-System with complex tubes of considerable length -Also called the alimentary tract -This group of organs that break down food into smaller particles or molecules -This breakdown makes it possible for the smaller digestive particles to pass through the intestinal wall into the bloodstream - Particles are then distributed to nourish all parts of the body Digestive System
Parts of the Digestive System
1. Oral Cavity - this is where food is mixed with the saliva secreted by several sets of salivary glands - Saliva dissolves and softens food and acts as a lubricant, facilitating swallowing and passage through the next portions of the digestive tract. Parts of the Digestive System
Teeth - This is where food is broken into smaller pieces by both biting and chewing. Tongue - manipulates the food during chewing and forms it into a mass called bolus , in preparation for swallowing. -Pushes the bolus through a cavity called the pharynx and into esophagus. Parts of the Digestive System
2. Esophagus - a long tube running through the throat and thorax and connecting to stomach in the upper portion of the abdominal cavity. Peristalsis – contraction movement of esophagus muscle Sphincter – special ring of muscle found on the junction between esophagus and stomach, which when contracted closes the entrance to the stomach. Parts of the Digestive System
Peristalsis in the Esophagus
3. Stomach - This is a large muscular sac, which functions as a storage organ, making discontinuous feeding possible. Rugae – folds of the stomach that increases its surface area. - churns the food, mixing it with the gastric juice Gastric Juice – contains enzymes that break down protein Chyme -soupy mixture that leaves the stomach and passes through the pyloric sphincter into the small intestines. Parts of the Digestive System
4. Small Intestine
This is where final digestion and absorption takes place
Measures 23 ft long in an adult
Duodenum – first section of the small intestines attached to the stomach
Jejunum – middle portion of the intestine
I leum – very long coiled section lying lower in the abdominal cavity
Villi – Finger-like projections in the inner wall of the small intestine that increases absorptive surface area.
5. Large Intestines - also known as colon - Reabsorbs much of the water used in the digestive process and excretes certain salts, such as those of calcium and iron. Caecum – this is a small and functionally unimportant for human Appendix – finger-like process found at the tip of the caecum Feces – undigested food excreted into the colon and eliminated from the body. Rectum – Last portion of the large intestines that functions as a storage chamber for the feces until defecation Parts of the Digestive System
- opening for the elimination of feces.
Parts of the Digestive System
Largest gland in the body
Aids in chemical digestion by producing bile.
Occupies much of the space in the upper portion of the abdomen
A small organ found on the surface of the liver which stores the bile.
Large glandular organ lying just below the stomach
Secretes different enzymes and pour these into the small intestines via the common bile duct
Enzymes secreted by Pancreas
Lipase – enzyme that digest fats or splits fat into soluble glycerol and fatty acids
Pancreatic amylase – acts like salivary amylase, splitting starch into a double sugar maltose
Trypsin and chymotrypsin – breaks proteins toamino acids.
Completes the digestion of food.
1. Peptidase – peptides to amino acids
2. Sucrase – sucrose to glucose
3. Maltase – Maltose to glucose and fructose
4. Lactase – lactose to galactose and glucose
Digestive Flow ORAL CAVITY ESOPHAGUS STOMACH SMALL INTESTINE LARGE INTESTINE RECTUM ANUS