Biological and Physical Sciences The Digestive System

Objective Identify the functions and process of the human digestive system in relation to Public Health.

OVERVIEW FunctionsProcess

Functions IngestionPropulsionMechanical Chemical Digestion AbsorptionDefecation

Process Alimentary Canal  Major organs  Mouth  Pharynx  Esophagus  Stomach  Small intestine  Large intestine

Process The Mouth Beginning of the alimentary canal Food is received and prepared for digestion Accessory structures work here

Process Pharynx Muscular tube common to both the respiratory and digestive systems Pushes the food into the esophagus

Process Esophagus Runs from pharynx to stomach 10 “ long Peristalsis (slow rhythmic squeezing) Passageway for food

Stomach Functions Storage tank Located on the left side of the abdominal cavity Site of food breakdown Chemical breakdown of protein begins Delivers processed food to the small intestine

Process Small Intestine Major digestive organ Most of nutrient absorption into the blood takes place Muscular tube measuring 22 feet long

Process Small Intestine Duodenum Attached to the stomach Mixes with digestive bile and helps break down food more Jejunum Attaches to the anterior side of the duodenum Ileum Extends from jejunum to large intestine

Process Large Intestine 5” long Four sections Absorption of water ChymeFeces

Process Accessory organs Salivary glands TeethPancreasLiver Gall bladder

Process Salivary Glands Saliva-producing glands Mixture of mucus and serous fluids Helps to form a food bolus Contains salivary amylase to begin starch digestion Dissolves chemicals so they can be tasted

Process Teeth Break down food into smaller pieces

Process Pancreas Aids in digestion Enzymes are secreted into the duodenum Produces a wide spectrum of digestive enzymes that break down all categories of food Alkaline fluid introduced with enzymes neutralizes acidic chyme

Process Liver Largest gland in the body Located on the right side of the body under the diaphragm Connected to the gall bladder via the common hepatic duct Secrets bile

Process Gall Bladder Stores bile Bile is introduced into the duodenum in the presence of fatty food Gallstones can cause blockages

Review of Digestive System Figure 14.1

Functions Ingestion – getting food into the mouth Propulsion – moving foods from one region of the digestive system to another Peristalsis – alternating waves of contraction Segmentation – moving materials back and forth to aid in mixing

Functions Mechanical digestion Mixing of food in the mouth by the tongue Churning of food in the stomach Segmentation in the small intestine

Functions Chemical Digestion Enzymes break down food molecules into their building blocks Each major food group uses different enzymes Carbohydrates are broken to simple sugars Proteins are broken to amino acids Fats are broken to fatty acids and alcohols

Functions Absorption End products of digestion are absorbed in the blood or lymph Food must enter mucosal cells and then into blood or lymph capillaries Defecation Elimination of indigestible substances as feces

Objective Identify the functions and process of the human digestive system in relation to Public Health.

Summary FunctionsProcess

Questions??