Anatomy & Physiology II Unit Three

Digestion The digestive tract is a tubular passage that extends from the lips of the mouth, through the body, and terminates with an anus This system can be divided into three regions: + oral cavity + pharynx + alimentary canal

Digestion The alimentary canal can be further divided into four segments: + esophagus + stomach + small intestine + large intestine

Digestion Associated with the system are four glands/organs that are located outside the tube, but secrete fluids into the system to aid in digestion: + salivary glands + liver + gall bladder + pancreas

Digestive System

Digestion The function of the digestive system is to mechanically & chemically breakdown food so that nutrients can be obtained through absorption and energy can be released

Digestion Mechanical digestion breaks the food into physically smaller particles, while chemical digestion breaks macromolecules into monomers

Digestion The monomers and other nutrients are now small enough to be absorbed through the wall of the digestive tract and into the bloodstream where they will be distributed to body cells for energy needs and building materials

Oral Digestion Oral structures involved in mechanical digestion: Hard palate Uvula Oral structures involved in mechanical digestion: * teeth * tongue * hard palate * cheeks Tonsil Soft palate Tongue Teeth

Oral Digestion Enamel Dentin Canines Incisors Pulp Gingiva Molars Premolars

Oral Digestion Oral structures involved in chemical digestion: * parotid salivary glands * submandibular salivary glands * sublingual Parotid salivary gland Submandibular salivary gland Sublingual salivary gland

Oral Digestion Structures involved in swallowing: * soft palate & Uvula Hard palate Structures involved in swallowing: * soft palate & uvula * pharynx * epiglottis * esophagus Pharynx Tonsils Epiglottis Glottis Esophagus

Oral Digestion Deglutition (swallowing)

Alimentary Canal Histology Serosa Mucosa Submucosa Muscularis externa (longitudinal muscle) Muscularis interna (circular muscle)

Alimentary Canal Movements Segmentation Peristalsis

Alimentary Canal Movements

Alimentary Canal Esophagus Diaphragm Stomach

Stomach Diaphragm Esophagus Fundic region Cardiac region Body A aa Lesser curvature Muscle layers Rugae Pyloric antrum Greater curvature Pyloric sphincter

Stomach Wall Rugae Gastric pit Mucosa Gastric gland Submucosa Muscularis layers Serosa

Cardiac or Pyloric Gland Stomach Wall Cardiac or Pyloric Gland Gastric Gland Mucous cell Parietal cell Chief cell G cell

Activation of Pepsin

Control of Gastric Secretion

Control of Gastric Secretion

Stomach Disorders Emesis - the forceful ejection of stomach or duodenal contents Bulimia – eating disorder in which emesis is induced so as to rid the body of the food recently eaten

Stomach Disorders Anorexia – eating disorder in which a person loses their appetite because they believe they are fat Peptic ulcers – erosion of the stomach lining caused by bacteria, aspirin, HCl or pepsin

Accessory Organ Anatomy Liver Common hepatic duct Gall bladder Anterior Posterior

Liver Function The liver carries out a number of functions: > degradation of toxins, drugs, etc. > cleaning bacteria and debris from the blood > produces and secretes plasma proteins

Liver Function The liver carries out a number of functions that concern digestion: > process the monomers of digestion > processes vitamins and iron > produces bile

Accessory Organ Anatomy

Liver Function Cirrhosis of the liver is the replacing of liver tissue with connective tissue, reducing the function of the liver

Liver Function Cirrhosis can have several causes: > viral (hepatitis) > drug abuse > trauma

Accessory Organ Anatomy Gall bladder Hepatic ducts Common hepatic duct Common bile duct Cystic duct Hepatopancreatic duct Pancreatic duct Pancreas Hepatopancreatic sphincter Duodenum

Small Intestine Anatomy

Small Intestine Physiology

Small Intestine Physiology Villus Microvilli (brush border) Capillaries Lacteal

Small Intestine Physiology

Large Intestine Anatomy

Large Intestine Disorders Diverticulitis Diarrhea Constipation Flatulence