Digestive system

Chapter 16: Digestive System Overview

Mouth

  • Amylase:

    • Enzyme present in saliva that initiates starch digestion.

    • Memory Tip: Mouth = Amylase = Starch digestion STARTS.

Stomach

  • Protein Digestion:

    • Begins in the stomach with the enzyme pepsin in the presence of hydrochloric acid (HCl).

    • Memory Tip: Protein = Pepsin = Stomach.

Small Intestine

  • Role:

    • Site of the most digestion.

    • Memory Tip: Small intestine = MAIN digestion site.

Liver

  • Function:

    • Produces bile which is essential for fat digestion.

    • Memory Tip: Liver = MAKES bile.

Gallbladder

  • Function:

    • Stores bile produced by the liver until it is needed for digestion.

    • Memory Tip: Gallbladder = STORES bile.

Cholecystokinin (CCK)

  • Role:

    • Hormone that triggers the release of bile from the gallbladder when fat enters the duodenum.

    • Memory Tip: Fat → CCK → Gallbladder releases bile.

Large Intestine

  • Function:

    • Primarily responsible for absorbing water from indigestible food matter.

    • Memory Tip: Large intestine = water recovery.

Ordered Steps of Digestion

Question 1: Order of Digestion

  • Correct Sequence: B. Mechanical processing → Secretion → Enzymatic hydrolysis → Absorption → Elimination.

    • Memory Tip: Break → Add enzymes → Chemically break → Absorb → Remove waste.

Question 2: Bird Digestion

  • Structure for Mechanical Digestion: E. Gizzard.

    • Function: Contains sand and rocks that act as a grinder for mechanical digestion.

    • Memory Tip: Gizzard = Grinder.

Enzymes in Digestion

Question 3: Salivary Enzyme

  • Human Saliva Contains: E. Amylase.

Question 4: Protein Digestion Begins

  • Site of Initiation in Humans: D. Stomach.

Question 5: Bile Production

  • Organ That Secretes Bile: A. Liver.

Question 6: Bile Storage

  • Structure that Stores Bile: A. Gallbladder.

Question 7: Starch Digestion Begins

  • Site of Initiation: C. Mouth.

Question 8: Majority of Digestion

  • Where Most Enzymatic Digestion Occurs: C. Small intestine.

Question 9: Large Intestine Function

  • Primary Function: E. Absorb water.

Question 10: Hormone for Fat Digestion

  • Hormone Triggered by Fat in Duodenum: A. Cholecystokinin (CCK).

Question 11: Gastrin Source

  • Organ Producing Gastrin: C. Stomach.

    • Function: Gastrin regulates stomach acid production.

    • Memory Tip: Stomach controls itself (gastrin → acid).

Question 12: Endocrine Digestive Organs

  • Organs Acting as Endocrine Glands: B. Pancreas & stomach.

Question 13: Enzyme Matching

  • Correctly Paired Enzyme and Substrate: C. Pancreatic amylase – starch.

    • Memory Tip: Amylase = carbs ONLY.

Question 14: Function of HCl

  • Primary Function in the Stomach: D. Kill bacteria.

    • Additional Role: Activates pepsin for protein digestion.

    • Memory Tip: HCl = acidic defense + activates pepsin.