Esophagus

Esophagus

The esophagusThe muscular tube that transports food from the pharynx to the stomach via peristalsis. is a long, hollow tube that collapses when not in use, unlike the constantly open trachea. It is covered with serosa below the diaphragm. In the thoracic cavityThe body cavity housing the heart and lungs., it is covered with adventitiaThe outermost connective tissue layer of an organ, such as the esophagus, which binds it to surround. This thickened layer prevents leakage into surrounding areas like the heart and lungs.

The diaphragm has a hole in it called the esophageal hiatus. That’s where the esophagus punches through the diaphragm and connects to the stomach.  Hiatal hernias result from a piece of the stomach poking through this hole. I knew a woman who once had a hiatal hernia. She underwent thoracic surgery, and it was a rough surgery. Hiatal hernias small ones can be dealt with through exercise force that piece of your stomach back through that hole.

Esophagus Serosa

The diaphragm separates the thoracic and abdominal cavities.  Both the trachea and the esophagus have their own adventitia. This white stripe separates these two open spaces on this histological slide. It is the adventitia that separates your trachea from your esophagus. Of course, getting air in your esophagus will probably just make you burp. In contrast, getting food into your trachea is definitely not a good thing.  This is why the esophagus is covered with this thickened adventitia between these two organs. It is also protected between the esophagus and other organs in the thoracic cavity like the heart and the lungs. This red layer surrounding the esophagus that looks like meat are the two layers of muscularis externaA smooth muscle layer of the digestive tract responsible for peristalsis and segmentation..  Of course the submucosa is unidentifiable because it’s always confusing period and our mucosaThe innermost lining of the digestive tract that contains mucus-secreting cells for protection and a of stratified squamous is represented by these purple stripes right here lining the lumenThe inside space of a hollow organ or structure. period

Esophagus Muscularis Externa

the muscularis externa of the esophagus has the two layers of smooth muscle fibers oriented in different directions. In the muscularis externa of the esophagus, the muscle type changes along its length. It transitions from skeletal voluntary muscle in the superiorAbove or toward the upper part of the body. portion. Near the stomach, it consists of smooth involuntary muscle in the inferiorBelow or toward the lower part of the body. portion. These two muscle layers are common to all of our digestive organs. However, the muscularis externa can be modified to suit the purposes of the specific organ. Here in the esophagus although gravity helps your food is propelled toward the stomach by a process called peristalsis Rhythmic contractions of smooth muscle that move food through the digestive tract.

Peristalsis

Peristalsis is alternating contractions of the muscularis externa that propel your food ball or bolusA rounded mass of food mixed with saliva that is ready for swallowing. toward the stomach. The circular layer of the muscularis externa contracts. It pushes the bolus forward. Then the longitudinal layer of the muscularis externa contracts. This further shortens the tube and pushes the bolus forward. These alternating contractions continue in cycles. They move your food bolus toward the lower esophageal sphincter. This sphincter separates the esophagus from the stomach. Peristalsis is used by all of our digestive organs to keep your food moving smoothly. Sometimes, your digestive system will experience a very strong contraction of peristalsis. It is prolonged throughout your digestive system. And this is one way in which your nervous systemThe organ system that controls body functions using electrical and chemical signals. ensures motility in your digestive system.

Esophagus Submucosa

The submucosa is the layer that doesn’t get a lot of play. People have a hard time recognizing it.  Recall that epithelial tissue usually soaks up a relatively dark purple stain. Much like the cutaneous membrane, this picture of the stratified squamous cellsThe basic structural and functional units of life. of the esophagus shows the dead layer of cells. These cells line the lumen. You can also see the live layer of cells that separates them from the submucosa. Submucosa throughout the digestive system is usually a mix of areolar and dense irregular connective tissue. These large purple ovals are collections of submucosal glandsGlands in the airway walls that secrete mucus. that secrete a bicarbonate(HCO₃⁻) – A crucial buffer in blood that helps maintain pH balance; formed when carbon dioxide solutionA homogeneous mixture of two or more substances.. Bicarbonate counteracts some of the acidity that’s created by chemical digestion with your saliva. In the esophagus, bicarbonate is quite mucousy and not watered down. Therefore, it also aids in the lubrication of the bolus. I have a diagram of a bicarbonate gland here. This also kind of looks like a sweat gland. As you can see the lumen of the gland is lined with simple cuboidal cells. And the gland opensextends through the mucosa and empties out into the lumen of the esophagus. Peeking out at the right side of this picture, you can also see the muscularis externa. It has a characteristic steak-like look.

Esophagus Mucosa

The mucosa in the esophagus is this purple line surrounding the lumen. The mucosa is stratified squamous like the mouthThe opening of the digestive tract where food enters and mastication begins. and the throat.   In the superior region of the esophagus, there are patches of keratinized stratified squamous epithelium. These are sprinkled among non-keratinized stratified squamous epithelium. This picture should remind you of skinThe body’s largest organ, providing protection and regulation.. The dead cells are closer to the open space or lumen. The live cells take up a darker stain and look much more plump in appearance. These big red areas are arteriesBlood vessels that carry oxygenated blood away from the heart (except pulmonary arteries, which carr and veinsBlood vessels that return deoxygenated blood to the heart (except pulmonary veins, which carry oxyge that are vascularizedTo invade a tissue with blood capillaries. using the submucosa.

The esophagus still experiences a large amount of mechanical abrasion as the bolus descends to the stomach. This stratified squamous epithelium, like the mouth, can lose cells as the bolus scrapes by. It remains mostly unaffected by that loss.

The esophagus’s histology can tip us off to a condition called Barrett’s Syndrome. In Barrett’s is that you usually have lots of heartburn. That heartburn can come from the inactivity or overactivity of the esophageal sphincter. The sphincter separating the esophagus from the stomach may open and close all the time, allowing acids into the esophagus. This is only one way that heartburn is caused there are many mechanisms that can cause it.

In Barrett’s esophagus, the mucosa close to the lower esophageal sphincter turns into simple columnar cells. This happens due to exposure to stomach acids. This is called Barrett’s esophagus, a precancerous condition. Control your heartburn, people.