Transcript Ch 8 Digestive System

Ch 8 Digestive System
Structures
Digestive System
• AKA alimentary canal
 Aliment means to nourish
 -ary means pertaining to
• Responsible for
• Intake & digestion of food
• Absorption of nutrients from digested food
• Elimination of solid waste products
Major Structures
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Oral Cavity
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Rectum
Anus
Accessory organs
– Liver
– Gallbladder
– pancreas
Gastrointestinal tract
• Divided into two sections
– Upper GI tract
• Mouth, esophagus, & stomach
– Lower GI tract
• Small intestine, large intestine, rectum, & anus
• Sometimes referred to as the bowels
Oral Cavity
• Lips aka labia
• Palate
– Hard palate
-Soft palate
– Rugae
-uvula
• Tongue
– Papillae aka taste buds
Oral Cavity
• Teeth
– Dentition refers to the natural teeth arranged in the
upper (maxillary) and lower (mandibular) arches.
• Primary or deciduous dentition
• Permanent dentition
– Edentulous means without teeth
• Periodontium – bone and soft tissues that surround teeth
– Gingiva aka gums, specialized mucous membranes
That surrounds the teeth
• Salivary glands secrete saliva that moistens food, begins the
digestive process, and cleanses the mouth
3 pairs; parotid, sublingual, & submandibular
Pharynx
• Aka throat
• Common passageway for both respiration &
digestion
• What structure closes off and prevents food from
entering
the trachea during swallowing?
Esophagus
• Sometimes called the gullet
• A collapsible tube that leads from the pharynx to
the
Stomach
• Has a ringlike muscle at the end that controls the
flow between the esophagus and the stomach
called the lower esophageal sphincter or cardiac
sphincter.
Stomach
• A saclike organ made of the fundus (upper,
rounded part), the body(main part), and the
antrum (lower part)
• Has folds in the mucosa lining called Rugae.
These folds have glands that make the gastric
juices.
• The pylorus is the narrow passage that connects
the stomach with the small intestine
• Pyloric sphincter is the muscle ring that controls
the flow from the stomach to the duodenum of
the small intestine.
Small Intestine
• Has 3 parts
– Duodenum, beginning
– Jejunum, middle
– Ileum, last portion
• Ileocecal sphincter controls the flow from the ileum of the
small intestine into the cecum of the large intestine
• Has little hairlike or fingerlike projections called villi that
line the walls. These absorb fats and fat soluble vitamins
Large Intestine
• Major parts;
– Cecum is a pouchlike structure at the beginning of the
large intestine. The vermiform appendix hangs from
the lower portion.
– Colon
• Ascending colon
• Transverse colon
• Descending colon
• Sigmoid colon
– Rectum is the third major division
– Anus is the lower opening of the digestive tract. Flow
of waste controlled by two anal sphincter muscles.
Accessory Digestive Organs
• Liver
– Found in the RUQ
– Removes excess glucose from bloodstream & stores it
as glycogen
– Destroys old erythrocytes
• Bilirubin is a pigment produced from the
destruction of hemoglobin
– Makes & secretes bile
• Digestive juice that has enzymes that break down
fat
Accessory Digestive Organs
• Gallbladder
– Pear shaped sac located inferior the liver
– Stores and concentrates bile for later use
• Pancreas
– Feather shaped organ located posterior to the stomach
– Has digestive and endocrine functions. We will discuss
the endocrine function in a different chapter.
– Synthesizes and secretes pancreatic juices. These
juices help the body process protein, carbs, & fats, as
well as helping to neutralize stomach acids.
DIGESTION
Digestion
• The process by which foods are broken down into nutrient
form the body can use.
• Enzymes are responsible for the chemical changes that
break foods down into simpler forms of nutrients the
body can use
• A nutrient is a substance, usually from food, that is
necessary for normal functioning of the body
Metabolism
• All the processes involved in the body’s use of nutrients.
– Anabolism, the building up of body cells or substances
– Catabolism, the breaking down of body cells or
substances
Miscellaneous Terms
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Mastication aka chewing
Peristalsis - wavelike contractions of the smooth muscles
Chyme – semifluid mass of partly digested food
Emulsification – digestion of fats by pancreatic juices
Feces or stools
Defecation or bowel movement
Flatulence, flatus, or gas
Borborygmus is the rumbling noise created by the
movement of gas in the intestine