Structures and Functions of the Digestive System

• Food is then swallowed and passes through the esophagus to reach the stomach.
• Digestion begins in the mouth with mechanical breakdown through chewing, followed by chemical breakdown through enzymatic action.
• 1. Ingestion- The first process in the digestive system. It involves taking in food or substances through the mouth.
• 2. Digestion- The second process in the digestive system. Chemical and Mechanical digestion starts in the mouth.
• When the food is mixed with the saliva it's called Bolus.
• Peristalsis is the movement of food in the esophagus, a wave-like movement.
• The accessory organs are the liver, gall bladder, and pancreas.
• Liver- produces bile, a green fluid that emulsifies large fats.
• Bile- is released into the small intestine to aid in the digestion of fat.
• The pancreas- produces three enzymes (amylase, peptidase, and lipase) it breakdown the carbohydrates, proteins, and fats.
• Gall bladder- is a small pear-shaped sac. This is the storehouse of the bile which can hold up to 50ml of bile.
• Small Intestine- breaks down food into substances like glucose for absorption by villi.
• Carbohydrates- are broken down into amino acids by enzymes like amylase, maltase, and lactase.
• Proteins- are broken down into amino acids by enzymes like trypsin and peptidase.
• Fats- are broken down into fatty acids by the enzyme lipase.
• What is Ingestion?

  Taking in food through mouth
• What are the 3 accessory organs?

  liver, pancreas and gall bladder
• what are the three enzymes?

  amylase, peptidase, lipase
• what do enyzmes breakdown?

  carbohydrates, proteins and fats
• What is gall bladder?

  storehouse of the bile
• 3. Absorption- the third process in the digestive system. It involves passing soluble food molecules through the villi in the small intestine.
• Villi- are finger-like projections on the intestinal wall containing blood capillaries for absorbing nutrients. It facilitates the absorption of water, glucose, amino acids, vitamins, minerals, and fatty acids, increasing nutrient absorption surface area.
• 4. Assimilation- the fourth process in the digestive system. It involves the movement of digested food nutrients into the blood vessels of the small intestine through diffusion.
• Nutrients- are used by the body cells through microvilli, which expand the surface area for diffusion and reduce volume.
• Large Intestine- it reabsorption of liquid, electrolytes, and some vitamins. Secretion of mucus for feces formation and maintenance of alkaline conditions.
• 5. Egestion- the final process in the digestive system. it involves the release of undigested food stored in the rectum as feces.
• Feces- are expelled from the body through the anus during defection.
• What does assimilation do?

  digested food nutrients into the blood vessel
• What does egestion do?

  release of undigested food
• Rectum- where feces or undigested food is stored.
• Anus- where feces are eliminated.
• What is rectum?

  rectum is the storage of undigested food.
• What do anus do?

  This is where the feces or undigested food are being expelled
• Esophagus - This organ connects the pharynx with the stomach. Food passes through this tube by peristalsis (muscular contractions).
• Mouth - The mouth is the beginning of the digestive tract. It contains teeth and tongue which helps in breaking down food mechanically. Saliva also plays a role as it moistens the food and contains enzymes such as amylase which breaks down carbohydrates.