Digestive System Functions Quiz

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Questions and Answers

Which of the following is NOT a primary function of the alimentary canal?

  • Nutrient absorption
  • Hormone production (correct)
  • Waste elimination
  • Food storage

Peristalsis is the mechanism by which food is moved through the alimentary canal.

True (A)

What is the main enzyme present in saliva, and what does it break down?

Salivary amylase, breaks down starch into maltose.

The process by which small molecules are taken into the bloodstream is known as ______.

<p>absorption</p> Signup and view all the answers

Match the following digestive structures with their function.

<p>Oesophagus = Transports food to the stomach Stomach = Mixes and stores food Small intestine = Primary site of absorption Large intestine = Absorbs water and forms feces</p> Signup and view all the answers

Which sphincter controls the passage of food from the stomach to the duodenum?

<p>Pyloric sphincter (C)</p> Signup and view all the answers

Egestion and excretion refer to the same biological process.

<p>False (B)</p> Signup and view all the answers

The process of breaking large insoluble food molecules into smaller soluble ones is called ______.

<p>digestion</p> Signup and view all the answers

What is the name of the ball of food formed in the mouth?

<p>Bolus (C)</p> Signup and view all the answers

Bile contains enzymes that digest fat.

<p>False (B)</p> Signup and view all the answers

What is the process called that moves food down the esophagus?

<p>Peristalsis</p> Signup and view all the answers

The stomach uses the enzyme ______ to break down proteins into peptides.

<p>pepsin</p> Signup and view all the answers

Match the enzyme with its substrate:

<p>Amylase = Starch Maltase = Maltose Lipase = Fats Pepsin = Proteins</p> Signup and view all the answers

What is the pH level at which pepsin works optimally?

<p>pH 2 (A)</p> Signup and view all the answers

The main function of the Gall Bladder is to produce bile.

<p>False (B)</p> Signup and view all the answers

Bile contains ________ which neutralises acids.

<p>Sodium Hydrogen Carbonate</p> Signup and view all the answers

Which of the following are absorbed directly into the blood?

<p>Monosaccharides and amino acids (C)</p> Signup and view all the answers

Lacteals absorb amino acids and sugars.

<p>False (B)</p> Signup and view all the answers

What is the function of the microvilli in the small intestine?

<p>To increase the surface area for absorption</p> Signup and view all the answers

Digested food products are transported to the ____ via the hepatic portal vein.

<p>liver</p> Signup and view all the answers

Match the following structures to their functions:

<p>Villi = Increase surface area Lacteals = Absorb fatty acids and glycerol Capillaries = Absorb amino acids and sugars Hepatic portal vein = Transport to the liver</p> Signup and view all the answers

What is the approximate length of the small intestine?

<p>5 meters (D)</p> Signup and view all the answers

The large intestine primarily functions to absorb water and salts from undigested food.

<p>True (A)</p> Signup and view all the answers

Name two adaptations of the small intestine that helps with the absorption process.

<p>Villi and microvilli</p> Signup and view all the answers

Flashcards

Bolus

A ball of food formed by the tongue for swallowing.

Peristalsis

The process of muscle contractions that move food through the oesophagus.

Oesophagus

The tube that carries food from the mouth to the stomach.

Gastric Pits

Glands in the stomach that secrete digestive substances.

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Pepsin

An enzyme that digests proteins into peptides in the stomach.

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Chyme

The mixture of food and gastric juices that exits the stomach.

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Bile

A digestive fluid produced by the liver, stored in the gallbladder, helps neutralize stomach acid.

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Lipase

An enzyme that breaks down fats into fatty acids and glycerol.

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Alimentary Canal

A muscular tube where food is digested and absorbed.

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Digestion

Process of breaking down large food molecules into smaller ones.

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Absorption

The process of small molecules passing into the bloodstream.

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Egestion

The removal of undigested food from the body as feces.

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Salivary Amylase

An enzyme that breaks down starch into maltose in the mouth.

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Assimilation

Using absorbed small molecules to build larger ones like proteins.

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Nutrients

Essential substances needed for energy, growth, and cell repair.

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Fatty Acids and Glycerol

Products of lipid digestion absorbed into lacteals.

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Lacteals

Vessels in the small intestine that absorb fats.

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Villi

Finger-like projections in the small intestine enhancing absorption.

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Microvilli

Even smaller projections on villi increasing surface area.

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Absorption in the Small Intestine

Process where digested nutrients enter the bloodstream.

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Hepatic Portal Vein

Vein that carries absorbed nutrients from the intestines to the liver.

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Excellent Blood Supply

Rich capillary presence in the small intestine for rapid absorption.

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Large Intestine

Final section of the digestive system absorbing water and salts.

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Study Notes

Alimentary Canal Overview

  • The alimentary canal is a muscular tube responsible for food movement, storage, digestion, absorption, and elimination.
  • Food is taken into the alimentary canal via ingestion.
  • Large insoluble molecules are broken down into small soluble ones through mechanical and chemical digestion.
  • Small molecules are absorbed into the bloodstream during absorption.
  • Small molecules are used by cells to make larger molecules (e.g., proteins) during assimilation.
  • Undigested food is removed as feces in the egestion process.
  • Autotrophic nutrition is where organisms make their own food (e.g., plants).

The Mouth

  • Mechanical digestion in the mouth involves increasing the food surface area for chemical digestion.
  • Salivary glands secrete saliva, which breaks down food into a bolus.
  • The tongue forms the food into a ball called a bolus.
  • The bolus is moved down the esophagus by a process called swallowing.
  • Teeth are used for mechanical digestion.

Types of Teeth

  • Different types of teeth (incisors, canines, premolars, and molars) have different shapes and functions, adapted to different diets.
  • Carnivores (e.g., tigers) have prominent canines for tearing flesh.
  • Herbivores (e.g., horses) have large molars for grinding grass.

Peristalsis

  • Food is squeezed down the esophagus by wavelike muscle contractions called peristalsis.
  • Circular muscles behind the bolus contract, squeezing food forward.
  • Circular muscles in front of the bolus relax, allowing the lumen to widen.

Stomach Functions

  • The stomach stores food (up to 2 hours) allowing time for digestion.
  • Chemical digestion of proteins into peptides occurs with enzymes like pepsin, which works best at a pH of 2.
  • Mechanical digestion of food happens through strong muscular contractions and relaxation, churning the food within the stomach.
  • Strong acid in the stomach (pH 2) disinfects food by killing microbes.

Gastric Pits

  • Glands in the stomach lining secrete:
    • Mucus as a lubricant
    • Hydrochloric acid to kill bacteria and maintain low pH
    • Pepsin to break down proteins into peptides (optimal in acidic conditions)

Digestion in the Small Intestine

  • Food exits the stomach through a sphincter.
  • Chyme (partially digested food) mixes with pancreatic juices containing enzymes like:
    • Amylase (starch to maltose)
    • Maltase (maltose to glucose)
    • Lipase (fats to fatty acids and glycerol).
  • Pancreatic and intestinal juices work best at a neutral pH (7). Bile neutralizes stomach acids.

Bile

  • Produced by the liver and stored in the gallbladder.
  • Bile contains sodium bicarbonate, which neutralizes acids.
  • Bile salts emulsify fats (break large fat droplets into smaller ones).
  • Bile pigments are excreted in feces.
  • Bile does not contain enzymes; it does not digest fats.

Digestion of Fats

  • Bile salts emulsify large fat droplets into smaller ones, increasing the surface area for lipase action.
  • Lipase digests fats into fatty acids and glycerol.
  • Fatty acids and glycerol are absorbed into lacteals.

Absorption in the Small Intestine

  • Small molecules (monosaccharides, amino acids, water, vitamins, and minerals) are absorbed directly into the blood.
  • Fatty acids and glycerol are absorbed into lacteals, which eventually feed into the blood vessels.

The Small Intestine

  • The small intestine is approximately 5 meters long.
  • Finger-like projections called villi line the small intestine, greatly increasing the surface area for absorption.
  • Microvilli, tiny projections on the villi, further increase the surface area for absorption.
  • The small intestine has an excellent blood supply via capillaries, assisting with absorption and transport of nutrients.
  • Lacteals are vessels in the villi that absorb fats.

Absorbed Food and the Liver

  • Absorbed food enters the bloodstream and travels to the liver via the hepatic portal vein.
  • The liver stores excess glucose as glycogen, breaks down food to release energy, and detoxifies or breaks down various substances.

The Large Intestine

  • The large intestine absorbs water and salts.
  • Approximately 30% of feces consists of bacteria.
  • Feces are stored in the large intestine until egested via the anal sphincter.
  • High-fiber diets are associated with lower incidences of bowel cancer.

Diet and Disease

  • High sugar intake leads to tooth decay.
  • High fat/energy intake and low exercise contribute to obesity.
  • Obesity is linked to arthritis, diabetes, high blood pressure, and heart disease.
  • High salt intake causes high blood pressure.
  • High cholesterol contributes to heart disease.
  • Low-fiber diets are linked to a higher risk of bowel cancer.

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