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Questions and Answers
What is the primary purpose of saliva in the digestive process?
What is the primary purpose of saliva in the digestive process?
Which of the following processes is responsible for the physical breakdown of food in the mouth?
Which of the following processes is responsible for the physical breakdown of food in the mouth?
Which enzyme in saliva begins the digestion of carbohydrates?
Which enzyme in saliva begins the digestion of carbohydrates?
What is the role of mucous in the digestive process?
What is the role of mucous in the digestive process?
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What does the chemical digestion process primarily involve?
What does the chemical digestion process primarily involve?
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Which of the following best describes the function of lysozyme in saliva?
Which of the following best describes the function of lysozyme in saliva?
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During which digestive process is food moved through the digestive tract by muscular contractions?
During which digestive process is food moved through the digestive tract by muscular contractions?
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What is the pH range of saliva?
What is the pH range of saliva?
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What type of digestion occurs in protozoa like flagellates and paramecium?
What type of digestion occurs in protozoa like flagellates and paramecium?
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What is the last stage of the digestive process?
What is the last stage of the digestive process?
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What is the primary action of amylase in the digestive process?
What is the primary action of amylase in the digestive process?
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Which enzyme is secreted by the pancreas as an inactive form and later activated?
Which enzyme is secreted by the pancreas as an inactive form and later activated?
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What is the main function of bile in the digestive system?
What is the main function of bile in the digestive system?
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During which phase of digestion is gastric secretion primarily controlled by gastrin?
During which phase of digestion is gastric secretion primarily controlled by gastrin?
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Which statement about the function of the colon is true?
Which statement about the function of the colon is true?
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What do mucous secretions in the gastrointestinal tract aid in?
What do mucous secretions in the gastrointestinal tract aid in?
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Which enzyme specifically hydrolyzes maltose into two glucose units?
Which enzyme specifically hydrolyzes maltose into two glucose units?
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What is the effect of enterokinase in the intestinal phase of digestion?
What is the effect of enterokinase in the intestinal phase of digestion?
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Which nutrient is primarily absorbed in the small intestine?
Which nutrient is primarily absorbed in the small intestine?
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What is the primary role of amylase in the oral cavity?
What is the primary role of amylase in the oral cavity?
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Which of the following statements about gastric digestion is correct?
Which of the following statements about gastric digestion is correct?
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What protects the stomach wall from being digested by its own acids and enzymes?
What protects the stomach wall from being digested by its own acids and enzymes?
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What triggers an increase in saliva secretion?
What triggers an increase in saliva secretion?
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Which enzyme is responsible for the hydrolysis of proteins in the stomach?
Which enzyme is responsible for the hydrolysis of proteins in the stomach?
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What is the role of gastric lipase in digestion?
What is the role of gastric lipase in digestion?
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In which part of the digestive system does no absorption of food occur?
In which part of the digestive system does no absorption of food occur?
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Which enzyme in the stomach is involved in the digestion of milk proteins?
Which enzyme in the stomach is involved in the digestion of milk proteins?
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What is responsible for converting pepsinogen to pepsin in the stomach?
What is responsible for converting pepsinogen to pepsin in the stomach?
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What is the primary function of mucin in the stomach?
What is the primary function of mucin in the stomach?
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Study Notes
Digestive System
- The digestive system breaks down large food molecules into smaller, absorbable units using enzymes and motility in the gastrointestinal tract (GIT).
- Examples of breakdown include: proteins to amino acids, lipids to fatty acids and glycerol, and carbohydrates to monosaccharides.
Digestion Processes
- Mechanical: Physical breakdown of food into smaller pieces, achieved through chewing, stomach contractions, and intestinal movements. Chemical structure remains unchanged.
- Chemical: Macromolecules are broken down into smaller molecules by enzymes (catabolism). This occurs from the mouth to the anus.
- Microbial: Some digestion is done by microorganisms like protozoa (e.g., flagellates and paramecia), particularly in the breakdown of cellulose.
Digestive Processes in Detail
- Ingestion: Taking food into the mouth.
- Mixing and Movement: Muscular contractions (peristalsis) mix food and move it through the digestive tract.
- Digestion: Breakdown of food through mechanical and chemical means.
- Absorption: Passage of digested food from the digestive tract into the bloodstream.
- Defecation: Elimination of waste.
Buccal Digestion (Mouth)
- Food is digested in the mouth by cutting and grinding with teeth, mixing with saliva.
- Saliva (99% water, 1% inorganic & organic):
- Amylase begins starch digestion.
- Mucus lubricates food (bolus).
- Lysozyme destroys bacteria.
- Electrolytes (e.g., Na, K, Cl, and bicarbonate ions).
- Saliva's pH is 6.8-7.0.
- Saliva moistens and cleans the oral cavity, helps form a bolus, and contains amylase for carbohydrate digestion.
- Note: This stage doesn't fully digest proteins or lipids.
Gastric Digestion (Stomach)
- The stomach digests food using gastric juices secreted by tubular glands.
- Hydrochloric acid (HCl): Converts pepsinogen to pepsin, helps in digestion, kills microorganisms.
- Pepsin: Breaks down proteins into peptones.
- Rennin: Digests milk protein in young mammals.
- Gastric Lipase: Digests lipids, but is slower.
- Mucin: Protects stomach lining from acid and enzymes.
Intestinal Digestion (Small Intestine)
- Food digestion continues in the small intestine via pancreatic juice, bile, and intestinal juices.
-
Pancreatic Juice: Contains enzymes for carbohydrate, protein, and fat digestion.
- Amylase: Breaks down carbohydrates to maltose.
- Trypsin: Breaks down proteins.
- Lipase: Breaks down fats.
- Sucrase, Lactase, Maltase: Break down specific sugars.
-
Bile: Produced in the liver and stored in the gallbladder. Aids in fat digestion (emulsification).
- It helps in fat digestion and absorption of fat-soluble vitamins.
- Intestinal juice contains enzymes that complete digestion.
Intestinal Digestion (Large Intestine)
- Main function: Reabsorption of water, some minerals, and vitamins from undigested material.
- Produces semi-solid feces for egestion.
Control of Digestive Secretion
- Cephalic Phase: Controlled by nerves.
- Gastric Phase: Controlled by gastrin.
- Intestinal Phase: Controlled by enterogaster.
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Description
Test your knowledge on the various processes involved in the digestive system, including mechanical, chemical, and microbial digestion. Explore how food is broken down into absorbable units and the roles of enzymes and movements in these processes.
