Download The Digestive System

The Digestive System
IntroductionFUNCTION

Preparing
food for
absorption
and use by
body cells
Vocab 17
Quiz on Friday 3/28
1.
2.
3.
4.
5.
6.
arteri/o- artery
bio- life
cheil/o- lips
clysis- washing or irrigation
col/o- large intestine
ecstasia- dilation or
stretching
7. gingiv/o- gums
8. hem/o- blood
9. hemat/o- blood
10.lys- destruct
11.myc/o- fungus
12.o- egg
13.Orrhagia – hemorrhage
14.orrhaphy- suture, stitch
15.pancreat/o- pancreas
16.proct- rectum and anus
17.rect/o- rectum
18.scop/o- examine
19.spermat/o- sperm
20.ur/o- urine
21.ureter/o- ureter
22.urethr/o- urethra
IntroductionDIVISIONS
1. Alimentary canal aka
gastrointestinal tract
(GI)- approx. 9 m long



Digests food
Absorbs digested food
through lining
Mouth, pharynx,
esophagus, stomach,
small intestine, large
intestine
IntroductionDIVISIONS
2. Accessory digestive
organs






Teeth
tongue,
gall bladder
salivary glands
Liver
pancreas
IntroductionDIGESTIVE PROCESSES



1. ingestion
2. propulsion via
swallowing and
peristalsis
3. mechanical
digestion e.g.
mastication,
stomach churning
IntroductionDIGESTIVE PROCESSES
4. chemical digestion via enzymes –ase
Examples: lipase, amylase, proteases like pepsin
and trypsin
Very specific in action
Function at a specific pH
5. absorption
6. defecation
Introduction4 tissue layers of GI
1. mucosa- innermost;
epithelial; secretion of
dig juices; absorption;
protection against
infection
2. submucosaconnective; vascular
3. muscularis- smooth
muscle; mixes and
propels food; sphincters
4. serosaoutermost;areolar +
squam.
Mouth


Aka oral cavity or
buccal cavity
Functions




Ingestion
Propulsion
mechanical digestion
chemical digestion
deglutition (swallowing)
MouthLIPS
Aka labia; skeletal m. covered by skin
1. actually extends from inferior nose to
superior chin. The reddened part is the
red margin.
Philtrum- shallow vertical groove of
upper lip
Labial frenulum- median fold that joins
each lip to the gum
MouthCHEEKS

Mostly buccinator
muscle and fat
MouthPALATE
Roof of mouth
1. hard palateunderlain by bone;
midline ridge is the
raphe
2. soft palate- mostly
sk. Muscle
fingerlike uvula  closes
of nasopharynx when
swallowing
MouthTONGUE
1. mostly skeletal
muscle
2. mixes food with
saliva to form
bolus
3. Lingual frenulum
secures tongue to
mouth
4. Root, tip, body
MouthTONGUE
5. papillae- projections
Vallate- v-shaped; at
back of tongue;
taste buds
Fungiform- taste buds;
mushroom-shaped
Filiform- roughness to
tongue; conicalshaped
MouthSALIVARY GLANDS
1. functions of saliva
Cleans mouth
Dissolves food so it
can be tasted
Moistens food and aids
in compacting it into
a bolus
Contains enzymes
(amylase) to break
down starches
MouthSALIVARY GLANDS
2. types
1.
2.
3.
Parotid glands
Submandibular glands
Sublingual glands
MOUTHTeeth
1. Allow for mastication
(chewing)
2. typical tooth
Crown- exposed portion
Neck- surrounded by
gingivae (gums)
Root- fits into sockets
(alveoli)
MOUTHTeeth
3. deciduous teeth aka milk or baby teeth;
approx 20
4. permanent teeth- 32
5. dental formula for perm. Teeth:
2I, 1C, 2 PM, 3M x 2 = 32 teeth
2I, 1C, 2 PM, 3M
Esophagus
25 cm
A. with cardiac or
gastroesophageal
sphincter
B.Peristalsis- wave-like
ripple in hollow
organs
Stomach
A. Size varies because of distension- holds 11.5 L
B. Divisions
1. Cardiac region- eso dumps into stomach
2. Fundus- enlarged part to L & above opening
of the eso to the stomach
3. Body- central
4. Pylorus- lower portion
5. Greater (lateral) & lesser (medial) curvatures
with greater & lesser omenta
Stomach
C. Sphincters
1. Cardiac- eso into
stomach
2. Pyloric- stomach into
duodenum of small
intestine
Talk about hard to swallow!!!
Stomach
D. Functions
1.
2.
3.
4.
5.
6.
7.
Food storage
secretes gastric juice- pepsin
churns the food (mechanical)
chemical digestion of proteins by pepsin
limited absorption
destroys pathogenic bacteria
propulsion of food into small intestine
Stomach: A closer look
Small Intestine
A. Divisions
1. duodenumuppermost; 25 cm
2. jejunum- middle;
2.5 m
3. ileum- end; 3.5 m
Small Intestine
B. Intestinal lining with plicae (folds) that contain
villi. Villi increase surface area which allows for
more absorption.
C. Functions
1.
2.
3.
4.
mechanical digestion
propulsion
chemical digestion
absorption
Large Intestine
A. Divisions
1. Cecum
Small (5-8 cm)
“blind pouch”
With vermiform
appendix (“wormshape”) appendiximmunity? Intestinal
flora?
Large Intestine
A. Divisions
2. Colon
Ascending- vertical;
with ileocecal valve
Transversehorizontal; above
sm int
Descending- vertical
Sigmoid- s-shaped
curve
Large Intestine
B. Functions
1. chemical digestion
2. absorption of
remaining water via
osmosis
3. propulsion
4. defecation
Accessory Digestive Organs
A. Liver- largest gland in the body
1. Lobes
Right- R lobe proper, caudate lobe, quadrate lobe
Left
Accessory Digestive Organs
A. Liver- largest gland in the body
2. Functions
1. detoxify substances
2. Secrete bile that will eventually go into the duodenum to
break up fat
3. Metabolism of proteins, fats, carbs
4. Store substances like Fe, vit A, vit D
5. Hematopoeisis in fetus
Accessory Digestive Organs
B. Gall Bladder
1. green sac about the size of a kiwi
2. stores 30-50 ml of bile
Accessory Digestive Organs
C. Pancreas
1. resembles fish with head and neck in the C-shaped curve of the
duodenum
2. Functions
Secrete pancreatic juice with digestive enzymes like trypsin
Secrete insulin hormone that affects carb metabolism
Secrete glucagon