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 substances They 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
U.S. Food Pyramid http://www.udoerasmus.com/pyramid/pyr_usda.htm
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
Want some fun? Check this out….. http://www.beaconlearningcenter.com/WebLessons/RightTrack/food02a.htm
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
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
Chewed food is mixed with saliva from 3 pairs of salivary glands, the food is now called a BOLUS Salivary Glands http://www.orthop.washington.edu/_Rainbow/Album/10357m30355344-9190-45c7-9cdc-c591f8b17bb5.gif
Food is pushed down the esophagus by muscular waves called PERISTALSIS http://www.innerbody.com/anim/mouth.html http://www.phon.ucl.ac.uk/home/shl10/firmfour/img00003.gif
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
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
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
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.
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.htm l
Salivary gland Teeth Tongue Epiglottis Esophagus Liver Stomach Gall Bladder Duodenum Bile duct Pancreas Colon (Large Intestine) Small Intestine Appendix Rectum (Anus) http://www.lessontutor.com/digestive_system4.gif