Transcript Digestive System

Nutrients…
• substances in food that provide energy
and materials for cell development,
growth, and repair.
Classes of Nutrient - Organic
Carbohydrates: main source of energy
Proteins: used for growth.
Fats: provide energy (stored)
helps body absorb vitamins
Vitamins: organic nutrients that help
your body to use other nutrients.
Classes of Nutrients - Inorganic
Minerals: Inorganic nutrients that
regulate many chemical reactions
Water: Enables chemical reactions to
take place in your cells.
Enzymes - Review
 speed 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 Canal
Mouth - 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 System
Stomach: muscular bag
Chemical Digestion: pepsin; gastric acid
Mechanical Digestion: stomach contractions;
food stays here ~2-6 hours,
End Product:
chyme: afood sludge
Digestive System
Liver: produces bile; stored in gallbladder.
Bile breaks up large particles of fats into
smaller particles.
Some of Liver’s Jobs
•
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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 System
Pancreas:
• 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 System
Small 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=CFjlRhs1
rR8
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 System
Rectum: 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/vi
deo/8362/DigestiveSystem-Animation