Digestive System Flashcards
What is the digestive system?
The digestive system is made up of the GI tract and accessory organ. It extends from the mouth to the anus
The Hollow organs that make up the GI tract are?
Mouth, esophagus, stomach, small intestine, large intestine, and anus
Accessory organ?
Salivary glands: parotid, sublingual and submandibular glands
Liver
Gallbladder
Pancreas
Where does digestion begin?
Mouth
When does the salivary glands activate ?
With sight and smell of food
What is a bolus?
Food ingested and masticated
Salivary amylase start what process?
Carbohydrate digestion
Lingual lipase start?
Lipid digestion
The 3 parts of the pharynx and their functions
Nasopharynx: posterior to nasal cavity transmit air only
Oropharynx: posterior to oral cavity transmits air, food and fluid
Laryngopharynx: posterior to larynx (voice box) transmits air, food and fluid
Location of esophagus
Located in the mediastinum, anterior to the spine and posterior to the trachea and heart
The esophagus
Extends from pharynx to the stomach
The lower esophageal sphincter (LES)
A muscular ring that closes off the esophagus from the stomach to prevent backflow of food
Epiglottis
A small flap that folds over the windpipe as you swallow to prevent choking
Peristalsis
A series of muscular contractions within the esophagus that delivers food to the stomach
The stomach
J shaped muscular organ found in the upper left quadrant of abdomen. Stores food during eating, secretes digestive fluids, and propels chyme into the small intestine
Stomach functions
To moisten bolus coming from the esophagus producing chyme
Gastric secretions include:
Mucus, HCl, intrinsic factor, and gastric lipase
Mucus
Protect stomach lining from digestion
HCl
Decrease stomach ph
Activates pepsinogen to pepsin for protein digestion
Deactivate salivary amylase stopping CHO digestion
Intrinsic factor
Essential for vitamin B12 absorption
Gastric lipase
Small amount of lipids digestion
Gastroesophageal junction
The inlet to the stomach
4 anatomical region of the stomach
The cardia (entrance)
Fundus
Body
Pylorus (outlet)
Pyloric sphincter
Circular smooth muscle in the wall of the pylorus that controls the opening between the stomach and the small intestine
The small intestine
6 meters. Longest segment of the GI tract, accounting for about 2/3 of the total length.
3 parts of the small intestine
Duodenum
Jejunum
Ileum
Absorption
The process by which nutrients enter the bloodstream through the intestinal walls
Ileocecal valve
Controls the flow of digested material from the ileum into the cecal. Prevent reflux of bacteria into the small intestine
Common bile duct
Allows the passage of both bile and pancreatic secretions into the duodenum
Appendix
Wormlike sac attached to the cecum
Pancreas
Both exocrine and endocrine organ
Pancreatic secretions
Proteolytic enzymes Pancreatic amylase Pancreatic lipase Bicarbonate ion Deoxyribonuclease
Bicarbonate ions
Neutralize the acidic chyme passing from the stomach and increase ph for the pancreatic enzymes to work
Liver
Largest digestive organ
Liver functions
Produces and secretes bile
How does bile leave the liver?
Via right and left hepatic ducts which unite to form the common hepatic duct
Where does bile get stored and concentrated?
Gallbladder
Bile can go directly into the duodenum via
Common bile duct
Gallbladder
Sacklike pouch located on the inferior surface of the liver
Large intestine is composed of:
Cecum, colon, rectum and anal canal
How does chyme get converted into feces?
Due to water and salt absorption
Parts of the colon
Ascending
transverse
descending
sigmoid (s shaped)
What regulates the anal outlet?
A network of striated muscle that forms both the internal and external anal sphincter
Sympathetic nerves
Exert an inhibitory effect on the GI tract, decreasing gastric secretions and motility and causing the sphincter and blood vessels to constrict
Parasympathetic nerve
Causes peristalsis and increases secretory activities
2 major flexures of the rectum
Sacral and anorectal flexure
Sacral flexure
Follows the sacrum and coccyx curve
Anorectal flexure
Formed the tone of the puborectalis muscle. Contributes to fecal continence
Types of anal lesions
Fistula anal fissure (ulcer) internal and external hemorrhoids
Digestion
The breakdown of large food particles into their component parts producing molecules small enough to be absorbed
How is digestion achieved?
Mechanical and chemical digestion
Mechanical digestion
Large particles broke down into smaller particles via mastication and mixing of food
Chemical digestion
Chemical enzymes act on the smaller molecules rendering them readily absorbable
Exocrine function of the pancreas
The release of pancreatic juice
The oral cavity boundaries:
Lips anteriorly Fauces Cheeks laterally Palate Muscles of tongue
Carbohydrates are broken down into
Monosaccharides
Proteins are broken down into
Amino acids
Fats (lipid) broken down into
Fatty acid and glycerol