Gastrointestinal System Flashcards
What are the two main structures of the digestive system?
- alimentary canal aka GI tract- tube that starts at the mouth and ends at anus [ peristalsis occurs here]
- accessory organs- secretes items to aid in digestion
What are the accessory organs?
- tongue
- salivary glands
- liver
- gallbladder
- pancreas
What are the main structures of the GI tract?
- mouth, pharynx, esophagus, stomach, small intestine (duodenum, jejunum, illeum), large intestines (appendix, cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, anal canal)
What is a function of the appendix
immune function (has good bacteria)
What is the function of the rectum?
temporarily stores feces
What are the functions of the digestive system?
- ingest, digest, absorb (nutrients like amino acids or glucose are absorbed into the bloodstream) food and eliminate the undigested food remains as feces
What are the two types of digestion done by the GI tract.
- mechanical digestion
- chemical digestion
Explain mechnical digestion
Name examples of mechanical digestion
- physical breakdown of food into smaller particles to aid in chemical digestion; NO chemical rxn
- examples: chewing and grinding in the mouth; churning and mixing in the stomach
Explain chemical digestion
Name examples of chemical digestion
- done by enzymes and acid; chemical rxn present (changes one substance into another)
- example: starch broken down into glucose; proteins broken down into AA; fats, lipids broken down into fatty acids and glycerol
Rest and digest is done by which arm of the nervous system?
parasympathetic
General pathway of food travel from the mouth to the anus
- mouth- teeth, tongue, salivary glands
- pharynx
- esophagus
- LES
- stomach
- pyloric sphincter
- small intestines- duodenum, jejunum, ileum
- large intestine- appendix, cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, anal canal
Where does mechnical digestion begin?
teeth of the mouth
Where is the first area of chemical digestion?
-
mouth, more specifically, the
saliva from salivary glands that contains amylase to digest starch, amylose
Where is the first site of protein digestion?
stomach
through pepsin released by chief cells
Where is most of the chemical digestion and absorption done?
chemical digestion: duodenum of the small intestines
absorption: proximal jejunum is the most, and then duodenum
What nerve does sensory control to the top teeth? bottom teeth?
CN 5 (trigeminal) -
* top teeth: maxillary branch
* bottom teeth: mandibular branch
tongue
- What type of muscle is the tongue?
- What is the function?
- What nerve does motor control?
- skeletal
- mixes the food with saliva
- CN 12 (hypoglossal)
Where is the food bolus made?
by the teeth, tongue, and salivary glands of the mouth
What is present in the saliva made by salivary glands?
amylase, which digests starches (a complex carb) into simple sugars AS WELL AS lipase
What are the 3 salivary glands? What nerves control them? What branch of the NS do those nerves belong to?
- parotid- CN9 (glossopharyngeal- parasympathetic)
- sublingual- CN 7 (facial- parasympathetic)
- submandibular- CN 7 (facial- parasympathetic)
What type of muscle is the esophagus? Explain the movements through it.
- smooth muscle
- when the m. contracts, it does peristalsis to push food bolus down.
What are the 2 important sphincters of the GI tract? What are the general functions of each?
- LES- closes to prevent food from going back up the esophagus
- Pyloric- closes to prevent food from leaving the stomach early before it is fully mixed up as chyme
Two pathological states of LES
- too tight- achalasia: food harder time to enter stomach and so pt loses weight bc not able to eat as much food
- too relaxed- GERD: food (acidic) goes up esophagus due to hormone (ie. relaxin from pregnancy) or mechanical (ie. preggo and large belly or overweight) or other reasons.
What is the function of the stomach?
- mechanical and chemical digestion
- copiouos amount of mechnical digestion are accomplished through it having 3 layers; it mixes and churns food and turns it into chyme.
- chemical digestion: pepsin in stomach to breakdown proteins