Digestive System Flashcards
What are the organs in the gastrointestinal tract?
mouth, pharynx, esophagus, stomach, small and large intestines
What are the main accessory organs?
Teeth, tongue, pancreas, liver, gallbladder
What are the 6 functions of the digestive system?
Ingestion - food entering
Mechanical breakdown - making the pieces smaller
Propulsion - moving ingested food
Chemical digestion - converts ingested food into useful chemicals
Absorption - bringing chemicals into body for use
Defection- excreting good waste
Which layer of digestive tissue lines the lumen?
Mucosa
What are the four layers of digestive tissue (deep—> superficial)?
Mucosa, submucosa, muscularis externa, serosa
What are the characteristics of the mucosa?
-thin epithelial cells
-functions in secretion, absorption, and protection
-made of two layers… lamina propria and muscularis propria (made of smooth muscle to help with movement)
What are the characteristics of the submucosa layer?
-connective tissue
-contains capillaries (absorption), lymph vessels/nodes, sensory nerve fibers, and elastic fibers (expansion)
What are the characteristics of the muscularis externa?
-2 smooth muscle layers
-functions in propulsion and mixture
What are the characteristics of the serosa?
-made of CT and epithelial cells
-has some immune cells
What is the job of the enteric nervous system?
move food from one place to another (has lots of reflex arcs that are fast and automatic)
What is the difference between simple and parallel processing?
simple requires no brain involvement and is fast/predictable, parallel requires the brain and has more diverse outcomes
What is the path of a long reflex arc?
stimulus –> receptor –> sensory neuron –> spinal cord –> motor neuron –> effector –> response
Which part of the long reflex arc is not involved in a short reflex?
spinal cord
What accessory organ in the mouth performs mechanical breakdown?
teeth
Can the mouth help with the digestion of food?
yes but not a lot because its only there for a short period of time
What type of cells line the mouth and why are they beneficial?
stratified squamous epithelium (protection)
What is a bolus?
a single swallow of food
Why is saliva slightly acidic?
helps to fight off pathogens
What does amylase do?
breaks down starch
What does lipase do?
breaks down fat
What type of glands are salivary glands?
exocrine
What are the three divisions of the pharynx?
nasopharynx, oropharynx, laryngopharynx
What type of cell is the pharynx made out of?
stratified squamous epithelium
What do the mucous producing glands of the pharynx do?
helps keep the bolus moving
What is deglutition?
swallowing
What are the two phases of swallowing?
buccal and pharyngeal-esophageal phase
What happens during the buccal phase of swallowing?
tongue presses against hard palate and bolus transfer is initiated (voluntary process)
What happens during the pharyngeal-esophageal phase of swallowing?
nasopharynx closes off and epiglottis blocks trachea to prevent aspiration (involuntary process)
What is the job of the esophagus?
move bolus to stomach
What are the sphincters in the esophagus for?
performing peristalsis
What is peristalsis?
bolus causes stretching and that causes a contraction above it which pushes it down the esophagus
What sphincter opens to allow bolus to enter stomach?
gastroesophageal sphincter
Why does the lumen of the esophagus have folds?
allows for expansion
What type of muscle tissue is found in the esophagus?
upper 1/3 = skeletal
middle 1/3 = transition from skeletal to smooth
lower 1/3 = smooth
What is the stomach responsible for?
reservoir for food, slowly release food into small intestine, mechanical breakdown, some chemical digestion, produce appetite control hormones, absorption (alcohol)
What does the gastroesophageal sphincter do?
keeps acid in stomach and allows bolus from esophagus to enter
Where is the fundus and what does it do?
upper portion of stomach, release hormones for satiety
What is the rugae?
folds in the stomach that help with stretching
Where is the pyloric sphincter?
opening to the small intestine… bottom of stomach
Where are stomach contractions the highest?
pyloric antrum
What are the greater and lesser omentums for?
supplying and storing nutrients
What is GERD?
gastroesophageal reflex disorder, result of long term and repeated acid reflex
How does acid reflex occur?
stomach has pacemaker cells so its always contracting and if there is a problem with the lower gastroesophageal sphincter, the acid can get into the esophagus
What are the four gastric gland cells?
mucous neck cells, chief cells, parietal cells, enteroendocrine cells
What makes up gastric juice?
enzymes and acid
Where is gastric juice produced?
gastric pits
What type of cells is the stomach mucosa made of?
simple columnar
What does the basic slime do?
helps protect cells from acid