Digestive System Flashcards
Digestive system divided into two groups
- Alimentary canal
2. Accessory digestive organs
- mouth, pharynx, and esophagus
- stomach, small intestine and large intestine
Alimentary canal
- teeth and tongue
- gallbladder, salivary glands, liver, and large intestine
- connected to the alimentary canal by ducts
- secretions contribute to breakdown of food stuffs
Accessory digestive organs
a serous membrane
peritoneum
surrounds digestive organs
visceral peritoneum
lines the body wall
parietal peritoneum
a slitlike potential space
peritoneal cavity
- connects to the posterior abdominal wall.
- a double layer of peritoneum
- holds organs in place
- sites of fat storage
- provides a route for circulatory vessels and nerves
Mesentery
binds anterior part of liver to anterior abdominal wall
falciform ligament (ventral mesenteries)
attaches liver to the lesser curvature of stomach
lesser omentum (ventral mesenteries)
- connects greater curvature of stomach to posterior abdominal wall
- a “fatty apron”
greater omentum (dorsal mesenteries)
holds transverse colon in place
transverse mesocolon (dorsal mesenteries)
connects the sigmoid colon to posterior pelvic wall
sigmoid mesocolon (dorsal mesenteries)
occurs in the mouth
ingestion
movement of food
propulsion
major means of propulsion
peristalsis
prepares food for chemical digestion
-chewing, churning food in stomach, segmentation
mechanical breakdown
rhythmic local constrictions of intestine
segmentation
complex molecules broken down to chemical components; mouth, stomach small intestione
chemical digestion
transport of digested nutrients
absorption
elimination of indigestible substances as feces
defecation
4 layers from esophagus to anus
- inner most ; mucosa
- external to mucosa ; submucosa
- external to submucosa ; muscular externa
- outermost layer ; serosa;
inner most layer of alimentary canal consists of epithelium, lamina propria, and muscular mucosa
mucosa
external to the mucosa of the alimentary canal.
-contains blood and lymphatic vessels, nerve fibers
submucosa
external to the submucosa of the alimentary canal ; consists of 2 layers; circular muscular (inner layer) and longitudinal muscular (outer layer)
muscular externa
outermost layer of the alimentary canal.
-is the visceral peritoneum
serosa
- Mucosa-lined cavity
- boundaries ;
- lips anteriorly
- cheeks laterally
- palate superiorly
- tongue inferiorly
- faces of oropharynx posteriorly
mouth (oral cavity)
innermost layer of the GI tract. It is made up of three layers: the epithelium, lamina propria, and muscularis mucosae. The mucosa surrounds the lumen, or open space within the digestive tube. This layer comes in direct contact with digested food (chyme).
mucosal layer
formed from orbiculares iris and buccinator muscles
lips and cheeks
- physical digestion, vocalization and taste. made up of 2 parts; oral and pharyngeal
- interlacing fascicles of skeletal muscle
- grips food and repositions it
- helps form some consonants
the tongue
muscles within the tongue
intrinsic muscles
external to the tongue
extrinsic muscles
secures tongue to the floor of the mouth
lingual frenulum
20 teeth ; first appear at 6 months of age
deciduous teeth
32 teeth ; most erupt by the end of adolescense
permanent teeth
shorthand ; formula for adult dentition indicates number and position of teeth
dental formula
exposed surface of teeth
crown
in tooth socket
root
outer layer of teeth
enamel
underlies enamel
dentin
center of tooth
pulp cavity
produces saliva
salivary glands
posterior to the sublingual gland
submandibular glands
lie in floor of oral cavity under tongue
-contain primarily mucous cells
sublingual glands
- parotid duct; parallel to zygomatic arch
- contain only serous cells
parotid glands
- passages for air and food
- lined with stratified squamous epithelium
- external muscle layer
- consists of superior, middle, and inferior pharyngeal constrictors
oropharynx and laryngopharynx
- gross anatomy; musclular tube
- begins as a continuation of the pharynx
- joins the stomach inferior to the diaphragm
the esophagus
closes lumen to prevent stomach acid from entering esophagus
cardiac sphincter
- pouch like dilation; acts as storage and place for mixing food with digestive juices before entering small intestine
- site where food is churned into chyme
- secretion of pepsin begins protein digestion
- -functions under acidic conditions
- food remains in stomach approximately 4 hours
- regions ; cardiac part, fundus, body, pyloric part
the stomach
longest portion of the alimentary canal
- site of most enzymatic digestion and absorption
- 3 subdivisions ; Duodenum, Jejunum, Ileum
- innervation
- -parasympathetic fibers from vagus nerve
- -sympathetic from thoracic splanchnic nerves
- folded multiple times
the small intestine
receives digestive enzymes and bile
- main pancreatic duct and common bile duct enter ___
- sphincters control entry of bile and pancreatic juices
the Duodenum
transverse ridges of mucosa and submuocosa
circular folds
- fingerlike projections in the small intestines that increase the surface area.
- covered with simple columnar eptihelium (small intestine)
Villi
Further increase surface area for absorption (small intestine)
Microvilli
- Digested residue contains few nutrients
- small amount of digestion by bacteria
- main functions
- absorb water and electrolytes
- mass peristaltic movements force feces toward the rectum
the large intestine
large intestine divided into 5 areas
cecum, appendix, colon, rectum, anal canal
contains lymphoid tissue
-neutralizes pathogens
appendix
divided into distinct segments
-ascending, transverse, descending, and sigmoid colon
colon
-descends along the inferior half of the sacrum
rectum
- the last subdivision of the large intestine
- lined with stratified squamous epithelium
anal canal
- villi are absent
- contains numerous goblet cells
- intestinal crypts ; simple tubular glands
- lined with simple columnar epithelial tissue
- epithelium changes at anal canal
- becomes stratified squamous epithelium
microscopic anatomy of large intestine
- largest gland in body
- performs over 500 functions
- digestive function
- bile production
- performs many metabolic functions
- tissue great at regenerating
the liver
- stores and concentrates bile
- expels bile into duodenum
- bile emulsifies fats
- connects to the common bile duct.
gallbladder
released from enteroendocrine cells in response to fatty chyme
cholecystokinin (coal a sis to ky nin)
- both exocrine and endocrine functions
- secondarily retroperitoneal
pancreas
produces insulin and glucagon
-regulates blood sugar
endocrine function
produces most enzymes that digest food in the small intestine
- acinar cells make, store, and secrete pancreatic enzymes
- enzymes are activated in the duodenum
exocrine function
- extends the length of the pancreas
- joins bile duct to form the hepatopancreatic ampulla
- empties into duodenum
- arterial supply is from hepatic, splenic, and superior mesenteric arteries
main pancreatic duct
- erosions of the mucosa of a region of the alimentary canal
- caused by Helicobacter pylori
- acid resistant
- binds to gastric epthelium
- induces over secretion of acid and inflammation
peptic ulcers
occur in pyloric region of the stomach
gastric ulcers
occur in duodenum of the small intestines
duodenal ulcers
- mechanical obstruction
- adhesions, tumors, or foreign objects
- nonmechanical obstruction
- halt in peristalsis
- trauma
- intestines touched during surgery
intestinal obstruction
- inflammation of the intestinal wall
- crohns disease
- ulcerative colitis
inflammatory bowel disease
- jaundice and flulike symptons
- major types A,B,C, and G
Viral hepatitis
Pancreatic ducts become blocked with mucus
- clogged ducts prevent pancreatic juices form entering small intestine
- leads to malabsorption of fats and other nutrients
cystic fibrosis and the pancreas
method that propels food through the digestive tract
peristalsis
space between the teeth and the lips and cheeks.
Vestibule
2 valves that control entry and exit to the stomach
- cardiac sphincter valve
2. pyloric sphincter valve.
lymphoid tissue in the walls of the small intestine that keep the bacteria in food from entering the blood stream
peters patches
- detoxifying bloodstream
- phagocytosis of old red blood cells and some bacteria
- produces anticoagulants such as heparin
- filter nutrients such as sugars for storage
- store other vitamins and minerals for body use.
more functions of liver
Also called “ampulla of vater” ; where pancreatic duct and common bile duct join to enter the duodenum
hepatopancreatic duct
specialized cell groups that produce insulin. Surround by ducts that connect to the duodenum
Islets of Langerhans
