Question

The sac-like structure between the small intestine and the large intestine in ruminants is
a) Lumen
b) Appendix
c) Rumen
d) Jejunum

Answer 1

Hint: Ruminants digest the cellulosic food material with the help of microbial fermentation. Microbes that help in degradation are methanogens.

Complete answer:
The rumen is composed of:
Muscular sacs
Cranial sac
Ventral sac Ventral blind sac
Reticulum.
The wall of the rumen is lined with small finger-like projections called papillae. These are flattened structure measures approximately 5 mm in length and 3 mm wide. The reticulum or net is lined with ridges that form a hexagonal honeycomb pattern. The ridges measure approximately 0.1–0.2 mm wide and are raised 5 mm tall. The ridges increase the surface area and facilitate the absorption of fatty acids.

So, the correct answer is (C) Rumen.

Note: Ruminants chew plant matter and mix it with saliva and swallow. The food then enters in the first two chambers of the stomach, the reticulum and rumen. The reticulum and rumen work in association and they separate solids and liquids. With the help of contractions, solid food particles are pushed back into the rumen, while liquids are drained into the reticulum. Methanogens live in the rumen and help ruminants break down cellulose. Solids are formed into a bolus, called “cud,” in the rumen and the solid cud is regurgitated back up to the mouth where it is chewed a second time and returned to the reticulorumen to repeat the process. The digested liquid in the reticulum is passed into the omasum where bloodstream absorbs nutrients and water. Later on, digesta is passed into the abomasum a structure analogous to the stomach of other animals from where the digesta moves through the small and large intestines. Ruminants intrigue the microbiologists since they have a unique ecosystem of bacteria, yeasts, protozoa, and fungi in their rumens. Vertebrates cannot produce cellulase to break down cellulose. So, ruminants depend on the symbiotic microbes in their guts to break down cellulose for digestion. This is an anaerobic region so bacteria found here are typically facultative anaerobes.