1. Biology 212 Anatomy & Physiology I
Lymphatic System

2. Lymphatic System Functions
1) Provide alternate pathway for extracellular fluids to
return to circulation.
2) Provide pathways for waste materials to be removed
from tissues and organs and destroyed.
3) Provide a protective lining along internal organs which
are exposed to the environment.
4) Provide places for surveillance, proliferation and
maturation of lymphocytes and other immune cells

3. Lymphatic System Two interrelated components:
1) Network of lymphatic vessels
2) Lymphatic organs, such as spleen & lymph nodes
Lymphatic tissues such as tonsils
Lymphatic cells dispersed through walls of many organs

6. Concentrated in
Cervical region
Along aorta in
thorax & abdomen
Axilla
Inguinal region

9. Other Lymphatic Organs and Tissues
Spleen, Thymus
Tonsils, Appendix,
Lymphatic tissue lining digestive system
trachea, bronchi, bronchioles
vagina
urethra

10. Spleen
Inferior to diaphragm on left side of abdomen
Large blood supply through splenic artery
(branch of celiac trunk from aorta)
Two types of tissue:
a) Red pulp produces erythrocytes in fetus & newborn
(can resume in adults if necessary)
reservoir for eythrocytes & platelets

11. Spleen
Inferior to diaphragm on left side of abdomen
Large blood supply through splenic artery
(branch of celiac trunk from aorta)
Two types of tissue:
b) White pulp contains lymphocytes & macrophages
removes bacteria, viruses, debris from blood
removes old & damaged erythrocytes

12. Thymus
Superior thorac, anterior to aorta & posterior to sternum
Large in children, involutes in adults
Secretes hormones which cause undifferentiated lymphocytes to mature into "thymic-derived" lymphocytes

13. Located just deep to epithelia, easily exposed to antigens
Lymphoid tissues (lymphocytes and macrophages) line many hollow organs exposed to bacteria, viruses, etc
Clusters, called lymphatic nodules, of closely-packed, proliferating lymphocytes & macrophages.
Located just deep to epithelia, easily exposed to antigens
Secrete antibodies into and across epithelia into lumen
Esophagus
Intestine
Bronchus
Urethra

14. Lymphoid tissues (lymphocytes and macrophages) line many hollow organs exposed to bacteria, viruses, etc
Some nodules given special names:
Tonsils in pharynx
Peyer's Patches in
small intestine