Digestion - general Flashcards
What are the 2 main groups of organs and what organs do they include?
Alimentary canal
- mouth, pharynx, esophagus, stomach, small intestine, large intestine
Accessory digestive organ
- teeth, tongue, gallbladder, salivary glands, liver, pancreas
What is the structure and function of the alimentary canal?
AC - continuous muscular tube from mouth to anus
- digest food, absorbs digested fragment through lining into the bloodstream
What is the structure and function of the accessory digestive organs?
all except teeth and tongue are connected to the GI tract
- produce secretory products (saliva, bile, enzymes to aid in the digestion of food)
Why is food in the lumen of the GI tract considered to be outside of the body?
none of the food inside the body is absorbed besides the nutrients that is absorbed
What is the abdominopelvic cavity and what is the main membrane and its function?
where most of the organs are
- peritoneum membrane is the most extensive serous membrane which reduces friction
What is the difference between the visceral and parietal peritoneum?
VP - covers external surfaces of digestive organs and is continuous with the PP
PP - lines walls of abdominopelvic cavity
What is the peritoneal cavity?
slitlike space between visceral and parietal peritoneal
- contains fluid secreted by the serous membrane
What is a mesentery?
fused double layer of parietal peritoneum
- holds organs in place
- carriers blood vessels, lymphatic vessels and nerves to organ of the GI tracts and contains visceral fat
Types of mesentery - what is the different functions between the dorsal and ventral mesentery?
DM - suspends MOST intraperitoneal digestive organs from the body wall
VM - suspends SOME intraperitoneal digestive organ from the body wall
What are retroperitoneal organs and 3 examples?
organs located at the back of the abdomen which lack mesenteries
- pancreas
- duodenum
- rectum
What are the 3 causes of peritonitis?
- ulcers
- poor surgical techniques (introduction of new bacteria)
- wounds
What is splanchnic circulation?
includes arteries that branch off abdominal aorta to serve digestive organs and hepatic portal circulation
What does hepatic portal circulation do?
delivers blood from the GI tract, spleen, gallbladder, and pancreas to the liver
What is the difference in the venous return from the abdominopelvic region vs. the digestive viscera?
AR - via inferior vena cava
DV - via hepatic portal circulation
Why does some blood from the body (hepatic portal circulation) go to the liver first?
- detoxifies
- absorbs processed material from GI and sends it to the right tissues
What are the four layers of the GI tracts from outside to inside?
- serosa
- muscularis externa
- submucosa
- mucosa
What are the 3 main functions of the mucosa?
- secretion: mucus, digestive enzymes, hormones
- absorption: end products of digestion
- protection: against infection
What are the 3 layers of the mucosa?
- surface epithelium
- lamina propria
- muscularis mucosae
What is the function of the surface epithelium?
columnar epi + goblets cells (produce musun) secrete enzymes into stomach and small intestine
What is the function of the lamina propria?
Loose connective tissues with capillaries, isolated lymph nodes, also part of MALT
What is the function of the muscularis mucosae?
thin layer of smooth muscle cells responsible for local movement of mucosa and causes folding in the small intestine to increase SA for absorption
What does the submucosa contain and what is its function?
dense connective tissue containing blood and lymphatic vessels, lymph nodules, nerve fibers
- is highly elastic which allows for stomach to regain shape after large meal
What structures does the muscularis externa contain and what is its role and the roles of the sphincters?
inner circular layer + outer longitudinal layer which thickens to form sphincters
- mixing, propulsive movements of GI tract
- mediates speed of food entering and is unidirectional to prevent backflow
What is the structure and role of the serosa?
loose connective tissue covered by single layer of squamous epi cells
- outermost, protective layer = visceral peritoneum
What is unique about the membrane of the esophagus?
has an adventitia instead of a serosa which binds the esophagus to surrounding tissues
What is unique about the membrane of retroperitoneal structures?
have both a serosa facing the peritoneal cavity and adventitia on the dorsal body wall
What type of epithelium is on the tongue?
stratified squamous epithelium
What is unique about the epithelium on the gums, hard palate and back of tongue?
keratinization to protect against abrasions
What is the scientific name for lips and cheeks and what is its function?
lips - orbicularis oris
cheeks - buccinators
- hold food in place during chewing and help in speech
What is the red margin?
the pink of the lips since there is some much blood vessels and no keratinization
What mouth structure is not considered in the oral cavity?
vestibule
What is the difference between the soft and hard palate?
HP - underlaid by palatine bones and palatine processes if maxillae,; tongue pushes food against it
SP - mostly skeletal muscles; closes nasopharynx when we swallow
What is the function of the palatopharyngeal?
arches join soft palate to the tongue and oropharynx
What does the tongue form with food?
bolus
What are the 2 types of skeletal muscles of the tongue?
intrinsic - within tongue, not attached to bone, 3 planes which changes shape of tongue in place (tube, clover)
extrinsic - attach bone of skull or soft palate to the tongue
What is the function of the lingual frenulum?
attaches tongue to floor of the month
- changes/ movement of tongue: up, down, forward, backward
What are the 4 types of tastebuds and what are their functions?
Filiform papillae: provides friction for manipulating food; no taste buds
- Fungiform papillae
- vallate papillae
- foliate papillae
