Circulatory System Quiz

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Questions and Answers

What is the primary function of the vasa vasorum?

To regulate body temperature

To collect blood from capillaries

To supply blood to the heart

To supply blood to the vascular walls themselves (correct)

What is the characteristic of continuous capillaries?

They are highly permeable

They have pores in the endothelial lining

They have a complete endothelial lining (correct)

They are found only in the liver and spleen

What is unique about sinusoids?

They have a complete endothelial lining

They are highly permeable

They are found only in the nervous system

They have a wide space between endothelial cells (correct)

What is the function of arteriovenous anastomoses?

To bypass the capillary bed Signup and view all the answers

What is the characteristic of elastic arteries?

They have many elastic fibers Signup and view all the answers

What is the function of veins?

To collect blood from capillaries in tissues and organs Signup and view all the answers

What is the characteristic of muscular arteries?

They have many muscle cells Signup and view all the answers

What is the function of the tunica externa?

To provide structural support Signup and view all the answers

What is the characteristic of capillaries?

They have a thin wall Signup and view all the answers

What is the function of fenestrated capillaries?

To permit rapid exchange of water and larger solutes Signup and view all the answers

What is the primary function of the circulatory system?

To carry blood and lymph to and from the tissues of the body Signup and view all the answers

Which of the following is NOT a part of the cardiovascular system?

Lymph nodes Signup and view all the answers

What is the primary function of arterioles?

To regulate blood pressure Signup and view all the answers

Which type of blood vessel is responsible for exchanging oxygen and nutrients with interstitial fluid?

Capillaries Signup and view all the answers

What is the outermost layer of the circulatory system?

Tunica externa (adventitia) Signup and view all the answers

What is the function of the internal elastic lamina in some vessels?

To separate the tunica intima from the tunica media Signup and view all the answers

What type of fibers are found in the tunica media?

All of the above Signup and view all the answers

What is the purpose of the external elastic lamina in some vessels?

To separate the tunica media from the tunica externa Signup and view all the answers

What is the main function of postcapillary venules?

To collect blood from capillaries Signup and view all the answers

Which type of vein has a thicker tunica media?

None of the above Signup and view all the answers

What is the main function of vein valves?

To prevent blood from flowing backward Signup and view all the answers

What is a characteristic of large veins?

They have all 3 tunica layers and a thick tunica externa Signup and view all the answers

What is a difference between arteries and veins?

Arteries have a thicker wall and higher blood pressure Signup and view all the answers

What is a characteristic of muscular venules?

They have a thin tunica media and few smooth muscle cells Signup and view all the answers

Which type of vein has a higher content of collagen?

Veins Signup and view all the answers

What is a characteristic of medium-sized veins?

They have a thin tunica media and few smooth muscle cells Signup and view all the answers

Study Notes

The Circulatory System

The circulatory system is a transport system that carries blood and lymph to and from the tissues of the body.
It consists of the cardiovascular system and the lymphatic system.

Cardiovascular System

The cardiovascular system includes the heart and vessels (arteries, arterioles, capillaries, venules, and veins).
There are five classes of blood vessels: • Arteries: carry blood away from the heart • Arterioles: smallest branches of arteries • Capillaries: smallest blood vessels, site of exchange between blood and interstitial fluid • Venules: collect blood from capillaries • Veins: return blood to the heart
Macrovasculature (>0.1mm) and microvasculature (interchanges) are parts of the cardiovascular system.

Common Structure of Blood Vessels

The wall of the circulatory system is composed of three layers: • Tunica intima: innermost layer, includes endothelial lining and connective tissue layer • Tunica media: middle layer, contains smooth muscle and elastic fibers • Tunica externa (adventitia): outer layer, contains connective tissue

Tunica Intima

The innermost layer, includes endothelial lining and connective tissue layer
In some vessels (arteries and large veins), there is a layer of elastic fibers in the outer margin of the tunica intima called the internal elastic lamina.

Tunica Media

The middle layer, contains concentric sheets of smooth muscle in loose connective tissue with variable amounts of elastic and reticular fibers.

Tunica Externa

The outer layer, contains connective tissue sheath principally of collagen (type I) and elastic fibers.

Vasa Vasorum

A system of vessels that supplies blood to the vascular walls themselves, found in tunica media and tunica externa of large arteries and veins.

Capillaries

The smallest blood vessels, with small diameter and thin walls
Chemicals and gases diffuse across the walls
No tunica media and externa, endothelial cell inside a thin basal lamina and pericytes

Types of Capillaries

Continuous capillaries: have a complete endothelial lining, found in all tissues except epithelia and cartilage
Fenestrated capillaries: have pores in the endothelial lining, permit rapid exchange of water and larger solutes
Discontinuous (sinusoids): enlarged diameter, endothelial cells with wide spaces, basal lamina is discontinuous, permit free exchange of water and large plasma proteins between blood and interstitial fluid.

Arteriovenous Anastomoses & Glomus

Direct connections between arterioles and venules, bypassing the capillary bed
Found in skeletal muscle and skin of the hands and feet, and tissue with intermittent metabolic activity

Artery Characteristics

From the heart to capillaries, arteries change from elastic arteries to muscular arteries to arterioles
Elastic arteries have many elastic fibers and few muscle cells
Muscular arteries have many muscle cells and few elastic fibers
Arterioles have little or no tunica externa and thin or incomplete tunica media

Veins

Collect blood from capillaries in tissues and organs and return blood to the heart
Three categories based on size: small veins (venules), medium-sized veins, and large veins
Small veins collect blood from capillaries and are divided into postcapillary venules and muscular venules
Medium-sized veins have a thin tunica media and few smooth muscle cells, with valves to prevent blood from flowing backward
Large veins have all three tunica layers, thin tunica media, and thick tunica externa with longitudinal bundles of smooth muscle and elastic fibers

Arteries vs. Veins

Arteries have thicker walls and higher blood pressure
Arteries are more elastic
Veins have a higher content of collagen than arteries
Collapsed artery has a small, round lumen, while a vein has a large, flat lumen
Veins have valves, are larger in diameter, and have thinner walls

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Description

Learn about the circulatory system, its functions, and its two main components - cardiovascular and lymphatic systems. Understand the importance of the heart, vessels, and lymphatic vessels in this system.