The Cardiovascular System 7: The Vascular System 3

1.

______ are thin-walled blood vessels that carry blood to the heart under relatively low pressure.
- A.
  
  Arteries
- B.
  
  Venules
- C.
  
  Arterioles
- D.
  
  Veins
- E.
  
  Capillaries
Correct Answer
D. Veins

Explanation
Veins are thin-walled blood vessels that carry blood to the heart under relatively low pressure. Unlike arteries, which carry oxygenated blood away from the heart under higher pressure, veins transport deoxygenated blood back to the heart. The thin walls of veins allow for the expansion and contraction of the blood vessels as blood flows through them. This low-pressure system helps to prevent the backflow of blood and allows for efficient return of blood to the heart.

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2.

________ are small veins (microscopic in size) that collect blood from __________ and deliver it to larger veins.

Correct Answer
Venules, capillaries

Explanation
Venules are small veins that collect blood from capillaries and deliver it to larger veins. Capillaries are microscopic blood vessels that connect arterioles and venules, allowing for the exchange of oxygen, nutrients, and waste products between the blood and tissues. Therefore, venules and capillaries work together in the circulatory system to transport blood from the smallest blood vessels (capillaries) to larger ones (venules) for further circulation throughout the body.

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3.

In adults, all veins except for the _____________ carry deoxygenated blood. Venous walls are similar to arterial walls but their ________ have greater diameters.

Correct Answer
pulmonary veins, lumens

Explanation
In adults, all veins except for the pulmonary veins carry deoxygenated blood. This is because the pulmonary veins are responsible for carrying oxygenated blood from the lungs back to the heart. Venous walls are similar to arterial walls but their lumens have greater diameters. The lumen refers to the inner space or opening of a blood vessel, and in veins, it is typically larger than in arteries to accommodate the lower pressure and slower flow of deoxygenated blood.

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4.

Just like arteries, veins contain three distinct layers which are the _________, the ______ and the __________.

Correct Answer
tunica interna, tunica media, tunica externa

Explanation
The correct answer is tunica interna, tunica media, tunica externa. Arteries and veins both have three layers, known as tunics. The innermost layer is called the tunica interna, which is made up of endothelial cells and provides a smooth surface for blood flow. The middle layer is called the tunica media, which contains smooth muscle cells and elastic fibers that help regulate blood pressure and control vessel diameter. The outermost layer is called the tunica externa, which consists of connective tissue and provides support and protection to the vein.

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5.

The tunica intima of the veins are composed of ___________.

Correct Answer
endothelium

Explanation
The tunica intima of the veins is composed of endothelium. The endothelium is a single layer of cells that lines the inner surface of blood vessels, including veins. It acts as a barrier between the blood and the surrounding tissues, regulating the exchange of substances such as oxygen, nutrients, and waste products. The endothelium also plays a role in maintaining blood vessel tone and preventing clot formation. Therefore, it is the correct answer for the composition of the tunica intima of veins.

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6.

The ___________ of the veins are poorly developed. They are composed of a thin layer of _________ and less __________ and their walls will _________ when empty.

Correct Answer
tunica media, smooth muscle, elastic tissue, collapse

Explanation
The veins have a poorly developed tunica media, which is the middle layer of the vein wall. This layer is composed of smooth muscle and elastic tissue. Due to their poor development, the walls of the veins will collapse when they are empty.

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7.

The ________ is the outermost and most ________ layer of the veins. It contains much more _____ and _________.

Correct Answer
tunica externa, prominent, collagen, elastic fibers

Explanation
The outermost and most prominent layer of the veins is called the tunica externa. This layer contains a significant amount of collagen and elastic fibers. These fibers provide strength and elasticity to the veins, allowing them to withstand the pressure and stretching that occurs during blood circulation.

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8.

Most veins that are larger than ___ millimeters in diameter have one-way ______ positioned in such a way that they can conduct blood against the force of _______.

Correct Answer
2, valves, gravity

Explanation
Veins that are larger than 2 millimeters in diameter have one-way valves positioned in such a way that they can conduct blood against the force of gravity. These valves prevent the backflow of blood and ensure that it flows in one direction, towards the heart. This is important because gravity tends to pull blood downwards, and without the valves, blood would accumulate in the lower extremities. The valves open when blood flows towards the heart and close to prevent backflow, allowing efficient circulation throughout the body.

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9.

Veins found in the ______ normally contain valves.

Correct Answer
extremeties

Explanation
Veins found in the extremities normally contain valves. The extremities refer to the outermost parts of the body, such as the arms and legs. Valves in veins help to prevent the backflow of blood and ensure that it flows in one direction towards the heart. Given that veins in the extremities are responsible for carrying blood back to the heart, it is essential for them to have valves to facilitate proper circulation.

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10.

The valves of the veins are usually composed of 2 _______ formed by ________ of the __________. They are arranged to permit blood flow toward the heart and not backward in the opposite direction. In other words they prevent _________.

Correct Answer
cusps, inward extensions, tunica interna, backflow

Explanation
The valves of the veins are usually composed of 2 cusps formed by inward extensions of the tunica interna. They are arranged to permit blood flow toward the heart and not backward in the opposite direction. In other words, they prevent backflow.

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The Cardiovascular System 7: The Vascular System 3

______ are thin-walled blood vessels that carry blood to the heart under relatively low pressure.

are small veins (microscopic in size) that collect blood from __ and deliver it to larger veins.

In adults, all veins except for the _____ carry deoxygenated blood. Venous walls are similar to arterial walls but their have greater diameters.

Just like arteries, veins contain three distinct layers which are the _, the and the ____.

The tunica intima of the veins are composed of ___________.

The _______ of the veins are poorly developed. They are composed of a thin layer of _ and less and their walls will ___ when empty.

The __ is the outermost and most layer of the veins. It contains much more _ and _______.

Most veins that are larger than _ millimeters in diameter have one-way positioned in such a way that they can conduct blood against the force of ___.

Veins found in the ______ normally contain valves.

The valves of the veins are usually composed of 2 _ formed by of the . They are arranged to permit blood flow toward the heart and not backward in the opposite direction. In other words they prevent _____.

The Cardiovascular System 7: The Vascular System 3

______ are thin-walled blood vessels that carry blood to the heart under relatively low pressure.

________ are small veins (microscopic in size) that collect blood from __________ and deliver it to larger veins.

In adults, all veins except for the _____________ carry deoxygenated blood. Venous walls are similar to arterial walls but their ________ have greater diameters.

Just like arteries, veins contain three distinct layers which are the _________, the ______ and the __________.

The tunica intima of the veins are composed of ___________.

The ___________ of the veins are poorly developed. They are composed of a thin layer of _________ and less __________ and their walls will _________ when empty.

The ________ is the outermost and most ________ layer of the veins. It contains much more _____ and _________.

Most veins that are larger than ___ millimeters in diameter have one-way ______ positioned in such a way that they can conduct blood against the force of _______.

Veins found in the ______ normally contain valves.

The valves of the veins are usually composed of 2 _______ formed by ________ of the __________. They are arranged to permit blood flow toward the heart and not backward in the opposite direction. In other words they prevent _________.

are small veins (microscopic in size) that collect blood from __ and deliver it to larger veins.

In adults, all veins except for the _____ carry deoxygenated blood. Venous walls are similar to arterial walls but their have greater diameters.

Just like arteries, veins contain three distinct layers which are the _, the and the ____.

The _______ of the veins are poorly developed. They are composed of a thin layer of _ and less and their walls will ___ when empty.

The __ is the outermost and most layer of the veins. It contains much more _ and _______.

Most veins that are larger than _ millimeters in diameter have one-way positioned in such a way that they can conduct blood against the force of ___.

The valves of the veins are usually composed of 2 _ formed by of the . They are arranged to permit blood flow toward the heart and not backward in the opposite direction. In other words they prevent _____.