Digestive System Quiz
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Questions and Answers

What blood vessel carries blood from the small intestine to the liver?

Hepatic portal vein

What is the main function of the lymphatic system in relation to the assimilation of digested food?

Transporting lipids (fats) absorbed from the small intestine to the bloodstream.

Describe one function of the liver in the metabolism of digested food.

The liver converts excess glucose to glycogen for storage.

How does the liver contribute to detoxification in the body?

<p>Liver cells remove toxic substances from the blood.</p> Signup and view all the answers

What is the main function of the large intestine?

<p>Absorption of water and vitamins and formation of faeces.</p> Signup and view all the answers

Name two substances absorbed by the large intestine.

<p>Water and mineral salts</p> Signup and view all the answers

What is the function of the mucus secreted by the walls of the large intestine?

<p>To lubricate and facilitate the smooth movement of faeces.</p> Signup and view all the answers

What triggers the need to defecate?

<p>Increased pressure in the rectum.</p> Signup and view all the answers

What are the two main types of digestion in the digestive system, and briefly describe each?

<p>The two main types of digestion are physical digestion and chemical digestion. Physical digestion refers to the mechanical breakdown of food into smaller particles, such as chewing and peristalsis. Chemical digestion involves the use of enzymes to break down complex molecules into simpler molecules that can be absorbed.</p> Signup and view all the answers

Describe the role of salivary amylase in the digestive process. What kind of molecule does it break down, and where in the digestive system does this occur?

<p>Salivary amylase is an enzyme found in saliva that hydrolyzes starch into maltose. This chemical digestion of carbohydrates begins in the mouth.</p> Signup and view all the answers

What is the role of the ileum in the digestive system, and how does its structure contribute to this function?

<p>The ileum is the primary site of nutrient absorption in the small intestine. Its internal layer has folds and tiny projections called villi, which increase the surface area available for absorption, maximizing the amount of nutrients that can be taken up.</p> Signup and view all the answers

Explain how the structure of the villi enhances the absorption of digested food in the ileum.

<p>Villi have several structural adaptations to facilitate nutrient absorption. They have a thin epithelial layer for quick absorption, goblet cells that secrete mucus to aid digestion, blood capillaries to transport absorbed nutrients, lacteals to carry fats, intestinal glands that release digestive enzymes, and microvilli that further increase surface area for efficient absorption.</p> Signup and view all the answers

What is the difference between physical and chemical digestion? Provide an example of each.

<p>Physical digestion involves the mechanical breakdown of food into smaller particles, like chewing with teeth. Chemical digestion uses enzymes to break down complex molecules into simpler ones, like the action of salivary amylase on starch in the mouth.</p> Signup and view all the answers

Why is the pH of saliva important for the function of salivary amylase?

<p>The pH of saliva is crucial for the optimal activity of salivary amylase. The enzyme operates best within a specific pH range, which is typically between 6.5 and 7.5. This ensures that salivary amylase can effectively break down starch into maltose.</p> Signup and view all the answers

What is the function of the lacteal in the villi, and what type of digested food does it transport?

<p>Lacteals are lymphatic capillaries found within the villi. They are responsible for the absorption and transport of fatty acids and glycerol, which are the end products of fat digestion.</p> Signup and view all the answers

How does the alimentary canal contribute to the digestive process?

<p>The alimentary canal is a long, muscular tube that runs from the mouth to the anus. It is responsible for the physical and chemical breakdown of food, as well as the absorption of nutrients. The different segments of the alimentary canal, such as the stomach and small intestine, have specialized functions that contribute to the overall digestion process.</p> Signup and view all the answers

What role does water intake play in maintaining bowel health?

<p>Water intake helps keep feces soft and aids in its movement through the large intestine, facilitating defecation.</p> Signup and view all the answers

Identify two health problems associated with poor eating habits.

<p>Two health problems are gastritis and anorexia nervosa.</p> Signup and view all the answers

How does gastritis occur, and what can be a consequence if left untreated?

<p>Gastritis occurs due to inflammation of the stomach lining from gastric juice when the stomach is empty, potentially leading to gastric ulcers if untreated.</p> Signup and view all the answers

What behaviors are characteristic of someone suffering from bulimia nervosa?

<p>Individuals with bulimia nervosa binge eat and then purge through vomiting or laxative use to control their weight.</p> Signup and view all the answers

What is muscle dysmorphia and what extreme measures do individuals take to address their concerns?

<p>Muscle dysmorphia is a condition where individuals see themselves as too small and engage in excessive weightlifting and may use steroids.</p> Signup and view all the answers

What is the primary process by which faeces are expelled from the body?

<p>The primary process is called defaecation.</p> Signup and view all the answers

Define a balanced diet and name the seven food classes it includes.

<p>A balanced diet consists of all seven food classes: carbohydrates, lipids, proteins, vitamins, mineral salts, fibre, and water.</p> Signup and view all the answers

How is the energy value of food measured?

<p>The energy value of food is measured in kilojoules per gram (kJ g<sup>-1</sup>).</p> Signup and view all the answers

What is one calorie equivalent to in joules?

<p>One calorie is equivalent to 4.2 joules.</p> Signup and view all the answers

What role does fibre play in the defaecation process?

<p>Fibre helps to smoothen bowel movements and is crucial in preventing constipation.</p> Signup and view all the answers

What are some common short-term side effects of gastric bypass surgery?

<p>Common short-term side effects include acid reflux, nausea, and vomiting.</p> Signup and view all the answers

How can excessive body weight or obesity be managed effectively?

<p>Obesity can be managed through diet management, routine exercise programs, or sometimes medical treatment.</p> Signup and view all the answers

Name two long-term side effects of gastric bypass surgery.

<p>Two long-term side effects include malnutrition and defaecation problems.</p> Signup and view all the answers

Study Notes

Digestive System

  • The human digestive system is a long, muscular tube (alimentary canal) starting at the mouth and ending at the anus.
  • Parts include the mouth, esophagus, stomach, small intestine, large intestine, and anus.
  • Other organs like the liver, gallbladder, and pancreas are also part of the system.
  • Salivary, gastric, and intestinal glands secrete digestive juices into the alimentary canal.

Digestion

  • Digestion breaks down large, complex food pieces into smaller, absorbable pieces.

  • It has two components: physical and chemical digestion.

  • Physical digestion involves mechanical breakdown of food, like chewing and peristalsis (muscle contractions).

  • Chemical digestion breaks down complex molecules into simpler ones using enzymes.

Carbohydrate Digestion (in the Mouth)

  • The digestive process begins in the mouth.
  • Food presence in the mouth stimulates salivary glands to release saliva.
  • Saliva contains salivary amylase, which hydrolyzes starch into maltose.
  • The optimal pH for salivary amylase is 6.5-7.5.
  • Saliva also forms bolus, making swallowing easier.
  • The epiglottis closes the trachea during swallowing to prevent food from entering the airway.

Protein Digestion (in the Stomach)

  • The stomach wall has epithelial cells (gastric glands) consisting of chief cells, parietal cells, and mucous cells.
  • Chief cells secrete pepsinogen, which is activated by hydrochloric acid (from parietal cells) to become pepsin.
  • Pepsin hydrolyzes proteins into polypeptides.
  • Mucous cells secrete mucus to protect the stomach lining from HCl's acidic effects.

Digestion in the Small Intestine

  • The small intestine (duodenum, jejunum, and ileum) receives chyme from the stomach.
  • Duodenum also receives bile from the liver and pancreatic juices.
  • Pancreatic amylase hydrolyzes starch to maltose.
  • Trypsin hydrolyzes polypeptides into shorter peptides.
  • Lipase hydrolyzes lipids into fatty acids and glycerol.
  • Bile emulsifies lipids, increasing the surface area for lipase action.

Absorption in the Small Intestine

  • The ileum's villi and microvilli increase the surface area for nutrient absorption.
  • The epithelial layer is one cell thick to enhance absorption rate.
  • Goblet cells secrete mucus to aid in digestion and protect the lining.
  • Blood capillaries absorb amino acids, glucose, and water.
  • Lacteals absorb fatty acids and glycerol.
  • Enzymes in the intestinal juice (like maltase, sucrase, lactase) further digest carbohydrates.

Assimilation and Liver Function

  • The liver controls the amount of nutrients entering the bloodstream.
  • Metabolises glucose for cellular respiration; amino acids for protein synthesis; excess amino acids to urea for excretion.
  • The liver detoxifies substances from the blood.
  • Stores glycogen from excess glucose.

Defaecation and Large Intestine Functions

  • The large intestine absorbs water and minerals.
  • Beneficial bacteria synthesize vitamins (B and K).
  • The remaining waste (faeces) forms as undigested materials.
  • Peristaltic movement in the large intestine pushes the faeces toward the rectum and then out through the anus (defaecation).
  • Fibre stimulates peristalsis and helps regulate glucose absorption (especially useful for diabetics).

Balanced Diet

  • A balanced diet comprises all food classes (carbohydrates, fats, proteins, vitamins, minerals, fibre, and water).
  • Proportions and quantities should meet individual needs for optimal health.
  • Energy value of food is the total energy released when a gram is completely oxidized.
  • Food energy value is measured in kilojoules per gram (kJ/g).
  • Other units include calories.
  • One calorie = 4.2 joules, and is equal to the amount of energy needed to raise water temperature of 1 g by 1°C.

Health Issues

  • Obesity: Excess fat storage due to imbalanced energy intake and energy expenditure.
  • Gastritis: Stomach lining inflammation from factors like irregular food intake, alcohol or painkillers.
  • Anorexia nervosa: Obsessive fear of gaining weight, leading to food avoidance and potential health problems.
  • Bulimia nervosa: Cycles of binge eating and compensatory behaviours (vomiting or laxative use) to control weight.
  • Muscle dysmorphia: Obsessive desire to gain muscle mass through extreme exercise.

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Digestive System PDF

Description

Test your knowledge about the human digestive system, including its parts and functions. This quiz will cover aspects of digestion, including both physical and chemical processes, along with specifics about carbohydrate digestion in the mouth. Challenge yourself and learn more about how our body processes food!

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