Download The Digestive System

Unit 2: Internal Systems
Components of
The Digestive System I
Components of the Digestive System
Homework take-up
Teeth:
Incisors (8)
Canines (4)
Premolars or bicuspids(8)
Molars (12)
Components of the Digestive System
Tongue:

Different parts of the
tongue are able to taste
one of four basic tastes.
sour
salty
bitter
sweet
Components of the Digestive System
Kinds of Teeth
Canines
Description
 long & pointy
 sharp
Function
 rip/tear
 very developed in predators
Incisors
 wide, but very thin
 bumps on bottom edges
Premolars
 flat & broad
 have 2 bumps on
surfaces called cusps
(bicuspids)
 grinding & mashing
 flat & broad
 have 4 cusps
 grinding & mashing
Molars
 cut like knives for biting
Components of the Digestive System
enamel
crown
(above
gums)
gingiva (gums)
pulp (cavity)
nerve endings
periodontal
membrane
root
dentin
(under gums)
root canal
nerve
artery
vein
Components of the Digestive System
enamel
Mouth
i. Teeth:
 enamel:
 contains calcium
 makes it the hardest substance in the body
 caries:
 tooth decay in enamel (cavity)
 caused by: i) acids produced by bacteria
ii) grinding

dentin:
 bone-like substance surrounding pulp
 pulp cavity:
 contains nerves & blood vessels
dentin
pulp (cavity)
root canal)
caries
Components of the Digestive System
Teeth:(continued)
 pulpitis:
 tooth ache caused by
inflammation of the pulp
 gingivitis:
 inflammation of the gums
 results in periodontal disease
 plaque:
 sticky film of bacteria & food
between gums & teeth
 removed by flossing
 root canal:
 dentist removes infected pulp &
sterilizes tooth
 keeps tooth alive
Components of the Digestive System
Organ
Comments
1. Mouth
opening to digestive
system
a) Teeth
Function
ingestion
different shapes for
tearing & grinding
physical
digestion
Components of the Digestive System
Organ
Comments
b) saliva
made by 3 pairs of
salivary glands
secrete saliva into
oral cavity
Parotid gland
Submandibular gland
Sublingual gland
Function
contains:
1. water:
to dissolve
food
2. mucus:
lubricates food
(makes it slippery)
3. salivary amylase:
enzyme which
digests starch
i.e. into mono &
disaccharides
.
Components of the Digestive System
Organ
c) tongue
Comments
very strong muscle
contains large
numbers of taste buds
bolus: ball of chewed
food
nerve endings
Function
1.sensory: taste &
temperature control
2. physical digestion:
chewing & mixing
food with saliva
3. swallowing:
a.pushes bolus up
& to the back of
the pharynx
b.causes epiglottis
to block trachea
4. speech
.
Components of the Digestive System
Organ
Comments
Function
d) epiglottis
flap of tissue at the
base of the tongue
above the trachea
prevents food from
going into lungs
(down windpipe) to
avoid choking
2) pharynx
back of the throat
common
passageway for
food & air
.
Components of the Digestive System
Organ
Comments
3) esophagus
narrow tube about 30
cm long connecting
pharynx to stomach
contains 2 muscle
layers which relax and
contract rhythmically for
peristalsis
Function
1. leads food into
stomach
2. ensures that food
(bolus) is pushed
into stomach
(mucus glands help
wave-like contractions
lubricate the bolus)
produced by circular &
longitudinal muscles
Components of the Digestive System
.
Components of the Digestive System
Organ
4) cardiac
sphincter
Comments
at the entrance of the
stomach
*sphincters: rings of muscles
(open/close)
heartburn: pain from
splashing of gastric acid into
the esophagus
5) pyloric
sphincter
pyloric sphincter
at the end of the stomach
cardiac
sphincter
Function
closes during
digestion to prevent
backflow of gastric
juice into esophagus
closes during
digestion to keep
chyme (semidigested food) in
stomach(2-3 hrs)
opens to allow
chyme to enter
small intestine
.
Components of the Digestive System
Organ
Comments
6) stomach
glands in lining make
gastric juice containing:
tough muscular bag
(j-shaped)
lined with 3 layers of
muscles to churn & mix
food with gastric juice
Function
1. hydrochloric acid:
a) physical digestion of
fibrous tissue
b) kills bacteria
c) dissolves minerals
d) converts pepsinogen
into pepsin (active)
ulcer:
wound in the
2. pepsin: enzyme
stomach lining
which breaks down
due to high acidity
proteins into amino
& low mucus
acids
3. mucus: thick layer to
chyme:
semi-digested
protect stomach wall
food (very acidic) from acid & pepsin
Components of the Digestive System
cardiac
sphincter
duodenum
pyloric
sphincter
oblique
muscles
circular
muscles
longitudinal
muscles
Components of the Digestive System
glands in stomach lining
ulcer in stomach lining
ENDOSCOPE VIDEOS
ACID REFLUX
GASTRIC FOLDS
STOMACH LINING & GASTRIC JUICE
ENDOSCOPE VIDEOS
STOMACH ULCER
MULTIPLE STOMACH ULCERS
Homework
 Page 212 Questions # 1-3
 Page 214 Questions # 1-2,4-6
 Page 216 Questions # 1-3