Download The Digestive System

Unit 3: Animal Anatomy &
Physiology
The Digestive System
Digestive System
• responsible for 4 major functions:
1.
ingestion
• intake of nutrients (eating)
2.
digestion
• the breakdown of food into small soluble molecules
a) physical digestion: (ex.) chewing
– mechanical digestion that cuts food into small pieces
– smaller pieces increase surface area for enzymes to work on
Digestive System
4 major functions (continued):
b) chemical digestion: ex. digestive secretions (saliva)
food
monomers
• enzymes in digestive juices chemically breakdown food molecules into
their monomers (soluble)
Digestive System
b) chemical digestion: (continued)
i) carbohydrates
i.e. polysaccharides
monosaccharides
&
disaccharides
Digestive System
b) chemical digestion (continued):
ii) proteins
amino acids
Digestive System
b) chemical digestion (continued):
iii) lipids
Digestive System
4 major functions (continued):
3.
absorption
• the uptake of nutrient molecules, first into the
cells of the small intestine
• then into the blood stream
4. Egestion:
• removal of solid undigested material (feces) from
anus
 eating cellulose (fiber) helps
** Excretion (part of the excretory system)
• removal of liquid soluble waste (urine) from the
bladder via urethra
Components of the Digestive System
digestive tract (alimentary canal)
really just a very long tube (~ 9 m long)
takes food ~ 24 - 33 hours to go through digestive tract
Mouth
Liver
Esophagus
Stomach
Gall Bladder
Pancreas
Small Intestine
Large Intestine
Rectum
Anus
Components of the Digestive
System
Organ
Comments
1. Mouth
opening to digestive
system
a) Teeth
different shapes for
tearing & grinding
Function
ingestion
physical
digestion
Mouth (Oral Cavity)
Components of the Digestive System
Teeth:
Incisors (8)
Canines (4)
Premolars or bicuspids(8)
Molars (12)
Anatomy of the Mouth
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:
help to
dissolve
2. mucus: food
lubricates food
(makes it slippery)
3. salivary amylase:
enzyme which
digests starch
i.e. into mono &
disaccharides
Mouth (oral cavity)
Tongue
Parotid gland
Sublingual gland
Submandibular gland
Salivary Glands
.
Components of the Digestive System
Organ
c) tongue
Comments
Function
very strong muscle
contains large numbers
of taste buds
bolus: ball of chewed
1.sensory: taste &
temperature control
2. physical digestion:
chewing & mixing
food with saliva
3. swallowing:
a. pushes bolus up &
to the back of the
throat
b.causes epiglottis
to block windpipe
food
nerve endings
4. speech
Components of the Digestive System
Tongue:
•
Different parts of the
tongue are able to taste
one of four basic tastes.
sour
salty
bitter
sweet
.
NOT IN YOUR NOTES
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 trachea) to
avoid choking
2) pharynx
back of the throat
common
passageway for
food & air
.
Components of the Digestive System
Organ
3) esophagus
Comments
Function
narrow tube about 24 cm 1. leads food into
long connecting pharynx
stomach
to stomach
contains 2 muscle layers
2. ensures that food
which relax and contract
(bolus) is pushed
rhythmically for peristalsis
wave-like contractions
into stomach
(mucus glands help
lubricate the bolus)
Esophagus (24 cm long, carries food)
• Lined with circular and longitudinal muscle
• Lower end of esophagus is thickened just
before stomach (sphincter) (ie: heartburn)
• Regurgitation – movement of food from the
stomach up the esophagus and out the mouth
SWALLOWING
Esophagus
Pharynx
Stomach
Stomach
• All your notes
Stomach
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
ACID REFLUX
GASTRIC FOLDS
STOMACH LINING & GASTRIC JUICE
ENDOSCOPE
STOMACH ULCER
MULTIPLE STOMACH ULCERS
Before food enters the small intestine:
• It must pass through the PYLORIC SPHINCTER
which is a valve that contracts and relaxes to
control the flow of food leaving the stomach
and going to the small intestine.
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
Salivary Glands
• Parotid Gland (below/ in front of ears,
largest)
• Sublingual Gland (floor of mouth,
smallest)
• Submandibular Gland (below and behind
sublingual)
Ducts and Saliva
• Ducts – tubular canals for carrying glandular
secretions from one part of the body to
another.
• Saliva
– Moisten and lubricate food
– First step in chemical digestion