Exam 1 Review:  Chapter 19:  General Terms

artery - Any of the muscular elastic tubes which form a branching system and which carry blood away from the heart to the cells, tissues, and organs of the body; they fall into three structural categories: large elastic conducting arteries, middle-sized muscular distributing arteries, and small arterioles; all arteries have the same histological design with three layers (tunics):  (1) an inner tunica interna = tunica intima composed of simple squamous endothelium, (2) a middle tunica media composed of smooth muscle and elastic connective tissue, and (3) an outer tunica adventitia = tunica externa composed of elastic connective tissue; the tension in the walls of arteries is maintained by the ANS and influenced by certain hormones.  nickname: resistance vessel

arteriole - The smaller arteries which distribute blood within organs and tissues by delivering the blood to capillary beds; they are thin-walled and wall composition varies depending on location -- there is less smooth muscle and more elastic connective tissue in the smaller vessels more distal from the heart; they regulate blood pressure and blood flow to capillary beds by adjusting muscular tension in their walls in in pre-capillary sphincters.

capillary - One of the minute blood vessels which connect arterioles and venules; these blood vessels form an intricate network throughout the body for the interchange of various molecules dissolved in water, such as oxygen and carbon dioxide, nutrients and wastes, between blood and tissue cells; they are lined by a semi-permeable simple squamous endothelium; three structural categories are recognized:  continuous, fenestrated, and sinusoid.  Note:  the term capillary is also used for the smallest lymphatic and biliary vessels.

venule - A small vein, especially one joining capillaries to larger veins; its three tunics are the thinnest.

vein - Any of the moderately muscular elastic tubes which form a branching system and which carry blood away from the cells, tissues, and organs of the body and back to the heart; they fall into three structural categories: large conducting veins, middle-sized veins, and small venules; all veins have the same histological design with three layers (tunics):  (1) an inner tunica interna = tunica intima composed of simple squamous endothelium, (2) a middle tunica media composed of smooth muscle and elastic connective tissue, and (3) an outer tunica adventitia = tunica externa composed of elastic connective tissue; the thickness of the outer two layers is always smaller than those of an artery of the same diameter; tension in the walls of veins is maintained by the ANS and influenced by certain hormones; some veins have valves to prevent back flow of blood; veins exhibit more anastomoses than arteries.

capacitance vessels - The blood vessels which hold the greatest portion (~70%) of the blood volume at any given moment in time; normally these are the large and medium-sized veins of the systemic circulation.

vasa vasorum - The general term for all small blood vessels (arterioles, capillaries, and venules) located within the walls of larger blood vessels.

lumen - The inner open space or cavity of a tubular organ, as of a blood vessel or an intestine.

List:

1. in correct sequence the types of blood vessels through which a blood cell passes in making a circuit through the systemic circulation.

elastic (conducting) arteries → muscular (distributing arteries) → arterioles → capillaries → venules→ veins

Sketch and Label:

1. a cross section of an artery, vein and capillary.  For more vessel images.

 

Artery	Capillary	Vein

Describe:

1. the function of each type of blood vessel in the circulatory system.

 

Artery	Capillary	Vein
Delivers blood from the heart to the capillary beds of various tissues.  Elastic recoil and smooth muscle contraction in the arterial walls assists with the forward movement of blood through the circulation and, therefore, assists in maintaining blood pressure.	Distributes blood through the intercellular spaces of connective tissues and permits diffusion of water,  oxygen, carbon dioxide, nutrients, electrolytes, regulatory and immune defense substances, and soluble wastes between the plasma and the interstitial fluid.	Collects blood from the capillary beds of various tissues and returns that blood to the heart.