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Blood vessels transport blood cells, nutrients, and oxygen to most of the tissues of a body. They also take waste and carbon dioxide away from the tissues. [2] Some tissues such as cartilage, epithelium, and the lens and cornea of the eye are not supplied with blood vessels and are termed avascular.
Veins (/ v eɪ n /) are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart.Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and fetal circulations which carry oxygenated blood to the heart.
The network of blood vessels are the great vessels of the heart including large elastic arteries, and large veins; other arteries, smaller arterioles, capillaries that join with venules (small veins), and other veins. The circulatory system is closed in vertebrates
The muscular systems in vertebrates are controlled through the nervous system although some muscles (such as the cardiac muscle) can be completely autonomous. Together with the skeletal system in the human, it forms the musculoskeletal system , which is responsible for the movement of the body .
The aorta is the largest blood vessel in human body. The aorta is the root systemic artery (i.e., main artery). In humans, it receives blood directly from the left ventricle of the heart via the aortic valve. As the aorta branches and these arteries branch, in turn, they become successively smaller in diameter, down to the arterioles.
An arteriole is a small-diameter blood vessel in the microcirculation that extends and branches out from an artery and leads to capillaries. [ 1 ] Arterioles have muscular walls (usually only one to two layers of smooth muscle cells ) and are the primary site of vascular resistance .
A muscular artery (or distributing artery) is a medium-sized artery that draws blood from an elastic artery and branches into "resistance vessels" including small arteries and arterioles. Their walls contain larger number of smooth muscles, allowing them to contract and expand depending on peripheral blood demand. [1]
For example, the pronator teres muscle of the forearm. Unipennate muscles have fibers that run the entire length of only one side of a muscle, like a quill pen. For example, the fibularis muscles. Bipennate muscles consist of two rows of oblique muscle fibres, facing in opposite diagonal directions, converging on a central tendon.