How digestion starts

Chewing breaks food into smaller bits and mixes it with saliva. Saliva wets the food and contains amylase, an enzyme that starts splitting starch. The tongue shapes a bolus and swallowing sends it down the oesophagus.

Swallowing is a reflex once it starts. A flap, the epiglottis, covers the windpipe so the bolus goes to the stomach and not the lungs. The oesophagus squeezes in a wave, peristalsis, so food moves even if you are not upright.

Mouth and stomach

The stomach is a muscular bag. It churns food with acid and with pepsin, an enzyme that begins on proteins. The acid also kills many microbes that rode in with the meal. A ring of muscle at the top usually stops the acid coming back up.

The result, a soupy mixture called chyme, is released a little at a time into the small intestine. Bile from the liver, stored in the gallbladder, helps break fats into droplets. The pancreas adds enzymes for starch, protein, and fat, plus bicarbonate to neutralise the acid.

Into the intestine

The small intestine’s lining is folded into villi, tiny fingers that give a huge surface. Digested sugars, amino acids, and fats cross that surface into the blood or the lymph. What cannot be absorbed passes to the large intestine, which takes back water.

This is the route, not a diet. Different foods take different times, and the organs do the same jobs whether the meal was plain or rich.

Mouth and stomach

Digestion begins in the mouth and continues as a chain of chemical breakdowns. The aim is to turn food into pieces the blood can carry. Chewing breaks food into smaller bits and mixes it with saliva. Saliva wets the food and contains amylase, an enzyme that starts splitting starch.

Put those two statements side by side. The first sets the condition. The second says what happens once that condition is met. How digestion starts needs both. Drop the first and the second has nothing to explain. Drop the second and the first is only the scene.

Into the intestine

Saliva wets the food and contains amylase, an enzyme that starts splitting starch. The tongue shapes a bolus and swallowing sends it down the oesophagus.

The order is the explanation. What the first sentence names has to be there before the result in the second sentence can show up. The piece does not ask you to accept the result first and hunt for a cause afterwards.

A check you can make

The tongue shapes a bolus and swallowing sends it down the oesophagus. Swallowing is a reflex once it starts.

A fair check is sequential. Confirm the first statement. Then see whether the second is the result of it, rather than a separate fact parked in the same piece. If the result shows up without the condition, this account does not cover what you are looking at.

The limit of the claim

Swallowing is a reflex once it starts. A flap, the epiglottis, covers the windpipe so the bolus goes to the stomach and not the lungs.

The two statements do different jobs. One says what is there, what it is made of, or what acts on it. The other says the change that follows. The title names the change. It is not an inventory of parts.

The same steps, in order

A flap, the epiglottis, covers the windpipe so the bolus goes to the stomach and not the lungs. The oesophagus squeezes in a wave, peristalsis, so food moves even if you are not upright.

Nothing in the second statement cancels the first. It carries the first forward or marks the limit of it. Remember only the result, and the cause goes missing. Remember only the cause, and you will not know what the piece says happens next.

Why the order matters

The oesophagus squeezes in a wave, peristalsis, so food moves even if you are not upright. The stomach is a muscular bag.

Read them as one path. Start at the first full stop and do not skip to the outcome. The words between the two statements are the mechanism. The title is the name of that path, not a second claim.

Condition, then outcome

The stomach is a muscular bag. It churns food with acid and with pepsin, an enzyme that begins on proteins.

The first statement can be true and still not finish the job. The second statement is the job finishing. Hold both, and the paragraph above stops being a list. It becomes the reason the title is worded as it is.

What the title is naming

It churns food with acid and with pepsin, an enzyme that begins on proteins. The acid also kills many microbes that rode in with the meal.

If you wanted a shorter version, it would be those two sentences and nothing else. Everything added around them is there so the dependence is obvious: the second does not happen unless the first has happened.

What has to come first

The acid also kills many microbes that rode in with the meal. A ring of muscle at the top usually stops the acid coming back up.

Put those two statements side by side. The first sets the condition. The second says what happens once that condition is met. How digestion starts needs both. Drop the first and the second has nothing to explain. Drop the second and the first is only the scene.