Transcript The Digestive System

The Digestive
System
WALL OF THE
DIGESTIVE TRACT
The four layers of tissue that form the
wall of the digestive tube is :
A. Mucosa - mucous epithelium
B. Submucosa - connective tissue
C. Muscularis - 2 or 3 layers of smooth
muscle
D. Serosa - serous membrane that covers the
outside of abdominal organs ; it attaches the
digestive tract to the wall of the
abdominopelvic cavity by forming folds
called mesenteries
MOUTH
A. The mouth or oral cavity is a hollow
chamber with a roof, a floor, and walls.
B. Roof - formed by hard palate and soft
palate, an arch-shaped muscle separting
mouth from pharynx
C. Floor - formed by tounge and its muscles ;
papillae, small elevations on mucosa of
tounge
SWALLOWING
TEETH
A. Names of teeth : 4 incisors, 2 canines, 4 biscuspids, and 6 tricuspids
(32 total)
Child - 4 incisor, 2 canines, 2 1st molar, 2 2nd molar, (20 total)
B. A person has a temporary set of twenty teeth and thirty-two teeth in
permanent set.
C. Average age for cutting 1st tooth about six months.
D. Average age for cutting permanent teeth , six.
E. Set complete of all teeth is ages of 17 to 24 years.
Panoramic x-ray
Children teeth
rd
3
molar impaction and cyst
Mandibular third molar
nd
impaction with 2 molar
involvment
Mand. 2nd molar root canal
therapy
Bite wing xay with decay
Dental implants
dental caries(decay)
SALIVARY
GLANDS
The three pairs of salivary glands :
A. Parotid glands - largest gland, lies just below and in front
of each ear at the angle of the jaw
B. Submandibular glands - located on either side of the
lingual frenulum
C. Sublingual glands - located on the floor of the mouth
PHARYNX
A. The tubelike structure made of muscle and
lined with mucous membrane.
B. Function - air must pass though the
pharynx on its way to the lungs, and food
must pass through it on its way to the
stomach.
ESOPHAGUS
A. The esophagus or food pipe, is the
muscular, mucus-lined tube that connects
the pharynx with the stomach.
B. It is about 25 centimeters long
C. Function - serves as a dynamic
passageway for food, pushing the food
toward the stomach.
STOMACH
A. Size - expands after large meals.
B. Pylorus - lower part of stomach; pyloric
sphincter muscle closes opening of pylorus
into duodenum
C. Wall - many smooth muscle fibers
D. Lining - mucous membrane; many
microscopic glands that secrete gastric juice
and hydrochloric acid into stomach
SMALL
INTESTINE
A. Size - about 7 meters
long and 2 cm in
diameter
B. Divisions
– Duodenum
– Jejunum
– Ileum
C. Wall - contains
smooth muscle fibers
that contract to
produce peristlsis
D. Lining - mucous
membrane
Large Intestines (Colon)
• Six feet - ascending, transverse, descending
• Appendix - Lower right - abs
• Completes digestion and absorption of
nutrients
• Water and electrolyte management
• Feces production
LIVER &
GALLBLADDER
A. Size - liver is the
largest gland
B. Location - fills upper
right section of
abdominal cavity and
extends over into left
side
C. Liver secretes bile
D. Location of
Gallbladder undersurface of liver
E. Function concentrates and
stores bile produced in
the liver
PANCREAS
A. Location - behind stomach
B. Functions
1. Pancreatic cells secrete pancreatic juice into
pancreatic ducts
2. Secrete hormones glucagon and insulin into the
blood
LARGE
INTESTINE
A. Divisions
1. Cecum
2. Colon - ascending,
transverse,
descending, and
sigmoid
3. Rectum
B. Opening to exterior anus
C. Wall - contains
smooth muscle fibers
that contract to
produce churning.
D. Lining - mucous
membrane
APPENDIX
A. Dead end tube off cecum
B. No important digestive functions in
humans
C. It contains lymphatic tissue and may play a
minor role in the immunologic defense
mechanisms of the body.
PERITONEUM
A. Peritoneum is a serous membrane lining
abdominal cavity and covering abdominal
organs
1. The parietal layer of peritoneum lines
abdominal cavity
2. Viscreal layer of peritoneum covers
abdominal organs
3. Peritoneal space lies between parietal and
visceral layers
B. Extensions - largest ones are the mesentery
and greater omentum
1. Mesentery is extension of parietal
peritoneum, which attaches most of small
intestine to posterior abdominal wall
2. Greater omentum, or “lace apron,”hangs
down from lower edge of stomach and
transverse colon over intestines
DIGESTION
Digestion is changing foods so that they can
be absorbed and used by cells
A. Mechanical digestion - chewing,
swallowing, and peristalis break food into
tiny particles, mix them well with digestive
juices, and move them along the digestive
tract
B. Chemical digestion - breaks up large
food molecules into compounds having
smaller molecules
C. Carbohydrate digestion - mainly in small
intestine
1. Pancreatic amylase - changes starches to
maltose
2. Intestinal juice enzymes
a. Maltase - changes maltose to glucose
b. Sucrase - changes sucrose to glucose
c. Lactase - changes llactose to glucose
D. Protein digestion - starts in stomach, completed in
small intestine
1. Gastric juice enzymes, renin and pepsin, partially
digest proteins.
2. Pancreatic enzyme, trypsin, completes
digestion of proteins to amino acids
3. Intestinal enzymes, peptidases, complete
digestion of partially digested proteins to
amino acids
E. Fat digestion - bile that contains no
enzymes but emulsifies fats. Pancreatic
lipase changes emulsified fats to fatty acids
and glycerol in small intestine.
ABSORPTION
A. Absorption is the digested food that moves
from intestine into blood or lymph
B. Where absorption occurs - foods and most
water from small intestine. Some water also
absorbs from large intestine