Post on 01-Jun-2020
http://www.lymphnotes.com/article.php/id/151/
http://www.youtube.com/watch?v=qTXTDqvPnRk
http://www.scribd.com/doc/60675255/Handouts-
Lymphatic-System-F11
http://www.learningace.com/doc/5949560/9178
e2f0064b410c8c8e9218bcc748e6/ama-180-
course-handouts
Lymphatic System
Lymph Fluid
Lymph Vessels
Lymph Nodes
Four Organs
Tonsils
Spleen
Thymus Gland
Peyer’s Patches
Functions
Drain from tissue spaces, protein-containing fluid
that escapes from the blood capillaries
Transport fats from the digestive tract to the blood
Produce lymphocytes
Develop Immunities
Interstitial Fluid
Blood pressure forces some of the blood plasma
through the single-celled capillary walls
Interstitial Fluid is in the spaces between cells
Most is reabsorbed into the capillaries
Some fluid is not and must be drained from the
tissue spaces to prevent swelling or Edema.
Lymphatic Capillaries – drain this fluid
Lymph is the fluid when it is in the vessels
Fat Absorption
Lacteals – lymphatic vessels in the villi of the small
intestine that absorb fats and transport them to the
blood.
Looks milky because of the fat content and is called
chyle.
Lymph Capillaries
Larger and more permeable than blood capillaries
Closed at one end
Occur singly or in extensive plexuses
Lymphatics
Combined capillaries
Larger
Beaded appearance
Similar to veins, but thinner walls and more valves
One way valves to prevent backflow
Lymph goes in one direction only
Have lymph nodes at various intervals
All Lymphatics converge
Thoracic Duct – the main collecting channel, Left
Lymphatic Duct
Right Lymphatic Duct
Lymph Nodes or Lymph Glands
Regions of aggregations – groin, armpits, neck
Oval to bean-shaped structures found along the
length of lymphatics
1 to 25 mm in length
Look like small seeds or almonds
Framework consists of the capsule, hilum and
trabeculae
Structure of a Node
Hilum - Depression on one side of the node
Efferent Lymphatic Vessels leave
Nodal artery enters
Nodal vein leaves
Covered by a Capsule of fibrous connective tissue that extends into the node
Trabeculae – divide the node internally into compartments that have lymphatic sinuses and tissue
Afferent Lymphatic Vessels – enter the node ad various sites
Lymphatic Tissue
Cortical or Lymph Nodules
6 different kinds of lymphocytes
Germinal Center – produces lymphocytes
Lymph Sinuses – spaces between the lymphatic
tissue
Network of fibers and macrophage cells
At the Node – a Sequence of Events
1. Lymph enters by an afferent lymphatic
2. Immune response is activated
3. Lymphocytes produced by germinal centers as a response to any microorganisms or foreign matter
4. Lymphocytes released into lymph
5. Eventually reach the blood and stimulate antibody production
6. Macrophages remove dead microorganisms and foreign substances by phagocytosis
Blood to Lymph
Blood plasma is filtered by blood capillaries
Passes in-between cells to become interstitial fluid
Passes into the lymph capillaries to become lymph
Water, plasma solutes (ions & gases), nutrients, proteins, (hormones & enzymes), and waste products
Lymph drains into lymph capillaries and lymph plexuses
Drains to Lymph vessels
Heads towards Lymph Nodes
At the Node
Afferent Vessels drain lymph into the node sinuses
Microorganisms and foreign substances trigger
lymphocytes to divide and activate immune
response
Macrophages engulf foreign bodies
Efferent Vessels leave the node and go to other
nodes or join with other vessels
Unite to form Lymph Trunks
Moving the Lymph Along….
Skeletal muscle contractions compress lymph vessels
and force the lymph through the one-way vessels
Normal movement helps circulate the lymph
Breathing causes pressure changes in the thorax
that help move the lymph
Smooth muscle contraction in the lymph vessels
Swelling or edema – a blockage in the vessels
cause a back up interstitial fluid between the cells
Efferent Vessels Unite
Form Lymph Trunks
Lumbar – lower extremities, walls and viscera of pelvis, kidneys, adrenals, abdominal wall
Intestinal – stomach, intestines, pancreas, spleen, surface of liver
Bronchomediastinal – thorax, lungs, heart, diaphragm, rest of liver
Intercostal – portions of the thorax
Subclavian – upper extremities
Jugular – head and neck
Trunks to Channels to Veins
Thoracic Duct – empties into the left subclavian vein
Right Lymphatic Duct – empties into the right
subclavian vein
Completing the Cycle
Tonsils – three groups
Palatine Tonsils – removed in a tonsillectomy, sides
of the oral cavity
Pharyngeal Tonsils – adenoids, near the nasal
cavity, when swollen interfere with breathing
Lingual Tonsils – back surface of the tongue at the
base
Ring of protection for the nose and oral cavity from
microorganisms
More functional in children
Spleen
Oval, 5 inches in length
Left upper corner of the abdominal cavity
Largest mass of lymphatic tissue in the body
Filters blood
Phagocytizes bacteria, worn-out platelets, and RBCs
Release hemoglobin to be recycled
Produces lymphocytes and plasma cells
Stores blood – blood reservoir
Extra blood when a hemorrhage occurs
Thymus Gland
Bi-lobed mass of tissue along the trachea behind
the sternum
Also part of the Endocrine System
Site for lymphocyte production and maturation in
the fetus and infants
Peyer’s Patches
Aggregated Lymphatic Follicles
Wall of small intestine
Similar to tonsils
Macrophages destroy bacteria to prevent infection
in the walls of the intestine
Immunity
The ability of the body to resist infection from disease
causing microorganisms or pathogens, damage from
foreign substances and harmful chemicals
Lymphocytes
B Lymphocytes – humoral (body fluids) immunity; produce
antibodies; circulating bacteria and viral infections; attack
the invading agents, become plasma cells in the tissues
T Lymphocytes – cellular immunity; from the thymus gland;
fungi, parasites, inside the cells viral infections, cancer cells
and foreign tissue implants
Antigens and Antibodies
Antigens – foreign proteins that gain access to the
body via an opening in the skin, or through the
digestive, circulatory, urinary or reproductive
systems.
Cause immune system to produce Antibodies or
Immunoglobulins to destroy this invader
High molecular weight proteins
Active Immunity
B-Lymphocytes produce antibodies against an
antigen that they came in contact with
Naturally acquired when you come in contact with a
bacterial or viral infection
Vaccines are a killed or weakened pathogens that
stimulate antibody production
Measles, smallpox, polio, tetanus, chickenpox,
pneumonia, diphtheria, and flu
Passive Immunity
Conferred naturally when a fetus receives mother’s
antibodies through the placenta
Artificially – gamma globulin, breast milk or immune
serum
Used after exposure to hepatitis
Snakebite, botulism, or rabies
Cells of the Immune Response
B cells
Plasma Cells
Helper T Cells
Killer T Cells – kill virus invaded body cells and cancerous body cells, graft rejections
Suppressor T Cells
Memory Cells – respond to future infections with the same pathogen
Macrophages – engulf and digest antigens
Monokines and lymphokines