Blood Vascular System Lecture 2025 PDF

BLOOD VASCULAR SYSTEM Lec Ass. Prof. Dr. Noha Ramadan Elswaidy A. The heart. B. Blood vessels 1-Arteries 2-Veins 3-Connecting vessels 3Tunics (coats) A. Tunica Intima. B. Tunica media. C. Tunica adventitia. A. Tunica Intima. 1. Endothelium. 2....

BLOOD VASCULAR SYSTEM Lec Ass. Prof. Dr. Noha Ramadan Elswaidy A. The heart. B. Blood vessels 1-Arteries 2-Veins 3-Connecting vessels 3Tunics (coats) A. Tunica Intima. B. Tunica media. C. Tunica adventitia. A. Tunica Intima. 1. Endothelium. 2. Subendothelial layer of C.T. 3. Internal elastic lamina ? In most arteries.  B.Tunica media Cells :circularly arranged smooth muscles Fibres: elastic fibres Matrix (ground substance): synthesized by smooth ms cells. External elastic lamina? May or may not be present ralucsum egral ni( seiretra)  C. Tunica adventitia (externa) Fine collagenous fibres. Few elastic fibres. Vasa vasorum (vessel of the vessel) N.B. adventitia is larger in veins than arteries.  Tunica Internal intima elastic lamina Smooth muscle cells Tunica media Tunica adventitia Blood vessel General structure of a Blood Vessel  Arteries They are: 1- Large arteries 2- Medium sized arteries 3- Arterioles  Aorta (Large elastic artery) Structure of large elastic artery (Aorta): a- It has a very thick elastic wall and a wide lumen. b- It consists of three layers: ❖Tunica intima: it is formed of: Endothelium. Subendothelium. Internal elastic lamina (indistinct). ❖Tunica media: It is very thick formed mainly of fenestrated laminae of elastic fibers separated by circularly arranged smooth muscles and collagenous fibers. Internal and external elastic laminae although present, are not distinct as they emerge with that of tunica media. ❖ Tunica adventitia: It is relatively thin. It contains elastic fibers, collagen fibers and vasa vasorum.  --Medium – sized (muscular) arteries -- Medium sized veins  Medium-sized artery Thick wall Rounded & narrow lumen. Medium-sized vein They accompany the medium sized arteries and carry their names Thin wall with valves. Wide and collapsed lumen. Medium-sized artery Well-developed. Well developed internal elastic lamina. Medium-sized vein Thin. Internal elastic lamina: absent. Medium-sized artery Thick. Smooth muscles. Elastic fibres. External elastic lamina Medium-sized vein: Thin. Smooth muscles. No elastic fibres. No ext. elastic lamina. Medium-sized artery: Thinner than media. Collagenous fibres. Elastic fibres. Medium-sized vein: Thicker than media. Collagenous fibres. No elastic fibres.  Medium sized artery Medium sized vein Wall: o Well-developed. o Thin. Lumen: o Narrow & rounded. o Wide & collapsed. o Valves: absent o Valves: present. T. intima o Thick o Thin. Internal elastic o Well developed o Absent. lamina T. media o Thick. o Thin. o Smooth muscle fibers and o Few circular smooth elastic fibers. muscle fibers only. External elastic o May be present o Absent. Lamina T. adventitia o Thinner than media o Thicker than media o Elastic and collagenous o Collagenous fibers only. fibers. Medium sized Medium sized vein artery Aorta Diameter:.mµ 10-8 Structure: 1.Endothelium (single layer) rest on Basal lamina (represent intima). 2.Pericytes:represent media. Between endothelium (E) & basal lamina (BL). Contain actin, myosin & tropomyosin. Function: essential for wound healing. 3.A thin layer of reticular fibers: represents the adventitia Thank You