DIGESTIVE SYSTEMKayla EtienneShané LewisJontasia Percentie

THE DIGESTIVE SYSTEM

FUNCTIONS The functions of the digestive system

include:1. Ingest food2. The break down of food into smaller molecules

to cross the plasma membranes3. Absorb the nutrient molecules4. Eliminate nondigestible wastes

ORGANS TUBES The organs within the system are in the:

alimentary canal gastrointestinal tract

THE MOUTH The mouth receives food and begins physical and

chemical digestion. The space between the teeth, the lips, and the cheek is the vestibule.

The tongue is composed of skeletal muscles whose contractions changes the shape of the tongue. Papillae, rough projections on the tongue, help it handle food and also contain taste buds, the sensory receptors. Posteriorly, the tongue is anchored to the hyoid bone.

The lingual frenulum, a fold of mucous membrane, on the underside of the tongue attaches it to the floor of the mouth. If too short, the individual cannot speak clearly and is

said to be tongue-tied.

THE MOUTH The mouth has a roof that separates it from

the nasal cavities. The anterior hard palate (towards the front of the

mouth) is formed by the maxilla and palatine bones

The posterior soft palate (towards the back of the mouth) is formed by muscle and glandular tissue The soft palate ends in the projection called the uvula

SALIVARY GLANDS There are three types of salivary glands:

Parotid gland Lie anterior and inferior to the ear between the cheeks

and the masseter muscles Have ducts that open on the inner surface of the cheek

at the location of the second upper molar Swells when a person has the mumps

Sublingual gland Located beneath the tongue and the glands open

underneath the tongue Submandibular gland

On the floor of the mouth in the inside surface of the lower jaw and like the sublingual gland, it opens under the tongue

SALIVA A solution of mucus and water Contains a bicarbonate and an enzyme called

salivary amylase, which begins the process of digesting carbohydrates

Moistens food and prepares it for swallowing Contains antibacterial lysozyme and

secretory antibodies which help protect the body

Removes microbes by constantly bathing the teeth, tongue, oral mucous membrane

PATH OF FOOD

PHARYNX From the mouth, the food proceeds on to the pharynx, which is

the passage for food and also air. Three parts of the pharynx:

1. Nasopharynx – posterior to nasal cavity and serves as passage for air2. Oropharynx – posterior to the soft palate, and is passageway for air

and food3. Laryngopharynx –superior to the esophagus and serves as

passageway to the esophagus In the pharynx and the tongue, three types of tonsils are

embedded: 1. Palatine tonsils – on either side of the tongue, close to the soft palate2. Lingual tonsils – sits at the base of the tongue

1. When working together with the palatine tonsils, they help prevent infection caused by microbes

3. Pharyngeal tonsil –sits in the posterior nasopharynx

SWALLOWING Has a voluntary phase, but when food or

liquids are pushed back to the oropharynx, swallowing becomes a reflex action

When swallowing, the soft palate moves back to close the nasopharynx and the trachea moves up under the epiglottis so that food is less likely to enter it. We not breathe when we swallow.

The tongue presses against the soft palate, sealing off the oral cavity, and the esophagus opens to receive a food bolus, a morsel of chewed and swallowed food or drink

THE ESOPHAGUS A muscular tube that passes from the

pharynx through the thoracic cavity and diaphragm into the abdominal cavity where it joins the stomach

Sole purpose is to transfer food bolus from the mouth to the stomach

Ordinarily collapsed, but opens and receives bolus when swallowing occurs

THE ESOPHAGUS Peristalsis, a rhythmic contraction, pushes

the food along the alimentary canal. Short segments of smooth muscle built into the wall of the digestive tract alternately contract and then relax begins in the esophagus and continues in all the

organs of the alimentary canal Constantly moves food through the digestive

tract Occasionally begins even if there is no food in

the esophagus

SPHINCTERS Sphincters are the muscles that encircle the

tubes and act as valves Tubes close when sphincters contract and open

when sphincters relax The entrance of the esophagus to the stomach

is marked by a constriction, called the esophageal sphincter (muscle is not as developed as in a true sphincter)

Relaxation of the sphincter allow bolus to pass into the stomach

Contraction of the sphincter prevents the acidic contents of the stomach from backing up into the esophagus

DISEASE AND INFECTIONS IN SYSTEM Esophagus

Heartburn, which feels like a burning pain rising up into the throat, occurs during reflux when some of the stomach contents escape into the esophagus When vomiting occurs, a contraction of the abdominal

muscles and diaphragm propels the contents of the stomach upward through the esophagus

PANCREAS Pancreas-a large gland behind the stomach that secretes

digestive enzymes into the duodenum. The pancreas is about 6 inches long and sits across the back

of the abdomen, behind the stomach. The head of the pancreas is on the right side of the

abdomen and is connected to the duodenum (the first section of the small intestine) through a small tube called the pancreatic duct.

The narrow end of the pancreas, called the tail, extends to the left side of the body.

The pancreas has two functional components: endocrine, to produce insulin and other hormones, and exocrine, to produce pancreatic juices for digestion. The pancreas is in direct contact with the stomach, duodenum, spleen, and major vessels of the abdomen.

PANCREAS DISEASES Because the pancreas is a storage depot for digestive

enzymes, injury to the pancreas is potentially very dangerous. A puncture of the pancreas generally requires prompt and experienced medical intervention.

Pancreatitis is inflammation of the pancreas. There are two forms of pancreatitis, which are different in causes and symptoms, and require different treatment:

Acute pancreatitis is a rapid-onset inflammation of the pancreas, most frequently caused by alcoholism or gallstones.

Chronic pancreatitis is a long-standing inflammation of the pancreas.

PANCREATIC CANCERCancer of the pancreas is the fourth-leading cause of cancer death in the U.S. Some risk factors for developing pancreatic cancer include Smoking Long-term diabetes Chronic pancreatitis Certain hereditary disorders

Pancreatic cancer is hard to detect because the pancreas is hidden behind other organs, health care providers cannot see or feel the tumors during routine exams.Because it is often found late and it spreads quickly, pancreatic cancer can be hard to treat. Possible treatments include surgery, radiation and chemotherapy.

SMALL INTESTINE The small intestine is a tubular structure within the

abdominal cavity that carries the food in continuation with the stomach up to the colon from where the large intestine carries it to the rectum and out of the body via the anus. The main function of this organ is to aid in digestion.

90% of the digestion and absorption of food occurs, the other 10% taking place in the stomach and large intestine.

Broken down nutrients (food) are absorbed by the inner walls of the small intestine into the blood stream.

The small intestine is good for absorption since it has a large inner surface area.

LARGE INTESTINE The large intestine (or bowel, colon) is the

last part of the digestive system. Its function is to absorb water from the remaining indigestible food matter, and then to pass useless waste material from the body.

The large intestine takes about 16 hours to finish the digestion of the food.

It removes water and any remaining absorbable nutrients from the food before sending the indigestible matter to the rectum.