like
                 threads spongy
                 bone that
                 surround a
                 network of
Cont. of Lymph Nodes
C. Functions of lymph nodes—perform two distinct
  1. Defense functions: filtration & phagocytosis—
       reticuloendothelial cells remove microorganisms
       and other injurious particles from lymph and
       phagocytose them; if overwhelmed, the lymph
       nodes can become infected or damaged.
  2. Hematopoiesis—process of blood cell formation,
     lymphatic tissue is the site for the final stages of
     maturation of some lymphocytes & monocytes.
Lymphatic drainage of the breast
A. Distribution of lymphatics in the breast
     1. Drained by two sets of lymphatic vessels
         a. Lymphatics that drain the skin over the breast with the
            exception of the areola & nipple
         b. Lymphatics that drain the substance of the breast as well
            as the skin of the areola & nipple
     2. Superficial vessels coverage to form a diffuse, cutaneous
            lymphatic plexus
     3. Subareolar plexus-this is located under the areola
            surrounding the nipple, where communication between
            the cutaneous plexus & larger lymphatics that drain the
            secretory tissue & ducts of the breast occurs
A.   Pectoralis major muscle
B.   Axillary lymph nodes:
     Levels I
C.   Axillary lymph nodes:
     Levels II
D.   Axillary lymph nodes:
     Levels III
E.   Subclavicular lymph
F.   Internal mammary
A. Location- under the mucous membranes in the
   mouth & back of the throat.
     1. Palatine tonsils-
        located on each side of the throat.

    2. Pharyngeal tonsils-
       located near the posterior opening of the
       nasal cavity.

    3. Lingual tonsils-
       located near the base of the tongue

B. Function- Protect against bacteria that may
    invade tissues around the openings the
    nasal & oral cavities.
A. Location & appearance of the Thymus
   1. Primary central organ of lymphatic system

   2. Single, unpaired organ located in the
      mediastinum, extending upward to the
      lower edge of the thyroid & inferiorly as far
      as the 4th costal cartilage

   3. Thymus is pinkish gray in children and
      wish advancing age, becomes yellowish as
      lymphatic tissue is replaced by fat.
B. Structure of the Thymus
  1. Pryamid-shaped lobes are subdivided into small lobules
   Cont. of Structure of the Thymus

2. Each lobule is composed
   of a dense cellular cortex
   & an inner, less dense,

3. Medullary tissue can be
   identified by presence of
   Thymic corpuscle.
    C. Function of the Thymus

1. Plays vital role in immunity mechanism
2. Source of lymphocytes before birth
3. Shortly after birth, the thymus secretes
   Thymosin, which enables lymphocytes to
   develop into T-Cells….
A. Location-in the left
   (either one of two
   regions of the
   abdomen), directly
   below the
   diaphragm, above
   the left kidney &
   descending colon,
   & behind the
   fundus (the base of
   an organ) of the
                  Cont of Spleen
B. Structure of the Spleen
  1. Ovoid in shape
  2. Surrounded by fibrous capsule with inward
     extensions that divide the organ into compartments.
  3. White pulp-dense masses of developing lymphocytes
  4. Red pulp-near outer regions, made up of a network of fine
     reticular fibers submerged in blood that comes from nearby

C. Functions of the Spleen
  1. Defense-macrophages lining the sunusoids of the spleen remove
     microorganisms from the blood & phagocytose them
  2. Hematopoiesis-monocytes & lymphocytes complete their development
     in the spleen.
  3. Red blood cell and platelet destruction-macrophages remove worn-out
     RBC’s and imperfect platelets and destroy them by phagocytosis;
     also salvage iron and globin from destroyed RBC’s
Don’t confuse Lymphedema with Edema…

                                       We’ll get to this later!
            Cycle of Life:
          Lymphatic System
A. Dramatic changes throughout life
B. Organs with lymphocytes appear before birth
   and grow until puberty
C. Postpuberty
  1. Organs atrophy (shrink in size, degenerate)
     through late adulthood and become fatty or fibrous.
  2. Spleen-it develops early and remains intact
         The Big Picture:
  The Lymphatic System & The Whole Body

A. Lymphatic system drains away excess water
    from large areas
B. Lymph is conducted through lymphatic
    vessels to nodes, where contaminants are
C. Lymphatic system benefits the whole body
    by maintaining fluid balance and freedom
    from disease
                            What Is Lymphedema?

Lymphedema is an accumulation of lymphatic fluid in the interstitial tissue that causes
swelling, mostly in the arm(s) and/or leg(s), and occasionally in other parts of the body.

 Lymphedema can develop when lymphatic vessels are missing or impaired (primary),
     or when lymph vessels are damaged or lymph nodes removed (secondary).

 When the impairment becomes so great that the lymphatic fluid exceeds the lymphatic
transport capacity, an abnormal amount of protein-rich fluid collects in the tissues of the
                                   affected area.

   Left untreated, this stagnant, protein-rich fluid not only causes tissue channels to
  increase in size and number, but also reduces oxygen availability in the transport
system, interferes with wound healing, and provides a culture medium for bacteria that
                           can result in lymphangitis (infection).

Lymphedema should not be confused with edema resulting from venous insufficiency,
which is not lymph-edema. However, untreated venous insufficiency can progress into
     a combined venous/lymphatic disorder which is treated in the same way as
              What Causes Lymphedema?

Primary lymphedema, which can affect from one to as many as
four limbs and/or other parts of the body, can be present at birth,
develop at the onset of puberty (praecox) or in adulthood (tarda),
all from unknown causes, or associated with vascular anomolies
such as: Port Wine Stain, and Klippel Trenaury (a rare congenital
medical condition in which blood vessels and/or lymph vessels fail
to form properly).

Secondary lymphedema, or acquired lymphedema, can develop as
a result of surgery, radiation, infection or trauma. Specific
surgeries, such as surgery for melanoma or breast, head and neck,
prostate or testicular, bladder or colon cancer, all of which currently
require removal of lymph nodes, put patients at risk of developing        Port Wine Stain
secondary lymphedema.

If lymph nodes are removed, there is always a risk of developing
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