VPB 121: Veterinary Physiology - II (2+1)

PROVENTRICULUS AND GIZZARD

Proventriculus

• The glandular stomach or proventriculus is relatively small and tubular.
• The wall is very thick composed of five layers:
  • Outer serous membrane.
  • Muscle layer composed of three separate layers:
    • Two thin longitudinal layers.
    • One thick circular layer.
  • Layer of areolar tissue containing blood and lymph vessels.
  • Thick layer composed mainly of glandular tissue.
  • Inner mucous membrane.

Gizzard

• The muscular stomach or gizzard is located immediately succeeding the proventriculus.
• It is placed partly between the lobes and partly behind the left lobe of the liver.
• Under the outer layer very powerful masses of red muscle are located.
• The inner surface is lined with a creamy colored, thick, horny tissue raised in ridges.
• The gizzard almost always contains quantities of hard objects such as gravel or other grit that aids in the disintegration of food - the primary function of the gizzard.
• The gizzard consists of number of layers of tissues in some of which straight tubular glands are located.
• The innermost layer is a strong, flexible skin able to withstand the potentially damaging effects of the muscular action of grinding the food often in the presence of stones or other insoluble material.
• The glands of the gizzard produce a liquid, keratinized material that passes to the surface of the horny lining where it hardens to replace tissue worn away by the grinding action of the organ.