Digestive System

Organs of the Digestive System

• mouth rectum• esophagus anus• stomach pancreas• small intestine gall

bladder• large intestine liver

Functions of the Digestive System

• Your cells need a lot of energy. They get energy from the food we eat.

• But, your digestive system has to break down the food we eat into microscopic nutrients before our cells can use it.

Functions of the Digestive System

• Digests food into molecules the body can use (physical or chemical change).

• Absorbs nutrient molecules and carries them around the body (physical change).

• Eliminates waste material from unused nutrients.

mechanical digestion

• mechanical digestion - food is physically broken down into smaller pieces by breaking, crushing and mashing.

• increases the surface area of the food• begins in the mouth

– teeth chewing/tearing– movement of smooth muscles

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chemical digestion

• chemical digestion - chemicals (enzymes)produced by the body break foods into their smaller nutrients.– mouth– stomach

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absorption

• absorption - process by which nutrient molecules pass through the wall of your digestive system into your blood.– The lining of the small intestine is covered

in villi that aid in absorption

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elimination

• elimination – removal of waste material left over after food is digested to prevent illness.

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mouth

• Digestion begins in the mouth– mechanical – teeth– chemical - saliva

salivary gland• salivary gland – gland that produces

enzymes that help to break down food chemically.

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esophagus• esophagus - muscular tube that

connects your mouth to your stomach.– moves food down into your stomach using involuntary muscle contractions

(peristalsis).– Lined with mucus that allows food to slide down.

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stomach• stomach – a muscular bag that crushed

food and contains acids and enzymes for breaking down food.

• Most mechanical digestion takes place in the stomach because it is made of thick smooth muscle.

• Chemical digestions also takes place• Mucus keeps the acids from burning a

hole in your stomach.

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Stomach

small intestine• small intestine – muscular tube where

most of the chemical digestion takes place and most nutrients are absorbed.

• Covered in villi which

enlarge the surface area

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small intestine

The villi increase the surface area that can absorb nutrients.

liver• liver – large organ that produces bile

and breaks down medicines and other chemicals.

• The gall bladder

stores bile

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pancreas• pancreas - secretes insulin to carry

glucose around the body and makes enzymes that help digest food.

• Causes diabetes when it does not make insulin.

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large intestine

• large intestine – muscular tube where vitamins B and K are made and water is removed from food waste.

• Food spends 18-24 hours here

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rectum and anus

• rectum – end of the large intestine, forms the solid waste– elimination

• anus – muscular opening at the end of the rectum– elimination

The digestive system interacts with:

• muscular system (smooth muscle) to move and digest food.• respiratory system to provide oxygen.• circulatory system to move nutrients.

Which cell parts are like the digestive system?

Which one makes energy?

Which one helps get rid of waste?

mitochondria

lysosomes

Which one allows materials to pass in and out?

cell membrane