VAN 121: Veterinary Gross Anatomy-II (2+2)

ARTERIES

• The tubes which convey blood from the heart to various organs are called arteries. These are pulmonary and systemic arteries.
  • Pulmonary artery leaves the heart by a single trunk, subdivides and reaches the lungs. This is called as pulmonary circulation.
  • The systemic arteries originate from the aorta, which arise from the left ventricle and conveys pure blood to all parts of the body.
  • The branches which result from the division of an artery at the termination of its course are named as terminal branches.
  • The branches arising from an artery at varying intervals along its course are called collateral branches.
  • The arteries are surrounded by a layer of connective tissue and may become related to the structures like veins, nerves, muscles, bones and skin.
  • In bone marrow, heart, liver and small blood vessels differ from the capillaries as they are wider with irregular lumen and have no connective tissue covering.
  •  Their endothelial cells are in direct contact with cells of the organs and their walls are often incomplete. These vessels are called as sinusoids.

Anastomoses

• Branches of adjacent arteries communicate with each other and form anastomoses.
• When two vessels converge and unite with each other at their termination it is termed as anastomoses by convergence.
• When two branches are directed towards each other and unite to form a single curved tube it is called as anastomoses by arches.
• When the transverse branches connect the two adjacent parallel arteries it is termed as anastomoses by transverse communication.

Histology

• The structure of the artery composed of three coats as tunica intima, tunica media and tunica adventitia.
• The tunica intima is an endothelial lining with delicate layer of connective tissue and internal elastic lamina.
• The tunica media consist of smooth muscle cells with varying amount of collagenous and elastic tissue.
• The tunica adventitia consists of external elastic lamina and connective tissue.