GENERAL HISTOLOGY

Detailed explanation-1: -The mechanical digestion of food in the mouth involves converting bite-sized pieces of food into smaller particles. This has the effect of increasing the surface area of the food particles and allowing saliva to be thoroughly mixed with them.

Detailed explanation-2: -Mechanical digestion involves physically breaking down food substances into smaller particles to more efficiently undergo chemical digestion. The role of chemical digestion is to further degrade the molecular structure of the ingested compounds by digestive enzymes into a form that is absorbable into the bloodstream.

Detailed explanation-3: -Mechanical digestion is a purely physical process that does not change the chemical nature of the food. Instead, it makes the food smaller to increase both surface area and mobility. It includes mastication, or chewing, as well as tongue movements that help break food into smaller bits and mix food with saliva.

Detailed explanation-4: -Microvilli: The cells on the villi are packed full of tiny hairlike structures called microvilli. This helps increase the surface of each individual cell, meaning that each cell can absorb more nutrients.

Detailed explanation-5: -Summary: The internal surface area of the gastro-intestinal tract has long been considered to be between 180 and 300 square meters. Scientists have used refined microscopic techniques that indicate a much smaller area.