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DIGESTIVE SYSTEM (DIGESTION
• The mechanical and chemical
breakdown of…
DIGESTIVE SYSTEM
DIGESTION
• The mechanical and chemical
breakdown of complex biological
molecules into their component parts.
• Lipids to fatty acids
• Proteins to individual amino acids
• Carbohydrates into simple sugars
• Nucleic acids into nucleotides
-
CHEMICAL DIGESTION
• Changes the chemical composition of food
with the aid of digestive enzymes
Carbohydrate
Protein
Lipid
• Digestive enzymes are special proteins that
help break up large molecules of food into
very tiny molecules that can be absorbed
and used by the cellss in the form of
nutrition.
FUNCTIONS
• Produces various chemicals to break
down the food
• Filters out harmful substances.
• Gets rid of solid wastes.
• Absorb nutrients
-
THE DIGESTIVE TRACT
•A long muscular tube
with many sections
and areas.
• Begins with the
mouth and ends with
the anus.
THE DIGESTIVE TRACT
• Food moves through the digestive system by the movement of smooth muscle – Peristaltic movement or Peristalsis.
PARTS OF THE DIGESTIVE TRACT:
•Mouth
• Pharynx
• Esophagus
• Stomach
• Small Intestine
• Large Intestine
•Anus
ACCESSORY PARTS
Organs that are not in the digestive
tract but helps in the digestion
•Teeth
•Tongue
• Salivary glands
• Liver
•Gall bladder
• Pancreas
MOUTH
• Functions:
Food enters in the
mouth/oral cavity
Tasting
Mechanical breakdown of
food
Secretion of salivary
glands (salivary amylase)
STRUCTURES IN THE MOUTH
• Teeth – cut, tear, crush and grind food.
• Salivary glands
produce and secrete saliva into the oral
cavity.
saliva moistens the food and contains
enzymes that begins digestion of starch
into smaller polysaccharides
PHARYNX
• The pharynx is located behind the mouth
and nose
• AKA throat.
• When food is pushed to the back of the
mouth, the trachea closes, and the food
moves into the pharynx.
• Then, a combination of both voluntary and
involuntary muscles work to swallow the
food, forcing it into the esophagus
EPIGLOTTIS
• A flap of tissue that covers the trachea when you swallow so food doesn't enter
• Is a part of the Pharynx
ESOPHAGUS:
• A straight muscular tube
that is about 25 cm long
which connects the mouth
with the stomach
• Food takes about 4 to 8
seconds as it passes
through to the stomach.
• Its walls contain muscles
that contracts in wavy
motion.
STOMACH:
• J-shaped muscular sac
• Has inner folds (rugae) that increases
the surface area of the stomach.
• Food is mixed with gastric juices
(hydrochloric acid and enzymes)
secreted by the stomach walls.
LIVER – ACCESSORY ORGANS:
• Largest gland of the
body
• Stores vitamins A,D,E,K
• Stores sugar and
glycogen
• Produces bile
• Secretes bile to the gall
bladder
GALLBLADDER – ACCESSORY ORGANS:
• Stores and secrets bile in between
meals
• Bile is an emulsifier – dissolves fat
into the watery contents of the
intestine.
PANCREAS – ACCESSORY ORGANS:
• Produces a juice that contains
enzymes to break down
carbohydrates, fats and protein.
SMALL INTESTINE:
• Long, coiled tube beneath the stomach.
• Has three parts:
• Duodenum – upper part; connected d to the
stomach - where the digestive juices s from
the pancreas and the liver combine with
chime making it thin and watery.
• Jejunum
• Ileum
SMALL INTESTINE:
• Takes about 4 to 8 hours to complete its
journey.
• Mucosa (inner wall) – secretes several
enzymes that acts on the food.
• Digested nutrients are absorbed through
intestinal walls.
• Absorbed materials cross the mucosa a into
the blood then other parts of the body for
storage or further chemical change.
LARGE INTESTINE:
• A.k.a. Colon
• larger diameter, but shorter
•Water is absorbed from the
undigested food making the waste
harder until it becomes solid.
•Waste stays for 10 to 12 hours.
LARGE INTESTINE:
•Waste is pushed into the expanded
portion (rectum) of the large intestine.
• Solid waste stays in the rectum until it is eliminated through the anus as
feces.