Fundamentals of Anatomy and Physiology

354 Chapter 15

Afferent lymphatic vessel

Capsule

Cortex

Nodal vein

Nodal artery

Hilum

Valve

(A)

Bacteria

Lymphocytes

Neutrophil (^)
(^) Plasma cell (^)
(B) Macrophage (^)
Efferent lymphatic vessel
Antibody molecule
(enlarged)
Antigen
(enlarged)
(^) ®
Learning
Cengage ©
(^) ®
Learning
Cengage ©
Figure 15- 4 Lymph node. (A) Section through a lymph node showing the flow of lymph. (B) Microscopic detail
of bacteria being destroyed within the lymph node.
Lymph Circulation
As the plasma of blood is filtered by the blood capillaries, it
passes into the interstitial spaces between tissue cells and is
now known as interstitial fluid. When this fluid passes from
the interstitial spaces into the lymphatic capillaries, it is
called lymph. Lymph is primarily water but it also contains
plasma solutes such as ions, gases,
nutrients, and some proteins and substances from tissue
cells such as hormones, enzymes, and waste products.
The lymph, drained by the lymphatic capillaries and
the lymphatic plexuses, is then passed to the lym-phatic
vessels that have a beaded appearance due to the one-way
valves that prevent backflow movement. The lymphatics
head toward lymph nodes. At the lymph nodes, afferent
vessels penetrate the capsules at various