Amy
Mouth
General Information
-The first portion of the alimentary canal that receives food and begins digestion by breaking up food particles into smaller pieces and mixing them with saliva.
-Also known as the oral cavity.
Functions
- Its primary role is to serve as the beginning of the digestive system.
- Ingestion- Tase buds (the papillae of the tongue) are stimluated from saliva.
- Mastication- also known as chewing. Muscles around the mouth are involved. This forces the upper and lower sets of teeth to press together. This makes the food break down into smaller pieces, which aids in further digestion.
- Digestion- begins in the mouth. Amylase (an enzyme) breaks down starch and carbohydrates. Amylase is in the saliva.
- Swallowing- The muscular action of the tongue shapes food into a ball, named "bolus". The tongue pushes the bolus into the pharynx so it can be further digested.
- Protection- The mucin and water containted in the saliva provides lubrication. Saliva also contains lysozyme, an enzyme that kills harmful organisms.
Antomy
-The oral mucosa (mucous membrane) epithelium lines the inside of the mouth.
- Hard palate and Soft palate- make up the roof of the mouth.
- Uvula- attached to soft palate
- Teeth- involved in mastication.
- Tongue- involved in swallowing.
Salivary Glands
Functions
- Exocrine glands that produce saliva.
- Secrete amylase, which breaks down starch into glucose.
-Produce saliva to moisten the mouth, initiate the digestion, and prevent teeth decay.
Anatomy
Parotid Glands
Also called "Stensens Duct".
They are the largest glands, but only produce about 25% of the saliva.
Located in the subcutaneous tissues of the face.
The secretion is serous in nature.
The secretion enters the mouth by passing through the Stensens Duct, after passing through intercalated ducts, which are very important in the parotid gland.
Submandibular Glands
Also called "Wharton's Ducts".
Located beneath the floor of the mouth.
The secretion is a mixture of serous and mucous.
Produces 70% of all saliva, even though it is much smaller than the parotid gland.
Sublingual Glands
Located beneath the floor of the mouth, anterior to the submandibular glands.
It is mainly mucous, although sometimes classified as a mixed gland.
It is very different from the parotid glands and the submandibular glands in that there are no striated ducts present in the ductal system of these glands.
Instead, they exit from 8-20 excretory ducts.
Produce 5% of all saliva.
Besides these 3 glands, there are also over 600 minor salivary glands within the oral mucosa.
Esophagus
Connects the nose and mouth to the stomach.
Connects the mouth and nose to the stomach.
Information
- Also known as the gullet.
- It is a muscular tube which passes food from the pharynx into the stomach.
- It passes through a hole in the thoracic diaphragm, called the esophageal hiatus.
- Around 25-30 cm long.
- Divided into 3 parts (cervical, thoracic, abdominal).
- Located in the chest and passes by the heart.
Functions
- Peristalsis- the process in which food is passed through the esophagus. A contraction of muscles to move food down to the digestive tract.
- The muscle that is lined in the esophagus helps with peristalsis, as the muscles act to push food down.
- Connects pharynx to the stomach, where further digestion takes place.
- A lot of acid passes through the esophageal sphincter, and the esophagus lacks mucus, causing a lot of irritation.
Anatomy
Stratified Squamous Epithelium- this lines the esophagus. It is very protective when we eat foods that are hot or crusty.
Muscle- One- third of the muscle in the esophagus is skeletal muscle. The other two- thirds are smooth muscles.
Smooth muscle- there are two layers in the esophagus. They are inner circular and outer longitudinal. The circular muscles help make the diameter of the esophagus shorter, while the longitudinal muscles shorten the organ as we swallow food.
Upper esophageal sphincter- below the junction of the throat and esophagus.
Lower esophageal sphincter- slightly above the junction of the esophagus and stomach.
These sphincters play a major role when the esophagus is not in use. In order for stomach acid and food (chyme) to not flow up from the stomach to the mouth, the sphincters contract. When esophagus is in use (swallowing), the sphincters relax, so food can pass through.
Diseases
Salivary gland Cancer
A very rare form of cancer. It occurs in any of the salivary glands. The cause is not clear, but radiation, use of tabacco, and family history will increase your risk. You develop a painless lump on your neck. Most malignant tumors develop in the parotid glands. Most tumors that develop in the other glands and benign. Tumors are measured in sizes 1-5.
Diagnosis: MRI, CT scan, Ultrasound of the mouth/neck.
Treatment- Depends on severity. The most common treatment is surgery. The surgeon removes the cancer and some of the nearby tissue. If the cancer has spread to the lymph nodes, sometimes the nodes are removed too. Other treatments are radiation therapy and chemotherapy.
Mumps
A virus that is spread throughout the body, but mainly the parotid glands. The infection makes the glands swell, causing a lump on the side of your cheeck. Usually occurs in children only. The symptoms are a high fever, headache and a lump on your cheeck, right by the parotid glands. It is very contagious and cannot be treated by antibiotics.
Salivary Gland Stones
Sometimes, the saliva that a duct carries to the mouth from a salivary gland is blocked and cannot make it to the mouth. This blockage is called a stone. The stone forms from salts contained in the saliva. Since the saliva is blocked and backed up in the duct and cannot enter the mouth, the salivary gland starts to swell. The salivary glands starts to build up bacteria.
Treatment: Surgery
Barrett's esophagus
An abnormal change in the cells of the lower end of the esophagus that were damaged by acid exposure. Squamous epithelium (normal lining of esophagus) is replaced with columnar epithelium (intestinal-type lining). It increases your risk of esophageal cancer. Many people do not have symptoms, but some are heartburn and vomiting blood.
Treatment: Laser treatment, surgery, radiation therapy, chemotherapy. New treatment: Photodynamic Therapy. Patients are given photosensitizer (Photofrin). They come back two days later and get a laser light endoscopy that destroys all abnormal cells in the esophagus.
Achalasia
This is a motility disorder. The smooth muscle layer of the esophagus loses its normal peristalsis (moving food down the esophagus) and the lower esophageal sphincter fails to relax when food is being swallowed. It is characterized by difficulty swallowing and chest pain.
Diagnosis: Biopsy, Barium swallow (observes flow of fluids through the esophagus), esophageal manometry (tube is inserted through the nose and measures muscle contractions).
Esophageal atresia
A birth defect in which the esophagus ends in a blind ended pouch instead of connecting to the stomach. Caused by an abnormal embryological development of the esophagus. Occurs in approximately 1 in 4425 births. It is suspected in newborns that have excessive drooling. They may be cyanotic.
Diagnosis: A catheter is passed into the esophagus to check for resistance. It EA is detected, oral feedings must be stopped and intravenous fluids are started.
Treatment: Surgery, where the esophagus and stomach are sewn together.
Comments (1)
csnanatomy said
at 2:51 pm on Apr 2, 2009
Considering highlighting important vocab words.
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