The main difference between sphincter and valve is that sphincters are circular muscles that surround a passage or orifice and can contract or relax to close or open it, while valves are structures that allow flow in only one direction.
In short, sphincters and valves are both structures that regulate the flow of substances through a tube or opening in the body. They differ in anatomical location and function.
Key Areas Covered
1. What is a Sphincter
– Definition, Location, Structure
2. What is a Valve
– Definition, Location, Structure
3. Similarities – Sphincter and Valve
– Outline of Common Features
4. Difference Between Sphincter and Valve
– Comparison of Key Differences
Key Terms
Sphincter, Valve
What is a Sphincter
A sphincter is a ring-shaped muscle that relaxes or tightens to open or close a passage or opening in the body. Some examples of sphincters are the anal sphincter, upper oesophagal sphincter, urethral sphincter, cervical sphincter, vaginal sphincter, lower esophageal sphincter, and pyloric sphincter. Sphincters are important components of many physiological systems in the body. These structures regulate the flow of materials through various passages and orifices, including the digestive, urinary, and reproductive systems.
Moreover, there are about 50 types of sphincters in the human body. Some function involuntarily, while some respond to stimuli, and others are controlled voluntarily. Meanwhile, the size of the sphincters varies. Some sphincters are large, whereas some sphincters are small and microscopic.
There are certain disorders associated with sphincters. One such disorder is achalasia, which affects the lower oesophagal sphincter and causes difficulty in swallowing food. This happens when the muscles of the lower oesophagal sphincter do not relax properly. Another condition is gastroesophageal reflux disease, where the stomach acid and content flow back up into the oesophagus. This causes symptoms such as heartburn, difficulty in swallowing, and regurgitation of food. This is caused due to the dysfunction of the lower oesophagal sphincter.
What is a Valve
A valve is a membranous structure found in various parts of the body, particularly in the heart, veins, and lymph ducts. Its function is to temporarily close a passage or orifice, allowing the movement of a fluid in one direction only. Moreover, a valve consists of a sphincter muscle or two or three membranous flaps or folds. These flaps are called leaflets.
In the heart, two values are present. They prevent the backflow of blood from the ventricles into the atria. The tricuspid valve is in the right of the heart, having three flaps of tissue. On the left side of the heart, there is a two-piece mitral valve. Moreover, the aortic valve regulates the blood flow from the left ventricle to the aorta. These leaflets are supported by a ring-shaped structure called the annulus. In addition, the function of the annulus is to keep the valve in place and prevent it from bulging or prolapsing.
Furthermore, there are valves present in the veins, as well. Veins carry blood from the body tissue back to the heart. Valves in the veins prevent the backflow of blood in the veins. Meanwhile, valves in the veins are very important in the legs. These valves support the blood flow against gravity. Valves are present in the lymphatic vessels, as well.
When the valves fail to operate, valve disorders occur. Some common valve disorders include valvular stenosis, valvular insufficiency, valve prolapse, and infective endocarditis.
Similarities Between Sphincter and Valve
- Sphincters and valves are structures that regulate the flow of substances through a tube or opening in the body.
- Moreover, both prevent backflow.
- However, a malfunction of sphincters and valves can cause various disorders.
Difference Between Sphincter and Valve
Definition
A sphincter is a ring-shaped muscle that relaxes or tightens to open or close a passage or opening in the body, while a valve is a membranous structure, especially in the heart, veins, and lymph ducts that temporarily closes a passage or an orifice permitting movement of a fluid in one direction only.
Location
A sphincter is usually located at the entrance or exit of a hollow organ, while valves are located inside the organ or in tubular structures like veins that carry substances.
Mechanism
Sphincters rely on muscular contractions to regulate the flow of substances through the opening, whereas the valves rely on pressure difference to open and close.
Conclusion
In brief, sphincters and valves are structures that regulate the flow of substances through a tube or opening in the body. However, they differ in anatomical location and function. The main difference between sphincter and valve is that sphincters are circular muscles that surround a passage or orifice and can contract or relax to close or open it, while valves are structures that allow flow in only one direction.
Reference:
1. Boeln Barbara. “What Is a Sphincter?” Very Well Health.
2. “Valve Anatomy.” Encyclopedia Britannica.
Image Courtesy:
1. “Anorectum-en” By Waterced – (CC BY-SA 4.0) via Commons Wikimedia
2. “Section through heart to show valves and blood flow” By Original uploader was Sunshineconnelly at en. Wikibooks – Transferred from en.Wikibooks; transferred to Commons by User:Adrignola using CommonsHelper. (CC BY 3.0) via Commons Wikimedia
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