How does mechanical digestion occur in the stomach?

Answer 1

I'm going to assume by "mechanical" digestion you're referring to the functions that take place in the stomach.

When food enters the stomach, it is broken down by hydrochloric acid (there are a few other enzymes included in the acid that assist in the break-up) churning in the stomach. As the process begins, the parietal cells (the cells that produce hydrochloric acid) begin to secrete 'intrinsic factor'. This allows for the body to absorb B12 which will be needed when the remainder of the food product makes its way into the small intestine.

The hydrochloric acid mixture continues to take apart the food product - stripping it of its nutrients so that the body can absorb them. Larger nutrient molecules make their way to the small intestine (they are able to do this because their nutrients are not able to be absorbed by the stomach) and further digestion takes place.

Answer 2

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As far as your question on mechanical digestion goes...you are right in saying churning is an aspect of stomach mechanical digestion. Here is why it is important. Imagine whatever food you ate, chewed, & swallowed sitting inside your stomach as a solid ball. When the gastric acid is secreted from the walls of the stomach, the HCl can only work on the surface area of the ball, leaving the interior of the 'food ball' unaffected. Churning and mixing of the food solves this problem by mixing the gastric acid with the food, and basically increasing the surface area available to gastric acid. Now chemical digestion of the stomach. The main chemicals to pay attention to here are gastric acid (a mixture containing HCl from parietal cells) and pepsinogen (from chief cells), both being secretions from the stomach wall (but from different cell types). Gastric acid plays a two part role in the stomach. First, it kills bacteria in the food by exposing them to a highly acidic environment (even more reasons for mechanical digestion) and second, it lowers the pH of the stomach contents enough to activate pepsinogen (pepsinogen's active form is called pepsin (usually the suffix -ogen denotes a precursor molecule). Pepsin's job is to start digesting proteins in the stomach. (There is very little digestion of much else other than proteins in the stomach, although startches (like bread, etc.) starts being broken down into sugars as early as the mouth by saliva components.Pepsin breaks food proteins down into peptides, which are small chains of amino acids (your building blocks of all proteins). The liver and gall bladder do not come into play until the small intestine, after the stomach. The gall bladder is a gland in the liver that stores bile, which is produced by liver cells (Hepatocytes) & moved to the gall bladder, where it waits to be moved to the sm. intestine. Once again, it has more than one role. Its first role is to raise the pH back up from its acidic state achieved back in the stomach (a big portion of bile is a watery base). The second is to help with digestion of fats. Basically, we can use the same analogy we used earlier to explain mechanical digestion. When fats are present in chyme, they exist as big blobs that stick together (think of oil in water). The salt portions of bile act to break up these big blobs into smaller and smaller blobs, until they are small enough to be absorbed, more or less, through the small intestine wall. Phew. Hope that helps

Answer 3

mechanical as well as chemical digestion occurs in the stomach.this is bcos the stomach is a muscular bag like structure.the circular and longitudinal muscles bring about peristaltic movements that help churn the food.and it is these movements that help move the food bolus forward. as far as mechanical digestion is concerned this is it. whatever occurs thereafter is chemical digestion.

Answer 4

Your stomach is outlined with muscle tissue that will move while trying to digest anything that you consumed-- by doing so, the food that you consumed will degrade with the help of acid, at a faster rate, thus getting ready for the next steps in digestion.

Answer 5

mechanical digestion doesn't occur in the stomach- CHEMICAL digestion does!
mechanical is when YOU are forcing it to happen- Chemical is where it automatically takes place!
Good question!

Answer 6

Mechanical digest occurs becuase muscular bands in teh somach contract and relax

Answer 7

Churning. The movement of the stomach muscles so that the gastric juices and the enzymes in the stomach mixes with the food to create chyme.

Answer 8

Storage: The stomach can change its volume to ten times its resting volume so that food can be stored temporarily in order for it to be just ‘trickled’ into the small intestines

ii. Mixing: Mixes food with gastric juice

iii. Movement of food into the duodenum at the appropriate rate

Answer 9

It just does. Deal with it.