digestive system

• The digestive system has two main roles: digestion and absorption
• Digestion is the process by which large food molecules are broken down into smaller molecules.
• Proteins are broken down into amino acids
• Carbohydrates are broken down into glucose
• Lipids are broken down into glycerol and fatty acids.
• Absorption occurs in the digestive tract and moves small molecules into the bloodstream.
• Arrange the organs of the digestive system in the order that food passes through them:

  1️⃣ Mouth

  2️⃣ Esophagus

  3️⃣ Stomach

  4️⃣ Small intestine

  5️⃣ Large intestine

  6️⃣ Rectum

  7️⃣ Anus
• What are the two main organs in the mouth?

  Teeth and salivary glands
• Teeth physically break down food, increasing its surface area for enzymes.
• Salivary glands release saliva, which contains the enzyme amylase
• What does amylase digest?

  Starch
• The food passes from the mouth to the stomach via the esophagus
• What are the three main functions of the stomach?

  Mix food, produce pepsin, produce hydrochloric acid
• Pepsin is a protease enzyme that breaks down proteins
• What does hydrochloric acid do in the stomach?

  Kills bacteria and provides pH for pepsin
• The pancreas and gallbladder release their contents into the small intestine.
• Match the enzyme with its function:

  Amylase ↔️ Breaks down carbohydrates

  Lipase ↔️ Breaks down lipids

  Protease ↔️ Breaks down proteins

  Pepsin ↔️ Breaks down proteins in stomach
• Bile is alkaline and neutralizes the acid from the stomach.
• Bile emulsifies lipids, which increases their surface area for enzyme action
• Where is bile produced?

  Liver
• The small intestine is the primary site for digestion and nutrient absorption.
• Villi have a single layer of surface cells, which reduces the distance for diffusion
• What are the finger-like projections in the small intestine called?

  Villi
• Villi have a good blood supply to maintain the concentration gradient for absorption.
• What is the role of microvilli on the surface of villi?

  Increase surface area
• The large intestine absorbs excess water and forms feces.