BSC2086LECTURE1

What is the primary function of the digestive system?

The digestive system disassembles food into molecules that can be absorbed and used by the body.

What are the main digestive functions?

Ingestion, digestion (mechanical and chemical), absorption, and defecation.

What are the two subdivisions of the digestive system?

The digestive tract and accessory organs.

What is the role of the mucosa in the GI tract?

The mucosa is the innermost layer, consisting of epithelium, lamina propria, and muscularis mucosae.

What does the enteric nervous system regulate?

It regulates motility, secretion, and blood flow independently of the CNS.

What is the function of saliva?

Saliva moistens food, begins starch and fat digestion, cleanses teeth, inhibits bacteria, and binds food into a bolus.

What is the significance of intrinsic factor?

Intrinsic factor is essential for the absorption of vitamin B12 in the small intestine.

How is gastric secretion regulated during the cephalic phase?

The vagus nerve stimulates gastric secretion in response to the sight, smell, taste, or thought of food.

What causes heartburn?

Heartburn is a symptom of acid reflux, where stomach acid comes back up into the esophagus.

What are the three primary types of cells found in gastric pits and their functions?

Mucous cells (secrete mucus), parietal cells (secrete HCl and intrinsic factor), and chief cells (secrete pepsinogen).

How does peristalsis function in the esophagus?

Peristalsis is a series of wave-like muscle contractions that moves food through the esophagus to the stomach.

What happens during the swallowing (deglutition) process?

The bolus is pushed back into the oropharynx, blocking the mouth and nasopharynx, while the pharyngeal constrictors push it down.

What is chyme?

Chyme is the soupy mixture of partially digested food and digestive juices in the stomach.

How does the stomach protect itself from gastric acid?

The stomach protects itself with a thick mucus layer, regular cell replacement, and tight junctions.

What is a peptic ulcer and its common causes?

A peptic ulcer is a break in the stomach's protective layer leading to inflammation, often caused by Helicobacter pylori, NSAIDs, or stress.

What triggers the release of gastric hormones like gastrin?

The presence of food or semi-digested proteins in the stomach stimulates the release of gastric hormones.

The ____ is the muscular tube that connects the throat (pharynx) with the stomach.

esophagus.

Food is churned and mixed with gastric juices in the ____ to form chyme.

stomach.

The ____ phase of digestion begins when food enters the mouth.

cephalic.

The primary site of nutrient absorption in the digestive system is the ____ intestine.

small.

The liver produces ____ which helps in the digestion of fats.

bile.

The process of breaking down food into smaller molecules is known as ____.

digestion.

The part of the digestive system where water is absorbed and feces are formed is the ____ intestine.

large.

The role of the ____ sphincter is to prevent the backflow of stomach contents into the esophagus.

lower esophageal.

Salivary glands secrete saliva, which contains the enzyme ____ that starts starch digestion.

amylase.

The ____ is a finger-like projection that hangs from the cecum and may play a role in gut flora.

appendix.

What is the purpose of digestion?

The purpose of digestion is to break down food into smaller molecules that can be absorbed and used by the body.

What is the first organ of the digestive system?

The first organ of the digestive system is the mouth.

What role do enzymes play in digestion?

Enzymes speed up the chemical reactions involved in breaking down food.

Where does protein digestion begin?

Protein digestion begins in the stomach.

What is the role of the pancreas in digestion?

The pancreas secretes digestive enzymes and bicarbonate to aid in digestion in the small intestine.

What is bile made from?

Bile is made from cholesterol and is produced in the liver.

What nutrients are primarily absorbed in the small intestine?

Carbohydrates, proteins, and fats are primarily absorbed in the small intestine.

How do bile salts aid in digestion?

Bile salts emulsify fats to increase their surface area for enzyme action.

What is the function of the large intestine?

The large intestine's function is to absorb water and form feces.

What is the role of the gallbladder?

The gallbladder stores and concentrates bile before releasing it into the small intestine.

The enzyme ____ breaks down proteins in the stomach.

pepsin.

The ____ is the longest part of the digestive tract.

small intestine.

The muscular contractions that move food through the digestive system are called ____.

peristalsis.

The ____ is a gland that produces enzymes and hormones, including insulin.

pancreas.

The part of the digestive system that connects the mouth to the stomach is the ____.

esophagus.

____ is the process by which nutrients are taken into the bloodstream from the digestive tract.

Absorption.

The ____ valve regulates the passage of chyme from the stomach to the small intestine.

pyloric.

The main site for the digestion of carbohydrates is in the ____.

mouth.

The ____ bile duct carries bile from the liver to the duodenum.

common.

The ____ is the layer of muscle that facilitates the movement of food in the digestive tract.

muscularis.