Digestion- breakdown of food by both mechanical and chemical processes
Absorption- passage of digested food from the GI tract to the circulatory system.
Defecation- Elimination of indigestible substances from the body
GI tract AKA?
Alimentary canal
What is the Gastrointestinal tract?
a tubular structure that runs from the mouth to the anus.
Accessory structures of the digestive system
teeth
tongue
salivary glands
liver
gallbladder
pancreas
4 layers of the GI tract
Mucosa
Submucosa
muscularis
Serosa (visceral peritoneum)
3 sublayers of the submucosa
epithelial mucosa
lamina propria
mucosal muscularis
What is the mucosal muscalris?
sublayer that contains muscle fibers that contract to throw the mucosa into small folds which increase the absorptive area
What does the submucosa consist of?
arterioles
venules
lymphatics
glands
nerves
What does the submucosal plexus do?
Regulates blood flow in the intestines.
What does the muscularis layer of the GI tract contain? What does it do?
Myenteric plexus (plexus of auerbach) which contains autonomic nerve fibers that control GI tract mobility.
What is the parietal peritoneum?
serous membrane that lines the wall of the abdominal cavity.
What is visceral peritoneum?
An extension of the parietal peritoneum that covers the serosa of the GI tract and several other organs.
The space between the parietal and visceral peritoneum?
Peritoneal cavity
What are the peritoneal folds?
mesocolon
falciform ligament
lesser omentum
greater omentum
mesentery
Mesocolon
supports the large intestine
falciform ligament
attaches the liver to the abdominal wall and diaphram
lesser omentum
supports the stomach
greater omentum (apron
contains many fat and lymph nodes
Mesentery
Supports the small intestine
Mouth AKA
Buccal Cavity
What is the mouth formed by?
The cheeks
hard/soft palate
tongue
Lips AKA
Labia
What forms the boundary of the mouth?
Lips
What kind of tissue are the lips?
Transitional epithelium
What attaches the lips to their respective gums?
labial frenulums
Fauces?
opening between palatoglossal arches leading to the pharynx
What dangles between the palatoglossal arches?
uvula
What initiates the breakdown of starch by reducing long polysaccharides?
Salivary amylase
polysaccharides
carbs
3 sets of salivary glands
Parotid
Submandibular
Sublingual
Parotid glands
located in front of the end underneath the ears
Mumps
viral infection of the parotid glands
Submandibular glands
lie below and inside the mandibular angles
Sublinual glands
Lie immediately underneath the tongue.
3 regions of the tooth
Crown
Neck
Root
Crown
part of the tooth above the level of the gums
neck of tooth
constricted portion between the crown and root. Surrounded by gums
Root of tooth
filled with pulp
Baby teeth
deciduous teeth
Permanent dentition
32 permanent teeth
Front 4 teeth
Incisors- adapted for biting
on each side of the incisors
canine tooth- pointed for tearing
Premolar teeth
(bicuspid)- cut and shear food
molar teeth
3 on each side of the jaw- equipped for grinding
Next major organ involved in swallowing after mouth is?
Esophagus
Esophagus lies
behind the trachea and pierces the diaphram at the esophageal hiatus
What permits food into the stomach?
Esophageal sphyncter
Stomach is divided into ___areas, they are?
4
Cardia
Fundus
Body
Pyloras
How long does it take the stomach to empty its contents?
2-6 hours
Order of digestion
Carbohydrates
Protein
fats are no digested in the stomach
Which surface of the stomach has large folds called rugae?
Mucosal
Chief (zymogenic) cells secrete?
Pepsinogen
Parietal cells produce
hydrochloric acid
intrinsic factor
Enteroendocrine (gastrin) cells produce?
gastrin
A head which has a ____ that joins the _________ to form the _______that empties both bile and pancreatic fluids into the proximal portion of the duodenum through the____?
pancreatic duct
common bile duct
ampula of vater
sphincter of oddi
Pancreatic amaylase digests?
Carbs
Trypsin digests?
Protein
Pancreatic Lipase digest?
Fat
What and where is fat emulified?
In the live by alkaline bile
The cystic duct connects with the gallbladder, joins the common hepatic duct and, at that point, becomes the common bile duct
Small intestine is divided into?
Duodenum
Jejunum
ileum
How long is the duodenum?
Jejunum?
Ileum?
10"
8'dead/3'live
12'dead/6'live
The lumen of the small intestine is lined with?
Villi
Each villus contains
an arteriole, venule,lymph vessel
Lymph vessel in the villus of the small intestine?
Lacteal
Crypts of Lieberkuhn cells
Enteroendocrine cells
paneth cells
Enteroendocrocrine cells
secrete cholecystokinin
secretin
gastric inhibitory peptide
paneth cells
secrete lysozyme
lysozyme
bacterial enzyme
Cecum
blind pouch below the ileocecal valve to which the vermiform appendix is attached.
Colon divided into 4 parts?
Ascending colon
transverse colon
descending colon
sigmoid colon
Last section of the GI tract?
Rectum
Where is the defecation reflex mediated
Nerve centers in the sacral portion of the spinal cord