Stomach anatomy Flashcards
The stomach is __-Shaped, It can hold ____ quarts of food, and changes shape when you eat
J
2-4
The stomach is _______ in tall people, and more _____ in short people
vertical
horizontal
Where does the esophagus meet the stomach?
Cardiac orifice
What are the 4 regions of the stomach?
Cardia
Fundus
Body
Pylorus
What is the cardia?
Small area where esophagus enters
What is the fundus?
“Storage area” The dome superior to the esophageal opening
What is the largest portion of the stomach?
The body
What does pylorus mean, and what are it’s 3 subparts?
“Gatekeeper”
Pyloric Antrum
Pyloric canal
Pyloric sphincter
What is the pyloric antrum?
“Funnel like” between the body and the pyloric canal
What is the pyloric canal?
A narrowing down, as pylorus approaches pyloric sphincter
What is the pyloric sphincter?
Muscle surrounding the very end of pylorus
A narrow passage into the duodenum
What is the gastroduodenal sphincter?
AKA pyloric sphincter
How is chyme made?
Smooth muscle in stomach creates chyme with enzymes, HCl, smooth muscle
What are rugae and what do they do?
Conspicuous longitudinal folds in the stomach- allow stomach to stretch when we eat
How is the stomach innervated?
PNS- Vagus (X) nerve
SNS- Celiac ganglion
What is the stomach’s blood supply?
Mostly from celiac trunk
Blood drains to hepatic portal vein to live
Where is the emetic center of the stomach?
In the medulla oblongata
How does vomiting occur physiologically?
Causes forceful ejection of stomach contents through mouth
Abdominal contractions drive chyme up and out as both esophageal sphincters open
Salivation occurs to protect lining
The _______ and _______ systems collaborate to increase gastric secretions and motility when food is eaten, AND to ________ them as the stomach empties.
nervous
endocrine
suppress
What are the 3 phases of stomach secretions?
Cephalic
Gastric
Intestinal
What activates the cephalic stage of stomach secretion?
Sensory receptors in head: Sight, smell, taste, and thought
Cephalic stage signals converge on the ________ and relay to the ________ ________. The ______ nerve fibers then stimulate the G-cells, and thus, secretion
hypothalamus
medulla oblongata
vagus
Gastric secretions begin before _____ enters stomach
food
What are the two feedback cycles in the gastric stage of stomach secretion?
Neural negative feedback cycle
Hormonal negative feedback cycle
What mechanisms activate the feedback cycles in the gastric stage of stomach secretion?
Activated by: Ingested food
1- Mechano receptors for stomach stretching
2- ↑ pH of contents of stomach, detected by chemoreceptors (add food, so pH ↑)
The neural negative feedback loop is part of what nervous system?
PNS
How does the neural negative feedback loop work?
Food in → distension → stretch receptors fire
Plexus of Meissner ↑ gastric juice secretion
Plexus of Auerbach- ↑ muscle churning
As food moves on, no stretching, so feedback loop stops
How does the hormonal feedback loop work?
Foods substances like alcohol, caffeine, partially digested proteins, or ↑ pH → stimulate G cells to release gastrin hormonally (↑ gastric juices, ↑ motility)
As food moves on, pH ↓ (As food moves on, HCl ↑, so pH ↓)
What controls the intestinal phase of gastric secretions?
Entrance of acidic chyme into duodenum
Receptors in duodenum send inhibitory signals to stomach
What happens in the intestinal phase of gastric secretions?
1- Slow exit of chyme from stomach
2- ↑ secretions of small intestine (and liver/pancreas)
What reflex is a break on gastric activity?
Enterogastric reflex
What three things happens in the enterogastric reflex?
1- Inhibit vagal nuclei in medulla oblongata
2- Inhibits local reflexes
3- Activate sympathetic fibers to tighten pyloric sphincter
How long does it take for the stomach to empty? What goes faster/slower?
~4 hours
Liquids go faster
Solids, slower, remain in stomach until well churned and mixed with gastric juices
