1. Lymphatic System and Immunity

2. Functions of the Lymphatic System
Fluid Balance, Fat Absorption, Defense
Fluid Balance:
30L of fluid exits capillaries only 27L will return to vascular system 3L enters the lymphatic capillaries as lymph
Water, plasma, hormones, enzymes & waste

3. Functions of the Lymphatic System
Fat Absorption:
Absorbs fats from digestive tract through lacteals making lymph appear milky-chyle

4. Functions of the Lymphatic System
Defense:
Destroy microorganisms and foreign substances. Lymphocytes act as part of the immune system & microorganisms are filtered by lymph nodes and by blood in the spleen

5. Lymphatic Anatomy Lymph-fluid Lymphocytes Lymphatic vessels
Lymph nodes
Tonsils
Spleen
Thymus gland

6. Functions of the Lymphatic System
Does not circulate fluid to and from tissues
Carries fluid from tissue capillaries to circulatory system
Lymphatic Capillaries are closed ended vessels made of simple squamous epithelium
More permeable than blood capillaries
Found in most all tissues of the body except CNS, bone marrow, epidermis and cartilage
Lymphatic capillaries join together to form lymph vessels with a beaded appearance due to overlapping valves

7. Functions of the Lymphatic System
Lymph moves from small vessels to larger vessels
Empty into blood in two locations
Right lymphatic duct empties into the right subclavian vein ¼ of body
Thoracic duct empties into the left subclavian vein ¾ of
Three factors that assist Transport of lymph
Contraction of skeletal muscle during activity
Contraction of smooth muscle in lymph vessels
Respiration pressure changes

8. Check Point Review

9. Lymphatic Organs and Tissues
Lymphatic Organs: Tonsils, Lymph nodes, spleen & Thymus
When blood and lymph filters through organs, fiber network traps microorganisms and other material
Fine reticular fiber network that holds lymphocytes in place and traps microorganisms
Lymphatic Tissues: Lymphocytes and other cells
Lymphocytes originate in red bone marrow & carried to lymphatic organs by blood
Lymphocytes divide and increase in number when in the presence of a foreign material causing an immune response

10. Tonsils Palatine Tonsils- “Tonsils” Pharyngeal Tonsils- “Adenoids”
Lingual Tonsils- “Posterior to tongue”
All provide protection against pathogens and other potentially harmful material entering from the nose and the mouth.
Soar throat when sick
Can become chronically infected and may require being removed.
In adults, can decrease in size and may eventually disappear.

11. Lymph Nodes The size of a small seed to an almond
Most lymph passes through at least one lymph node before entering the blood
Surrounded by a dense connective tissue capsule
Lymphatic tissue
Lymphatic sinuses-spaces between lymphatic tissue which contains macrophages network of fibers
Lymph enters nodes through afferent vessels
Lymph leaves nodes through efferent vessel

12. Lymph Nodes Superficial Locations: Two Functions:
Inguinal –nodes in the groin
Axillary- nodes in armpit
Cervical- nodes in the neck
When swollen, signs of infection!
Two Functions:
Removal of microorganism and foreign substances from the lymph as macrophages
Activation of the immune system
Activation of the immune system includes:
Germinal centers-rapidly dividing lymphocytes.

13. Swollen Nodes

14. Spleen Two Specialized types of lymph tissues
White pulp: Lymphatic tissue surrounding arteries
Red pulp: Consists of fibrous network filled with RBC’s & macrophages associated with veins
Major functions of the spleen:
Filters blood instead of lymph
Destroys old RBCs
Removes foreign substances in the blood through phagocytosis

15. Other Functions of the Sleep
The spleen serves as a reservoir for blood that can be released in case of emergencies
A second function of the spleen is to filter red and white blood cells from the blood.
A third job of the spleen is to store platelets
Most important role of the spleen is to bring blood into contact with the spleen’s lymphocytes
Finally, the spleen manufactures red blood cells for the fetuses

16. Thymus Bi-lobed triangular gland Located in the mediastinum
Increases in size until 1 years old, then remains the same
After 60 years, decreases in size
By 40 year, most of thymus is replaced with adipose tissue
Functions as a site for the production and maturation of lymphocytes
Lymphocytes do not respond to foreign substances while in the thymus
After maturation, lymphocytes enter blood and travel to other lymphatic tissues.

17. Thymus