Which of the following statements about digestion of food in...

Which of the following statements about digestion of food in the large intestines is true?

a. Mechanical digestion occurs by bacteria.
b. Semi-solid waste is moved by wave-like muscle contractions.
c. Most nutrients are absorbed.
d. Peristaltic mixing occurs.

Labs

Want to see this concept in action?

NEW

Explore this concept interactively to see how it behaves as you change inputs.

View Labs

Key Concepts

Large Intestine Physiology

The large intestine primarily functions in absorbing water and electrolytes, concentrating waste, and facilitating the formation and expulsion of feces. It plays a minor role in nutrient absorption compared to the small intestine and is more focused on water reabsorption and bacterial fermentation.

Intestinal Motility

The movement of contents in the gastrointestinal tract is governed by various types of muscle contractions, including peristalsis and segmentation. In the large intestine, wave-like muscle contractions, often referred to as haustral churning, help in propelling semi-solid waste along the colon, rather than mixing it extensively as seen in other parts of the digestive system.

Role of Intestinal Bacteria

The bacteria residing in the large intestine contribute to the fermentation of undigested carbohydrates, leading to the production of short-chain fatty acids and gases. Their contribution is primarily chemical in nature, assisting in further breakdown of food residues, rather than performing mechanical digestion.

Nutrient Absorption

While the large intestine absorbs some vitamins and electrolytes, the majority of nutrient absorption occurs in the small intestine. The large intestine’s primary role is in water and salt uptake, with only limited absorption of additional nutrients.

Transcript

Please give Ace some feedback