AP BIOLOGY

ANIMAL PHYSIOLOGY

DIGESTION IN HUMANS

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Food is broken down in the mouth both mechanically by chewing, and chemically, by ____ present in the saliva.
A
surface area
B
amino acids
C
enzymes
D
urine
Explanation: 

Detailed explanation-1: -Mechanical digestion in the oral cavity consists of grinding of food into smaller pieces by the teeth, a process called mastication. Chemical digestion in the mouth is minor but consists of salivary amylase (ptyalin, or alpha-amylase) and lingual lipase, both contained in the saliva.

Detailed explanation-2: -The organ system responsible for breaking down food for nutrition is the digestive system. This is one of the larger organ systems in the body, beginning with the mouth and ending with the anus. Food is first mechanically and chemically digested in the mouth by the teeth and saliva.

Detailed explanation-3: -The mouth is the point of ingestion and the location where both mechanical and chemical breakdown of food begins. Saliva contains an enzyme called amylase that breaks down carbohydrates. The food bolus travels through the esophagus by peristaltic movements to the stomach.

Detailed explanation-4: -As food travels from your mouth into your digestive system, it’s broken down by digestive enzymes that turn it into smaller nutrients that your body can easily absorb. This breakdown is known as chemical digestion. Without it, your body wouldn’t be able to absorb nutrients from the foods you eat.

Detailed explanation-5: -Saliva contains special enzymes that help digest the starches in your food. An enzyme called amylase breaks down starches (complex carbohydrates) into sugars, which your body can more easily absorb. Saliva also contains an enzyme called lingual lipase, which breaks down fats.

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