Mechanism of Lymph Flow

In large part, the lymphatic vessels beyond the lymphatic capillaries propel the lymph within them by their own contractions. The smooth muscle in the wall of the lymphatics exerts a pumplike action by inherent rhythmical contractions. Since the lymphatic vessels have valves similar to those in veins, these contractions produce a one-way flow toward the points at which the lymphatics enter the circulatory system. The lymphatic-vessel smooth muscle is responsive to stretch, so when there is no accumulation of interstitial fluid, and hence no entry of lymph into the lymphatics, the smooth muscle is inactive. As lymph

PART THREE Coordinated Body Functions

Vander et al.: Human Physiology: The Mechanism of Body Function, Eighth Edition

PART THREE Coordinated Body Functions

Lymph node

Lymphatic vessel

Valve

Lymph capillaries

Blood capillaries in lungs

Lymph node

Lymphatic vessel

Lymph capillaries

Lymph node

Lymphatic vessel

Valve

Lymph Lymphatic Vessels Lymph Nodes

Blood capillaries in lungs

Artery

Systemic blood capillaries

Lymph capillaries

FIGURE 14-51

The lymphatic system (green) in relation to the cardiovascular system (blue and red). The lymphatic system is a one-way system from interstitial fluid to the cardiovascular system. %

SECTION D SUMMARY

Artery

Systemic blood capillaries

Lymph capillaries

FIGURE 14-51

The lymphatic system (green) in relation to the cardiovascular system (blue and red). The lymphatic system is a one-way system from interstitial fluid to the cardiovascular system. %

formation increases, however, say as a result of increased fluid filtration out of blood-vessel capillaries, the increased fluid entering the lymphatics stretches the walls and triggers rhythmical contractions of the smooth muscle. This constitutes a negative-feedback mechanism for adjusting the rate of lymph flow to the rate of lymph formation and thereby preventing edema.

In addition, the smooth muscle of the lymphatic vessels is innervated by sympathetic neurons, and excitation of these neurons in various physiological states such as exercise may contribute to increased lymph flow. Lymph flow is also enhanced by forces external to the lymphatic vessels. These include the same external forces we described for veins—the skeletal-muscle pump and respiratory pump.

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Essentials of Human Physiology

Essentials of Human Physiology

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Responses

  • LEILA
    How lymph flow prevent edema formation?
    8 years ago
  • erno
    How is a lymph part of insulin mechanism?
    1 year ago
  • Belba
    What are the mechanisms of flow in the lymph?
    8 months ago
  • ethel pearson
    What mechanisms maintain flow of lymph?
    7 months ago

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