The Digestive System

• Liver: produces bile (that helps digest fats), produces bile salts to emulsify insoluble fats and make them smaller and sends bile into the gall bladder
• 4 Types of macromolecules:

  • Carbohydrates
  • Proteins
  • Lipids
  • Nucleic acids
• Nucleic acids are broken down by nucleuses in the small intestine
• Oral cavity - teeth, tongue

  Salivary glands

  Epiglottis - covers trachea

  Pharynx

  Larynx - voice box

  Esophagus - peristaltic contractions

  Cardiac sphincter

  Stomach - rugae, HCL, gastric juice, walls lined by protective mucus

  Pyloric Sphincter

  Small intestine:

  Duodenum, jejunum, ileum

  Large intestine:

  Ileocecal sphincter

  Cecum / appendix

  Ascending / Descending colon

  Rectum

  Anus
• What is a monosaccharide?


  A single unit of sugar like glucose/fructose
• What is a disaccharide?


  Formed by a bond between 2 monosaccharides. Eg; sucrose, maltose, lactose
• Why are lipids a better energy source?

  They store more energy per gram
• 2 Functions of pancreatic fluid

  Delivers enzymes for the break down of food (pancreatic amylase for carbs) and produces bicarbonate to neutralize acidity
• What happens to partially digested food when it leaves the stomach?

  Chyme passes through the duodenum where it receives digestive secretions from the pancreas, liver, and gall bladder. Then it goes into the jejunum and ileum where more digestion occurs and nutrients are absorbed by villi and sent to the blood stream
• What is the role of the gall bladder?


  Stores bile produced by liver. Bile contains bile salts that digest insoluble fats by breaking them down into fat droplets so that they’re easier to digest / absorb
• What is the longest organ

  Small intestine
• Where does most absorption in the digestive system take place?

  Large intestine
• Why does gastric juice not damage the walls of the stomach?

  Its lined by a barrier of mucus
• Why are most digestive enzymes not found in the stomach?

  Proteins are digested in the stomach, therefor digestive enzymes which are proteins would be broken down because of the stomach’s acidity
• How does the body absorb water?

  From food matter passing through the large intestine
• What process disassembles macromolecules?

  Enzymatic hydrolosis
• What vital roles does water play in the body?


  Transports nutrients, eliminates wastes, regulates body temperature
• What is osmosis?

  Osmosis is the movement of water molecules from an area of (more water) lower solute concentration to an area of higher solute concentration (less water) across a semi-permeable membrane.
• What does the gall bladder do?


  Store bile in between meals
• What does the pancreas do?

  secretes pancreatic fluid into duodenum, produces bicarbonate to neutralize acidity - increasing enzymatic efficiency. Makes insulin
• What does pepsinogen do?

  Makes pepsin (enzyme) that helps digest proteins into polypeptides, dipeptides then amino acids
• What is hydrolysis?

  A chemical reaction where water breaks apart macromolecules into smaller molecules
• What does amylase do?

  Break down complex carbs into simple sugars. It‘s found in saliva
• What digests carbohydrates?

  Amylase from saliva in the mouth, and pancreatic amylase that is secreted into the jejunum
• Why must macromolecules be broken down?

  Because they’re too big to enter the cell directly to be absorbed. So, enzymatic hydrolysis breaks them down into smaller molecules that are easily absorbed for the body to use
• What are lipids broken down by?

  pancreatic lipase and bile salts in the small intestine
• Broken down carbs are what?

  Complex carb -> polysaccharide -> disaccharide -> monosaccharide
• Protein broken down:

  Polypeptide -> dipeptide -> amino acids
• Lipids broken down:

  Fatty acids + glycerol
• What breaks down proteins?

  Pepsin in the stomach and then hydrolyzed by pancreatic enzymes in the small intestine
• Digestive system functions:

  1. Ingestion
  2. Digestion
  3. Absorption
  4. Egestion (elimination)
• What are macromolecules?

  Large molecules made up of smaller ones that are linked together
• What are macromolecules made up of?

  Monomers, and a macromolecule is a polymer
• Examples of monomers:

  Sugar, amino acids, fatty acids and nucleotided
• The 4 main macromolecules are also known as ??

  Essential nutrients
• Example of a polysaccharide:

  Starch, cellulose
• Amino acids are held together by what?

  Peptide bonds
• What happens during hydrolysis?

  A water molecule is added to the macromolecule which breaks the chemical bonds that hold together the monomers that make up the macromolecule. This breakdown of the chemical bonds involves protein molecules called enzymes that are secreted by organs in the digestive tract. Enzymes increase the rate of chemical reactions without being used up by the reaction. The different types of enzymes are amylase, pancreatic lipase, pepsin and pancreatic nuclease
• How do digestive enzymes help the process of hydrolysis?

  They speed the process of hydrolysis up
• What happens after enzymatic hydrolysis?

  Once the digestive system breaks down food into a state that can be absorbed by the villi and microvilli lining the small intestine, the monomers can be absorbed into the circulatory system where the blood transports these substances to different cells of the body where they’re needed