HUMAN DIGESTIVE SYSTEM

Celeste Roderno-Desingaño

Digestive System -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

Parts of the Digestive System

Parts of the Digestive System1. 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 SystemTeeth

- 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.

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

Parts of the Digestive System3. 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.

4. Small Intestine This is where final digestion and absorption takes place Measures 23 ft long in an adultDuodenum – first section of the small intestines attached to the

stomachJejunum – middle portion of the intestineIleum – very long coiled section lying lower in the abdominal cavityVilli – 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 humanAppendix – finger-like process found at the tip of the caecumFeces – 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

6. Anus - opening for the

elimination of feces.

Parts of the Digestive System

Liver Largest gland in the

body Aids in chemical

digestion by producing bile.

Occupies much of the space in the upper portion of the abdomen

Gall bladder A small organ found on

the surface of the liver which stores the bile.

Chemical Digestion

Pancreas Large glandular

organ lying just below the stomach

Secretes different enzymes and pour these into the small intestines via the common bile duct

Chemical Digestion

Enzymes secreted by Pancreas

1. Lipase – enzyme that digest fats or splits fat into soluble glycerol and fatty acids

2. Pancreatic amylase – acts like salivary amylase, splitting starch into a double sugar maltose

3. Trypsin and chymotrypsin – breaks proteins toamino acids.

Chemical Digestion

Intestinal Glands Completes the

digestion of food.1. Peptidase – peptides to

amino acids2. Sucrase – sucrose to

glucose3. Maltase – Maltose to

glucose and fructose4. Lactase – lactose to

galactose and glucose

Chemical Digestion

Digestive Flow ORAL CAVITY

ESOPHAGUS

STOMACH

SMALL INTESTINE

LARGE INTESTINE

RECTUM

ANUS