blood islands

(noun)

Structures in the developing embryo that lead to many different parts of the circulatory system.

Related Terms

Examples of blood islands in the following topics:

  • Development of Blood

    • Commonly known as white blood cells, they are derived from common lymphoid progenitors.
    • In developing embryos, blood formation occurs in aggregates of blood cells in the yolk sac, called blood islands.
    • For the stem cells and other undifferentiated blood cells in the bone marrow, blood cells are determined to specific cell types at random.
    • Blood islands form in the yolk sac of an embryo by cellular differentiation of hemangioblasts into endothelial cells.
    • Next, the capillary plexus forms as endothelial cells migrate outward from blood islands and form a random network of continuous strands.

  • WBC Formation

    • Haematopoiesis refers to the formation of blood cells components.
    • Haematopoiesis refers to the formation of blood cellular components, including both white and red blood cells.
    • All cellular blood components are derived from haematopoietic stem cells located within the bone marrow.
    • In developing embryos, blood formation occurs in aggregates of blood cells in the yolk sac called blood islands.
    • However, most of blood supply comes from the mother through the placenta.

  • Development of Blood and Blood Vessels

    • As part of the circulatory system, blood vessels play a critical role in transporting blood throughout the body.
    • Formation of new blood vessels occurs by two different processes: vasculogenesis and angiogenesis.
    • The latter occurs when new vessels are built from preexisting blood vessels.
    • In the yolk sac's blood islands, HPCs and EC lineages emerge from the extraembryonic mesoderm in near unison.
    • In 1917, Florence Sabin first observed that the development of blood vessels and red blood cells in the yolk sac of chick embryos occur in close proximity and time.

  • Overview of Pancreatic Islets

    • The pancreatic islets are small islands of cells that produce hormones that regulate blood glucose levels.
    • Hormones produced in the pancreatic islets are secreted directly into the blood flow by five different types of cells.
    • Glucagon is a hormone that raises blood glucose levels by stimulating the liver to convert its glycogen into glucose.
    • Insulin lowers blood glucose levels by stimulating cells to take up glucose out of the blood stream.
    • Amylin slows gastric emptying, preventing spikes in blood glucose levels.

  • Types of Cells in the Pancreas

    • The pancreatic islets are small islands of cells that produce hormones that regulate blood glucose levels.
    • Hormones produced in the pancreatic islets are secreted directly into the blood flow by five different types of cells.
    • Glucagon is a hormone that raises blood glucose levels by stimulating the liver to convert its glycogen into glucose.
    • Insulin lowers blood glucose levels by stimulating cells to take up glucose out of the blood stream.
    • Amylin slows gastric emptying, preventing spikes in blood glucose levels.

  • Transfusions of Whole Blood

    • Whole blood refers to human blood transfusion from a standard blood donation.
    • Whole blood may also be altered and processed for use in blood transfusion.
    • Historically, blood was transfused as whole blood without further processing.
    • Whole blood transfusion has similar risks to those of transfusion of red blood cells.
    • Whole blood is a term used in transfusion medicine for human blood from a standard blood donation.

  • Introduction to Blood Pressure

    • Blood pressure is a vital sign reflecting the pressure exerted on blood vessels when blood is forced out of the heart during contraction.
    • Blood pressure is the pressure that blood exerts on the wall of the blood vessels.
    • This pressure originates in the contraction of the heart, which forces blood out of the heart and into the blood vessels.
    • Differences in mean blood pressure are responsible for blood flow from one location to another in circulation.
    • The rate of mean blood flow depends on the resistance to flow presented by the blood vessels.

  • Physical Characteristics and Volume

    • Blood contains plasma and blood cells, some of which have hemoglobin that makes blood red.
    • The average blood volume in adult is five liters.
    • Blood contains red blood cells (RBCs), white blood cells (WBCs), platelets, and other cell fragments, molecules, and debris.
    • In order to maintain homeostasis, blood volume and blood pressure must be high enough that blood can reach all of the body's tissues, a process called tissue perfusion.
    • Two tubes of EDTA-anticoagulated blood.

  • Diagnostic Blood Tests

    • Blood tests are laboratory analyses performed on a blood sample typically taken from a vein in the arm for diagnostic purposes.
    • Although the term blood test is used, most routine tests (except for most hematology) are done on blood plasma instead of blood cells.
    • If only a few drops of blood are needed, a fingerstick is performed instead of drawing blood from a vein.
    • Also, respiratory therapists are trained to extract arterial blood for arterial blood gases.
    • Blood tests can also be used to analyze the blood cells.

  • Blood Flow in the Brain

    • Cerebral circulation is the movement of blood through the network of blood vessels supplying the brain, providing oxygen and nutrients.
    • Cerebral circulation refers to the movement of blood through the network of blood vessels supplying the brain.
    • The arteries deliver oxygenated blood, glucose, and other nutrients to the brain and the veins carry deoxygenated blood back to the heart, removing carbon dioxide, lactic acid, and other metabolic products.
    • The amount of blood that the cerebral circulation carries is known as cerebral blood flow (CBF).
    • Too little blood flow (ischemia) results in tissue death.