Gastrointestinal Function Overview

Questions and Answers

What is the primary role of Cholecystokinin (CCK)?

Deliver bile into small intestines and stimulate pancreatic enzyme secretion (correct)

Stimulate upper gastrointestinal tract motility

Stimulate insulin secretion from the pancreas

Inhibit acid secretion in the stomach

Which cells secrete Secretin in the duodenum?

I cells

K cells

M cells

S cells (correct)

Which type of food primarily stimulates GLIP secretion?

Only fatty acids

All major food types including carbohydrates, proteins, and fatty acids (correct)

Only proteins

Only carbohydrates

What is a function of Motilin in the gastrointestinal tract?

Stimulate upper GIT motility and account for migrating motility complex Signup and view all the answers

Which hormone inhibits acid secretion in the stomach?

Nature's antacid Signup and view all the answers

What is the primary effect of CCK on the sphincter of Oddi?

Relax, allowing bile flow into the intestine Signup and view all the answers

What is a characteristic of GLIP?

Stimulates insulin secretion from the pancreas Signup and view all the answers

What is secreted by M cells in the duodenum?

Motilin Signup and view all the answers

What is the main effect of sympathetic nerves on the GI tract?

Decrease GI secretion and motility Signup and view all the answers

Which reflex is primarily involved in signaling the intestines to increase motility?

Gastroenteric reflex Signup and view all the answers

Which nerve pathway is responsible for the defecation reflex?

Spinal cord to the rectum Signup and view all the answers

What triggers the release of gastrin?

Protein digestion products in the stomach Signup and view all the answers

Which reflex inhibits stomach motility and secretion?

Vagovagal reflex Signup and view all the answers

What is the purpose of the gastroileal reflex?

Relax the ileal sphincter Signup and view all the answers

Which statement correctly describes the intestinal-intestinal reflex?

Inhibits bowel movement during distension Signup and view all the answers

Which hormone is primarily responsible for stimulating gastric acid secretion?

Gastrin Signup and view all the answers

What is the initial step in the digestive process?

Ingestion Signup and view all the answers

Which organ is NOT part of the functional segments of the gastrointestinal tract?

Pancreas Signup and view all the answers

What type of digestion breaks down food molecules into smaller components?

Chemical digestion Signup and view all the answers

Which process involves the release of substances such as water and enzymes into the GI tract?

Secretion Signup and view all the answers

What role do sphincters play in the gastrointestinal tract?

They regulate the passage between different segments. Signup and view all the answers

Which of the following is part of the absorption process in the digestive system?

Passage through enterocytes Signup and view all the answers

Which of the following correctly describes defecation?

Emptying the rectum of wastes Signup and view all the answers

What factor is NOT involved in regulating the digestive processes?

Mechanical factors Signup and view all the answers

What initiates the pharyngeal stage of swallowing?

The presence of food in the pharynx Signup and view all the answers

Which part of the nervous system is primarily involved in controlling the esophageal stage of swallowing?

Enteric nervous system Signup and view all the answers

What role does nitric oxide play during swallowing?

Transmitter for receptive relaxation Signup and view all the answers

What characterizes primary peristalsis during the esophageal stage?

Coordinated by the swallowing center Signup and view all the answers

Which statement is true regarding the relaxation of the lower esophageal sphincter (LES) during swallowing?

It involves low-pressure reception and relaxation Signup and view all the answers

What is the primary role of interstitial cells of Cajal in the gastrointestinal tract?

They generate slow waves that regulate muscle contractions. Signup and view all the answers

Which ions primarily cause depolarization in GI smooth muscles?

Calcium ions and sodium ions through calcium-sodium channels. Signup and view all the answers

What is peristalsis primarily stimulated by?

Distension of the gut. Signup and view all the answers

What characterizes the action potentials in the gastrointestinal system compared to other neurons?

They are slower and last longer than in other neurons. Signup and view all the answers

What is the significance of the myenteric plexus in gastrointestinal movements?

It requires functional integrity for peristalsis. Signup and view all the answers

What is the main outcome of the hepatic portal vein's role in splanchnic circulation?

It filters blood and removes microorganisms in the liver. Signup and view all the answers

Which of the following correctly describes the effect of parasympathetic stimulation on the gastrointestinal system?

It promotes peristalsis and digestive secretions. Signup and view all the answers

What type of movements are primarily responsible for mixing food within the gastrointestinal tract?

Segmental movements. Signup and view all the answers

Study Notes

Introduction to Gastrointestinal Function

Digestion is necessary to break food down to a molecular size for absorption and cell use.

Overview of the Digestive System

The gastrointestinal (GI) tract comprises the mouth, pharynx, esophagus, stomach, small intestine, and large intestine, including sphincters between segments.
Accessory organs aiding digestion include teeth, tongue, salivary glands, liver, gallbladder, and pancreas.
Digestion encompasses six basic processes: ingestion, secretion, mixing and propulsion, digestion (mechanical and chemical), absorption, and defecation.
Digestive processes are regulated by neural, hormonal, and local factors.

Layers of the GI Tract

Sympathetic nerves decrease GI secretion and motility via norepinephrine.
Gastrointestinal reflexes that regulate GI motility and secretion include:
- Gastrocolic reflex: stomach signals colon to increase motility.
- Gastroenteric reflex: stomach signals intestines to increase motility.
- Enterogastric reflex: intestines signal stomach to inhibit motility.
- Vagovagal reflex: regulates stomach motility and secretion via vagus nerve.
- Defecation reflex: regulates bowel movement in response to colon/rectal distension.

Hormones of the GI Tract

Gastrin: Secreted by G cells; stimulates gastric acid secretion and mucosal growth.
Cholecystokinin (CCK): Secreted by I cells; contracts gallbladder and stimulates enzyme secretion from the pancreas.
Secretin: Secreted by S cells; stimulates bile and pancreatic bicarbonate secretion.
GLIP: Enhances insulin secretion in response to major nutrients.
Motilin: Secreted by M cells; stimulates upper GI motility and regulates migrating motility complex (MMC).

GI Motility Mechanisms

Two primary movement types:
- Propulsive movements: Mainly peristalsis, moving food towards the anus.
- Mixing movements: Segmentation that mixes food continuously.
Peristalsis triggered by gut distension, requiring a functional myenteric plexus and acetylcholine secretion.

Splanchnic Circulation

Blood from the GI tract, pancreas, and spleen drains through the liver via the hepatic portal vein for filtration.
Kupffer cells in the liver remove microorganisms from the blood.

Pharyngeal and Esophageal Stages of Digestion

Pharyngeal stage: Involuntary swallowing reflex initiated by food presence, allowing passage through the upper esophageal sphincter (UES).
Esophageal stage consists of:
- Primary peristalsis: Coordinated by the swallowing center, utilizing skeletal muscles.
- Secondary peristalsis: Triggered by distension, involving smooth muscles and the enteric nervous system (ENS).
Receptive relaxation of the lower esophageal sphincter (LES) and fundus during swallowing is mediated by nitric oxide.

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Description

Explore the intricate process of digestion and the structure of the gastrointestinal system in this informative quiz. Learn about the organs involved, their functions, and the essential roles they play in nutrient absorption. Perfect for students studying human biology or health sciences.