Digestive system 1/2

Motility

movement of food bolus

digestion

hydrolysis of macromolecules

absorbtion

assimilation of macro/micro molecules

capillary transport

takes nutrients to the bloodstream

lacteal transport

takes nutrients to the lymphatic system

The lumen

the hallow/inside of the stomach

what does the mucosa do?

secreting digestive chemicals/mucus and absorbs nutrients

submucosa

transports nutrients via blood/lymphatic vessels away from GI tract

Muscilaris externa

the smooth muscle that acts as the engine to chun/propel food down the GI tract

Segmentation

Primarily occurring in the small intestine, rhythmic contractions of the circular muscle layer slosh the chyme back and forth. This mixes it thoroughly with digestive enzymes and maximizes contact with the mucosal absorptive surface.

peristalsis

The coordinated, wave-like contraction of both muscle layers. Rings of circular muscle contract behind the food bolus to prevent it from slipping backward, while longitudinal muscle contractions ahead of it shorten the tract, pushing the food smoothly along the digestive pathway.

serosa

Outer layer of the digestive tract

Visceral peritoneum (serosa)

It acts as the outer protective skin (serosa) of these organs, providing a slick, frictionless surface as they move against one another.

parietal peritoneum (serosa)

It anchors organs in place, secretes lubricating serous fluid into the peritoneal cavity to reduce friction, and forms a continuous barrier against infection and trauma.

main function of the mouth

Ingestion, mastication, and saliva

main function of the esophagus

Upper esophageal sphincter

Located at the top, it prevents air from entering the esophagus during breathing and stops food from refluxing back into the throat.

Lower esophageal sphincter

Located at the junction with the stomach, it relaxes briefly to let food enter, then snaps shut. When the LES fails to close properly, stomach acid leaks upward, causing the burning sensation known as acid reflux or heartburn (GERD).

Role of the goblet cells in stomach

Secret an alkaline mucus that coats and protects the stomach lining from being digested by its own acid and enzymes

Which cells when combined create the protein degrading eyzme pepsin

parietal cells and chief cells

where does carbohydrate digestion start?

Mouth

Main role of the small intestine

absorption, stomach acid neutralization, and fat digestion

Where does Bile come from and what is its role in the small intestine

comes from the liver/gallbladder and its main role is to break down (not digest) fats

the roles of the pancreatic enzymes

neutralize the acid with sodium bicarb and relesses enzymes that digest carbs,proteins, and lipids

Pilcae circulares/ villis

the finger structures with hairs (micro villi) that hold capillaries/lacteals that send nutrients to the liver /lymphatic system.

the Ileocecal valve

valve at the end of the small intestine that leads to the large one

explain the absorption of H2O and elytrolytes in the large intestine

remaining water and any other nutrients that have made it past the small intestine like electrolytes are absorbed here

what is the main role of liver

Bile production,storage and blood filtering

explain the process of the liver

It pulls out excess glucose to store as glycogen, grabs amino acids to build proteins, and repackages fats. Whatever the body needs right now is allowed to stay in the blood; the rest is stored or converted and is then delivered to the circulatory system.

Kupffer cells

immune cell in the liver that destroys bacteria/harmful particles through phagocytosis

The enteric nervous system

A large network of neurons imbedded in within the walls of the GI tract that coordinates movement(muscle contractions) of GI tract, enzyme secretion and blood flow without input from the brain or spinal cord.

The Meissner Plexus

Regulates the secretion, absorption and bloodflow of GI

The Auerbach Plexus

Controls the motility of the GI tract with control over sphincters and velocity of segmentation of peristalsis