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Questions and Answers
What is the primary purpose of digestion in the gastrointestinal tract?
What is the primary purpose of digestion in the gastrointestinal tract?
Which process involves the movement of food through the gastrointestinal tract?
Which process involves the movement of food through the gastrointestinal tract?
What is chyme and what role does it play in digestion?
What is chyme and what role does it play in digestion?
In the process of absorption, how is fluid transported in the gastrointestinal tract?
In the process of absorption, how is fluid transported in the gastrointestinal tract?
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Which phase of digestion involves making larger food particles physically smaller?
Which phase of digestion involves making larger food particles physically smaller?
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What is the final product of fluid absorption in the large intestine?
What is the final product of fluid absorption in the large intestine?
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During which stage does the gastrointestinal tract experience disinfection?
During which stage does the gastrointestinal tract experience disinfection?
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What role does the enteric nervous system play in the gastrointestinal tract?
What role does the enteric nervous system play in the gastrointestinal tract?
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What is the primary function of the small intestine in the digestive process?
What is the primary function of the small intestine in the digestive process?
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How much fluid is absorbed by the large intestine?
How much fluid is absorbed by the large intestine?
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What causes the urge to defecate?
What causes the urge to defecate?
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What is the purpose of the sphincters around the anus during defecation?
What is the purpose of the sphincters around the anus during defecation?
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During digestion, what is the function of the stomach?
During digestion, what is the function of the stomach?
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What substance is added to the chyme in the duodenum to neutralize its acidity?
What substance is added to the chyme in the duodenum to neutralize its acidity?
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How much water is absorbed by the small intestine during digestion?
How much water is absorbed by the small intestine during digestion?
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What is primarily responsible for the lubrication of food during mastication?
What is primarily responsible for the lubrication of food during mastication?
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Study Notes
Gastrointestinal Tract
- The gastrointestinal (GI) tract is responsible for digestion and absorption.
- Digestion converts food into a sterile, neutral, isotonic substance (small sugars, amino acids, etc.).
- Excretion is the removal of waste products.
- Motility involves smooth muscle contractions to move ingested food from mouth to anus.
- Absorption is the uptake of nutrients from the GI tract into the bloodstream.
Digestive System Adaptations
- The GI tract has structural variations that relate to functional processes.
- Fluid balance in the gut is crucial for digestion and absorption.
- Hormones and the enteric nervous system regulate GI activity.
Objectives
- Outline the function and general structure of the digestive tract.
- Identify regional structural variations and their functional connections.
- Describe fluid balance within the gut.
- Explain the role of hormonal and enteric nervous systems.
Organs of the GI Tract
- Mouth
- Esophagus
- Liver
- Stomach
- Gall bladder
- Pancreas
- Small intestine
- Large intestine
- Appendix
- Rectum
Function of the GIT System
- Digestion: Breaks down food physically and chemically.
- The non-specific phase physically reduces large particles.
- The specific phase uses enzymes to break down food molecules.
- Chyme formation: semiliquid, sterile mixture of ingested food due to stomach acid.
- Motility: Muscle contractions mix/move food.
- Absorption: Nutrients and water transferred to the bloodstream.
Initial Physical Disruption
- Food is ingested, and initial chemical changes occur, creating chyme.
- Chyme is disinfected and diluted by chemical reactions.
- Nutrients and electrolytes are absorbed.
- Water and electrolytes are absorbed.
- Feces are produced for elimination.
Absorption
- Absorption: Specific uptake of nutrients, water, and electrolytes (active or passive).
- The small intestine has a high surface area (villi & microvilli) for efficient absorption.
- Most water is absorbed in the small intestine.
- Water and electrolytes are absorbed in the large intestine.
- Remaining water and electrolytes are reabsorbed, faeces are produced.
Excretion
- Faeces are propelled into the rectum.
- The urge to defecate occurs when the sphincters relax.
- Defecation is the expulsion of faeces.
- Diarrhoea and vomiting are major causes of dehydration due to loss of water before reabsorption.
Balance of Gut
- Detailed accounting of water and electrolytes in the GI tract during digestion and absorption process.
Small Intestine
- Absorbs nutrients and electrolytes.
- Fluid passes slowly through the small intestine.
- Epithelial cells actively and passively absorb molecules.
- Absorption is often coupled with sodium (Na+) transport.
- Nutrients are transported to the liver via the hepatic portal circulation.
- The majority of water is absorbed in the small intestine.
Large Intestine
- Final absorption of water (0.15L)
- Slow transit time for further water and electrolyte absorption.
- Faeces are formed and collected in the descending and sigmoid colon.
Rectum
- Faeces are periodically propelled into the rectum.
- Defecation occurs after sphincter relaxation.
Enteric Nervous System
- A subdivision of the autonomic nervous system.
- Controls GI motility.
- Two nerve plexuses in the gut wall (short reflex pathway).
- Parasympathetic control primarily affects GI activity.
Hormonal Activations
- Peptide hormones are released by endocrine cells in the GI tract walls.
- Some hormones act locally (paracrine action).
- Other hormones affect distant parts of the gut (endocrine action).
- Gastrin and secretin groups are important examples.
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Description
Explore the functions and structures of the gastrointestinal (GI) tract in this quiz. Learn about the processes of digestion, absorption, and excretion, as well as the adaptations of the digestive system that support these functions. Test your knowledge on the organs involved and their roles in maintaining digestive health.
