Digestive Video 1 Flashcards
What is the layer lining the lumen?
Mucosa
Name 2 distinct features of the mucosa
First is mucosal epithelium then lamina propria
What the is the lumen?
Inside space where food passes through
Name the 4 layers of the digestive tract
Mucosa
Submucosa
Muscularis externa
Serous
What is the mucosa made of?
Mucosal epithelium & Lamina propria
What layer is after the mucosa ?
Submucosa
What does the Submucosa contain?
Contains the submucosal plexus (group of nerves)
What does the muscularis external contain?
2 muscle layers
Circular- inner layer
Longitudinal layer- outermost
What is between the circular muscle layer and the longitudinal muscle layer?
Myentric plexus
What is above the muscularis externa?
Serous -wraps all of the digestive layers
If serous is not present what is?
Adventitia
Where is adventitia present?
Oral cavity, pharynx, esophagus, rectum
What does adventitia do?
Attaches the digestive tract to other structures, wraps up your muscularis externa
Where does peristalsis occur?
Pharynx, esophagus, stomach
Where does segmentation occur?
Small intestine
What does segmentation involve?
Constrictive rings around the chime making a churning motion. The smaller the rings get as you go down the small intestine
What is the intra peritoneum?
Organs that are completely covered by the visceral peritoneum like the stomach and liver.
What is retroperitoneum?
Organs partially covered by the peritoneum (duodenum , pancreas)
What are mesenteries?
mesenteries are visceral peritoneum that combines to form structures that hold organs together
What does the transverse mesocolon do?
holds transverse colon in place
What does the lesser omentum do?
attaches liver to stomach
What does the greater omentum do?
protects the stomach from the abdominal wall (stomach to transverse colon )
What does the mesentery proper do?
holds small intestine in place
What does the sigmoid mesocolon intestine do?
holds the large intestine
What does the faciform ligament do?
connectes liver to diaphragm
What is the first phase of swallowing?
buccal (oral cavity) phase
What does the epiglottis do?
closes your trachea
What occurs in the buccal phase? What organs are involved? What does the tongue do?
chewing, involves the teeth and tongue
tongue: breaks down food and pushes food backwards
Is the buccal phase voluntary?
yes
What phase follows the buccal phase?
Pharyngeal phase
Is the pharyngeal phase voluntary?
No, it’s involuntary.
What happens in the pharyngeal phase?
The food is now called the bolus and in this phase it passes through the pharynx. The epiglottis close your trachea to prevent it from going into the trachea.
What phase follows the pharyngeal phase?
Esophageal phase
What occurs in the esophageal phase
leaves he pharynx and is going down the esophagus and ends in the stomach
Is the esophageal phase voluntary?
No, involuntary.
What sphincters are in involved in the esophageal phase?
Upper esophageal sphincter
Lower esophageal sphincter
What does the upper esophageal sphincter do?
Stays open never closed food just passes through here and continues down
What does the lower esophageal sphincter do?
Usually closed because it prevents the acid from the stomach from going into your esophagus. When food is passing through it opens.
What can does a disease of the sphincters cause?
Diseases can cause the sphincters not to open, and cause the bolus to build up in the esophagus and kill you
What happens in heart burn?
lower esophageal sphincter is opening and allowing the acid in your stomach to go up into your esophagus
What is the esophagus?
a structure for passage of food content
What is food called after is passes your oral cavity?
Bolus
What is the outer layer of the esophagus called?
adventitia.
What layers are below the adventitia?
muscularis externa, then submucosa, mucosa
What is unique about the inner layer of the esophagus?
ridges form inside the lumen that allow stretching in case we chew something that is big
What kinda of epithelia do we have in the esophagus?
stratified squamous epithelia
Why do we have stratified squamous epithelia in the esophagus?
because we might chew something that is rough and that will destroy some cells so we need to replace those cells
Where is the stomach located?
left side of our abdominal cavity
What are the 4 regions of the stomach?
Cardia (close to your heart)
Fondus
Pylorus
Body
What is the cardia?
The opening of the esophagus into the stomach.
What is the fondus?
The fondus is the area located next to the cardia
What is the pylorus?
the opening from the stomach into the duodenum (small intestine).
What is the body of the stomach?
Is the main portion of the stomach
What is located in the pylorus?
The pylorus sphincter prevents food from from the stomach into the duodenum
What body part is after the stomach?
The duodenum
What holds the stomach in place?
a mesentery called the lesser omentum
What does the greater omentum do?
its a mesentery that protects the abdominal cavity, looks like an apron of fat.
Name the curves of the stomach.
Lesser curvature
Greater curvature
What leaves from the lesser curvature?
Lower omentum leaves from the lesser curvature
What leaves from the greater curvature?
Greater omentum leaves from the greater curvature
Where does you left gastric artery originate from?
Originates from your celiac trunk (celiac trunk is the first branch off of your abdominal aorta)
What does the celiac trunk do?
Gives rise to your left gastric artery
What 2 arteries does she mention are in the liver?
Left gastric artery
Right gastric artery
What are the 3 layers of the stomach from outer - inner?
Longitudinal muscle layer
Circular muscle layer
Oblique muscle layer
Name the special feature of the innermost layer of the stomach.
Rugae is a series of ridges produced by the foldings of the wall of the stomach.
What does rugae do?
Rugae helps break down the stomach contents
What is food called in the stomach?
Bolus
Once the food that is called the bolus reaches the pylorus in the stomach what is it called?
Chyme
What type of movement occurs in the stomach?
peristalsis
What happens once peristalsis gets stronger (starts off weak)?
you have a type of segmentation, since the pylorus is closed it causes a type of churning. This is named retropulsion.
What is retropulsion? What does it help with?
strong mechanism of peristalsis that churns the contents of the stomach back in forth. Helps break down the food into smaller pieces before it reaches the small intestine.
What does the pyloric sphincter do?
Controls what leaves the stomach and enters duodenum
What three region includes the stomach?
Epigastric region
Left hypochondriac region
Umbilical region
Tiny piece in lumbar region
What are the layers of the stomach?
mucosa
submucosa
muscularis externa
serosa
What 3 muscle layers does the stomach have?
Oblique muscle layer
circular muscle layer
longitudinal muscle layer
What type of mucosa epithelium does the mucosa have?
simple columnar epithelium
What is a gastric pit?
surface that stretches so we can eat more
What cells does the gastric pit have?
Muscle neck cell
What does the muscle neck cell do?
secretes mucos at the top of the gastric pit
What happens to the stomach when you’re full?
relaxes
Where can you store food?
stomach (rectum sigmoid colon)
What is receptive relaxation?
when your stomach relaxes because its full
What cells does the epithelia of the stomach secrete?
Parietal cells (also called oxyntic cells) Chief cells (also called zymogen cells)
What do oxyntic (parietal) cells do?
They secrete hydrochloric acid.
What do zymogen (chief) cells secrete?
they secrete pepsinogen
What does the acid secreted by parietal (oxygenic) cells do?
The acid will act on the chief cells and transform the pepsinogen that is produced by the chief cells (zymogen cells) into an active enzyme called pepsin.
What does pepsin do?
enzyme breaks up protein
If you don’t have hydrochloric acid released from your parietal cells (oxyntic cells)what happens?
Can’t transform the pepsinogen from your chief cells (zymogen cells) into pepsin therefore can’t digest protein
What enzyme do newborns have that adults don’t?
Rennin- coagulate (cause a fluid to change to a solid) milk proteins
Gastric lipase- initiate the digestion of milk fats
Do children have enzymes that adults don’t have?
yes because they only digest milk
What do g cells secrete?
gastrin into the gastric pit
When are g cells release?
G cells are released when food enters the stomach
What is the function of g cells?
Stimulate the release of chief cells (oxyntic) cells & parietal cells (zymogen) .
Stimulate smooth muscle to contract which helps with the mixing & churning activity of the stomach
What stimulates zymogen (chief) cells?
G cells & parietal cells (oxyntin cells)
What is the function of the small intestine?
Absorption and Digestion of nutrients (90% in the small intestine, some is digested in the stomach)
What are the three layers that the small intestine is divided into? (20 feet)
DJ Ilium:
Duodenum
Jejunum
Ileum
How many muscles types are in the small intestine’s muscularis externa?
2 -types
Circular muscle layer
longitudinal muscle layer
(the oblique muscle layer is only present in the stomach)
Does the small intestine have adventitia or serosa?
Serosa
What are lacteals?
They are present in the small intestine
What is unique to the duodenum?
They have submucosal glands (only here not in the jejunum or ileum)
What is unique about the jejunum?
has a lot more plicae
What is unique about the ileum ?
has more Peyer’s patches which are aggregated lymphoid nodules))
