Digestive System Nutrients Substances in food that provide

Digestive System

Nutrients • Substances in food that provide raw materials and energy the body needs to live • Our digestive system turns the chemical energy in these nutrients into energy we can use

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

Digestion • body breaks down food into small nutrient molecules – mechanical – chemical

Mechanical Digestion • Food is physically broken down into smaller pieces • Begins in the mouth – Teeth chewing/tearing – Movement of smooth muscles

Chemical Digestion • Chemicals produced by the body break foods into their smaller nutrients – mouth – stomach

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

Elimination • Materials that are not absorbed leave the body as waste • The waste material left over after food is digested must leave the body to prevent illness

Which is not a function of the digestive system? a) b) c) d) Breaking down food into molecules the body can use Absorbing food molecules into the blood to deliver to the body Changing waste into molecules the body can use Eliminating undigested waste from the body

Organs of the Digestive System • • • Mouth Esophagus Stomach Small intestine Large intestine Rectum Anus Pancreas Gall Bladder Liver

Mouth • Digestion begins in the mouth – Mechanical – teeth – Chemical - saliva

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

The Stomach • J-shaped muscular pouch • Most mechanical digestion takes place in the stomach • Chemical digestions also takes place – Stomach secretes digestive juice (enzymes) that break down food • Average adult stomach holds 2 liters • Mucus keeps the acids from burning a hole in your stomach

Stomach

Modeling • Place the marble in the end of the tube and squeeze it down into the balloon.

Modeling • What do you think this could be a model of? – What is the tube? esophagus – What is the balloon? stomach – What is the marble? food – What is the soap? saliva and mucus

Which is not an example of mechanical digestion? a) Teeth chewing food b) Tongue breaking up food c) Smooth muscles in stomach churning food d) Hydrochloric acid breaking down proteins

Small Intestine • Where most of the chemical digestion takes place • Where most of the absorption takes place • Covered in villi which enlarge the surface area

Small Intestine a) Most digestion happens here. b) Intestinal juice (full of enzymes) breaks down food. c) Digestive Helpers • Liver, Gall bladder, Pancreas d) Digested food is absorbed through the villi into a network of blood vessels that carry the nutrients to all parts of the body. e) By the time food leaves the small intestine, it is empty of all nutrients except water.

Small Intestine The villi increase the surface area that can absorb nutrients

Where does most digestion take place? a) b) c) d) Mouth Stomach Small intestine Liver

Liver • Breaks down medicines and other chemicals • Produces bile that breaks up fat particles • The gall bladder stores bile

Pancreas • Produces enzymes that flow into the small intestine • Secretes insulin • Causes diabetes when it does not make insulin

Large Intestine • • Last section of the digestive tract Food spends 18 -24 hours here Where water is absorbed Vitamins B & K are made by bacteria in the large intestine

Rectum and Anus • Rectum – end of the large intestine, forms the solid waste – elimination • Anus – muscular opening at the end of the rectum – elimination

Which cell parts are like the digestive system? Which one makes energy? mitochondria Which one allows materials to pass in and out? cell membrane Which one helps get rid of waste? lysosomes

The Digestive System Interacts with: • muscular system (smooth muscle) to move and digest food • respiratory system to provide oxygen • circulatory system to move nutrients