L1 Blood circulatory system histo - PDF

# Faculty of Medicine - Delta University for Science and Technology ## Level 2, Semester 3 - Module (CVS) # The Blood Circulatory System ## Dr Samar Asker ### Prof of Histology and Cell Biology ## Learning Outcomes By the end of the lecture, the students will be able to: 1. Identify the types an...

# Faculty of Medicine - Delta University for Science and Technology ## Level 2, Semester 3 - Module (CVS) # The Blood Circulatory System ## Dr Samar Asker ### Prof of Histology and Cell Biology ## Learning Outcomes By the end of the lecture, the students will be able to: 1. Identify the types and structure of blood vessels. 2. Describe the histological structure of the blood vessels at both LM & EM levels. 3. Correlate the structure of the blood vessels with their function. ## The Blood Circulatory System ### Includes - The heart - Blood vessels ## Types of Blood Vessels 1. **Arteries** - Large elastic (Aorta) - Medium-sized (muscular) arteries - Arterioles 2. **Connecting vessels between arteries and veins:** - Blood capillaries - Blood sinusoids - Arteries venous anastomosis 3. **Veins** - Venules - Medium-sized veins - Large veins (IVC) ## Arteries - **Large Arteries**: aorta carries blood from the heart. - **Medium-sized arteries**: carry blood to organs. - **Small Arteries (arterioles)** regulate blood flow to capillaries. ## General Structure of Blood Vessels | | Description | | ----------- | ----------- | | I | Tunica Intima | | II | Tunica Media | | III | Tunica Adventitia | ### Tunica Intima 1. **Endothelial lining**: simple sq. epithelium. 2. **Subendothelial layer**: loose C.T. rich in elastic fiber. 3. **Internal elastic lamina**: wavy membrane of elastic fibers. ### Tunica Media 1. Smooth muscle 2. Elastin fibers 3. Fine collagenous and reticular fiber. 4. **External elastic lamina**: present in outer part of media of muscular arteries. ### Tunica Adventitia Connective tissue containing 1. Fine collagenous fibers 2. Elastic fibers. 3. Tiny blood vessels called *vasa vasorum* (vessels of vessels) to supply blood to the wall of large blood vessels. ## Large arteries (Aorta) - **Tunica Intima (10%)** - 1/6 of the thickness of the wall - Lining: simple squamous endothelium - Subendothelial C.T. rich in elastic fiber. - Undifferentiated internal elastic lamina - **Tunica Media (70%)** - Fenestrated **elastic membrane** (40-70 layer) - Smooth muscles in-between collagen fibers. - Ground substance mainly of **chondroitin sulfate** - **Tunica Adventitia (20%)** - Loose CT rich in elastic fibers. - Contains *vasa vasorum* which is a small blood vessels that supply the outer part of T. media & T. adventitia ### Functions of large arteries is 1. Trasport blood away from heart 2. Maintai diastolic pressure ## Lage veins - Inferior Vena Cava - Thick wall & wide lumen. - **Tunica Intima** - Thin - No internal elastic lamina - **Tunica Media** - Thin contains only **Smooth muscles fibers**. - **Tunica Adventitia (20%)** - Very thick loose CT contain collagenous **fibers**. - Contains *vasa vasorum* and nerves - Contains longitudinal arranged bundles of smooth muscl ## Medium sized artery & vein | | Medium sized artery | Medium sized vein | | ----------- | ----------- | ----------- | | Wall | Thick wall. | Thin wall. | | Lumen | Narrow lumen. <br> Not contain blood after death. <br> No valve in the lumen. | Wide lumen usually contains blood after death.<br> Valve present. | | Flow of Blood | It has a rapid flow to the whole body. | It has a slow flow of venous blood from the tissues. | | T. Intima | **Thick.**<br> Folded due to internal elastic lamina. | **Thin.** <br> Not Folded. | | T. Media | **Thick.** <br> Some elastic membrane. <br> External elastic lamina may be present | **Thin.**<br> Formed of few smooth muscle fibers. <br> No external elastic lamina. | | Adventitia | Thin and contain elastic fibers. | Thicker <br> No elastic fibers | ## Specialized medium-sized arteries | | Basilar (cerebral) artery | Coronary artery: | Umbilical artery | | ----------- | ----------- | ----------- | ----------- | | T. Intima | Well developed IEL | Well developed IEL<br> Thick subendothelial CT<br> Contain fat droplets & longitudinal smooth muscle | No IEL | | T. Media | **Thin** | Thick + EEL | smooth muscle<br> Inner longitudinal & outer circular | | Adventitia | thin | Thin | Mucoid CT | ## Arteriole & Venule | | Arteriole | Venule | | ----------- | ----------- | ----------- | | Wall | End of muscular arteries <br>Thin wall. | Begin of muscular veins <br>Thin wall. | | Lumen | **Narrow lumen.** | | | T. Intima | Endothelium.<br> Thin subendothelial. <br> Absent internal elastic lamina. | No elastic fibers. | | T. Media | Two layers of smooth muscle with elastic fibers in between. <br> **No EEL** | Contained contractile pericytes. | ## It's MCQ Time - **External elastic lamina** is well developed in: - A. Capillaries. - B. Veins. - C. Basilar artery. - D. Sinusoids - E. **Muscular arteries.** - Which layer in an **elastic artery** is the largest thickest? - A. Tunica intima. - B. Tunica albuginea - C. Tunica externa - D. Tunica adventitia - E. **Tunica media.** - Which blood vessels **their media contain pericytes**? - A. Arteriole. - B. Veniole. - C. Fenestrated capillaries. - D. Blood sinusoids. - E. Continuous capillaries. ## References - Ross MH &Pawlina W. 2011: Histology. A Text and Atlas. - Junqueira LC and Carneiro J. 2003:Basic Histology. A Text and Atlas. - https://youtu.be/WLT7rhMVpk0 ## Thank You!