Ch 19 Blood Vessels

Ch 19 Blood Vessels - Ch 19 The Cardiovascular System Blood...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Ch 19: The Cardiovascular System: Blood Vessels Blood vessels comprise the 3 rd component of the Cardiovascular system: blood is the transport vehicle, the heart provides the motor that moves the vehicle and blood vessels are the routes over which blood must travel to deliver goods and pick up wastes. Anatomically, blood vessels connect the heart with the rest of the body and allow blood to move, like the postman, on its assigned rounds. There are three categories of blood vessels: ARTERIES----->move blood away from the heart VEINS----->move blood back to the heart CAPILLARIES----->connect arteries to veins Anatomy of Blood Vessels The basic structure of the wall of a blood vessels consists of 3 layers: Tunica externa/adventitia = fibrous connective tissue Tunica media = smooth muscle, collagenous & elastic fibers Tunica interna/intima = simple squamous epithelium facing blood ----->endothelium plus underlying connective tissue (+/-elastici fibers) All arteries & veins except the smallest have all 3 layers. Arterioles & venules lack 1 layer: Arterioles lack a tunica externa Venules lack a tunica media Capillaries consist of ONLY a tunica interna/intima----->a naked endothelium. There are differences in the structure of these layers that are reflective of the different challenges presented to arteries and veins in fulfilling their role in circulation: In general ----->arterial walls are thicker ----->arterial walls are more muscular (autonomic tone acts here) ----->arterial walls are more elastic ----->allows for vasoconstriction and vasodilation NB: Except under extreme stimulation, veins do not dilate or constrict Arteries & Veins are sub-categorized based on their histological structure. These sub-categories are named based on either structural/functional characteristics, relative diameter: ARTERIES VEINS Elastic arteries Large veins Muscular/distributing arteries Medium-sized veins Arterioles Venules (Capillaries) There are 2 types of capillaries, characterized by how “leaky” they are. ----->fenestrated (“windowed” in Latin) have gaps between endothelial cells = Pores ----->continuous lack gaps = a continuous (=uninterrupted) endothelium
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Structure/Function correlates for subtypes of arteries & veins : Arteries: ELASTIC arteries ---->examples = aorta, pulmonary trunk, common carotid, subclavian Structure: Tunica media is thickest layer----->LOTS of elastic fibers Internal elastic layer of tunica interna prominent Lgest diameter arteries (aorta~1” in diameter) Function: Receive blood under relatively high pressure ----->must be able to expand during ventricular systole and recoil during ventricular diastole to maintian BP MUSCULAR(structure)/DISTRIBUTING(function) arteries ----->examples = external carotids, brachial, femoral Structure: Tunica media thickest layer due to LOTS of smooth muscle ----->fewer elastic fibers = not very resilient Medium-sized arteries: diameters ~ 0.15” Function: Distribution of blood to tissues ARTERIOLES Structure: lack tunica externa----->endothelium wrapped in smooth muscle Diameter~30 microns (very small, but still 3-4x > capillaries)
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern