vein

Examples of vein in the following topics:

• Types of Leaf Forms

  • Each leaflet is attached to the rachis (middle vein), but may have its own stalk.
  • In a pinnately compound leaf, the middle vein is called the midrib.
  • Bipinnately compound (or double compound) leaves are twice divided; the leaflets are arranged along a secondary vein, which is one of several veins branching off the middle vein.
  • The pinnules on one secondary vein are called "pinna".
  • (d) The honey locust has double compound leaves, in which leaflets branch from the veins.

• Arteries, Veins, and Capillaries

  • The capillaries converge again into venules that connect to minor veins, which connect to major veins that take blood high in carbon dioxide back to the heart.
  • The major veins drain blood from the same organs and limbs that the major arteries supply.
  • The veins are thinner walled as the pressure and rate of flow are much lower.
  • In addition, veins are structurally different from arteries in that veins have valves to prevent the backflow of blood.
  • This diagram illustrates the major human arteries and veins of the human body.

• Leaf Structure and Arrangment

  • Within each leaf, the vascular tissue forms veins.
  • The arrangement of veins in a leaf is called the venation pattern.
  • Monocots have parallel venation in which the veins run in straight lines across the length of the leaf without converging.
  • In dicots, however, the veins of the leaf have a net-like appearance, forming a pattern known as reticulate venation.
  • Petioles, stipules, veins, and a midrib are all essential structures of a leaf.

• Blood Flow Through the Body

  • The heart pumps oxygenated and deoxygenated blood throughout the body in a complex system of arteries, veins, and capillaries.
  • Blood primarily moves in the veins by the rhythmic movement of smooth muscle in the vessel wall and by the action of the skeletal muscle as the body moves.
  • Because most veins must move blood against the pull of gravity, blood is prevented from flowing backward in the veins by one-way valves.
  • (b) Valves in the veins prevent blood from moving backward.
  • Blood leaves the heart through the pulmonary artery and aorta, while blood enters the heart through the two venae cavae and pulmonary veins.

• Structures of the Heart

  • The right atrium receives deoxygenated blood from the superior vena cava, which drains blood from the veins of the upper organs and arms.
  • The right atrium also receives blood from the inferior vena cava, which drains blood from the veins of the lower organs and legs.
  • The left atrium then receives the oxygen-rich blood from the lungs via the pulmonary veins.
  • (b) Blood vessels of the coronary system, including the coronary arteries and veins, keep the heart muscles oxygenated.
  • Blood is pumped from veins of the systemic circuit into the right atrium of the heart, then into the right ventricle.

• Kidney Structure

  • The arteries, veins, and nerves that supply the kidney enter and exit at the renal hilum.
  • Renal blood supply starts with the branching of the aorta into the renal arteries (which are each named based on the region of the kidney they pass through) and ends with the exiting of the renal veins to join the inferior vena cava.

• Open and Closed Circulatory Systems

  • The circulatory system is effectively a network of cylindrical vessels (the arteries, veins, and capillaries) that emanate from a pump (the heart).

• Deuteromycota: The Imperfect Fungi

  • The blue veins in Roquefort cheese and the white crust on Camembert are the result of fungal growth.

• Diversity of Angiosperms

  • Other anatomical features shared by monocots include veins that run parallel to the length of the leaves and flower parts that are arranged in a three- or six-fold symmetry.
  • Veins form a network in leaves, while flower parts come in four, five, or many whorls.

• Blood Pressure

  • In the capillaries and veins, the blood pressure continues to decease, but velocity increases.