Blood vessel

The arterial system

The blood vessels are part of the circulatory system and function to transport blood throughout the body. This is an article about the rock music band "Circulatory System" Blood is a specialized Bodily fluid that delivers necessary substances to the body's cells ��such as nutrients and oxygen—and transports Waste products The most important vessels in the system are the capillaries, the microscopic vessels which enable the actual exchange of water and chemicals between the blood and the tissues, while the conduit vessels, arteries and veins, carry blood away from the heart and through the capillaries or back towards the heart, respectively. Capillaries are the smallest of a body's Blood vessels measuring 5-10 μm in diameter which connect Arterioles and Venules and enable the interchange Arteries are Blood vessels that carry blood away from the Heart. In the Circulatory system, a vein is a Blood vessel that carries Blood back toward the Heart (as opposed to Artery, a blood vessel The heart is a muscular organ in all Vertebrates responsible for pumping Blood through the Blood vessels by repeated rhythmic

1 Anatomy
2 Types
3 Physiology
4 Role in disease
5 See also

Anatomy

The arteries and veins have the same basic structure. There are three layers, from inside to outside while the capillaries have only one thick cell:

Tunica intima (the thinnest layer): a single layer of simple squamous endothelial cells glued by a polysaccharide intercellular matix, surrounded by a thin layer of subendothelial connective tissue interlaced with a number of circularly arranged elastic bands called the internal elastic lamina. The tunica intima (or just intima) is the innermost layer of an Artery or Vein. The endothelium is the thin layer of cells that line the interior surface of Blood vessels forming an interface between circulating Blood in the Polysaccharides are relatively complex Carbohydrates They are Polymers made up of many Monosaccharides joined together by Glycosidic bonds Connective tissue is one of the four types of tissue in traditional classifications (the others being epithelial, Muscle, and Nervous tissue)
Tunica media (the thickest layer): circularly arranged elastic fiber, connective tissue, polysaccharide substances, the second and third layer are separated by another thick elastic band called external elastic lamina. The tunica media (or just media) ( middle coat) is the middle layer of an Artery or Vein. The tunica media may (especially in arteries) be rich in vascular smooth muscle, which controls the caliber of the vessel. Vascular smooth muscle refers to the particular type of Smooth muscle found within and composing the majority of the wall of Blood vessels Vascular smooth muscle
Tunica adventitia: entirely made of connective tissue. The tunica externa, also known as the tunica adventitia, is the outermost layer of a Blood vessel, surrounding the Tunica media. It also contains nerves that supply the muscular layer, as well as nutrient capillaries (vasa vasorum) in the larger blood vessels. A nerve is an enclosed cable-like bundle of peripheral Axons (the long slender projections of Neurons. The vasa vasorum is a network of small Arterioles capillaries and Venules that supply the outer tissues of large Blood vessels like the Aorta

Capillaries consist of little more than a layer of endothelium and occasional connective tissue. Capillaries are the smallest of a body's Blood vessels measuring 5-10 μm in diameter which connect Arterioles and Venules and enable the interchange

When blood vessels connect to form a region of diffuse vascular supply it is called an anastomosis (pl. Anastomoses occur normally in the body in the Circulatory system, serving as backup routes for blood to flow if one link is blocked or otherwise compromised anastomoses). Anastomoses provide critical alternative routes for blood to flow in case of blockages.

Laid end to end, the blood vessels in an average human body will stretch approximately 62,000 miles (100,000 km)--2 times around the earth.

Types

There are various kinds of blood vessels:

Arteries
- Aorta (the largest artery, carries blood out of the heart)
- Branches of the aorta, such as the carotid artery, the subclavian artery, the celiac trunk, the mesenteric arteries, the renal artery and the iliac artery. Arteries are Blood vessels that carry blood away from the Heart. In Human anatomy, the common carotid artery is an Artery that supplies the head and neck with Oxygenated blood; it divides in the neck to form the In Human anatomy, the subclavian artery is a major Artery of the upper Thorax that mainly supplies blood to the head and arms The celiac artery, also known as the celiac trunk and also spelled as coeliac, is the first major branch of the Abdominal aorta and branches from the aorta The renal arteries normally arise off the side of the Abdominal aorta, immediately below the Superior mesenteric artery, and supply the Kidneys with
Arterioles
Capillaries (the smallest blood vessels)
Venules
Veins
- Large collecting vessels, such as the subclavian vein, the jugular vein, the renal vein and the iliac vein. An arteriole is a small diameter Blood vessel that extends and branches out from an Artery and leads to capillaries. Capillaries are the smallest of a body's Blood vessels measuring 5-10 μm in diameter which connect Arterioles and Venules and enable the interchange A venule is a small Blood vessel that allows deoxygenated Blood to return from the Capillary beds to the larger blood vessels called Veins In the Circulatory system, a vein is a Blood vessel that carries Blood back toward the Heart (as opposed to Artery, a blood vessel In Human anatomy, the subclavian veins are two large Veins one on either side of the body The jugular veins are Veins that bring deoxygenated blood from the Head back to the heart via the Superior vena cava. The renal veins are Veins that drain the Kidney. They connect the kidney to the Inferior vena cava. In Human anatomy, iliac vein refers to several anatomical structures located in the Pelvis: External iliac vein - terminates at the common iliac
- Venae cavae (the 2 largest veins, carry blood into the heart)

They are roughly grouped as arterial and venous, determined by whether the blood in it is flowing away from (arterial) or toward (venous) the heart. The superior and inferior vena cava are collectively called the venae cavae. The heart is a muscular organ in all Vertebrates responsible for pumping Blood through the Blood vessels by repeated rhythmic The term "arterial blood" is nevertheless used to indicate blood high in oxygen, although the pulmonary artery carries "venous blood" and blood flowing in the pulmonary vein is rich in oxygen. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the The pulmonary arteries carry Blood from the Heart to the Lungs. The four pulmonary veins carry Oxygen -rich Blood from the Lungs to the left atrium of the Heart. This is because they are carrying the blood to and from the lungs, respectively, to be oxygenated.

Physiology

Blood vessels do not actively engage in the transport of blood (they have no appreciable peristalsis), but arteries - and veins to a degree - can regulate their inner diameter by contraction of the muscular layer. In the Esophagus After food is chewed into a bolus it is swallowed to move it into the esophagus This changes the blood flow to downstream organs, and is determined by the autonomic nervous system. &trade The autonomic nervous system ( ANS) (or visceral nervous system) is the part of the Peripheral nervous system that acts as a Control Vasodilation and vasoconstriction are also used antagonistically as methods of thermoregulation. Thermoregulation is the ability of an Organism to keep its body temperature within certain boundaries even when temperature surrounding is very different

Oxygen (bound to hemoglobin in red blood cells) is the most critical nutrient carried by the blood. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Hemoglobin ( also spelled haemoglobin and abbreviated Hb or Hgb) is the Iron -containing Oxygen -transport Metalloprotein Red blood cells are the most common type of Blood cell and the Vertebrate body's principal means of delivering Oxygen to the body tissues via the Blood In all arteries apart from the pulmonary artery, hemoglobin is highly saturated (95-100%) with oxygen. In all veins apart from the pulmonary vein, the hemoglobin is desaturated at about 75%. The four pulmonary veins carry Oxygen -rich Blood from the Lungs to the left atrium of the Heart. Hemoglobin ( also spelled haemoglobin and abbreviated Hb or Hgb) is the Iron -containing Oxygen -transport Metalloprotein (The values are reversed in the pulmonary circulation. lung is the essential Respiration organ in air-breathing Animals including most Tetrapods a few Fish and a few Snails The most primitive )

The blood pressure in blood vessels is traditionally expressed in millimetres of mercury (1 mmHg = 133 Pa). Blood pressure is also the title of a short story by Damon Runyan in Guys and Dolls and Other Stories The torr (symbol Torr) is a non- SI unit of Pressure defined as 1/760 of an atmosphere. In the arterial system, this is usually around 120 mmHg systolic (high pressure wave due to contraction of the heart) and 80 mmHg diastolic (low pressure wave). Diastole is the period of time when the heart fills with blood after systole (contraction In contrast, pressures in the venous system are constant and rarely exceed 10 mmHg.

Vasoconstriction is the constriction of blood vessels (narrowing, becoming smaller in cross-sectional area) by contracting the vascular smooth muscle in the vessel walls. Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels particularly the large Arteries, Arterioles Vascular smooth muscle refers to the particular type of Smooth muscle found within and composing the majority of the wall of Blood vessels Vascular smooth muscle It is regulated by vasoconstrictors (agents that cause vasoconstriction). Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels particularly the large Arteries, Arterioles These include paracrine factors (e. Paracrine signaling is a form of Cell signaling in which the target cell is near (" Para " = near the signal-releasing cell g. prostaglandins), a number of hormones (e. A prostaglandin is any member of a group of Lipid compounds that are derived enzymatically from Fatty acids and have important functions in the Animal body Hormones (from Greek ὁρμή - "impetus" are chemicals released by cells that affect cells in other parts of the body g. vasopressin and angiotensin) and neurotransmitters (e. Arginine vasopressin ( AVP) also known as vasopressin, argipressin or antidiuretic hormone ( ADH) is a Hormone found in Angiotensin causes blood vessels to constrict and drives blood pressure up See Chemical synapse for an introduction to concepts and terminology used in this article g. epinephrine) from the nervous system.

Vasodilation is a similar process mediated by antagonistically acting mediators. The most prominent vasodilator is nitric oxide (termed endothelium-derived relaxing factor for this reason). Nitric oxide or nitrogen monoxide is a Chemical compound with Chemical formula N[[Oxygen O]] This article is about the biological functions of Nitric oxide.

Permeability of the endothelium is pivotal in the release of nutrients to the tissue. The endothelium is the thin layer of cells that line the interior surface of Blood vessels forming an interface between circulating Blood in the It is also increased in inflammation in response to histamine, prostaglandins and interleukins, which leads to most of the symptoms of inflammation (swelling, redness and warmth). Inflammation ( Latin, inflamatio, to set on fire is the complex biological response of vascular tissues to harmful stimuli such as Pathogens Histamine is a Biogenic amine involved in local immune responses as well as regulating physiological function in the gut and acting as a Neurotransmitter A prostaglandin is any member of a group of Lipid compounds that are derived enzymatically from Fatty acids and have important functions in the Animal body Interleukins are a group of Cytokines (secreted Signaling molecules) that were first seen to be expressed by White blood cells ( Leukocytes hence

Role in disease

Blood vessels play a role in virtually every medical condition. Cancer, for example, cannot progress unless the tumor causes angiogenesis (formation of new blood vessels) to supply the malignant cells' metabolic demand. Cancer (medical term Malignant Neoplasm) is a class of Diseases in which a group of cells display uncontrolled Angiogenesis is a physiological process involving the growth of new Blood vessels from pre-existing vessels Atherosclerosis, the formation of lipid lumps (atheromas) in the blood vessel wall, is the prime cause of cardiovascular disease, the main cause of death in the Western world. Atherosclerosis is a Disease affecting arterial Blood vessels It is a chronic inflammatory response in the walls of arteries in large part due to the accumulation Lipids are broadly defined as any fat- Soluble ( lipophilic) naturally-occurring Molecule, such as fats oils waxes cholesterol sterols fat-soluble In Pathology, an atheroma (plural atheromata is an accumulation and swelling (-oma in Artery walls that is made up of cells (mostly Macrophage cells Cardiovascular disease or cardiovascular diseases refers to the class of diseases that involve the Heart or Blood vessels ( arteries and

Blood vessel permeability is increased in inflammation. Inflammation ( Latin, inflamatio, to set on fire is the complex biological response of vascular tissues to harmful stimuli such as Pathogens Damage, due to trauma or spontaneously, may lead to haemorrhage. Treatment of physical trauma is described here and in First aid. Bleeding, technically known as hemorrhaging / haemorrhaging (see American and British spelling differences) is the loss of Blood from In contrast, occlusion of the blood vessel (e. g. by a ruptured atherosclerotic plaque, by an embolised blood clot or a foreign body) leads to downstream ischemia (insufficient blood supply) and necrosis (tissue breakdown). In Medicine, an embolism occurs when an object (the embolus, plural emboli) migrates from one part of the Body (through circulation A thrombus, or blood clot, is the final product of the Blood coagulation step in Hemostasis. In Medicine, ischemia ( Greek ισχαιμία, isch- is restriction hema or haema is Blood) is a restriction Necrosis (in Greek Νεκρός = "dead" is the name given to unnatural Death of cells and living tissue.

Vasculitis is inflammation of the vessel wall, due to autoimmune disease or infection. Vasculitis (plural vasculitides) a group of diseases featuring Inflammation of the wall of Blood vessels including veins ( Phlebitis) arteries Inflammation ( Latin, inflamatio, to set on fire is the complex biological response of vascular tissues to harmful stimuli such as Pathogens Autoimmune diseases arise from an overactive Immune response of the body against substances and tissues normally present in the body An infection is the detrimental Colonization of a host Organism by a foreign Species.

Dictionary

-noun

(anatomy) referring to any vessel in which blood is carried, such as arteries, capillaries or veins

© 2009 citizendia.org; parts available under the terms of GNU Free Documentation License, from http://en.wikipedia.org
network: | |

Contents