Arpita Srivastava Content Writer
Content Writer
Semilunar Valves is a type of valve that participates in regulating the blood from the heart to other organs of the body. It is situated at the base of the aorta and pulmonary trunk.
- Semilunar Valves is in the shape of two pocketlike half-moons.
- The four valves present in the heart have a specific function individually.
- Two out of them are atrioventricular valves, while the other two are semilunar valves.
- It is an important valve that prevents blood from flowing backwards to the heart.
- All these valves function together for the smooth operation of the circulatory system in humans.
- Semilunar valves are made up of endocardium.
- The endocardium is found on the inner layer of the heart.
- These valves work in association with atrioventricular valves.
Read More: What is an open type Circulatory System?
Key Terms: Semilunar Valves, Valves, Ventricles, Arteries, Aorta, Heart, Pulmonary Valve, Atrioventricular Valves, Circulatory System, Endocardium
Semilunar Valves
[Click Here for Sample Questions]
Semilunar valves are defined as a type of valve that allows the blood to flow into arteries from the ventricles. They are named after their crescent moon shape. There are two semilunar valves in a human heart. One is located on the left side of the heart, and the other is on the right side of the heart.
- The left and right semilunar valves are between the ventricles and arteries.
- The semilunar valve on the left side of the heart is known as the aorta.
- The valve located on the right side is known as the pulmonary valve.
- Semilunar valves prevent the blood from entering back inside the heart.
- Pooling of blood is avoided because of the presence of these valves.
Semilunar Valve
Read More:
Types of Semilunar Valve
[Click Here for Sample Questions]
Semilunar Valve is divided into two categories which are as follows:
Aortic Valve
Aortic Valve is a type of valve that is found between left ventricle and aorta. The gates of these valves are opened when pressure rises in the left ventricle and become greater than the pressure found in the aorta. It has three cusp. These valves are responsible for allowing blood to leave the left ventricle and enter the aorta.
Read More: Growth Hormone
Pulmonary Valve
Pulmonary Valve is another type of semilunar valve. It is found between the right ventricle and the pulmonary artery. These valves are opened when pressure inside the right ventricle rises above the pulmonary artery. Like aortic valve, these valves are made of pulmonary valve.
Read More: Gonads
Location of Semilunar Valves
[Click Here for Sample Questions]
There are two semilunar valves found inside the human heart, namely the pulmonary valve and the aorta valve, whose location is as follows:
- The pulmonary valve is located on the right side of the heart.
- It has three cusps, viz. left, right, and anterior.
- This valve is located between the right ventricle and the pulmonary orifice.
- The aorta is located on the left side of the heart.
- It has three cusps, viz. left, right, and posterior.
- It is located between the left ventricle and the aortic orifice.
- The location of these valves helps the blood to flow outside the heart.
Heart viewed from the top
Read More: Leprosy
Functions of Semilunar Valves
[Click Here for Sample Questions]
The functions of the semilunar valve are as follows:
- Semilunar valves help to transport blood from the heart to other parts of the body.
- It ensures an even flow of blood to all parts of the body.
- The valve is responsible for ensuring that blood flows from the heart to outside organs without any difficulty.
- It prevents the blood from flowing in the opposite direction.
- Semilunar valves ensure that blood does not pool in the heart.
- These valves are shut down when the atrioventricular valves open and vice versa.
Anterior view of the heart
Read More:
Problems of Semilunar Valves
[Click Here for Sample Questions]
The problems associated with semilunar valves are as follows:
- Regurgitation and stenosis are the two most common problems faced by valves.
- Stenosis of the value is a condition in which the valve cannot open fully due to its narrowing.
- The narrowing of the valve can be caused by scarring from rheumatic fever or a build-up of calcium.
- It can lead to heart failure or cardiac hypertrophy.
- Regurgitation of the valve is the condition in which blood flows back into the heart.
- The issue arises as the valve is not closed completely.
- This condition usually is minor, but severe cases can cause heart failure.
Hypertrophy
Read More: Disorders of the Circulatory System
Things to Remember
- Semilunar Valves is a connector between the ventricles and arteries.
- A human heart has four valves: two atrioventricular valves and two semilunar valves.
- The atrioventricular valves, also known as AV valves, are a connector between the ventricles and the atria.
- The two semilunar valves are the pulmonary artery and the aorta.
- Semilunar Valves does not have any form of chordae tendineae.
- They are similar to the valves found in veins.
Read More:
Sample Questions
Ques. What are the symptoms of valve stenosis? Can it be resolved. How. (2 Marks)
Ans. Symptoms of valve stenosis:
- Shortness of breath
- Angina
- Syncope
- Left ventricular hypertrophy
Valve stenosis can be resolved in some cases. Severe cases tend to cause heart failure. However, mild cases can be treated surgically with balloon valvuloplasty or valve replacement.
Ques. Compare the semilunar valves of animals with humans. (2 Marks)
Ans. Semilunar valves of humans differ from those of animals in several ways. Their shapes and sizes are different. Human valves have fewer muscles than most other animals. The length of the aorta is different for different animals. In humans, the aorta is the widest. In animals such as sheep, the membranous septum is absent.
Ques. State the functions of semilunar valves. (2 Marks)
Ans. Functions of semilunar valves:
- Semilunar valves prevent the blood from flowing in the opposite direction.
- It ensures that blood does not pool in the heart.
- These valves help transport blood from the heart to other body parts.
- Semilunar valves ensure even blood flow at all times.
Ques. Give the location of semilunar valves. (3 Marks)
Ans. There are two semilunar valves: the pulmonary artery and the aorta. These valves are located exactly between the outflow vessels of the heart. The pulmonary artery is located on the right side of the heart between the right ventricle and the pulmonary orifice. The aorta is located on the left side of the heart between the left ventricle and the aortic orifice.
Ques. How does the aorta operate. (3 Marks)
Ans. When the heart is in systole, the pressure rises in the left ventricle. When the pressure in the left ventricle becomes more than the pressure of the aorta, it opens up. Blood then flows into the aorta from the ventricle. When enough blood flows in this direction, the pressure in the ventricle decreases. This leads to the closing of the aorta. The closing of the valve causes a sound that is considered a component of the heartbeat.
Ques. What are atrioventricular valves. (3 Marks)
Ans. The atrioventricular valves are located between the ventricles and atria. They ensure that blood is transported to the ventricles from the atria. There are two atrioventricular valves in a human heart. One is located on the right side of the heart and the other on the left. The atrioventricular valve located on the right side of the heart is known as the tricuspid valve, and the one located on the left side is known as the bicuspid valve.
Ques. Differentiate between atrioventricular valves and semilunar valves. (3 Marks)
Ans. The difference between atrioventricular valves and semilunar valves are as follows:
| Atrioventricular Valves | Semilunar Valves |
|---|---|
| Atrioventricular valves prevent the backward flow of blood from ventricles to atria. | Semilunar valves prevent the backward flow of blood from arteries to ventricles |
| Atrioventricular valves are composed of leaflets | Semilunar valves are composed of cusps |
| Atrioventricular valves are attached to the walls of ventricles | Semilunar valves are not attached to the walls of arteries |
Ques. State and explain the two semilunar valves present in a human heart. (3 Marks)
Ans. The two semilunar valves present in a human heart are the pulmonary artery and the aorta.
- Pulmonary artery: The semilunar valve located on the right side of the heart is known as the pulmonary valve. It has three cusps, viz. left, right, and anterior. This valve is located between the right ventricle and the pulmonary orifice.
- Aorta: The semilunar valve on the left side of the heart is known as the aorta. It has three cusps, viz. left, right, and posterior. It is located between the left ventricle and the aortic orifice.
Ques. What are Atrioventricular Valves. (5 Marks)
Ans. The atrioventricular valves, also known as AV valves, are a connector between the ventricles and the atria. These valves are located directly between the ventricles and atria. They ensure that blood is transported to the ventricles from the atria.
- There are two atrioventricular valves in a human heart.
- One is located on the right side of the heart and the other on the left.
- The atrioventricular valve on the right side of the heart is known as a tricuspid valve, and the one on the left is known as a bicuspid valve.
- The bicuspid valve is also known as the mitral valve.
- The tricuspid valve has three cusps: anterior, posterior, and septal.
- These cusps open to let the blood pass and then close to prevent the blood from flowing back in.
- The bicuspid valve has only two cusps, viz. anterior and posterior.
Ques. What is the use of valves. (2 Marks)
Ans. Valves are found in the heart that regulates the flow of blood by opening and closing various passageways. If a heart doesn't have valves, the blood will pool back inside the heart's cavity and cause it to swell and eventually burst. The valves prevent this from happening. It allows blood flow only in one direction. There are two types of valves present in a human heart. They are atrioventricular valves and semilunar valves. In total, a human heart has four valves. Two are atrioventricular valves, while the other two are semilunar valves.
Ques. What is the difference between aortic valve and pulmonary valve. (3 Marks)
Ans. The difference between aortic valve and pulmonary valve are as follows:
| Aortic Valve | Pulmonary Valve |
|---|---|
| Aortic Valve is located between left ventricle and aorta. | Pulmonary Valve is located between the right ventricle and the pulmonary artery. |
| These valves are opened when when pressure in the left ventricle rises above the pressure found in the aorta. | These valves are opened when pressure inside the right ventricle rises above the pulmonary artery. |
| It allow the blood to leave the left ventricle and enter the aorta. | It allow the blood to leave the right ventricle and enter the pulmonary artery. |
Ques. Explain (A) Endocardium (B) Electrocardiogram (2 Marks)
Ans. (A)
Endocardium: The endocardium is the innermost layer of tissue that is found inside the human heart. It is made up of endothelial cells, which control the functioning of the myocardial. It acts as a blood-heart barrier that controls the composition of the extracellular fluid.(B) Electrocardiogram: Electrocardiogram is a type of electronic device used to measure and monitor the heart's activity through the skin. It will produce a distinct wave in response to the electrical signals received from the heart.
Ques. Explain the structure of the Semilunar valve. (3 Marks)
Ans. The structure of the semilunar valve is made up of leaflets or flaps. The margin found between the flaps is connected to the arterial wall, which is responsible for forming a moon-like shape. This is the reason why semilunar valves are called semilunar.
- Each flap of the valve is made up of fibrous tissue along with endothelial tissue.
- These valves have a layer of elastin.
- Semilunar valves are called the backbone of the heart and are made up of a collagen layer.
- They provide protection to the pulmonary artery and aorta.
Check-Out:
Comments