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Nutrients…• substances in food that provide
energy and materials for cell development, growth, and repair.
Classes of Nutrient - Organic
CarbohydratesCarbohydrates: main source of energy
ProteinsProteins: used for growth. FatsFats: provide energy (stored) helps body absorb vitamins
VitaminsVitamins: organic nutrients that help your body to use other nutrients.
Classes of Nutrients - Inorganic MineralsMinerals: Inorganic nutrients that
regulate many chemical reactions
WaterWater: Enables chemical reactions to take place in your cells.
Enzymes - Reviewspeed up the rate of
chemical reactions
They do this without being changed or used up.
speed up reactions by reducing amount of energy necessary for a chemical change to begin.
Digestive Enzymes
AMYLASE secreted in the mouth; breaks down carbohydrates (starches).
PEPSIN, found in the stomach, breaks down proteins.
Lipase made in pancreas; breaks down fats
Additional Chemical Digestives
• Gastric Juice – found in stomach; very acidic; (3 million times more acidic than your bloodstream) a combination of HCL and Pepsin; breaks proteins
• Bile – made in liver; first process in breaking fats.
Digestion Processes
• Chemical: chemicals in the body break large molecules into smaller ones
• Mechanical: physical, using teeth or muscle to help break food down
The Alimentary CanalMouth - chemical digestion •glands in mouth produce saliva, which contains amylase, which breaks down starch
Mouth• Mechanical Digestion:
– Teeth and tongue break food into smaller pieces
Digestive System
Esophagus: muscular tube connects throat to stomach.
Moves food down by squeezing (peristalsis)
Peristalsis• Rhythmic contraction of esophagus to move
food to stomach.• https://www.youtube.com/watch?v=rJS-Kh5wCQU
Your Digestive SystemStomach: muscular bag
Chemical Digestion: pepsin; gastric acid
Mechanical Digestion: stomach contractions; food stays here ~2-6 hours,
End Product:chyme: afood sludge
Digestive SystemLiver: produces bile; stored in
gallbladder. Bile breaks up large particles of fats into
smaller particles.
Some of Liver’s Jobs
• filters the blood coming from the digestive tract
• detoxifies chemicals and metabolizes drugs.
• secretes bile (breaks down fats)
• makes proteins important for blood clotting
Your Digestive System
Gall Bladder: small sac that stores bile produced by liver (breaks down fats)
Your Digestive SystemPancreas: • produces substances that stop the action of
stomach acid• produces lipase which breaks fats
Pancreas’ Other Jobs• excretes enzymes to break down the
proteins, lipids, carbohydrates, and nucleic acids in food.
• as an endocrine gland, secretes the hormones insulin and glucagon to control blood sugar levels throughout the day.
Digestive SystemSmall Intestine:
digestive juices from liver and pancreas are added
villi increase surface area for absorption of nutritents from chyme
Villi
Small Intestines
• absorbs about 90% of the nutrients from the food we eat.
• only 1 inch in diameter, making it less than half the diameter of the large intestine.
https://www.youtube.com/watch?v=CFjlRhs1rR8
3 Parts of Small Intestine - FYI
• duodenum – connects to the pyloric sphincter of the
stomach.
• Partially digested food, or chyme, from the stomach is mixed with bile from the liver and pancreatic juice from the pancreas to complete its digestion in the duodenum.
3 Parts of Small Intestine - FYI
• The jejunum is the middle section; primary site of nutrient absorption
• The ileum is the final section and completes the absorption of nutrients that were missed in the jejunum.
Digestive System
•Large Intestine: absorbs (removes) water from undigested food; – unabsorbed
materials become more solid (waste - poop).
Your Digestive SystemRectum: where muscles control
the release of wastes from the body
https://www.youtube.com/watch?v=Ujr0UAbyPS4
The Human Digestive System
http://www.dnatube.com/video/8362/Digestive-System-Animation