Chapter 10 - Blood and Circulation Flashcards
Why is blood important to all systems?
transports oxygen & nutrients required for cell metabolism, removal of wastes, immune system/maintain homeostasis
What are the two separate circulations
Pulmonary circulation (allows for exchange of oxygen & CO2 in the lungs), systemic circulation (exchange of nutrients and wastes between blood and cells of the body)
Arteries
transport blood away from the heart into the lungs or to body tissues
Arterioles
Control the amount of blood flowing into the capillaries through vasoconstriction or dilation
Capillaries
very small vessels organized in numerous networks that form the microcirculation. Blood flows very slowly through capillaries.
What determines the amount of blood flowing from the arterioles into the individual capillaries?
Precapillary sphincters do, depending on the metabolic needs of the tissues
Flow of blood in veins
capillary beds –> venules –> larger veins (capacitance vessels)
What does blood flow in the veins depend on?
skeletal muscle action, respiratory movements, and gravity. Valves in larger veins in arms and legs are important. Respiratory movements assist the movement of blood through the trunk.
Tunica intima
endothelial layer, is the inner layer of blood vessels. simple squamous epithelium
Tunica Media
layer of smooth muscle that controls the diameter and lumen size (diameter) of the blood vessel, is the middle layer.
Tunica Adventitia (externa)
outer connective tissue layer. Connective tissue with fibrocytes, collagen (type I), and elastic fibers
Autoregulation
Controls localized vasodilation or vasoconstriction in arterioles.
A reflex adjustment in a small area of a tissue or an organ, which varies depending on the needs of the cells in the area.
What system controls vasomotor tone at all time?
SNS, even at rest to ensure continued circulation of blood
What is the pH of blood?
7.35-7.45
How much blood does the adult body contain?
5L
Hematocrit
proportion of cells (essentially erythrocytes) in blood and indicates the viscosity of the blood. Percent by volume of cellular elements in blood.
Plasma
Clear yellowish fluid remaining after the cells have been removed
Serum
Refers to the fluid and solutes remaining after the cells and fibrinogen have been removed
Where do all red blood cells originate from?
The red bone marrow
How do the various blood cells develop?
from a single stem cell (pluripotential hematopoietic stem cell) during the process of hemopoiesis or hematopoiesis.
Dyscrasia
A pathological condition of the blood that usually refers to disorders involving the cellular components of blood
What is Erythropoietin?
A hormone that originates in the kidney & stimulates erythrocyte production in the red bone marrow in response to tissue hypoxia, or insufficient oxygen available to cells.
What is hemoglobin?
globin portion, two pairs of amino acid chains, and four heme groups, each containing a ferrous iron atom, to which the oxygen molecule can attach.
How is CO2 transported in the blood?
transported as bicarbonate ion in the buffer pair.
Hemochromatosis
“iron overload”; results in large amounts of hemosiderin accumulating in the liver, heart, and other organs, causing serious organ damage.
What removes old/damaged blood cells?
Liver and spleen
Hemolysis of erythrocyte
Hemoglobin –> Heme & Globin
Globin - amino acids are recycled.
HEME –> Iron & Bilirubin
Iron recycled to bone marrow or stored.
Bilirubin is unconjugates, transported with serum albumin in the blood to the liver where is conjugates with glucuronic acid –> then secreted as bile
Leukopoiesis
Production of WBC
How does Leukopoiesis work?
Stimulated by colony-stimulating factors produced by cells such as macrophages and T lymphocytes.
5 types of lymphocytes
Lymphocytes Neutrophils Basophils Eosinophils Monocytes
Lymphocytes
Make up 30-40% of the WBCs. B and T lymphocytes are significant in the immune response. Cell mediated humoral immunity
Neutrophils
Most common leukocyte; 50-60% of WBCs; survive only 4 days; first response to any tissue damage and commence phagocytosis.
Immature neutrophil called “band” or “stab”
Increase in numbers by bacterial infection
Basophils
Migrate from blood and enter tissue to become mast cells that can release histamine and heparin. Inflammatory response
Eosinophils
Combat the effects of histamine
Increased by allergic reactions and parasitic infections. Allergic response.
Monocytes
Can enter the tissue to become macrophages, which act as phagocytes when tissue damage occurs. largest cells in the circulation. Phagocytosis.
Thrombocytes
“platelets”, essential part of the blood clotting process or hemostasis.
Not cells; small, irregularly shaped, non-nucleated fragments from large megakaryocytes.
Process of Blood Clotting/Hemostasis
Vasoconstriction/vascular spam of blood vessels. In small blood vessels, this decreases blood flow and may allow a platelet plug to form.
Thrombocytes tend to adhere to the underlying tissue at the site of injury and, if the blood vessel is small, can form a platelet plug in the vessel. Platelet clot.
In larger vessels, blood clotting or coagulation mechanism is required through a sequence of reactions.
Clot formation/coagulation sequence
Damaged tissues and platelets release factors that stimulate a series of reactions involving numerous clotting factors ultimately producing prothrombin activator (PTA) –> prothrombin (factor II) converted into thrombin & fibrinogen (factor I) is converted into fibrin threads –> fibrin mesh forms to trap cells, making a thrombus to stop flow of blood. Clot gradually sinks or retracts pulling the edges of damaged tissue closer together and sealing the site
Which minerals are important for synthesis of clotting factors/in the process?
Vitamin K and calcium
How is inappropriate thrombus formation prevented?
Coagulation inhibitors such as anti-thrombin III circulate in the blood. Heparin & Natural Fibrinolytic process