Human Anatomy: Stomach Function Quiz

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Questions and Answers

What is the main function of the cardia region of the stomach?

Functions as a mixing bowl

Secretes mucus to protect the esophagus from stomach acid/enzymes (correct)

Serves as a holding reservoir

Produces intrinsic factor

What is the function of the stomach's muscular layer?

It helps to move food through the digestive tract. (correct)

It absorbs nutrients from food.

It secretes hormones that regulate digestion.

It produces enzymes for digesting food.

What is chyme?

A layer of tissue that lines the stomach.

A type of enzyme produced by the stomach.

A hormone that regulates digestion.

A viscous, highly acidic, soupy mixture formed from the combination of food, saliva, and gastric gland secretions. (correct)

Which of the following regions of the stomach is the largest?

Body (A) Signup and view all the answers

What is the primary function of the lesser curvature of the stomach?

It is attached to the mesentery of the lesser omentum (A) Signup and view all the answers

What is the primary function of the oblique layer in the stomach's muscularis externa?

It contracts to aid in the mixing and churning of food. (D) Signup and view all the answers

What is the primary function of the parietal cells in the stomach?

They secrete hydrochloric acid (HCl) which activates pepsinogen, kills microbes, and denatures proteins. (D) Signup and view all the answers

Which enzyme becomes more active in the stomach, acting on triglycerides?

Lingual lipase (D) Signup and view all the answers

What is the purpose of the mixing waves in the stomach?

To break down food into smaller particles and mix it with gastric secretions. (B) Signup and view all the answers

What is the name of the process by which small amounts of chyme are released from the stomach into the duodenum?

Gastric emptying (B) Signup and view all the answers

What is the inactive form of pepsin called?

Pepsinogen (D) Signup and view all the answers

What is the primary function of the mucous neck cells in the stomach?

They secrete mucus to protect the stomach lining from the acidic environment. (A) Signup and view all the answers

What is the role of intrinsic factor in digestion?

It is a glycoprotein that aids in the absorption of vitamin B12. (C) Signup and view all the answers

Which layer of the digestive tract is responsible for the secretion of enzymes and absorption of nutrients?

Mucosa (C) Signup and view all the answers

What is the main process by which fats are chemically digested in the digestive system?

Hydrolysis (D) Signup and view all the answers

Which of the following actions is NOT a part of mechanical digestion?

Breaking down chemical bonds (A) Signup and view all the answers

Which component is considered an accessory organ of the digestive system?

Pancreas (A) Signup and view all the answers

What type of contraction in the GI tract helps propel food along its length?

Peristalsis (B) Signup and view all the answers

What is the primary function of the pyloric sphincter?

To control the exit of chyme into the duodenum (D) Signup and view all the answers

What do the rugae of the stomach allow for?

Temporary expansion during digestion (D) Signup and view all the answers

Which cells in the gastric glands are primarily responsible for secreting hydrochloric acid?

Parietal cells (A) Signup and view all the answers

Which structure connects the pyloric antrum to the duodenum?

Pyloric canal (C) Signup and view all the answers

What is the role of the gastric pits in the stomach?

To communicate with gastric glands for secretion (A) Signup and view all the answers

How much gastric juice do the gastric glands secrete daily?

1.5 L (B) Signup and view all the answers

What type of epithelium is the mucosa of the stomach composed of?

Simple columnar epithelium (B) Signup and view all the answers

What is primarily secreted by the glands in the pylorus?

Mucus and hormones (A) Signup and view all the answers

What characterizes zone 3 of the hepatic acinus?

It surrounds the hepatic venule. (D) Signup and view all the answers

What type of blood supply contributes about one-third of the liver's blood flow?

Hepatic artery proper (B) Signup and view all the answers

Which cells in the liver play a role in engulfing pathogens and storing iron?

Kupffer cells (B) Signup and view all the answers

What is the primary role of bile in digestion?

Digestion of fats (B) Signup and view all the answers

How does blood flow through the sinusoids of the liver before reaching the central vein?

From branches of the hepatic portal vein and hepatic artery. (D) Signup and view all the answers

What do hepatocytes secrete into bile canaliculi?

Bile (D) Signup and view all the answers

What is the principal bile pigment derived from the breakdown of hemoglobin?

Bilirubin (C) Signup and view all the answers

What follows after bile canaliculi merge?

Bile ducts (A) Signup and view all the answers

Which cell type makes up the majority of the liver's mass and is responsible for various functions including bile secretion?

Hepatocytes (D) Signup and view all the answers

What is the primary function of the gallbladder?

Stores bile temporarily (A) Signup and view all the answers

What structure is typically found at the corners of a hepatic lobule?

Portal triads (A) Signup and view all the answers

Which structure primarily facilitates the immune function within the liver?

Stellate macrophages (Kupffer cells) (D) Signup and view all the answers

What type of blood do hepatic sinusoids predominantly receive?

Both oxygenated and deoxygenated nutrient-rich blood (C) Signup and view all the answers

The portal triad consists of three structures. Which of the following is NOT part of the portal triad?

Central vein (D) Signup and view all the answers

How many functional units can liver tissue be organized into based on the portal triad?

Three (D) Signup and view all the answers

What shape does a hepatic lobule typically have when viewed in cross-section?

Hexagonal (C) Signup and view all the answers

Study Notes

Digestive System Part 2 Lecture Overview

The lecture will cover the stomach, small intestine, pancreas, liver, and gallbladder.

Review from Last Class

No specific information is provided about the review from the previous class.

Digestive System Anatomy

The digestive system consists of the gastrointestinal (GI) tract and accessory organs.
The GI tract is a muscular tube that moves food from the mouth to the anus.
Accessory organs produce secretions that assist in digestion and flow into the GI tract.
There are diagrams of the GI tract and accessory organs showing all the parts.

Functions of the Digestive Tract – Mechanical Digestion

Mechanical digestion involves movements to assist in digestion, such as chewing, swallowing, mixing (churning), and peristalsis.
These movements physically break down food and propel it through the digestive tract.
Muscular contractions in the GI tract wall churn the food and propel it along.
Mixing with fluids secreted within the GI tract helps to break down food particles for digestion.

Functions of the Digestive Tract – Chemical Digestion

Enzymes from accessory organs and cells lining the tract break down food chemically.
This primarily involves hydrolysis, breaking chemical bonds using water.
Fats are broken down to fatty acids and glycerol.
Carbohydrates break down to monosaccharides.
Proteins are broken down into amino acids.

Layers of the GI Tract

The GI tract has four major layers: mucosa, submucosa, muscular layer, and serosa (or adventitia).
These layers are consistent from the esophagus to the anal canal.
Diagrams show the different layers and their respective structures, such as muscle layers and the epithelium in the mucosa layer.

The Stomach

Function: connects the esophagus to the duodenum, acts as a mixing chamber and reservoir, participates in mechanical and chemical digestion.
Function: digestion of starch (briefly), proteins (begin), triglycerides (increase), and absorption of certain substances.
Structure: muscular, expandable, J-shaped organ with three layers in the muscular layer.
Structure: highly variable shape depending on contents (empty vs. full).
Structure: viscous, highly acidic, soupy mixture of food, saliva, and gastric gland secretions = chyme.
Curvatures: lesser curvature (medial surface, connected to lesser omentum), greater curvature (lateral and inferior surfaces, connected to greater omentum).
Regions: fundus, cardia, body, pylorus.
Pylorus includes the pyloric antrum, pyloric canal, and pyloric sphincter.
Chyme leaving the stomach is controlled by the pyloric sphincter.
Rugae are Wrinkles/permanent mucosal folds that allow the stomach to expand.
Histology: mucosa is simple columnar epithelium producing alkaline mucus to protect epithelial cells.
Stomach: gastric pits communicates with several gastric glands.
Cells of gastric glands: Parietal cells (secrete intrinsic factor, hydrochloric acid (HCl), and activates pepsinogen), chief cells (secrete pepsinogen that becomes pepsin with HCl, gastric lipase), mucous neck cells (secrete mucus), G cells (secrete gastrin).

Digestion in the Stomach

Chemical digestion begins in the stomach, where salivary amylase continues activity until mixed with acidic gastric juices. Lingual lipase becomes more active in the stomach and acts to digest triglycerides into fatty acids and diglycerides. Hydrochloric acid (HCl) is secreted by parietal cells to kill microbes, denature proteins, and promote the release of bile and pancreatic juices.
Pepsin is secreted by chief cells as pepsinogen (inactive form), which becomes active with HCl. Pepsin acts to break down proteins into smaller peptide fragments. Gastric lipase is secreted by chief cells, splitting triglycerides into fatty acids and monoglycerides.
Absorption of nutrients is minimal in the stomach limiting to water, ions, short chain fatty acids, and small amounts of alcohol and some drugs.

The Small Intestine

The small intestines play a critical role in the digestion and absorption of nutrients.
90% of nutrient absorption occurs here.
The small intestine is ~6m (19.7ft) long and its diameter changes from 4cm (1.6in.) near the stomach to 2.5cm (1in.) nears large intestine
Three segments: Duodenum, Jejunum, Ileum.
Duodenum functions as a "mixing bowl" receiving chyme, digestive secretions from liver, gallbadder, and pancreas.
Duodenal glands secrete mucus that helps neutralize acidic chyme. Has few circular folds and small villi.
Jejunum is between the duodenum and ileum and is about 2.5m (8.2ft) long in the peritoneal cavity. It contains prominent circular folds and abundant villi.
Ileum is the final segment, ~ 3.5 m (11.5 ft) in length ending at the ileocecal valve. Features few circular folds in the distal portion, and stubby villi. Contains aggregated lymphoid nodules.
Histology: mucosa layer contains simple columnar epithelium features absorptive cells, goblet cells (produce mucus), intestinal glands, Paneth cells (lysozyme), S cells, CCK cells, and K cells (secrete GIP)
Abundant MALT/Peyer's patches in the ileum.
Submucosa contains Duodenal/Brunner's glands, which secrete alkaline mucus to neutralize acid. Muscle layer has an outer longitudinal and inner circular layer. Serosa completely surrounds the small intestine except for the majority of the duodenum and is retroperitoneal.
Special structures include circular folds, villi/villus, and microvilli.
Microvilli increase surface area for absorption.
Internal structure of a villus features extensive capillary network, and lacteal (lymphatic capillary).
External muscle layers promote stomach content mixing and assist with lymph movement, exposing surfaces to intestinal contents.

The Pancreas

The pancreas is a retroperitoneal (behind the peritoneum) organ that lies posterior to the greater curvature of the stomach, consisting of the head, body, and tail.
Exocrine functions assist in digestion.
Pancreatic acinar cells secrete pancreatic enzymes and buffers.
Pancreatic islets secrete hormones like glucagon, insulin, somatostatin, and pancreatic polypeptide.
The pancreas delivers exocrine secretions to the duodenum via the pancreatic duct (duct of Wirsung) that joins the common bile duct.
The accessory pancreatic duct (Santorini duct) branches and empties separately into the duodenum.
Pancreatic juice (~ 1200-1500mL produced daily) is mostly water and ions from epithelial cells lining the ducts and exocrine secretions containing enzymes and buffers.
Components of pancreatic juice include sodium bicarbonate, pancreatic amylase (which digests starch) proteolytic enzymes (digest protein), pancreatic lipase (main fat digesting enzyme) and nucleases (digest RNA and DNA). A note is provided describing the activation of enzymes in the duodenum.

The Liver

The liver is the largest visceral organ, weighing ~1.5kg (3.3 lb).
Located inferior and covering most of the right hypochondriac and epigastric region of the abdominopelvic cavity.
It is wrapped in tough fibrous capsules, with a layer of visceral peritoneum.
Four lobes: Left, Right, Caudate, Quadrate.
Associated Structures: Gallbladder, Bile Duct.
Functions: Carbohydrate, Lipid, Protein metabolism, Drug and hormone processing, Bilirubin excretion, Bile salt synthesis, Storage, Phagocytosis, Vitamin D Activation.
Cells of the liver: Hepatocytes, Stellate Macrophages (Kupffer cells). Hepatocytes make up 80% of the liver and are mostly metabolic, secreting, and endocrine. Stellate Macrophages are for immune function engulfing pathogens, debris, and damaged blood cells.
Bile canaliculi/bile ductules drain into the bile ducts, which then drain into the common hepatic duct, joining the common bile duct.
Internal structure of a villus includes extensive capillaries, lacteal and other tissues in the lamina propria.
Liver lobules, portal lobules, and hepatic acini are three functional units.

The Gallbladder

A hollow pear-shaped organ that stores and concentrates bile secreted from the liver.
It is located in a depression on the posterior surface of the liver's right lobe.
Divided into three regions (fundus, body, and neck).
The mucosa layer in the gallbladder consists of simple columnar epithelium arranged in rugae similar to that in the stomach
Bile flows from the liver through the hepatic ducts, where they unite to form common hepatic duct and enters the common bile duct.
When needed, contraction of smooth muscle fibers ejects the gallbladder contents into the cystic duct and to the common bile duct.
Hepatopancreatic sphincter encircles the lumens of the pancreatic and common bile ducts where they enter the duodenum, regulating bile flow into the duodenum except at mealtime.
Liver produces about 1 liter of bile per day.
Release of CCK by the duodenum triggers bile ejection into the duodenum through dilation of the hepatopancreatic sphincter and contraction of the gallbladder.
Bile salts break apart lipid droplets through emulsification.

Bile

Hepatocytes secrete 800-1000 mL of bile daily which is mostly water, bile salts, cholesterol, lecithin, bile pigments, and ions such as bilirubin (principally).
Bile is a partially excretory and digestive secretion.
Bile salts aid in bile emulsification, increasing the absorption of lipids.

Summary of Enzymes and Digestive Hormones

Tables summarizes pancreatic enzymes, their source, and functions.
Digestive hormones like Gastrin, CCK, Secretin, and GIP with their targets, effects, and stimuli for release is also summarized.

Review Questions

What are rugae? and What is their function?
Which cells secrete pepsinogen? and How is pepsinogen activated to become pepsin?
What substances are absorbed in the stomach?
What is the name of the pancreatic cells that release pancreatic enzymes?
Where do pancreatic enzymes act, and how do they reach their destination?
What are the three regions of the small intestine?

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Description

Test your knowledge about the functions and structures of the stomach in human anatomy. This quiz covers aspects such as the roles of different stomach regions, cells, and digestive processes. Enhance your understanding of gastrointestinal physiology.