BIO 241 1st EditionLecture 7Outline of Current Lecture II. Arterial anatomyIII. Arterial propertiesIV. Arterial typesV. ArteriolesVI. CapillariesVII. Capillary typesVIII. Venules and veinsCurrent LectureII. The lumen is the hollow part in the middle of the artery where blood flows. The actual artery itself has three layers. The tunica intima is the innermost layer, which consists of the endothelium, basement membrane, and the internal elastic lamina. The middle layer, tunica media, consists of circular smooth muscle and the external elastic lamina. The outermost layer is the tunica adventitia.III. Arteries have two major properties. One is contractility which consists of vasodilation (vessels enlarging) and vasoconstriction (vessels decreasing in diameter). Increased norepinephrine leads to full vasoconstriction. Decreased norepinephrine leads to full vasodilation. The other is extensibility/elasticity which is because of the layered walls that allow for stretching. It also relates to potential energy which happens during systole. The surge of blood into the aorta stretches its elastin fibers and allows it to “store” blood. Kinetic energy occurs during diastole. The drop in blood pressure allows the elastin fibers to rebound and propel the blood forward. IV. There are three types of arteries. The first is elastic which is known as the conducting or largearteries. The tunica media is rich in elastin fibers and pressure reservoirs. Examples are the aorta and its intermediate branches. The second type is muscular which is known as distributingor medium arteries. The tunica media is rich in smooth muscle. It is responsible for both blood shunting(using contractility to move blood through vessels) and most of the These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.anastomoses/collateral circulation (conjoining of blood vessels and blood flow). Examples are regional arteries like the brachial, femoral, renal, and splenic arteries. There are also resistance arteries which are the small arteries throughout the body. V. The arterioles are 1-5 layers thick of smooth muscle cells. It has the highest contractility with both vasoconstriction and vasodilation. It is also what is responsible for blood shunting.VI. Capillaries are the smallest: they are microscopic. It aids in distribution and exchange of blood. They are simple squamous epithelial tissue. They contain precapillary sphincters which control blood movement throughout capillary beds. They aid in vasomotion which is the stop and go motion where they drop off their passengers when needed. VII. There are three capillary types. The first is continuous which are clefts where exchange happens and it has endothelium tissue around it. The second is fenestrated which does best rapid exchange. The third is sinusoid which are where RBCs can leave. Their walls are very fragmented which allows for escape. VIII. Venules and veins have the same basic tunics although they do have a larger lumen and a thinner tunica media. They are very distensible (can expand) and contain valves much like the ones discussed in the
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