Transcript Digestive System

Digestive System
(Gastrointestinal)
Functions of the Digestive system:
1. Intake and digestion of food
2. Absorption of nutrients from digested food
3. Elimination of solid waste products
Accessory Organs of Digestion:
Include the liver, gallbladder,
and pancreas
Anatomy
Structures are divided into two sections:
1. Upper GI Tract– mouth, esophagus, stomach
2. Lower GI Tract– small intestine, large
intestine, rectum, anus
Oral Cavity (mouth)
1. Lips – form opening to the mouth
2. Hard palate – anterior portion of roof of mouth
3. Soft palate – posterior portion of roof of mouth,
closes off nasal passage during swallowing
4. Uvula – helps in producing sound and speech
Upper GI tract Cont’d.
Tongue – strong and flexible, aids in speech and
moves food during chewing and swallowing,
contains papillae which are also known as taste
buds.
Teeth – 20 baby teeth, 32 permanent teeth; four kinds:
1. Incisors
2. Canines
3. Premolars (bicuspids)
4. Molars
Upper GI tract Cont’d.
Parts of a tooth
1. Crown – the part of the tooth that is
visible, covered with enamel
2. Root – holds the tooth securely in the dental arch
3. Dentin – makes up the bulk of the tooth
Gingiva (gums) – surrounds teeth, covers the bone of
the dental arches, forms the lining of cheeks
Salivary Glands – secretes saliva to moisten food,
begins digestive process, cleanses the mouth
Upper GI tract Cont’d.
Pharynx (also known as the throat)
• common passageway for food and air
• during swallowing, food is prevented from moving
from the pharynx into the lungs by the epiglottis.
Esophagus
• collapsible tube that leads from the
pharynx to the stomach
• the lower esophageal sphincter is a muscle that
controls the flow between the esophagus and
the stomach.
Upper GI tract Cont’d.
Stomach
• has 3 sections: fundus, body, and the antrum
• the pyloric sphincter controls flow from stomach into
the duodenum of the small intestine.
Lower GI tract
Small Intestine – extends from pyloric sphincter to the
large intestine; in the small intestine is where
nutrients are absorbed into bloodstream; 20 feet in
length; has three sections:
1. Duodenum – first section, closest to the stomach
2. Jejunum – middle section, between duodenum and
ileum
3. Ileum – last section, closest
to the large intestine
Lower GI tract Cont’d.
Large Intestine – waste products of digestion are processed in
the large intestine and excreted through the anus; has 6
sections
1. Cecum – pouch that extends from the ileum to the
beginning of the colon
2. Ascending colon – travels upward from cecum
3. Transverse colon – passes right to left toward the spleen
4. Descending colon – travels down
the left side of abdominal cavity
5. Sigmoid colon – joins descending
colon with the rectum
6. Rectum – last division of the large intestine
Anus – solid waste is passed out of the body through the anus
Accessory Organs of Digestion
Liver (located in the right upper quadrant)
• removes excess glucose from the bloodstream
• destroys old red blood cells
• removes poisons from blood
• makes some blood proteins
• secretes bile to break down fat
Gallbladder
• stores and concentrates bile for later use
Pancreas
• located posterior to the stomach, creates pancreatic
juices to neutralize stomach acids and digestive
enzymes to process protein, carbohydrates, and fat.
Definitions
Digestion– process by which
complex foods are broken down into
nutrients that the body can use
Metabolism – all of the processes
involved in the body’s use of these
nutrients(building up and breaking
down of body cells)
Absorption – process where
digested nutrients are taken into the
circulatory system
Definitions Cont’d
Mastication – also known as
chewing, breaks down food into
smaller pieces
Peristalsis – series of wavelike
contractions of smooth muscles in a
single direction.
Chyme – semi-fluid mass of
partially digested food that passes
from stomach into small intestine
Defecation – evacuation or
emptying of the large intestine
Flow through the Digestive System
You will need
to know the
order of flow
for food
moving
through the
digestive
system on
your next test.
The Language of Medicine, 7th Edition; Chabner, Davi-Ellen; Saunders, 2004
ACTIVITY
How The
Stomach
Works