Digestive System

• Food - Nourishing substance that we take into our body through eating or drinking
• Nutrients - provides energy, promotes growth, sustains life, regulates various chemical processes
• Carbohydrates, lipids or fats, proteins, vitamins, and water are examples of nutrients.
• Digestion - the process by which the body breaks down food into

  smaller molecules that can be absorbed into the bloodstream and used for energy, growth, and repair.
• The functions of the digestive system - Ingestion, transport food, secretion of materials, digestion of food, absorption, and secretion.
• INGESTION - the process of taking food into the mouth.
• TRANSPORT OF FOOD - food travels through the digestive tract, which includes the mouth, esophagus, stomach, small intestine, large

  intestine, rectum, and anus.
• SECRETION OF MATERIALS - Various glands in the digestive system secrete substances that aid in digestion.
• DIGESTION OF FOOD - the process of breaking down food into smaller molecules that can be absorbed by the body.
• ABSORPTION - Nutrients are absorbed through the walls of the small intestine and into the bloodstream.
• EXCRETION - The final stage of digestion involves the elimination of

  indigestible material and waste products from the body.
• Ingestion

  ❑ first stage of digestion

  ❑ food enters the mouth

  ❑ begins with mastication

  or chewing
• Teeth

  ❑ breaks, cuts, and grinds

  the food into smaller

  pieces
• Tongue

  ❑ helps mix the saliva with

  the food.
• Saliva

  ❑ a liquid that contains 99

  % water

  ❑ lubricates the food and

  begins its chemical

  digestion

  ❑ drains into the mouth

  through the small ducts

  or opening
• Saliva

  ❑ contains an enzyme

  called ptyalin and saliva

  amylase.
• Teeth

  ❑ incisors and canine are

  used for tearing and

  biting food

  ❑ premolars and molars

  are ideal for chewing
• Human adults usually

  have 32 teeth
• children have 22

  primary teeth
• Bolus

  ❑ starchy ball of food

  ❑ Rounded soft mass of

  chewed food
• The Pharynx (throat)

  ❑ connects the mouth to the esophagus

  ❑ passageway for food and air
• Epiglottis

  ❑ closes windpipe upon swallowing the food
• Esophagus

  ❑ muscular tube that is approximately 25 CM long

  ❑ passageway for food and air
• Peristalsis

  ❑ the series of involuntary, wave-like muscular contractions that usually occur in

  the digestive tract.
• Stomach

  ❑ muscular expandable organ

  located on the left side of the

  upper abdomen

  ❑ The stomach muscles contract

  periodically to further mix and

  churn the food.
• Stomach

  ❑ secrete gastric juices

  and mucus that help

  enhance the digestion

  process
• Stomach - composed of

  hydrochloric acid and

  the digestive enzyme

  called pepsin.
• Chyme -thick, Semi-liquid food

  mass
• The normal transit time of the food, emptying in the

  stomach to the small intestine, takes about two to

  five hours
• Small Intestine

  ❑ 6 to 7 meters long in about 2 to 4 CM wide
• Small intestine - 90% of chemical digestion and

  absorption of food nutrients and minerals

  occur.
• Small Intestine - duodenum, jejunum, ileum
• duodenum - 25 CM long, digestion, neutralization of

  the chyme’s acidity.
• Jejenum and Ileum - absorption of nutrients

  coming from the digested food into the bloodstream in

  the walls of the intestines.
• ileum - 3.6 m long
• jejunum - 2.5 m long
• Pancreas - long narrow gland, secretion of the pancreatic juice, a mixture of water, digestive enzymes, bicarbonates, and electrolytes.
• Liver - the largest solid organ in your body that produces 500 different functions.
• Liver - the only organ that can regenerate is dubbed the most resilient organ as it acts as the filter.
• The Liver continuously produces bile