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Questions and Answers
What role does the liver play in the metabolism of glucose?
What role does the liver play in the metabolism of glucose?
Which of the following substances are primarily absorbed in the large intestine?
Which of the following substances are primarily absorbed in the large intestine?
What is the main function of the rectum in the digestive system?
What is the main function of the rectum in the digestive system?
Which of the following statements about the liver is correct?
Which of the following statements about the liver is correct?
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What is the process of egestion primarily responsible for?
What is the process of egestion primarily responsible for?
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What role does amylase play in the digestive process?
What role does amylase play in the digestive process?
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What is the primary function of the oesophagus in digestion?
What is the primary function of the oesophagus in digestion?
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Which statement best describes the nature of chyme?
Which statement best describes the nature of chyme?
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How does the stomach contribute to the process of digestion?
How does the stomach contribute to the process of digestion?
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What is the optimal pH level for pepsin to function effectively?
What is the optimal pH level for pepsin to function effectively?
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What is the primary purpose of digestion in the human body?
What is the primary purpose of digestion in the human body?
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Which type of digestion occurs in the mouth?
Which type of digestion occurs in the mouth?
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What role do teeth play in the digestive process?
What role do teeth play in the digestive process?
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Which digestive enzyme is responsible for breaking down starch into maltose?
Which digestive enzyme is responsible for breaking down starch into maltose?
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Which of the following statements about digestion is true?
Which of the following statements about digestion is true?
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What are the products of protein digestion?
What are the products of protein digestion?
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Which of these is NOT a function of the digestive system?
Which of these is NOT a function of the digestive system?
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How does digestion contribute to energy production in the body?
How does digestion contribute to energy production in the body?
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What is the primary function of the small intestine?
What is the primary function of the small intestine?
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Which enzyme is responsible for the digestion of starch into maltose?
Which enzyme is responsible for the digestion of starch into maltose?
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Which accessory organ produces bile that aids in fat digestion?
Which accessory organ produces bile that aids in fat digestion?
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What does bile primarily do to fats in the digestive system?
What does bile primarily do to fats in the digestive system?
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What condition is characterized by the loss of healthy villi in the small intestine?
What condition is characterized by the loss of healthy villi in the small intestine?
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What structure in the small intestine increases the surface area for absorption?
What structure in the small intestine increases the surface area for absorption?
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Which of the following is NOT a product of digestion in the duodenum?
Which of the following is NOT a product of digestion in the duodenum?
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What is the purpose of assimilation in the digestive process?
What is the purpose of assimilation in the digestive process?
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Study Notes
Digestion: The Breakdown of Food
- Digestion is the process where large, insoluble food molecules are broken down into smaller, soluble molecules that be absorbed.
- This process is necessary because food molecules are too large or insoluble to be absorbed directly into the bloodstream and cells.
- Digestion breaks down food into glucose (from carbohydrates), amino acids (from proteins), and fatty acids and glycerol (from lipids).
- These smaller molecules can then be absorbed into cells to provide energy (glucose), build new cells (amino acids), and other functions (fatty acids).
Types of Digestion
- Mechanical Digestion: Physically breaking down food into smaller pieces. This is done by chewing (mouth) and churning (stomach).
- Chemical Digestion: Breaking down food molecules using enzymes.
Digestive Enzymes
- Carbohydrases: Break down carbohydrates (e.g., amylase digests starch into maltose, maltase breaks down maltose into glucose).
- Proteases: Break down proteins (e.g., pepsin and trypsin break down polypeptides into amino acids).
- Lipases: Break down lipids (e.g., lipase breaks down lipids into fatty acids and glycerol).
The Digestive System
- Alimentary Canal: A long, coiled, muscular tube that runs from the mouth to the anus.
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Mouth (Buccal Cavity):
- Mechanical Digestion: Teeth cut, tear, and grind food into smaller pieces, increasing surface area for enzymes.
- Chemical Digestion: Saliva moistens food and amylase from saliva begins breaking down starch into maltose.
- Tongue: Rolls the partly digested food into a bolus for swallowing.
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Oesophagus (Gullet):
- Peristalsis: Muscular contractions push the food bolus to the stomach.
- No digestive enzymes produced, but saliva's amylase continues digesting starch.
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Stomach:
- Mechanical Digestion: Muscles churn food, further breaking it down.
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Chemical Digestion: Gastric juice (HCl and pepsin) is released:
- Pepsin: Breaks down proteins into polypeptides.
- HCl: Kills bacteria, provides an acidic pH for pepsin's optimal function.
- Chyme: Mixture of food and gastric juice.
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Small Intestine (Duodenum): MOST DIGESTION & ABSORPTION OCCURS HERE
-
Chemical Digestion: Pancreatic juice (from pancreas) contains enzymes:
- Amylase: Continues starch digestion.
- Maltase: Completes maltose digestion to glucose.
- Trypsin: Digests polypeptides into amino acids.
- Lipase: Digests lipids into fatty acids and glycerol.
-
Chemical Digestion: Pancreatic juice (from pancreas) contains enzymes:
-
Accessory Organs: Help with digestion but are not part of the alimentary canal:
- Pancreas: Secretes pancreatic juice into the small intestine.
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Liver: Produces bile, stores it in the gall bladder, and releases it into the duodenum.
- Bile: Emulsifies fats, increasing surface area for lipase to work.
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Small Intestine (Overall):
- Villi: Finger-like projections on the small intestine wall, increasing surface area for absorption of nutrients.
- Microvilli: Tiny projections on each cell of the villi - further enhancing absorption.
- Digested food: Diffuses through the villi into the bloodstream.
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Large Intestine:
- Absorption: Water and mineral salts are absorbed.
- Formation of Faeces: Undigested food, fiber, and bacteria form faeces.
- Rectum: Temporarily stores faeces until egestion.
- Anus: Egestion - the removal of faeces from the body.
Assimilation
- Movement of digested food molecules into body cells for use.
- Glucose: Used in respiration for energy.
- Amino acids: Used to build new proteins.
- The Liver plays a crucial role in assimilation:
- Converts glucose to glycogen for storage.
- Converts amino acids into proteins.
- Breaks down alcohol, drugs, and toxins.
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Description
Explore the fascinating process of digestion, where large food molecules are transformed into smaller, absorbable units. This quiz covers both mechanical and chemical digestion, as well as the critical role of digestive enzymes. Test your understanding of how nutrients are broken down and absorbed by the body.
