Venous blood

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Concentrated blood after oxygenation Bloodbags.jpg
Concentrated blood after oxygenation

Venous blood is deoxygenated blood which travels from the peripheral blood vessels, through the venous system into the right atrium of the heart. Deoxygenated blood is then pumped by the right ventricle to the lungs via the pulmonary artery which is divided in two branches, left and right to the left and right lungs respectively. Blood is oxygenated in the lungs and returns to the left atrium through the pulmonary veins.

Venous blood is typically colder than arterial blood, [1] and has a lower oxygen content and pH. It also has lower concentrations of glucose and other nutrients and has higher concentrations of urea and other waste products. The difference in the oxygen content of arterial blood and venous blood is known as the arteriovenous oxygen difference.[ citation needed ]

Most medical laboratory tests are conducted on venous blood, with the exception of arterial blood gas tests. Venous blood is obtained for lab work by venipuncture (also called phlebotomy), or by finger prick for small quantities.

Color

The color of human blood ranges from bright red when oxygenated to a darker red when deoxygenated. [2] It owes its color to hemoglobin, to which oxygen binds. Deoxygenated blood is darker due to the difference in shape of the red blood cell when oxygen binds to haemoglobin in the blood cell (oxygenated) versus does not bind to it (deoxygenated). Though veins might make it appear as such, human blood is never naturally blue. [3]

The blue appearance of surface veins is caused mostly by the scattering of blue light away from the outside of venous tissue if the vein is at 0.5 mm deep or more. Veins and arteries appear similar when skin is removed and are seen directly. [4] [5]

Related Research Articles

<span class="mw-page-title-main">Blood</span> Organic fluid which transports nutrients throughout the organism

Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells.

<span class="mw-page-title-main">Artery</span> Blood vessels that carry blood away from the heart

An artery is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in the pulmonary circulation that carry blood to the lungs for oxygenation, and the umbilical arteries in the fetal circulation that carry deoxygenated blood to the placenta.

<span class="mw-page-title-main">Blood vessel</span> Tubular structure of the circulatory system which transports blood

Blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away from the tissues. Blood vessels are needed to sustain life, because all of the body's tissues rely on their functionality.

<span class="mw-page-title-main">Vein</span> Blood vessels that carry blood towards the heart

Veins 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. In the systemic circulation, arteries carry oxygenated blood away from the heart, and veins return deoxygenated blood to the heart, in the deep veins.

<span class="mw-page-title-main">Circulatory system</span> Organ system for circulating blood in animals

The circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, that consists of the heart and blood vessels. The circulatory system has two divisions, a systemic circulation or circuit, and a pulmonary circulation or circuit. Some sources use the terms cardiovascular system and vascular system interchangeably with circulatory system.

<span class="mw-page-title-main">Cyanosis</span> Decreased oxygen in the blood

Cyanosis is the change of body tissue color to a bluish-purple hue, as a result of decrease in the amount of oxygen bound to the hemoglobin in the red blood cells of the capillary bed. Cyanosis is apparent usually in the body tissues covered with thin skin, including the mucous membranes, lips, nail beds, and ear lobes. Some medications may cause discoloration such as medications containing amiodarone or silver. Furthermore, mongolian spots, large birthmarks, and the consumption of food products with blue or purple dyes can also result in the bluish skin tissue discoloration and may be mistaken for cyanosis. Appropriate physical examination and history taking is a crucial part to diagnose cyanosis. Management of cyanosis involves treating the main cause, as cyanosis isn’t a disease, it is a symptom.

<span class="mw-page-title-main">Air embolism</span> Vascular blockage by air bubbles

An air embolism, also known as a gas embolism, is a blood vessel blockage caused by one or more bubbles of air or other gas in the circulatory system. Air can be introduced into the circulation during surgical procedures, lung over-expansion injury, decompression, and a few other causes. In flora, air embolisms may also occur in the xylem of vascular plants, especially when suffering from water stress.

<span class="mw-page-title-main">Pulmonary artery</span> Artery in pulmonary circulation carrying deoxygenated blood from heart to lungs

A pulmonary artery is an artery in the pulmonary circulation that carries deoxygenated blood from the right side of the heart to the lungs. The largest pulmonary artery is the main pulmonary artery or pulmonary trunk from the heart, and the smallest ones are the arterioles, which lead to the capillaries that surround the pulmonary alveoli.

<span class="mw-page-title-main">Pulmonary vein</span> Veins that transfer oxygenated blood from the lungs to the heart

The pulmonary veins are the veins that transfer oxygenated blood from the lungs to the heart. The largest pulmonary veins are the four main pulmonary veins, two from each lung that drain into the left atrium of the heart. The pulmonary veins are part of the pulmonary circulation.

The Fick principle states that blood flow to an organ can be calculated using a marker substance if the following information is known:

<span class="mw-page-title-main">Fetal circulation</span> Circulatory system of fetuses

In humans, the circulatory system is different before and after birth. The fetal circulation is composed of the placenta, umbilical blood vessels encapsulated by the umbilical cord, heart and systemic blood vessels. A major difference between the fetal circulation and postnatal circulation is that the lungs are not used during the fetal stage resulting in the presence of shunts to move oxygenated blood and nutrients from the placenta to the fetal tissue. At birth, the start of breathing and the severance of the umbilical cord prompt various changes that quickly transform fetal circulation into postnatal circulation.

Levo-Transposition of the great arteries is an acyanotic congenital heart defect in which the primary arteries are transposed, with the aorta anterior and to the left of the pulmonary artery; the morphological left and right ventricles with their corresponding atrioventricular valves are also transposed.

A right-to-left shunt is a cardiac shunt which allows blood to flow from the right heart to the left heart. This terminology is used both for the abnormal state in humans and for normal physiological shunts in reptiles.

A cardiac shunt is a pattern of blood flow in the heart that deviates from the normal circuit of the circulatory system. It may be described as right-left, left-right or bidirectional, or as systemic-to-pulmonary or pulmonary-to-systemic. The direction may be controlled by left and/or right heart pressure, a biological or artificial heart valve or both. The presence of a shunt may also affect left and/or right heart pressure either beneficially or detrimentally.

A pulmonary shunt is the passage of deoxygenated blood from the right side of the heart to the left without participation in gas exchange in the pulmonary capillaries. It is a pathological condition that results when the alveoli of parts of the lungs are perfused with blood as normal, but ventilation fails to supply the perfused region. In other words, the ventilation/perfusion ratio of those areas is zero.

The Shunt equation quantifies the extent to which venous blood bypasses oxygenation in the capillaries of the lung. “Shunt” and “dead space“ are terms used to describe conditions where either blood flow or ventilation do not interact with each other in the lung, as they should for efficient gas exchange to take place. These terms can also be used to describe areas or effects where blood flow and ventilation are not properly matched, though both may be present to varying degrees. Some references refer to “shunt-effect” or “dead space-effect” to designate the ventilation/perfusion mismatch states that are less extreme than absolute shunt or dead space.

<span class="mw-page-title-main">Arterial blood</span> Blood in an artery

Arterial blood is the oxygenated blood in the circulatory system found in the pulmonary vein, the left chambers of the heart, and in the arteries. It is bright red in color, while venous blood is dark red in color. It is the contralateral term to venous blood.

The arteriovenous oxygen difference, or a-vO2 diff, is the difference in the oxygen content of the blood between the arterial blood and the venous blood. It is an indication of how much oxygen is removed from the blood in capillaries as the blood circulates in the body. The a-vO2 diff and cardiac output are the main factors that allow variation in the body's total oxygen consumption, and are important in measuring VO2. The a-vO2 diff is usually measured in millilitres of oxygen per 100 millilitres of blood (mL/100 mL).

The Senning procedure is an atrial switch heart operation performed to treat transposition of the great arteries. It is named after its inventor, the Swedish cardiac surgeon Åke Senning (1915–2000), also known for implanting the first permanent cardiac pacemaker in 1958.

<span class="mw-page-title-main">Bronchial circulation</span> Circulation of blood supplying lungs tissues

The bronchial circulation is the part of the systemic circulation that supplies nutrients and oxygen to the cells that constitute the lungs, as well as carrying waste products away from them. It is complementary to the pulmonary circulation that brings deoxygenated blood to the lungs and carries oxygenated blood away from them in order to oxygenate the rest of the body.

References

  1. Bostock, J. (1826). An elementary system of physiology. Vol. 1. p. 263. Retrieved 2013-03-16.
  2. "Is blood really blue". scienceworld.ca/blog/blood-really-blue. 10 December 2015. Retrieved 2019-07-31.
  3. "UCSB Science Line". scienceline.ucsb.edu. Retrieved 2022-03-07.
  4. Misconceptions in Primary Science. McGraw-Hill International. 1 February 2010. pp. 33–34. ISBN   978-0-335-23588-9 . Retrieved 7 May 2013.
  5. Kienle, Alwin; Lilge, Lothar; Vitkin, I.; Patterson, Michael; Wilson, Brian; Hibst, Raimund; Steiner, Rudolf (1996). "Why Are Veins Blue?". Applied Optics. 35 (7): 1151–1160. doi:10.1364/AO.35.001151. PMID   21085227 . Retrieved 7 May 2013.