PNB 2265 Exam 3- Questions and Answers | 2026
UPDATED | 100% CORRECT
GI functions
- bring food into the body
- mechanically and chemically digest nutrients through motility and secretions
- breakdown nutrients to a size where they can be absorbed and used
- anything not absorbed will be excreted
gross anatomy of GI tract
- long tube that runs from mouth to anus
- one directional flow (so can add more nutrients)
- mouth
- esophagus
- stomach
- small intestine
- large intestine
- rectum
accessory organs
- salivary glands
- liver
- pancreas
- gallbladder
sphincter muscles
,keep the GI tract functionally and physically separate
biological valves, contracting and relaxing to control the opening, closing, and passage of
substances through body passages
they remain closed to prevent backflow
peritoneum
- serous membrane along the abdominal cavity
- parietal peritoneum - lines the walls of the abdominal cavity
- peritoneal fluid
- visceral peritoneum - covers the surface of the organs
- visceral and parietal can fold in on themselves and create subcompartments - big one is the
greater omentum that covers the ventral surface of the abdomen and stores lots of fat
histology of GI tract
- 4 tissue layers throughout the GI tract
- Serosa
- Muscularis
- Submucosa
- Muscosa
serosa
outermost layer
connective tissue wrapper
muscularis
, second layer
2 layers of smooth muscle and nervous tissue
- longitudinal layer - outer layer fibers go in the direction of the GI tract, when they contract,
they determine the length of the tube
- circular layer - inner layer, fibers are concentrically, when contract control radium
- nervous tissue - separates the two muscle layers - where the myenteric plexus is (major site of
sensory and motor innervation, receives signals from gut and brain (PNS), uses ACh to help)
this layer is responsible for the muscular contraction of the GI system - peristalsis and
segmentation, and also controls the sphincter muscles
submucosa
third layer
connective tissue layer
intermediate layer
mucosa
fourth layer
innermost layer
3 sublayers
- muscularis mucosa - smooth muscle, creates the shape of folds in the GI tract
- lamina propria - connective tissue, supports small vessels and lymph nodes, protects from
pathogens - GALT
- epithelium - forms lumen, simple/stratified columnar, contains most secretory and absorptive
UPDATED | 100% CORRECT
GI functions
- bring food into the body
- mechanically and chemically digest nutrients through motility and secretions
- breakdown nutrients to a size where they can be absorbed and used
- anything not absorbed will be excreted
gross anatomy of GI tract
- long tube that runs from mouth to anus
- one directional flow (so can add more nutrients)
- mouth
- esophagus
- stomach
- small intestine
- large intestine
- rectum
accessory organs
- salivary glands
- liver
- pancreas
- gallbladder
sphincter muscles
,keep the GI tract functionally and physically separate
biological valves, contracting and relaxing to control the opening, closing, and passage of
substances through body passages
they remain closed to prevent backflow
peritoneum
- serous membrane along the abdominal cavity
- parietal peritoneum - lines the walls of the abdominal cavity
- peritoneal fluid
- visceral peritoneum - covers the surface of the organs
- visceral and parietal can fold in on themselves and create subcompartments - big one is the
greater omentum that covers the ventral surface of the abdomen and stores lots of fat
histology of GI tract
- 4 tissue layers throughout the GI tract
- Serosa
- Muscularis
- Submucosa
- Muscosa
serosa
outermost layer
connective tissue wrapper
muscularis
, second layer
2 layers of smooth muscle and nervous tissue
- longitudinal layer - outer layer fibers go in the direction of the GI tract, when they contract,
they determine the length of the tube
- circular layer - inner layer, fibers are concentrically, when contract control radium
- nervous tissue - separates the two muscle layers - where the myenteric plexus is (major site of
sensory and motor innervation, receives signals from gut and brain (PNS), uses ACh to help)
this layer is responsible for the muscular contraction of the GI system - peristalsis and
segmentation, and also controls the sphincter muscles
submucosa
third layer
connective tissue layer
intermediate layer
mucosa
fourth layer
innermost layer
3 sublayers
- muscularis mucosa - smooth muscle, creates the shape of folds in the GI tract
- lamina propria - connective tissue, supports small vessels and lymph nodes, protects from
pathogens - GALT
- epithelium - forms lumen, simple/stratified columnar, contains most secretory and absorptive
