What Are The Primary Blood Vessel Types And Their Functions? Check All That Apply.

What are Blood Vessels?

The vessels inside the human body, which are hollow pipes that have a tube-like structure and are responsible for carrying the blood in both directions, from and to the body, are known as blood vessels. If these blood vessels stop functioning, a person would die of a sudden cardiac arrest. Veins, arteries, and capillaries are the three types of blood vessels forming a major part of the cardiovascular system. A blood vessel carries the blood from the heart to other parts of the body while another carries it from the body to the heart.

Blood Vessels

Blood Vessels

Structure of Blood Vessel

The structure of the artery and the vein are very similar when compared to capillaries. Blood flows in all the blood vessels through a structure known as the lumen which are hollow tubes of space inside. The blood vessel (artery and veins) consists of three layers:

Tunica intima

It is the thinnest layer located deep inside which has only a single flat endothelial cell which is surrounded by subendothelial connective tissue. Internal elastic lamina is the circular organization of the elastic bands which act as an inner layer. The structure reduces the friction inside the blood vessel walls and the blood.

Tunica media

It is the middle layer of the blood vessels and the thickest layer in the arteries as it maintains the diameter of the artery with the help of smooth muscle tissues. It is made up of connective tissues and elastic fibers. The external elastic lamina separates the second and third layers by its elastic band. The veins contain thinner forms of tunica media as compared to that of the arteries.

Tunica adventitia

It is the outermost layer of the blood vessels and forms the thickest layer of the veins. It is made up of collagens, nerves, and connecting tissues. Tunica adventitia connects the vessels to the surrounding structure and also protects and strengthens them.

Structure of Capillary, Vein, and Artery

Structure of Capillary, Vein, and Artery

Function of the blood vessels

Besides transporting blood in the body, the blood vessels also carry water, nutrients, hormones, minerals, and other relevant minerals for the proper metabolism of the body
The pure or oxygenated blood is transported from the lungs to the other parts of the body by the arteries or the arterioles and the impure or deoxygenated blood from the body to the lungs is carried by the veins or the venules.
Blood vessels carry oxygenated red blood cells which are important for daily activities. A higher amount of red blood cells in the body leads to conditions such as dehydration or any other heart disease whereas a lower proportion of red blood cells in the body leads to anemia or loss of blood in the body. The loss of blood during injuries is checked by the blood vessels
The body temperature of an organism is maintained by the blood vessels.
Redness, pain, warmth, and swelling due to conditions such as histamine, interleukins, and prostaglandins occur due to the increase in inflammation.
Gaseous exchange is also regulated by the blood vessels.

Types of Blood Vessels

There are three types of blood vessels that form a major part of the human circulatory system.

Arteries

The oxygenated blood from the heart to the other parts of the body is carried by the arteries. They have thick walls because there is a heavy pressure exerted by the arteries while the heart pumps blood. They are located deep within the body facing the downward direction. The aorta is the largest artery in the body extending from the heart to the abdomen which pumps blood from the left ventricle of the heart in high pressure. The small branches of the aorta are known as arterioles. The coronary arteries carry oxygenated blood whereas the pulmonary arteries carry deoxygenated blood which is an exception.

Artery Wall Structure

Artery Wall Structure

Veins

The deoxygenated, impure blood which is rich in carbon dioxide is carried from the body to the heart by the veins. The flow of blood towards the heart is ensured by the presence of valves. Valves present in the leg veins prevent the blood, which is being pumped against gravity, to flow backward. They are thin and elastic blood vessels present close to the surface of the skin. The maximum amount of blood is stored in the veins which is why it is known as the capacitance blood vessel. There are four pulmonary veins that carry oxygenated blood. The two largest veins in the body are the inferior and superior vena cava. Venules are the small branches that collect blood from different organs and join to form veins that transport the blood to the heart.

Veins

Capillaries

They are the smallest blood vessels found within the tissue which facilitates the exchange of materials between the surrounding tissues and the blood. The exchange of blood and substances takes place through a capillary bed which is formed by the network of venules and arterioles. They are formed by a single layer of epithelial tissues. The substances which are exchanged consist of water, glucose, oxygen, and carbon dioxide.

Structure of Blood Vessel

Structure of Blood Vessel

Anastomoses

Anastomoses refer to the process in which the blood vessels come together to develop a region of diffused vascular supply. During blockage of any sort, anastomoses create an alternative route for the easy flow of blood.

Conditions that affect the blood vessels

There are various conditions that interfere with the normal working of the blood vessels. Some of the conditions which affect the structure and function of the blood vessels are:

Inflammation
Hypertension: Rapid increase in the blood pressure due to the narrowing of the arterioles.
Atherosclerosis: Accumulation of fat in the arterial endothelium.

Vasoconstriction and vasodilation

Vasoconstriction or vasodilation happens when the regular muscles of the veins and arteries can relax or contract. Vasoconstriction is recognized as the narrowing of the lumen of the blood vessel and vasodilation is the widening of the lumen of the blood vessel. They maintain the blood pressure by allowing the arteries and the arterioles to contract or relax accordingly. The autonomic nervous system along with the pressure-sensitive sensory receptors is responsible for controlling these actions.

Normal vs Vasocotriction vs Vasodilation Cross-Section

Normal vs Vasocotriction vs Vasodilation Cross-Section

Things to Remember

The tube-like structure which transports blood through tissues, organs, and cells is known as blood vessels.
Pulmonary arteries are the arteries that carry deoxygenated blood away from the heart to different organs
The thinnest blood vessels in the body are capillaries which connects the veins and the arteries in order to exchange gases in the blood
Arteries have thicker walls as they carry oxygenated blood from the heart to the rest of the body part with high pressure.
Blood flows in all the blood vessels through a structure known as the lumen which are hollow tubes of space inside.
There are three types of blood vessels, Arteries, Veins, and Cappilaries, that form a major part of the human circulatory system.
The places where the pulse can be felt in the body are the wrist, neck, and upper arm. The normal pulse rate is between 72 and 80.

Sample Questions

Ques. What are some of the disorders that affect the blood vessels? (1 mark)

Ans. Some of the common problems that affect your blood vessels are aneurysm, arterial disease, atherosclerosis, blood clot, high blood pressure, Raynaud's disease, varicose veins, vascular malformations, and vasculitis.

Ques. Who are the people at higher risk for blood vessel disorder? (2 marks)

Ans. Some conditions elevate the risk of having vascular diseases. Conditions such as obesity, age 65 and above, diabetes and high cholesterol, smoke, no exercise, an existing illness that hampers the blood vessels, and an existing vascular disorder that affects the family increase the possibility of having a blood vessel disorder.

Ques. What are the possible symptoms that indicate blood vessel disorder? (3 marks)

Ans. There are several underlying symptoms that indicate the onset or severity of the blood vessel disorders. One should see a doctor as soon as he/she experiences certain symptoms such as:

Pain in abdomen, chest, and body parts
Shortness of breath
Tiredness or fatigue
Change in skin color
Difficulty in performing physical activities
Numbness in the body parts
Edema or swelling of hands and legs
Sudden vision loss

Ques. What are the different tests recommended by physics to diagnose blood vessel disorder? (2 marks)

Ans. Some of the tests that detect blood vessel disorders are ultrasound, electrocardiography, ct scan, MRI, tilt table test, cardiac catheterization, angiography, exercise stress test, and echocardiography. It can be treated by taking medications that reduce the cholesterol level in the body, reducing alcohol consumption and smoking, and open surgery.

Ques. Why does blood flow in the arteries in one direction in spite of the absence of valves? (2 marks)

Ans. The left ventricle pumps blood in high pressure through the artery. Because of the high pressure in the artery, it is made of thick elastic walls. Blood flows in one direction in the arteries because the heart pumps blood to the body in high pressure and the blood vessels are elastic.

Ques. What is the work of the pulmonary arteries? (1 mark)

Ans. The veins carry deoxygenated blood from the body to the heart. The pulmonary arteries carry this blood to the lungs to remove carbon dioxide.

Ques. What is an aneurysm? (2 marks)

Ans: Aneurysm is a vascular disease where a bulge is formed on the wall of any blood vessel. It is called thoracic if the aortic aneurysm is caused in the chest and is called abdominal if it is caused in the belly. They do not cause any problem in the mild state but pose a threat to the body if it goes untreated. The sudden rupture of the aortic aneurysm can be fatal.

Ques. What is the major difference between arteries and veins? (2 marks)

Ans. There are several features that differentiate arteries and veins. The one major difference between them is that arteries transport blood under high pressure and veins carry blood under negative pressure.

Ques. What are the five types of blood vessels? (2 marks)

Ans. The five blood vessels are veins, arteries, capillaries, arterioles, and venules. Arteries are also known as "bifurcating" or "branching" vessels. Veins are known as "joining "or "converging" vessels.

Ques. What are the major branches of the aorta? (3 marks)

Ans. The aorta is the largest artery. The four major regions of the aorta are the ascending aorta, aortic arch, abdominal aorta, and thoracic aorta. The arterial branches of the aortic arch are left subclavian, left common carotid, and brachiocephalic. The branches of the thoracic aorta are pericardial, bronchial, mediastinal, oesophageal, and posterior intercostal.