Gastrointestinal System Flashcards
(23 cards)
What are the 4 fundamental tissue layers of the GIT tract?
- Mucosa
- Submucosa
- Muscularis
- Serosa/Adventitia
These layers contribute to the overall function of the gastrointestinal tract.
What is the primary function of the mucosa layer in the GIT?
First point of contact with food
It is involved in secretion and absorption.
What is the role of the submucosa in the gastrointestinal system?
Support network containing blood vessels, nerve plexi, lymphatic vessels, and exocrine glands
Exocrine glands secrete buffers and enzymes into the digestive tract.
What type of muscle is found in the muscularis layer of the GIT?
Smooth muscle in two layers (inner circular layer; outer longitudinal layer)
This muscle is involved in mechanical processing and movement along the tract.
What is the function of the serosa layer in the GIT?
Provides movement and protection
It is a layer of visceral peritoneum along the digestive tract.
What occurs during ingestion in the gastrointestinal system?
Food or fluid enters the mouth
This is the first step in the digestive process.
What processes are involved in mechanical processing of food?
- Crushing
- Shearing
These actions make material easier to move through the tract.
What is the definition of secretion in the context of the gastrointestinal system?
Release of water, acids, buffers, enzymes, and salts by the epithelium
This occurs in the GI tract and glandular organs.
What is the role of absorption in the digestive process?
Movement of organic substrates, electrolytes, vitamins, and water across digestive epithelium
This is crucial for nutrient uptake.
What is the purpose of excretion in the gastrointestinal system?
Removal of waste products from body fluids
This helps maintain homeostasis.
What is peristalsis?
Wave-like muscle contractions that move food through the digestive tract
It is essential for the progression of food along the GIT.
What is segmentation in the context of digestion?
Cycles of contraction that churn and fragment the bolus
This occurs in most areas of the small intestine.
What is the main function of the stomach in digestion?
- Storage of ingested food
- Mechanical breakdown
- Production of intrinsic factor
Intrinsic factor is required for absorption of vitamin B12.
What is the role of gastric pits?
Open onto the gastric surface and communicate with gastric glands
They secrete acid and enzymes for digestion.
What is the alkaline tide?
Sudden influx of bicarbonate ions into the bloodstream
This occurs when gastric glands are very active.
What triggers the release of gastrin in the gastric regulation phase?
Stretch receptors in the stomach wall
Gastrin stimulates gastric activity.
What is the primary site of nutrient absorption in the GIT?
Small intestine
About 90% of absorption occurs here.
What are the three segments of the small intestine?
- Duodenum
- Jejunum
- Ileum
Each segment has distinct roles in digestion and absorption.
What is the function of the large intestine?
- Reabsorption of water
- Compaction of intestinal contents into feces
- Absorption of vitamins produced by bacteria
- Storage of fecal material
These functions are vital for waste processing.
What vitamins are produced in the large intestine?
- Vitamin K
- Biotin
- Pantothenic acid (B5)
These vitamins play crucial roles in various metabolic processes.
What is the gastroileal reflex?
Stimulates movement of chyme into the caecum while eating
This reflex helps coordinate digestion.
What is the role of the microbiome in the large intestine?
Bacteria convert bilirubin, break down peptides, and feed on indigestible carbohydrates
They also produce flatus (intestinal gas).
What is the process of defecation triggered by?
Movement of fecal material into the rectum
This stimulates the defecation reflex.
