Digestive System & Diet
SBI 3U
Ms. Raper
All organisms need to obtain energy from essential nutrients.Heterotrophs get energy from other organisms.
Plants are Autotrophs, they make food from simple substancesThey use the process of photosynthesis to make food.
What is Diet?• Diet is
everything you eat and drink
Different food groups
• Carbohydrates– Starches– Sugars– Fiber
• Proteins• Fats & lipids• Vitamins & Minerals• Water
Healthy Diet
http://www.hpb.gov.sg/data/hpb.home/media/images/haz/healthy_diet_pyramid.jpg
Canada’s Food Guide
http://www.udoerasmus.com/pyramid/pyr_usda.htm
U.S. Food Pyramid
http://www.colorado.edu/studentgroups/wellness/NewFiles/MedFoodPyramid.gif
Vegetarian Food Pyramid
http://www.vegetarian-diet.info/images/vegetarian-food-pyramid.jpg
http://www.ariseandshine.com/templates/user/default/images/Vegetarian-Food-Pyramid1.jpg
Heart Healthy Pyramid
http://www.ariseandshine.com/templates/user/default/images/Vegetarian-Food-Pyramid1.jpg
Indian Food pyramid
http://www.diabetesindia.com/diabetes/images/nonveg_triangle.jpg
http://www.beaconlearningcenter.com/WebLessons/RightTrack/food02a.htm
Want some fun? Check this out…..
How much do you need?• Food provides nutrients for
– Energy– Material for growth and repair– Health
• Energy is measured in Joules (J)• Number of joules/day depends on:
– Age– Gender– Occupation/activity level
The 5 processes....• Ingestion: taking in food (eating)• Digestion: breaking down food into simpler
substances.• Absorption: digested food passes into the
blood.• Assimilation: Digested food is used by
cells of the body.• Egestion: Elimination of waste undigested
food.
What happens to the food you eat?
• Food is made of complex insoluble macro-molecules.
• Has to be broken down into small soluble micro-molecules (glucose, amino acids, fatty acids and glycerol)
• Breaking down food into small soluble molecules is called DIGESTION.
Digestion
• Two types– Mechanical– Chemical
• Mechanical– Teeth– Muscular contractions
• Chemical– Enzymes
http://www.sara-jordan.com/img/a-canal2.jpg
Digestive system
• A long tube starting at the mouth and ending at the anus
The digestive system consists of
• A tube lined with glandular cells that secrete digestive juices and enzymes
• Associated organs– Liver– Pancreas– Gall bladder– Salivary glands
Mouth• Mechanical digestion
– Teeth break food into smaller pieces that increases the surface area for digestion
– Saliva creates a basic pH of about 8 & moistens food allowing soluble chemicals to dissolve.
• Chemical digestion– 3 pairs of Salivary glands produce the
enzyme AMYLASE – this begins the breakdown of STARCH
Salivary Glands
• Chewed food is mixed with saliva from 3 pairs of salivary glands, the food is now called a BOLUS
http://www.orthop.washington.edu/_Rainbow/Album/10357m30355344-9190-45c7-9cdc-c591f8b17bb5.gif
Swallowing…
http://www.sghhealth4u.com.sg/Health4U/otolaryngology/Tour_images/swallowing.gif
http://www.dysphagiaonline.com/en/images/Swallowing_Mechanism.jpg
http://www.phon.ucl.ac.uk/home/shl10/firmfour/img00003.gif
Food is pushed down the esophagus by muscular waves called PERISTALSIS
http://www.innerbody.com/anim/mouth.html
Peristalsis
http://www.biotech.um.edu.mt/home_pages/chris/GIT/GITimages/Peristalsis.jpg
The Stomach• Food enters the stomach
through a valve known as the
CARDIAC SPHINCTER• The stomach churns the
food like a blender.• Food is liquefied and now
is known as CHYME• Food stays in the
stomach for several hours
http://www.yourdictionary.com/images/ahd/jpg/A4stomac.jpg
The stomach• “Epithelial cells line inner surface of the stomach, and
secrete about 2 liters of gastric juices per day. Gastric juice contains hydrochloric acid, pepsinogen, and mucus; ingredients important in digestion. Secretions are controlled by nervous (smells, thoughts, and caffeine) and endocrine signals. The stomach secretes hydrochloric acid and pepsin. Hydrochloric acid (HCl) lowers pH of the stomach so pepsin is activated. Pepsin is an enzyme that controls the hydrolysis of proteins into peptides. The stomach also mechanically churns the food. Chyme, the mix of acid and food in the stomach, leaves the stomach and enters the small intestine.”
http://www.emc.maricopa.edu/faculty/farabee/biobk/BioBookDIGEST.html
The Pancreas
• Produces digestive juices through the pancreatic duct.
• Produces enzymes that digest carbohydrates, proteins and fats.
• Produces bicarbonate salts to neutralize the stomach acid.
• The pancreas is also an endocrine organ that produces insulin and glycogen to help in the metabolism of sugar
http://www.yourdictionary.com/images/ahd/jpg/A4pancre.jpg
Gall bladder
• Lies under the liver• Stores bile – a
greenish liquid• Bile emulsifies fats.• Has a common duct
with the pancreas
http://gensurg.co.uk/images/Biliary%20anatomy%20-%20hsk.jpg
http://www.emc.maricopa.edu/faculty/farabee/biobk/BioBookDIGEST.html
Small Intestine
• The small intestine is where final digestion and absorption occur. The small intestine is a coiled tube over 3 meters long. Coils and folding plus villi give this 3m tube the surface area of a 500-600m long tube. Final digestion of proteins and carbohydrates must occur, and fats have not yet been digested. Villi have cells that produce intestinal enzymes which complete the digestion of peptides and sugars. The absorption process also occurs in the small intestine. Food has been broken down into particles small enough to pass into the small intestine. Sugars and amino acids go into the bloodstream via capillaries in each villus. Glycerol and fatty acids go into the lymphatic system. Absorption is an active transport, requiring cellular energy.
http://www.emc.maricopa.edu/faculty/farabee/biobk/BioBookDIGEST.html
Small intestine continued
• Has an increased surface area due to fingerlike projections called VILLI
• Produces enzymes that complete the digestion of carbohydrates, proteins and fats.
• Consists of 3 areas– Duodenum– Jejunum– Ileum
Villi
Villus
http://www.colorado.edu/kines/Class/IPHY3430-200/image/villi.jpg
Absorption in Villi
Liver
http://www.liverdoctor.com/images/detox_pathways.jpg
Liver…
• Detoxifies poisons such as alcohol
• Stores glycogen
• Deanimates proteins (breaks them down into urea)
• Produces bile salts
• Recycles hemoglobin from red blood cells
• Produces heat
Large Intestine & Appendix
• Comprised of the ascending, transverse, descending and sigmoid colon
• Absorbs water, vitamins and minerals
• Stores waste (feces)
• Eliminates feces through the anus
http://www.mobyhealth.com/sub/graphics/colon.jpg
Appendix/caecum
• In humans the appendix has no known function.
• In herbivores such as rabbits the appendix or caecum is used to digest cellulose.
Conclusion: 5 steps of the process..
• Ingestion - taking in food.
• Digestion – breaking down food.
• Absorption – digested food goes into the blood.
• Assimilation – digested food is used by the body.
• Egestion:- Elimination, waste is removed from the body.
Summary of Digestive Enzymes
FOOD TYPE ENZYME SOURCE PRODUCTS
CARBOHYDRATES Salivary amylase Pancreatic amylaseMaltase
Salivary glands PancreasSmall intestine
Maltose MaltoseGlucose
PROTEINS Pepsin TrypsinPeptidases
Stomach mucosa Pancreas Intestinal mucosa
Peptides PeptidesAmino acids
FATS Lipase Pancreas Fatty acidsand glycerol
Enzymes by source
SOURCE ENZYME FOOD PRODUCT
MOUTH (salivary glands) Salivary amylase Polysaccharides Maltose
STOMACH Pepsin Proteins Peptides
PANCREAS Pancreatic amylase TrypsinLipase
Polysaccharides ProteinsFats
Maltose PeptidesFatty acidsand glycerol
SMALL INTESTINE Maltase Peptidases
Maltose Peptides
Glucose Amino acids
Resources
http://www.innerbody.com/htm/body.html
http://health.howstuffworks.com/adam-200142.htm
http://www.northarundel.com/aniplayer/
http://www.wiley.com/legacy/college/bio/tortora366927/resources/student/anatomydrill/ch24.html
http://www.besthealth.com/besthealth/bodyguide/reftext/html/dige_sys_fin.html
http://www.lessontutor.com/digestive_system4.gif
Teeth
Epiglottis
Liver
Gall Bladder
Bile duct
Colon(Large Intestine)
Appendix
Salivary gland
Tongue
Esophagus
Stomach
Duodenum
Pancreas
Small Intestine
Rectum(Anus)
Gall Bladder Pancreas
Duodenum
Bile duct
Pancreatic Duct
Artery
Vein
Lymph vessel
Epithelial LiningCells produce enzymes and
absorb digested food
Digestion of Starch
“Carbohydrates are digested in the mouth, stomach and small intestine. The saliva in your mouth contains amylase. If you chew a piece of bread for long enough, the starch it contains is digested to sugar, and it begins to taste sweet.” BBC. Bitesize biology,
http://www.bbc.co.uk/schools/ks3bitesize/science/biology/diet_4.shtml
Digestion of Proteins
“Proteins are digested in the stomach and small intestine. Digestion of proteins in the stomach is helped by stomach acid, which is strong hydrochloric acid. This also kills harmful micro-organisms that may be in the food.” BBC; bitesize biology.
http://www.bbc.co.uk/schools/ks3bitesize/science/biology/diet_4.shtml
Digestion of Fats (lipids)
“Digestion of fat in the small intestine is helped by bile, made in the liver. Bile breaks the fat into small droplets that are easier for the lipase enzymes to work on.” BBC; bitesize Biology
http://www.bbc.co.uk/schools/ks3bitesize/science/biology/diet_4.shtml
http://www.bbc.co.uk/schools/ks3bitesize/science/biology/diet_5.shtml
http://www.bbc.co.uk/schools/ks3bitesize/science/