Presentation on theme: "Human digestive system"— Presentation transcript:
1 Human digestive system After chewing and swallowing, it takes 5 to 10 seconds for food to pass down the esophagus to the stomach, where it spends 2 to 6 hours being partially digested.Final digestion and nutrient absorption occur in the small intestine over a period of 5 to 6 hours.In 12 to 24 hours, any undigested material passes through the large intestine, and feces are expelled through the anus.
2 The Digestive System How is food digested? Purpose of the Digestive system:Breaks down food into substances that cells can absorb and use.How is food digested?Breaking down of food into smaller pieceThe mixing of foodMovement through the digestive tractChemical breakdown of the large molecules of food into smaller molecules
3 Nutrition Process by which organisms obtain and utilize their food. There are two parts to Nutrition:1. Ingestion- process of taking food into the digestive system so that it may be hydrolized or digested.2. Digestion- the breakdown of food (either chemically or mechanically) in order to utilize nutrients
4 Types of Nutrients Micronutrients- vitamins, minerals, & water Macronutrients- proteins, lipids, carbohydrates, etc…
5 Mouth Mechanical digestion - teeth Chemical digestion – saliva Chewing mixes the food with saliva, from salivary glands around the mouth and face, to make it moist and easy to swallow = BOLUSEnzymes in the saliva begin digestion of carbohydrates.Epiglottis – flap of cartilage that blocks trachea when swallowing
6 Esophagus Muscular tube It moves food by waves of muscle contraction called peristalsis.Physically moving the food along to the stomach.Mechanical Digestion
7 StomachThe stomach lining produces strong digestive juices (HCl, pepsin)– chemical digestionThese create chemical reactions in the stomach, breaking down and dissolving its nutrients = CHYMEDigests proteins and fats in the stomachPeristalsis = mechanical digestion
8 Small IntestineEnzymes continue the chemical reactions on the food – chemical digestionThe nutrients are broken down small enough to pass through the lining of the small intestine, and into the blood (diffusion).Digests proteins, fats, and carbohydrates.Peristalsis = mechanical digestion
9 Absorption by Small Intestines Absorption through villi & microvillifinger-like projectionsincrease surface area for absorption
11 Pancreas Accessory organ Food does not go through the pancreas Produces chemicals to help break down macromolecules = chemical digestionAlso produces insulin = helps control blood sugar levels
12 LiverProduces bile to help digest fat – Mechanical Digestion, fats are broken into smaller “fat globules”Bile is stored in the Gall Bladder and released into the small intestine
13 Large intestines (colon) Functionre-absorb water(NO DIGESTION)use ~9 liters of water every day in digestive juices> 90% of water reabsorbednot enough water absorbeddiarrheatoo much water absorbedconstipation
14 Large Intestine Solid materials pass through the large intestine. These are undigestible solids (fibers).Water is absorbed.Vitamins K and B are reabsorbed with the water.Rectum- solid wastes exit the body.
15 You’ve got company!Living in the large intestine is a community of helpful bacteriaEscherichia coli (E. coli)produce vitaminsvitamin K; B vitaminsgenerate gasesby-product of bacterial metabolismmethane, hydrogen sulfide