Transcript The DIGESTIVE System

The DIGESTIVE System
Digestion defined
Breakdown of food into useable
nutrients
Two kinds
Mechanical
Chemical
Chemical Vs Mechanical Digestion
Chemical: Enzymes break down for
absorption--ENZYMES
Mechanical: broken down into
smaller parts--MASTICATION AND
MACERATION
Alimentary canal
Tube food passes
through
Begins at mouth ends with anus
Food is chewed
Bolus created
Bolus swallowed
Pharynx
Bolus moves into
pharynx
fancy word for
throat
has three parts
– Nasopharynx
– Oropharynx
– Laryngopharynx
Esophagus
8-12 inches long
Smooth muscle
contractions called:
Peristalsis-rhythmic
Cardiac (aka
Gastroesophageal)
sphincter
Has no mucous
membrane to protect
from Hcl from stomach
Stomach
J-shaped
3 sets of muscle in different
directions
Hcl= chemical breakdown
Pepsin begins protein
disgestion
Contain rugae to increase
surface area
Change bolus into chyme
Mucus protects stomach
lining
Small intestine
3 parts
Duodenum--most chemical
digestion takes place here
Jejunum-absorption
continues
Ileum absorption continues
15-22 ft long
Absorbs some of the water
in food & what you drink
Villi
Nutrients are absorbed through structures
called villi
Large intestine
called the colon
Main function
water absorption +
Vit K absorption
Begins with cecumcontains lymphatic
organ called
appendix
Ascending colon
Large intestine
Ascending colon
Transverse colonmakes hunger
sounds
Descending colon
Sigmoid colon
Rectum
Anal canal
Anus
Accessory organs
CONTRIBUTE to digestion process
NOT part of the canal or tube
Food DOES NOT pass through them
Tongue and teeth
Teeth break food
down into smaller
pieces
Tongue moves food
to the back of throat
Parts of a tooth
Crown = exposed
portion above gum
line
Neck = between
crown & root
Gingivae-gums
Root = one to three- embedded in
mandible &
maxillae
Parts of a tooth
Enamel = outermost
part, protects from
wear & tear
– the hardest substance
in the body
Dentin = calcified
connective tissue
Gives tooth it’s basic
shape & rigidity
Parts of a tooth
Pulp Cavity = large
cavity enclosed by
dentin--filled with
pulp
Cementum = a
bone-like substance
covers--dentin of
roots
Parts of a tooth
Periodontal
Ligament
an area of dense
fibrous connective
tissue
anchors teeth in
position
serves as a shock
absorber when
chewing
Salivary glands
Saliva is:
Mostly water
Enzymes that digest
carbs—Amylase—
breaks starch into
maltose
Soften and moisten
food
Salivary glands
6 total--3 pair
Parotid,
submandibular,
and sublingual
Liver and Gall Bladder
Liver makes bile
Bile is stored in gall
bladder (sac)
Bile breaks down
fats--emulsification
Secreted as it is
needed
Eliminated through
intestines
Pancreas
Located posterior to
stomach
Secretes enzymes to
chemically breakdown
fats, carbs, and
proteins
Increases pH of chyme
Pancreatic juice—thru
pancreatic duct—thru
heptopancreatic
sphincter
Mastication
Chewing--makes
bolus
Teeth mechanically
break down food
Food is mixed with
saliva
Deglutition
Swallowing
Tongue pushes food to
back of throat
Oropharynx--second
part of throat
Smooth Muscles
contract causing
peristalsis
Voluntary
Peristalsis
General term for
wave-like
contractions in
esophagus and
intestines
Rhythmic smooth
muscle contractions
Maceration
Stomach contracts
and Bolus mixed
with gastric juices
and Hcl until it is
liquid-like
Bolus is changed to
chyme
Empties through
pyloric sphincter
Segmental contraction
Each segment of
small intestine
contracts
Helps mix bile and
pancreatic juices
with chyme
Smooth Muscle
contractions
peristalsis in each
segment
Absorption
Nutrients absorbed in
jejunum and illeum
Some nutrients &
water absorbed thru
stomach
Some water absorbed
through small intestine
Most water absorbed
through large intestine
Haustral churning
Each segment in
large intestine is
called a haustra
Smooth muscle
contractions move
contents along
(type of peristalsis)
Water is absorbed
in large intestine
Defecation
Elimination of
material that is
undigestible
Plant fiber-necessary for health
of the intestines
Formation of feces
and elimination of
feces
Nutrients are broken down in different
places in digestive system
Carbohydrates
Begin digestion in
mouth with enzyme
AMYLASE from
salivary glands
Amylase breakdown
continues in stomach
Finish breakdown in
duodenum (pancreatic
juice)
Fats
Fats begin mixing with
gastric juices in
stomach
Bile from gall bladder
goes into small
intestine to break them
down
Pancreas secretes
enzymes (lipase) to
finish chemical
breakdown
Proteins
Begin mixing with
pepsin in stomach
Finish with
secretions from
pancreas into
duodenum
Digestion system End