Download Digestive System & Diet

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
Canada’s Food Guide
U.S. Food Pyramid
http://www.udoerasmus.com/pyramid/pyr_usda.htm
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
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 macromolecules.
• 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
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
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 amylase
Maltase
Salivary glands
Pancreas
Small intestine
Maltose
Maltose
Glucose
PROTEINS
Pepsin
Trypsin
Peptidases
Stomach mucosa
Pancreas
Intestinal mucosa
Peptides
Peptides
Amino acids
FATS
Lipase
Pancreas
Fatty acids
and
glycerol
Enzymes by source
SOURCE
ENZYME
FOOD
PRODUCT
MOUTH (salivary glands)
Salivary amylase
Polysaccharides
Maltose
STOMACH
Pepsin
Proteins
Peptides
PANCREAS
Pancreatic amylase
Trypsin
Lipase
Polysaccharides
Proteins
Fats
Maltose
Peptides
Fatty acids
and 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.htm
l
Salivary gland
Teeth
Tongue
Epiglottis
Esophagus
Liver
Stomach
Gall Bladder
Bile duct
Duodenum
Pancreas
Colon
(Large Intestine)
Small Intestine
Appendix
http://www.lessontutor.com/digestive_system4.gif
Rectum
(Anus)
Gall Bladder
Pancreas
Pancreatic Duct
Bile duct
Duodenum
Epithelial Lining
Cells produce enzymes and
absorb digested food
Artery
Lymph vessel
Vein
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/