anatomy exam 3 part 3/4

What five functions does the large intestine perform?

Water absorption, electrolyte absorption, vitamin absorption, feces formation, feces propulsion/storage.

What are the four main parts of the large intestine and what occurs in each?

Cecum (receives chyme, begins compaction);

Colon (water/vitamin absorption);

Rectum (stores feces);

Anal canal (defecation).

What are the six areas of the colon?

• ascending colon

• hepatic flexure

• transverse colon

• splenic flexure

• descending colon

• sigmoid colon

Be able to locate the appendix.

Attached to the cecum.

Describe the histology of the large intestine.

• Lined by simple columnar epithelium

• Lacks villi

• Abundant goblet cells and mucous glands

• Lubrication

• Circular smooth muscle

• Teniae coli – remnants of longitudinal smooth

muscle layer

What is the function of goblet cells?

Produce mucus for lubrication.

Describe the muscularis externa of the large intestine.

Outer longitudinal layer is incomplete and forms teniae coli; inner circular layer is complete.

How is it different from the esophagus and jejunum?

Esophagus/jejunum have complete longitudinal layers; colon has teniae coli.

What are teniae coli?

Three bands of longitudinal smooth muscle.

What are haustra?

Pouches formed by contraction of teniae coli.

Rectal defecation reflexes are stimulated by what?

Stretch of the rectal wall.

Describe the two defecation reflexes.

Intrinsic reflex: local enteric reflex causing weak peristalsis. Parasympathetic reflex: stronger reflex via spinal cord increasing peristalsis.

What does “intrinsic” refer to?

Local enteric nervous system.

Which anal sphincter is under conscious control?

External anal sphincter.

What effects does the parasympathetic ANS have on the digestive system?

Increases motility and secretion.

What effects does the sympathetic ANS have on the digestive system?

Decreases motility and secretion.

What stimulates the release of gastrin by G‑cells in the stomach?

Proteins and stomach distension.

What are the effects of gastrin?

Increases HCl secretion and gastric motility.

What hormone is secreted in varying amounts depending on fat content of chyme?

Cholecystokinin (CCK).

What effects does CCK have?

Stimulates gallbladder contraction and pancreatic enzyme release.

What stimulates secretion of gastric inhibiting peptide (GIP)?

Glucose and fats in chyme.

What effects does GIP have?

Inhibits gastric activity; stimulates insulin release.

A drop in pH of the duodenum stimulates secretion of what hormone?

Secretin.

What are the effects of secretin?

Stimulates bicarbonate release; inhibits gastric activity.

What are the effects of vasoactive intestinal peptide (VIP)?

Stimulates intestinal secretion and vasodilation.

Where would we find brush border enzymes and what is their function?

On microvilli; complete digestion of carbs and proteins.

Why are there two types of transport (facilitated diffusion and secondary active transport) for carbs and proteins?

Some nutrients follow gradients; others require energy‑coupled transport.

Where are monosaccharides and amino acids transported once inside epithelial cells?

Into intestinal capillaries.

Where does nutrient‑rich blood from intestinal capillaries go?

To the liver via the hepatic portal vein.

Triglycerides are broken down into what?

Monoglycerides and fatty acids.

What occurs after these components enter an epithelial cell?

They are reassembled into triglycerides.

How is this large structure transported out of the epithelial cell?

Exocytosis of chylomicrons.

How do chylomicrons enter circulation if too large for capillaries?

Enter lacteals (lymphatic vessels).

Where do they enter general circulation?

At the left subclavian vein.

How is water reabsorbed into the body?

Osmosis following solute absorption.

What is the vessel carrying nutrient‑rich blood called?

Hepatic portal vein.

Where is it taking this blood?

To the liver.