Chapter 19: Cardiovascular System and Blood Flashcards
Which 3 interrelated components make up the cardiovascular system?
Blood, heart, blood vessels.
Blood.
Liquid connective tissue. Cells surrounded by a liquid extracellular matrix (plasma) which suspends cells and cell fragments.
Interstitial fluid.
Fluid that bathes body cells and is constantly renewed by blood.
What are the 3 functions of blood?
Transportation, regulation and protection.
What is the blood’s role in transportation?
Transports O2 from lungs to body cells. Transports CO2 from body cells to lungs. Transports nutrients from GI to body cells. Transports hormones from endocrine glands to body cells. Transports heat and waste to organs for elimination.
What is the blood’s role in regulation?
Maintains homeostasis, regulates pH levels using buffers, adjusts body temperature using water in plasma, regulates osmotic pressure, regulates water content of cells.
What is the blood’s role in protection?
Clotting decreases blood loss after an injury, WBCs protect against disease-carrying pathogens, and blood proteins protect against disease.
What is the average blood volume of an adult male and an adult female?
Male: 5-6 L. Female: 4-5 L.
What are the components of blood?
55% blood plasma. 45% formed elements.
Describe centrifuged blood.
Bottom: cells. Middle: buffy coat (WBCs, platelets). Top: plasma.
Blood plasma components.
Watery liquid ECM containing dissolved substances. 91.5% water. 8.5% solutes (electrolytes, enzymes, hormones, gases, waste).
Formed elements components.
Cells and cell fragments. 99% RBCs. 1% WBCs and platelets.
Hepatocytes synthesize which cells to make plasma proteins?
Albumins: 54%. Globulins: 38%. Fibrinogen: 7%.
Gamma globulins.
Antibodies. Plasma proteins.
Hematocrit.
The percentage of total blood volume occupied by RBCs.
What is the normal range of hematocrit for adult males and for adult females?
Males: 40-54%. Females: 38-46%.
Which hormone stimulates the production of RBCs, and stimulates its synthesis:
Erythropoietin. Stimulated by testosterone.
A significant drop in hematocrit indicates:
Anemia.
Polycythemia.
Indicates an abnormally high RBC count, with a hematocrit of 65%+. Increased viscosity, resistance to flow, BP, risk of stroke. Causes: RBC production increase, tissue hypoxia, dehydration, blood doping, athletic EPO use.
Platelets.
Fragments of cells without a nucleus. Release chemicals to promote blood clotting when vessels are damaged.
Thrombocytes.
Functionally equivalent to platelets. Nucleated cells found in lower vertebrae.
What is responsible for regulating the number of RBCs and platelets in circulation.
Negative feedback.
Which component of formed elements varies in abundance?
WBCs. Due to invading pathogens and foreign antigens.
Hemopoiesis.
Process by which formed elements develop. Before birth, it occurs in the yolk sac of an embryo and later in the liver, spleen, thymus and lymph nodes of fetus. Red bone marrow then becomes the primary site in the last 3 months before birth and throughout life.
Red bone marrow.
Highly vascularized connective tissue. Located between trabeculae of spongy bone tissue. Present in bones of axial skeleton, pectoral girdle, pelvic girdle, and proximal epiphyses of humerus and femur.
Describe red and yellow bone marrow throughout a lifetime.
In newborns, all bone marrow is red and active in blood cell production. As an individual ages, the rate of blood cell production decreases. Red bone marrow in medullary cavity of long bones becomes inactive and is replaced by yellow bone marrow.
What can happen to yellow bone marrow during severe bleeding?
It can revert back to red bone marrow. Blood-forming stem cells from red bone marrow move into yellow bone marrow, which is then repopulated by pluripotent stem cells.
Pluripotent stem cells.
Hemocytoblasts. >1% of red bone marrow cells. Derived from mesenchyme.
Reticular cells.
Produce reticular fibres, which form the stroma that supports red bone marrow cells.
Formed elements do not divide once they leave red bone marrow, except for which cell?
Lymphocytes.
Pluripotent stem cells in red bone marrow produce 2 types of stem cells:
Myeloid stem cells: give rise to RBCs, platelets, monocytes, neutrophils, eosinophils, basophils, mast cells. Lymphoid stem cells: give rise to lymphocytes and NK cells.
Where do the myeloid stem cells and lymphoid stem cells begin their development?
Myeloid: red bone marrow. Lymphoid: red bone marrow –> lymphatic tissues.
What is the histological appearance of stem cells and progenitor cells?
They cannot be distinguished histologically, and they both resemble lymphocytes.
Progenitor cells.
Derived by some myeloid stem cells. They are no longer capable of reproducing themselves, and are committed to giving rise to more specific elements of blood.
Colony-forming units (CFUs).
Some progenitor cells are known as CFUs. CFU-E: produces RBCs. CFU-Meg: produces megakaryocytes. CFU-GM: produces granulocytes and monocytes.
After progenitor cell, the next generation of cells are called:
Precursor cells (blasts). Have recognizable microscopic appearances.
Erythropoietin (EPO).
Increases the number of RBC precursor cells. Produced by kidney cells. Renal failure –> decreased EPO release –> decreased RBC production –> decreased hematocrit –> decreased ability to deliver oxygen throughout body.
Thrombopoietin (TPO).
Stimulates the formation of platelets from megakaryocytes. Produced by liver cells.
What regulates the development of different blood types?
Cytokines.
Cytokines.
Small glycoproteins that act as local hormones. Stimulate proliferation of progenitor cells in red bone marrow and regulate the activities of cells involved in nonspecific defences and immune responses.
Hemoglobin.
Pigment that gives blood its red colour. Oxygen-carrying protein. Each RBC contains 280 million hemoglobin molecules. Transports 23% of all CO2. Regulates blood flow and BP.
How many RBCs are in an average adult male and an adult female?
Male: 5.4 million per microlitre of blood. Female: 4.8 million per microlitre of blood.
To maintain normal numbers of RBCs, new mature cells must enter the circulation at what rate?
2 million per second.
Describe a RBC.
Plasma membrane is strong and flexible, allowing it to deform without rupturing when moving through vessels. No nucleus. No organelles. Cannot reproduce or carry on extensive metabolic activities. Cytosol contains hemoglobin molecules. All internal space is available for oxygen transport. They do not use any of the oxygen they transport. Their shape maximizes surface area for diffusion of gas molecules.
Describe a hemoglobin molecule.
Consists of a global protein composed of 4 polypeptide chains, with a ringlike heme pigment bound to each of the 4 chains. At the centre of each heme ring is an Fe that can combine reversibly with an O2, allowing each hemoglobin molecule to bind 4 O2 molecules. Each O2 molecule picked up from the lungs is bound to an Fe –> as blood flows through tissue capillaries the Fe-O2 reaction reverses –> hemoglobin releases O2 –> O2 diffuses into interstitial fluid and into cells.
How is some CO2 transported back to the lungs for exhalation by hemoglobin?
Blood flowing through tissue capillaries picks up CO2 –> some combines with amino acids in globin part of hemoglobin –> CO2 is released from hemoglobin in the lungs.
How does hemoglobin regulate blood flow and BP?
Endothelial cells of blood vessels produce NO –> binds to hemoglobin –> releases NO under certain conditions –> causes vasodilation –> improves blood flow and enhances oxygen delivery.