anatomy exam 3 part 2/4

Which of the seven main functions of the digestive system are performed by the small intestine?

Digestion, secretion, absorption, propulsion.

List the three parts of the small intestine in order.

Duodenum, jejunum, ileum.

How long is the duodenum compared to the two other parts of the small intestine?

Shortest segment (~10 inches).

What four functions does the duodenum perform?

Neutralizes acid,

receives enzymes/bile,

begins chemical digestion,

begins absorption.

What circular muscle regulates the passage of accessory organ secretions into the duodenum?

Hepatopancreatic sphincter (sphincter of Oddi).

The pancreas is both endocrine and exocrine. What is its exocrine function?

Secretes digestive enzymes and bicarbonate into the duodenum.

Which cells of the pancreas make digestive enzymes?

Acinar cells.

What is the role of buffers?

Neutralize acidic chyme.

Which pancreatic cells make insulin and glucagon?

Pancreatic islets

• beta cells make insulin

• alpha cells make glucagon

What are the functions of insulin and glucagon?

Insulin lowers blood glucose; glucagon raises blood glucose.

What are the functions of the liver?

Detoxification, metabolism, bile production, storage, synthesis of plasma proteins.

How many lobes are in the liver?

Four lobes.

Blood arrives at the liver from two sources. What are they?

Hepatic artery (oxygen‑rich);

Hepatic portal vein (nutrient‑rich, oxygen‑poor).

What is a portal system?

Two capillary beds connected by a vein; allows nutrient processing.

What products from digestive organs travel to the liver via the hepatic portal system?

Nutrients, toxins, drugs, and absorbed molecules from stomach, spleen, pancreas, intestines.

Deoxygenated blood leaves the liver through which veins?

Hepatic veins.

What are the functional units of the liver called?

Liver lobules.

Describe hepatocytes.

Liver cells that perform metabolic and synthetic functions.

Describe the capillaries in the liver.

Sinusoids that allow exchange between blood and hepatocytes.

What structures make up the portal triad?

Branch of hepatic artery, branch of portal vein, bile duct.

Describe how this structure facilitates liver function.

Blood flows through sinusoids for processing; bile flows opposite direction toward ducts.

Describe the flow of bile from the liver to the gallbladder and duodenum.

Hepatocytes → bile canaliculi → bile ducts → hepatic ducts → common hepatic duct → cystic duct → gallbladder → cystic duct → common bile duct → duodenum.

Identify the function of the gallbladder.

Stores and concentrates bile.

What hormone stimulates gallbladder contraction and bile release?

Cholecystokinin (CCK).

What is the function of bile?

Emulsifies fats to aid digestion.

Why maximize surface area in the jejunum?

To increase nutrient absorption.

What are circular folds?

Permanent folds of mucosa/submucosa that slow chyme and increase surface area.

What are villi?

Fingerlike projections that increase absorption.

What two important structures are found within each villus?

• Capillaries

• Intestinal epithelium transports nutrients to capillaries (except chylomicrons)

• Lacteal

• lymphatic capillary into which chylomicrons diffuse and are carried through the lymphatic system to the left subclavian vein

• Intestinal glands/crypts

• secrete defensins and lysozyme control microbial growth in the small intestine

What are microvilli?

Cell membrane extensions that form the brush border.

What are brush border enzymes?

Enzymes on microvilli that complete digestion.

Where are intestinal crypts located?

Between villi.

What do intestinal crypts secrete?

secrete defensins and lysozyme

What is the thin smooth muscle strip below the lamina propria?

Muscularis mucosae.

How many layers make up the muscularis externa of the small intestine?

Two: inner circular, outer longitudinal.

What is the purpose of these layers?

Peristalsis and segmentation.

What type of epithelium lines the small intestine?

Simple columnar epithelium.

Why this type and not stratified squamous?

Optimized for absorption, not abrasion protection.

What mucous cells are interspersed within the epithelium?

Goblet cells.

What are Peyer’s patches?

Large lymphoid nodules in the ileum

• Immune defense against gut pathogens

What is their function?

Immune defense against gut pathogens.

What important nutrient is absorbed in the ileum and requires intrinsic factor?

Vitamin B12.

What is the autonomic nervous system (ANS)?

Involuntary motor system controlling smooth muscle and glands.

What are the two divisions of the ANS?

Sympathetic and parasympathetic.

Which is “fight or flight”?

Sympathetic.

Which is “rest and digest”?

Parasympathetic.

What effects does the sympathetic division have on digestion?

Decreases motility and secretion.

What effects does the parasympathetic division have on digestion?

Increases motility and secretion.

What stimulates secretion of gastrin?

Proteins in stomach; stomach distension.

Where is gastrin secreted from?

G cells of the stomach.

What effect does gastrin have?

Increases HCl secretion and gastric motility.

What stimulates secretion of secretin?

Acidic chyme in duodenum.

Where is secretin secreted from?

Duodenum.

What effect does secretin have?

Stimulates bicarbonate release; inhibits gastric activity.

What stimulates secretion of CCK?

Fats and proteins in chyme.

Where is CCK secreted from?

Duodenum.

What effect does CCK have?

Stimulates gallbladder contraction and pancreatic enzyme release.

What stimulates secretion of VIP?

Chyme in duodenum.

Where is VIP secreted from?

Duodenum.

What effect does VIP have?

Stimulates intestinal secretion and vasodilation.

What stimulates secretion of GIP?

Glucose and fats in chyme.

Where is GIP secreted from?

Duodenum.

What effect does GIP have?

Inhibits gastric activity; stimulates insulin release.