VB | Small and Large Intestine

Mechanical and chemical digestion in the stomach results in?

Chyme

What propels chyme through the pyloric sphincters into the duodenum of the small intestine?

Peristaltic Waves

What lines the interior wall of the small intestine?

Finger-like projections called Villi

Most absorption of nutrients from ingested food occurs through?

Villi

What happens to nutrients and chyme in the small intestine?

It is further broken down by secretions from organs

Inside each Villus is a?

Lacteals

• from lymphatic system

Purpose of lacteals?

Fatty acids pass into them and capillary beds of the circulatory system, in which other nutrients pass

Water and other substances from chyme that are not absorbed move?

Into the large intestine for further absorption, digestion, or elimination.

When chyme passes from the stomach into the duodenum, what begins?

Absorption of nutrients

What increases the surface area available for absorption?

• Circular folds in the walls of the small intestine

• Tiny raised projections called villi

What is not absorbed in the small intestine moves through the?

Large Intestine

The small and large intestines are supplied with oxygenated blood by which branches of arteries?

• Superior Mesenteric Arteries

• Inferior Mesenteric Arteries

The small and large intestines are drained of blood by which branches of arteries?

• Superior Mesenteric Veins

• Inferior Mesenteric Veins

What are the regions of the small intestine?

• Duodenum

• Jejunum

• Ileum

In the small intestine, nutrients in chyme are?

• Further broken down by secretions from organs

• Then taken up by intestinal lining cells

• Then digested further by intracellular enzymes

What two structures of the digestive system have similar layers?

• Intestines

• Stomach

The small intestine wall consists of how many layers?

Four

• Inner mucosa

• Submucosa

• Muscularis

• Serosa

The layers of the small intestine have structural features that?

• Facilitate nutrient absorption

• Digestion

• Mucus and enzyme secretion

• Immune response

The mucosa of the stomach consists of?

• Simple columnar epithelium

  • Goblet Cells

• Areolar connective tissue

• Lymphoid tissue

• Smooth muscle

The submucosa of the stomach consists of?

• Areolar connective tissue

• Mucus-secreting duodenal glands

  • only in the duodenum

The muscularis of the stomach consists of?

• Inner circular smooth muscle

• Outer circular smooth muscle

The smooth muscles in the muscularis layer of the stomach produce the?

Peristalsis Waves

The serosa that surrounds the stomach is an extension of?

Visceral Peritoneum

What does the retroperitoneal duodenum have that the Ileum and Jejunum do not?

Adventitia

Distinct structural features in the small intestine’s mucosa and submucosa facilitate?

It’s digestive and immune functions

What forms spirals in the lumen that increase its surface area for nutrient absorption and slow the movement of chyme, allowing time for digestion?

Submucosal circular folds

What further increases the surface area, facilitating nutrient diffusion through the simple columnar epithelium into blood and lymphatic capillaries?

Fingerlike mucosal villi

What forms the brush border on the apical membranes of absorptive cells, increasing their surface area for nutrient absorption and containing brush border enzymes that aid in digestion?

Cytoplasmic Extensions or microvilli

What are the four layers of the large intestine wall?

• Mucosa

• Submucosa

• Muscularis

• Serosa or adventitia

What structure in the large intestine is formed by the thickened outer longitudinal muscle?

Taenia coli

What are haustra?

Pouches formed when taenia coli contract

Which parts of the large intestine are covered by serosa?

• Cecum

• Transverse colon

• Sigmoid colon

Which parts of the large intestine have adventitia on their posterior surface?

Ascending colon, descending colon, rectum, anal canal

What is the function of the large intestine wall structures overall?

Water absorption, mucus secretion, feces formation and passage

What type of epithelium lines most of the large and small intestine?

Simple columnar epithelium

What type of epithelium lines the anal canal?

Stratified squamous epithelium

• to protect from abrasions

Why does the large intestine lack circular folds and villi?

Because less absorption occurs there, so it does not need that much surface area for that

What structural feature is thicker in the large intestine compared to the small intestine?

The mucosa

What type of cells in the large intestine have microvilli?

Absorptive cells

What is the function of microvilli in the large intestine?

Facilitate water absorption

What structural feature is absent in the large intestine but present in the small intestine?

Villi

What is the function of mucus in the large intestine?

Eases the passage of feces

What is the final stage of digestion?

Absorption and the process of elimination

Where do the final stage of digestion occur?

Large intestine (colon)

Where does chyme enter the large intestine?

Through the ileocecal valve from the ileum

What breaks down remaining carbohydrates and other substances in chyme in the large intestine?

Bacteria in the colon

Which vitamins are produced by bacteria in the colon?

Vitamins B and K

How are vitamins B and K absorbed?

They are absorbed by the colon

What movements push chyme through the colon?

Peristalsis and haustral churning

What happens to water in the large intestine?

It is absorbed

How is stool formed?

Undigested material compacts as water is absorbed

What eliminates feces from the body?

The defecation reflex

What does is the large intestine composed of?

• Colon

• Cecum

• Appendix

• Rectum

• Anal Canal

What are the regions of the colon?

• Ascending Colon

• Transverse Colon

• Descending Colon

• Sigmoid Colon

What are a band of longitudinal muscles running along the outside of the colon?

Taenia Coli

The taenia coli contracts to produce?

Haustra or bulges

What pushes chyme from one bulge to the next and mix its contents?

Haustral Contractions

What is the sequence of defecation?

Rectum stretches → defecation reflex → internal sphincter relaxes → feces enter anal canal → voluntary relaxation of external sphincter → defecation

What triggers the defecation reflex?

Stretching of the rectum when feces enter

What happens to the internal anal sphincter during the defecation reflex?

It relaxes

What allows feces to enter the anal canal?

Relaxation of the internal anal sphincter

What action is voluntary during defecation?

Relaxation of the external anal sphincter

What must occur for defecation to happen?

Voluntary relaxation of the external anal sphincter