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/