What is the primary function of the vascular system?
Service the needs of the tissues. Provide nutrients and blood flow to tissues and return waste products to appropriate organs.
What are the two main divisions of the vascular system?
Pulmonary arc and Systemic arc
What cell type lines blood vessels?
What is the path of blood through the pulmonary arc?
1. Heart pumps blood via elastic (pulmonary) arteries to the lungs 2. Blood is returned to the heart via elastic (pulmonary) veins
What is the path of blood through the systemic arc?
1. Heart pumps blood via elastic arteries and muscular arteries 2. Muscular arteries branch to form arterioles which terminate as the terminal vascular bed 3. Terminal vascular bed is drained by venules which then converge on muscular veins 4. Muscular veins join elastic veins
What is the lymphatic system?
An extensive drainage network that helps keep bodily fluid levels in balance and defends the body against infections.
What is the path of fluid through the lymphatic system?
1. Tissue fluid enters small lymph vessels, which empty into large lymph channels 2. Fluid is returned to the vascular system when large lymph channels join the elastic veins returning blood to the heart.
What 3 components are found in each layer of the vascular tubular wall?
Collagen, elastic fibers, and smooth muscle
True or false: Blood vessels are organs?
True Blood vessels are organs that have their own blood supply (vasa vasorum)
What are the 3 layers comprising a blood vessel?
1. Tunica intima (1st) 2. Tunica Media (2nd) 3. Tunica Adventitia (3rd)
This layer of the vascular wall consists primarily of endothelium, basal lamina, and subendothelial connective tissue, and a few smooth muscle cells?
True or False: The Tunica Intima is vascularized?
The Tunica intima is avascular
What is the elastic layer that forms the outer most part of the tunica intima, separating it from the tunica media?
Internal Elastic Lamina
The tunica media consists predominantly of _____ in muscular vessels and _____ in elastic vessels
smooth muscle and elastic
*Collagenous fibers are intermixed with the smooth muscle and/or elastic fibers
How are the fibers arranged in the 3 layers of a blood vessel?
1. Tunica Intima has fibers oriented parallel to the long axis of the vessel
2. Tunica media has fibers arranged concentrically (perpendicular-90 deg)
3. Tunica Adventitia has fibers that run parallel to the long axis of the vessel
What is the outermost part of the Tunica Media?
External Elastic Lamina
How does the tunica media receive nourishment?
Vasa vasorum supply the outer half of the tunica media but the inner half receives nourishment via diffusion through gaps in the internal elastic lamina part of the tunica intima.
This layer of blood vessel is composed primarily of connective tissue-collagen and elastic fibers-and contains vasa vasorum and nervi vasorum
What is the one constant feature of all vascular components?
Discuss the difference in arteries and veins in relation to shape and lumen to wall ratio.
Shape of arteries is more regular (or round) than that of veins and the lumen to wall ratio is small in arteries and large in veins
The ____ is the thickest layer in arteries while the _____ is the thickest layer in veins.
The tunica media is thickest in arteries and the tunica adventitia is thickest in veins
Do arteries or veins have thicker walls? Give the reason for this.
Arteries transport blood away from the heart and are under high pressure so the walls are substantially stronger. Veins transport blood back to the heart and the pressure is substantially lower thus the walls are thiner and the tunica media contains a considerable amount of collagen intermixed with the smooth muscle.
What structure is present in veins and lymph vessels but not arteries?
What are two distinguishing characteristics of lymph vessels?
1. Walls of lymph vessels lack distinct organization
2. Precipitate may be present in the lumen of the lymph vessel
What is the only blood cell present in the lumen of lymph vessels?
What is the function of elastic and muscular arteries?
Elastic arteries conduct blood away from the heart and muscular arteries distribute the blood to various parts of the body.
What is a primary characteristic of elastic vessels?
Tunica media consisting primarily of concentric, fenestrated elastic laminae
What is the primary component of tunica media in muscular vessels?
In elsastic veins the ____ is usually thicker than the ____.
Tunica adventitia is usually thicker than the tunica media
What is plaque formation and how does it occur?
Plaque formation occurs due to a build up of elastic and collagen fibers produced from smooth muscle following injury to the tunica intima.