Vena cava

From The School of Biomedical Sciences Wiki
Jump to: navigation, search

The vena cava is split into two structures the superior and the inferior vena cava, forming part of the cardiovascular system, being the two largest veins in the human body[1]. The veins are a key component in the pulmonary circulatory system passing deoxygenated blood into the right atrium of the heart from the rest of the body tissues, this allows the blood to then be passed via the hearts double circulatory system into the lungs to be re-oxygenated finally then is pumped through the aorta to the body tissues again allowing continual supply of oxygen to the muscles and cells to meet demand.

The superior vena cava, also known as the anterior vena cava, passes deoxygenated blood to the right atrium from the upper cheat regions; head, neck and upper limbs. Positioned beside the aorta and pulmonary artery in the heart structure[2]. It is formed from the connected brachiocephalic veins, which are positioned either side of the neck, and the azygos vein, which transports deoxygenated blood from the rib cage as it runs up the side of the thoracic vertebral column[3]. The azygos vein is connected to both the superior and the inferior vena cava, and this allows an alternate route if there is a blockage in one the veins[4], allowing continuation in the flow of the circulatory system but at a lower efficiency.

The inferior vena cava also referred to as the posterior vena cava, transports deoxygenated blood from the lower and middle regions of the body to the posterior region of the right atrium in the heart. The vein is positioned alongside the spine and travels in parallel to the descending aortic vessel[5]. It is formed from the connection of the two common iliac veins; the internal iliac vein connects the blood supply from the visceral organs, and the external iliac vein transports the deoxygenated blood from the femoral veins in the legs[6].

Structure

The vena cava have walls comprised of three tissue layers which are characteristic to both arteries and veins; tunica initima, tunica media and tunica externa. The tunica initima is the thinnest and innermost layer, forming the endothelium lining – endothelial cells – which secretes molecules that lead to the promotion of smooth blood flow. Tunica media is the smooth muscle layer also composed of elastic fibres, but at a lower concentration than in the arteries, and connective tissues, all structured in a circular manner around the vessel[7]., this layer forms a connection between the blood vessel and the nervous system[8]. The outer layer tunica externa is formed primarily of collagen[9]. and connective fibres with an elastic lamina on the outside of the vessel, which is thicker in veins in comparison to arteries, this plays a key function in attaching the vein to the surrounding tissues; anchoring the vein in place is vital to ensure protection, especially to the superficial veins, and to prevent the structures collapsing[10].

References

  1. ThoughtCo. Regina Bailey. Superior and Inferior Venae Cavae. 2018 [Cited 06/12/18] Available from: https://www.thoughtco.com/venae-cavae-anatomy-373253
  2. ThoughtCo. Regina Bailey. Superior and Inferior Venae Cavae. 2018 [Cited 06/12/18] Available from: https://www.thoughtco.com/venae-cavae-anatomy-373253
  3. healthline. Brachiocephalic vein. 2015 [Cited 06/12/18] Available from: https://www.healthline.com/human-body-maps/brachiocephalic-vein#1
  4. healthline. Brachiocephalic vein. 2015 [Cited 06/12/18] Available from: https://www.healthline.com/human-body-maps/brachiocephalic-vein#1
  5. ThoughtCo. Regina Bailey. Superior and Inferior Venae Cavae. 2018 [Cited 06/12/18] Available from: https://www.thoughtco.com/venae-cavae-anatomy-373253
  6. healthlineRED. Common iliac vein. 2015 [Cited 06/12/18] Available from: https://www.healthline.com/human-body-maps/common-iliac-vein#1
  7. lumencandela. Cardiovascular System: Blood Vessels. Blood Vessel Structure and Function. [Cited 06/12/18] Available from: https://courses.lumenlearning.com/boundless-ap/chapter/blood-vessel-structure-and-function/
  8. ThoughtCo. Regina Bailey. Superior and Inferior Venae Cavae. 2018 [Cited 06/12/18] Available from: https://www.thoughtco.com/venae-cavae-anatomy-373253
  9. ThoughtCo. Regina Bailey. Superior and Inferior Venae Cavae. 2018 [Cited 06/12/18] Available from: https://www.thoughtco.com/venae-cavae-anatomy-373253
  10. lumencandela. Cardiovascular System: Blood Vessels. Blood Vessel Structure and Function. [Cited 06/12/18] Available from: https://courses.lumenlearning.com/boundless-ap/chapter/blood-vessel-structure-and-function/
Personal tools
Namespaces
Variants
Actions
Navigation
Toolbox