Bio 15.1 Alimentary Canal Components and Functions

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Questions and Answers

What is the primary role of the teeth in the oral cavity during digestion?

Transporting food to the stomach

Mastication of food (correct)

Absorbing nutrients

Secreting saliva

Which enzyme in saliva is responsible for beginning the digestion of fats?

Salivary amylase

Pepsin

Trypsin

Lingual lipase (correct)

What is formed when mechanically digested food is compressed by the tongue and cheeks?

Bolus (correct)

Micturition

Chyme

Bile

Which structure controls the passage of food from the esophagus into the stomach?

Lower esophageal sphincter Signup and view all the answers

What is the function of the stomach in the alimentary canal?

Chemical and mechanical digestion Signup and view all the answers

What type of glands produce saliva in the oral cavity?

Exocrine glands Signup and view all the answers

What is the primary function of hydrochloric acid in the stomach?

To activate digestive enzymes and create an acidic environment Signup and view all the answers

Which component of the alimentary canal is involved in the initial chemical digestion of starch?

Oral cavity Signup and view all the answers

Which type of cell in the stomach produces pepsinogen?

Chief cells Signup and view all the answers

What role does gastrin play in the stomach?

It stimulates secretion of hydrochloric acid Signup and view all the answers

What happens to undigestible materials in the alimentary canal?

They are excreted from the body. Signup and view all the answers

What is chyme?

A semifluid mixture of digestive substances Signup and view all the answers

How do mucous cells contribute to stomach health?

By forming a protective mucus barrier Signup and view all the answers

Which secretion is essential for the absorption of vitamin B12?

Intrinsic factor Signup and view all the answers

What is the role of gastric lipase produced by chief cells?

To hydrolyze lipids in the stomach Signup and view all the answers

What forms the acid-neutralizing buffer under the mucus barrier in the stomach?

Bicarbonate ions Signup and view all the answers

What is the primary function of gastric lipase secreted by chief cells?

Hydrolyzes lipids in the stomach Signup and view all the answers

Which type of cell in the stomach is responsible for producing intrinsic factor?

Parietal cells Signup and view all the answers

What role does gastrin play in stomach function?

Encourages hydrochloric acid secretion Signup and view all the answers

Which structure controls the flow of chyme from the stomach into the small intestine?

Pyloric sphincter Signup and view all the answers

In which subdivision of the small intestine is nutrient absorption predominantly completed?

Jejunum Signup and view all the answers

What is the function of bile when secreted into the small intestine?

Emulsifies fats Signup and view all the answers

What triggers the release of bile into the duodenum?

Presence of meal-derived fats and acidity of chyme Signup and view all the answers

Which secretory product is primarily responsible for killing microbes in the stomach?

Hydrochloric acid Signup and view all the answers

What is the primary function of the circular folds in the small intestine?

Increase surface area and slow the movement of chyme Signup and view all the answers

Which enzyme is responsible for digesting proteins in the small intestine?

Dipeptidase Signup and view all the answers

What role does enteropeptidase play in protein digestion?

It converts trypsinogen to trypsin Signup and view all the answers

Which hormone is released by the small intestine and helps regulate digestive tract pH?

Secretin Signup and view all the answers

What is the primary role of cholecystokinin (CCK) in digestion?

Promote pancreatic enzyme and bile release Signup and view all the answers

Which structures in the small intestine maximize the surface area for nutrient absorption?

Villi and microvilli Signup and view all the answers

What is the function of disaccharidases in the small intestine?

To hydrolyze disaccharides Signup and view all the answers

How do microvilli contribute to nutrient absorption in the small intestine?

By increasing surface area available for absorption Signup and view all the answers

What is the main function of the small intestine?

To absorb nutrients and water from chyme Signup and view all the answers

Which of the following correctly describes the subdivisions of the colon?

Ascending colon, transverse colon, descending colon, sigmoid colon Signup and view all the answers

What is the role of gut flora in the large intestine?

Metabolizing undigested carbohydrates into usable energy Signup and view all the answers

What is the ileocecal sphincter's primary function?

To regulate the passage of material from the small intestine to the large intestine Signup and view all the answers

What is the role of the colon in the digestive system?

Reabsorption of electrolytes and water Signup and view all the answers

Which layer of tissue makes up the peritoneum?

Double-layer epithelial tissue Signup and view all the answers

What is stored in the rectum before elimination from the body?

Feces Signup and view all the answers

What occurs in the cecum of the large intestine?

Connection to the appendix Signup and view all the answers

Study Notes

Alimentary Canal Components and Functions

The alimentary canal, also known as the gastrointestinal tract, is a continuous tube that begins at the mouth and ends at the anus.
Components of the alimentary canal include:
- Oral Cavity: Initial site of mechanical digestion (mastication), lubricates food with saliva, and begins chemical digestion of some macromolecules.
- Esophagus: A passageway for food to move from the mouth to the stomach.
- Stomach: Storage site, mixes food into chyme, and performs both chemical and mechanical digestion.
- Small Intestine: Completes macromolecular digestion and is the primary site for nutrient absorption.
- Large Intestine: Reabsorbs electrolytes and water from indigestible material and compacts it into feces.

Oral Cavity and Esophagus

Mechanical digestion in the oral cavity occurs through chewing (mastication).
Saliva, secreted from salivary glands, lubricates food contains enzymes for initial chemical digestion:
- Lingual Lipase: Hydrolyzes triglycerides into free fatty acids, glycerol, monoglycerides, and diglycerides.
- Salivary Amylase: Hydrolyzes starch into maltose.
The tongue and cheeks compress the mechanically digested food into a bolus.
The bolus passes through the pharynx and the upper esophageal sphincter into the esophagus.

Stomach

The lower esophageal sphincter (cardiac sphincter) regulates food entry from the esophagus into the stomach.
The stomach converts the food bolus into chyme, a semifluid mixture of digested and undigested materials.
The stomach lining contains specialized cells that secrete different products:
- G cells: Produce the hormone gastrin, which stimulates parietal cells to secrete hydrochloric acid.
- Parietal cells: Produce hydrochloric acid and intrinsic factor (essential for vitamin B12 absorption).
- Chief cells: Produce pepsinogen (inactive form of pepsin), which breaks down proteins into smaller peptides, and also secrete gastric lipase for lipid digestion.
- Mucous cells: Produce mucus and bicarbonate ions, which protect the stomach lining from autodigestion by acidic gastric juice.

Small Intestine

The pyloric sphincter controls the flow of chyme from the stomach into the small intestine.
Three subdivisions of the small intestine:
- Duodenum: Primary site of chemical digestion.
- Jejunum: Continues digestion and absorbs nutrients.
- Ileum: Absorbs nutrients.
The duodenum receives bile and pancreatic secretions:
- Bile: Produced by the liver and stored in the gallbladder, it aids in fat digestion and neutralizes acidic chyme.
- Pancreatic Secretions: Include enzymes for digesting fats, proteins, and carbohydrates, as well as bicarbonate for neutralizing chyme.
Surface modifications of the small intestine increase surface area and promote absorption:
- Circular folds: Increase surface area and slow chyme movement.
- Villi: Fingerlike projections from the lining.
- Microvilli: Smaller projections on individual absorptive cells, forming the brush border.
Intestinal enzymes complement pancreatic enzymes:
- Lipases: Further digest fats.
- Proteolytic enzymes: Hydrolyze polypeptides.
- Dipeptidase: Digests proteins.
- Enteropeptidase: Activates trypsinogen into trypsin.
- Disaccharidases: Hydrolyze disaccharides.
Hormones produced by the small intestine regulate digestive processes:
- Secretin: Promotes pancreatic secretions and bicarbonate release, inhibits gastric acid secretion, and slows digestive tract motility.
- Cholecystokinin (CCK): Promotes pancreatic enzyme and bile release.
The small intestine absorbs nutrients and water.

Large Intestine

The large intestine is wider and shorter than the small intestine.
Three subdivisions:
- Cecum: A small pouch connected to the appendix.
- Colon: Reabsorbs electrolytes and water, forming feces.
- Rectum: Stores feces before elimination.
Gut flora (bacteria) residing in the large intestine participate in digestion:
- Breakdown of indigestible carbohydrates into short-chain fatty acids, which serve as an energy source for the body.
- Synthesis of certain vitamins.

Peritoneum

The peritoneum lines the abdominal cavity.
Two layers of tissue:
- Parietal peritoneum: Lines the abdominal wall.
- Visceral peritoneum: Covers the organs.
The peritoneal cavity is the space enclosed by the peritoneum.

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Description

This quiz explores the components and functions of the alimentary canal, starting from the oral cavity to the large intestine. Understanding each part's role in digestion, absorption, and waste compaction is crucial for comprehending human physiology. Test your knowledge on the digestive system's intricacies!