test_3_updated notes - VESSELS CHAP 21 Blood vessels form a...

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

View Full Document Right Arrow Icon
VESSELS CHAP 21 Blood vessels form a network of tubes that carry blood away from the heart, delivering O2 to the tissues through the capillaries and then returning it , deoxygenated , to the heart. OVERVIEW: Heart arteries arterioles metarteriole capillaries venules veins heart ARTERIES: a. vessels carrying blood away from the heart b. usually, this blood is oxygenated c. large diameter d. 3 layers ( tunicas ) of tissue make up the artery wall. 1. TUNICA INTIMA (INTERNA): deepest tunica consisting of ENDOTHELIUM = single layer of epithelial cells lining the heart and vessels, and an INTERNAL ELASTIC MEMBRANE 2. TUNICA MEDIA: usually thickest layer consisting of SMOOTH MUSCLE and in some vessels, an EXTERNAL ELASTIC MEMBRANE 3. TUNICA EXTERNA (ADVENTICIA): elastic and collagen fibers Due to this anatomy and the presence of elastic fibers, arteries will expand during ventricular systole and recoil during ventricular diastole and a PULSE can be detected (The alternate expansion and recoiling of elastic arteries after each ventricular systole of the left ventricle creating a pressure wave that travels through the arteries). A pulse can be detected in a superficial artery that lies over a bone or other firm tissue. Common pulse locations= ARTERIOLES and METARTERIOLES a. small arteries b. connect arteries with capillaries c. Important in the regulation of flow of blood through the capillaries CAPILLARIES: (exist thoughout the body EXCEPT lens, cornea, epithelium, cartilage) a. Composed of single layer of endothelium b. Lumen size large enough to allow one RBC to flow per unit time - allows for diffusion of gases in and out of RBC (decreased velocity) c. exist in capillary beds ( capillary networks) - when tissue needs are low, blood will flow only through a small portion of the network. When needs increase, the entire capillary bed is full of blood. Regulated by _________________________________.
Image of page 1

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

View Full Document Right Arrow Icon
d. Capillaries are the site of material moving in and out of the circulatory system. There is gas exchange occurring at the tissue level and there is BULK FLOW of large amounts of ions, proteins, other nutrients and water. The bulk flow OUT of the capillary occurs at the arteriole end. At the venule end, the fluid moves INTO the capillary from the tissue spaces. In health, approximately 85% of the fluid at the arteriole ends of the capillaries is reabsorbed at the venule end. Some of the escaped fluid and proteins will be returned to the blood via the lymphatic system Approximately 20 liters of fluid filters out of the capillaries each day, 17 liters will be reabsorbed by the capillary and 3 liters enter the lymphatics. Occasionally, the balance between this filtration and reabsorption of the interstitial fluid is interrupted, and less than normal fluid is reabsorbed. This abnormal increase in interstitial fluid is termed EDEMA.
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