Introduction to Digestive System

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Questions and Answers

Where is the liver located in the body?

Lower right portion of the abdominal cavity

Central portion of the thoracic cavity

Upper left portion of the abdominal cavity

Upper right and central portions of the abdominal cavity (correct)

What is one of the metabolic functions of the liver?

Protein synthesis

Hormone production

Carbohydrate metabolism (correct)

Blood clotting

What type of cells are present in the liver that aid in immunity functions?

Kupffer's cells (correct)

Lymphocytes

Neutrophils

Macrophages

What is the exocrine portion of the pancreas responsible for secreting?

Digestive enzymes Signup and view all the answers

During which phase of secretion does food enter the stomach?

Gastric phase Signup and view all the answers

What is the primary function of the colon?

Storage and expulsion of fecal matter Signup and view all the answers

What type of secretions does the stomach secrete?

Both exocrine and endocrine secretions Signup and view all the answers

What is the function of the submucosa layer in the intestinal wall?

Support and connective tissue Signup and view all the answers

What is the function of the enteric nervous system?

Control of GIT motility and secretion Signup and view all the answers

Which neurotransmitter excites GI activity?

Acetylcholine Signup and view all the answers

What is the name of the plexus that is located between the longitudinal and circular muscle layers?

Myenteric plexus Signup and view all the answers

What is the function of the mucosa layer in the intestinal wall?

Absorption of nutrients Signup and view all the answers

Which salivary gland is rich in amylase?

Parotid gland Signup and view all the answers

What is the main function of the gastrointestinal system?

Digestion and absorption of nutrients Signup and view all the answers

What is the primary purpose of the alimentary tract?

To provide the body with a continual supply of water, electrolytes, and nutrients Signup and view all the answers

What is the process of breaking down large food molecules into their monomers called?

Hydrolysis Signup and view all the answers

What is the term for the movement of food through the digestive tract?

Motility Signup and view all the answers

What is the process of taking food into the mouth called?

Ingestion Signup and view all the answers

What is the process of breaking down proteins, fats, and complex carbohydrates into absorbable units?

Digestion Signup and view all the answers

What is the term for the rhythmic, wave-like contractions that move food through the gastrointestinal tract?

Peristalsis Signup and view all the answers

What is the process of passing nutrients from the small intestine into the blood or lymph?

Absorption Signup and view all the answers

What is the result of digestion and absorption in the small intestine?

The body is supplied with essential nutrients Signup and view all the answers

Study Notes

Introduction to the Digestive System

The digestive system provides the body with a continuous supply of water, electrolytes, and nutrients.
The system requires movement of food, secretion of digestive juices, absorption of nutrients, circulation of blood, and control of these functions.

Functions of the Digestive System

Motility: movement of food through the digestive tract, including ingestion, mastication, deglutition, and peristalsis.
Secretion: includes exocrine and endocrine secretions, such as gastric juice, digestive enzymes, and hormones.
Digestion: breakdown of food molecules into smaller subunits.
Absorption: passage of digested end products into the blood or lymph.
Storage and elimination: temporary storage and elimination of indigestible food molecules.

Intestinal Wall Structure

The intestinal wall consists of five layers: serosa, longitudinal muscle layer, circular muscle layer, submucosa, and mucosa.
The mucosa contains sparse bundles of smooth muscle fibers called mucosal muscle.

Neural Control

The enteric nervous system (ENS) controls gut motility and secretion.
The autonomic nervous system (ANS) also plays a role in neural control.
The ENS consists of two major networks: myenteric plexus (Auerbach's plexus) and submucosal plexus (Meissner's plexus).

Neurotransmitters Secreted by ENS

Acetylcholine (ACH): excites GI activity.
Norepinephrine: inhibits GI activity.
ATP: neurotransmitter.
Serotonin: neurotransmitter.
Dopamine: neurotransmitter.
Cholecystokinin (CCK): neurotransmitter.
Somatostatin: neurotransmitter.
Nitric oxide (NO) and carbon monoxide (CO): gases.
Vasoactive intestinal peptide (VIP): neurotransmitter.

Salivary Glands and Saliva

Three main salivary glands: parotid, submandibular, and sublingual.
Saliva contains enzymes, such as amylase.

The Liver and Bile

The liver is the largest organ in the body, located in the upper right and central portions of the abdominal cavity.
Functions of the liver include:
- Formation and secretion of bile.
- Metabolic functions, such as carbohydrate, protein, and fat metabolism.
- Vascular function for storage and filtration of blood.
- Immunity functions, including the presence of Kupffer's cells.

The Pancreas

The pancreas is a complex organ composed of endocrine and exocrine portions.
The endocrine portion secretes insulin and glucagon.
The exocrine portion secretes digestive enzymes.

Phases of Secretion

Cephalic phase: begins before food reaches the stomach and possibly even before eating.
Gastric phase: begins when food enters the stomach.
Intestinal phase: begins after food enters the small intestine.

The Small Intestine

The small intestine is divided into duodenum, jejunum, and ileum.
The intestinal contents are mixed with mucosal secretion, pancreatic juice, and bile, and digestion is completed in the small intestine.

The Colon

The principal functions of the colon are:
- Absorption of water and electrolytes from the chyme to form solid feces.
- Storage of fecal matter until it can be expelled.

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Description

Learn about the functions of the digestive system, including motility, secretion, and absorption of nutrients.