Chapter 19: The Cardiovascular System: The Blood Flashcards
Define blood and its 3 general functions
Blood is a liquid connective tissue that consists of cells surrounded by a a liquid EXC matrix called blood plasma
- Transportation - O2, CO2, nutrients, waste products
- Regulation - homeostasis, pH through buffers, body temp, water content
- Protection - clotting for blood loss, fight disease
Define interstitial fluid
Bathes body cells and is constantly renewed by the blood
Describe the physical characteristics of blood
- Denser and more viscous (thicker) which a sticky feel
- 38 deg C (1 deg higher than oral/rectal body temp)
- Has an alkaline pH ranging from 7.35 to 7.45
- Bright red when saturated with oxygen, dark red when unsaturated
- Volume is 5 to 6 L in an adult male and 4 to 5 L in a female
Blood plasma and formed elements are the _______
two components of whole blood
Since WBC’s and platelets are denser than RBCs but less dense than plasma they form a:
a) single coat
b) inner coat
c) buffy coat
c) buffy coat
What is the composition of blood plasma?
91.5% water, 7% proteins, and 1.5% other solutes
Define plasma proteins and list them (3)
Proteins that are confined only to blood plasma - mostly produced by the liver
- Albumins: smallest and most numerous protein that maintains osmotic pressure
- Globulins: large proteins that produce immunoglobulins (antibodies) that help attack viruses and bacteria
- Fibrinogen: large proteins that platys essential role in blood clotting
Describe the 3 principal formed elements in the blood:
- RBC’s
- WBC’s
- Platelets
RBCs (erythrocytes) transport oxygen from the lungs to body cells and delivery carbon dioxide from body cells to the lungs
WBCs (leukocytes) protect the body from invading pathogens and other foreign substances
Platelets do not have a nucleus and release chemicals that promote blood clotting when blood vessels are damaged - similar to thrombocytes (has a nucleus)
Define hematocrit
% of total blood volume occupied by RBCs
Normal range for adult females in 38-46% and for adults 40-54% - higher due to testosterone levels
What is the significant of lower-than-normal or higher-than-normal hematocrit?
Anemia - lower-than-normal hematocrit which can cause excessive blood loss
Polycythemia - higher-than-normal hematocrit (65% or higher) causes increased viscosity and can contribute to high BP and increased risk of stroke
Describe how homeopoiesis changes throughout the lifespan
The process by which the formed elements of blood is developed
Prior to birth it occurs in the yolk sac and later in the liver, spleen, thymus, and lymph bodes of a fetus
Last 3m prior to birth red bone marrow becomes and continues to be the primary site of homeopoiesis
Define red bone marrow
Highly vascularized connective tissue located in the microscopic spaces between trabecular of spongy bone tissue
Mainly located in the axis skeletal, pectoral and pelvic girdles, and proximal epiphyses of the humerus and femur
Define pluripotent stem cells
aka hemoblasts which are derived from mesenchyme that have the capacity to develop into many different types of cells
These stem cells develop into either myeloid stem cells or lymphoid stem cells
Define progenitor cells
Developed by myeloid stem cells and no longer capable of reproducing themselves and are committed to giving rise to more specific elements of the body
Colony-forming unit—erythrocyte -> RBCs
Colony-forming unit—megakaryocyte -> platelets
Colony-forming unit—granulocyte macrophage -> eosinophil, basophil, neutrophil
Define precursor cells
Precurosr cells or ‘blasts’ develop from progenitor cells or lymphoid stem cells and over several cell divisions the develop into the actual formed elements of the blood
What are hemopoietic growth factors? Describe:
Erythropoietin (EPO)
Thrombopoietin (TPO)
Cytokines
They regulate the differentiation and proliferation of particular progenitor cells
EPO increases the number of RBC precursors and is primarily produced by cells located between the kidney tubules - low EPO decreases ability of transportation of oxygen and nutrients
TPO is produced in the liver and stimulates the formation of platelets from megakaryocytes
Cytokines are small glycoproteins that act as local hormones stimulating proliferation of progenitor cells in red bone marrow to regulate activities of cells in immune responses
What are the two important families of cytokines that stimulate WBC formation?
Colony-stimulating factors (CSFs) and interleukins
Which oxygen-carrying proteins in RBCs give whole blood its red colour?
Hemoglobin
Describe the anatomy of RBCs
They are biconcave discs that have a strong and flexible plasma membrane that allows them to deform without rupturing as they squeeze through narrow blood capillaries
They lack a nucleus and other organelles can neither reproduce or carry on extensive metabolic activities
Their cytosol contains hemoglobin molecules that are synthesized before the loss of nucleus during RBC production
RBCs generate ATP:
A) aerobically
B) anaerobically
B) anaerobically
Which is why they do both use up any of the oxygen they transport
Describe the components and physiology of a hemoglobin molecule
Each RBC contains about 280 million hemoglobin molecules
It consists of a protein called globin that has 4 polypeptide chains that has a ringlike nonprotein called heme bound to each of the 4 chains
At the center of each heme is an iron ion that can combine reversibly with one oxygen molecule, allowing each hemoglobin molecule to attach to 4 oxygen molecule and then reverses as oxygen is delivered to tissues
Hemoglobin picks up carbon dioxide which is relaased into lungs for exhalation
Hemoglobin regulates nitric oxide (NO) as it binds to hemoglobin and when released causes vasodilation to improve blood flow
Describe how RBCs are recycled (9 steps)
- RBCs only last ~120 days as wear and tear cause them to burst and are removed from circulation by fixed phagocytic macrogphases in spleen, liver, or red bone marrow
- Globulin and heme protons are split apart
- Globulin is broken down into amino acids, which can be reused to synthesize other proteins
- Iron is removed from the heme as Fe3+, which associates with the plasma protein transferrin, a transporter for Fe3+ in the bloodstream
- In muscle fiers, liver cells, and macrophages of liver and spleen, Fe3+ detaches from transferrin and attaches to an iron-storage protein called ferritin
- On release from a storage site or absorption from the GI tract, Fe3+ reattaches to transferrin and is carries to red bone marrow, where RBC precursor cells take it up through endocytosis for hemoglobin synthesis, needed for the heme portion
- Erythropoiesis in red bone marrow results in the production of RBCs, which enter into circulation
- When iron is removed from heme, the non-iron portion of heme is covered to biliverdin (green pigment) and bilirubin (yellow pigment)
- Bilirubin enters blood and is transported to the liver where it is released into bile, passed through the small intestine into the large intestinewehre is it covered into urobilogen and excreted in urine or in faces in the form of stercobilin
What is erythropoiesis?
Erythropoiesis is the production of RBCs which starts in red bone marrow with a precursor cell called a proerythroblast that divides several times, producing cells that begin to synthesize hemoglobin
A cell near the end of the development sequence ejects its nucleus and becomes a reticulocyte where the center of the cell begins to develop its biconcave shape
They pass from red bone marrow into the bloodstream by squeezing between the endothelial cells of blood capillaries and develop into mature RBCs within 1 to 2 days after their release from red bone marrow
Define hypoxia
Cellular oxygen deficiency that occurs in their is too little oxygen entering the blood such as during anemia, associated with low hematocrit
Whatever the cause, hypoxia stimulates the kidneys to step up the release of erythropoietin, which speeds the development of proerythoblasts into reticulocytes in the red bone marrow
What factors speed up and slow down erythropoiesis?
There is a negative feedback regulation of erythropoisesis
Lower oxygen content of air at high altitudes, anemia, and circulatory problems may reduce oxygen delivery to the body which is detected bye kidney cells
This increases erythropoietin secretion into blood received by the control corer causing the release of reticulocytes into the blood which increases oxygen delivery
Kidneys detect this increase oxygen and reduce the erythropoietin secretion
How do white blood cells differ from RBCs?
Unlike RBCs, WBC’s have a nuclei and a full complement of other organelles but lack hemoglobin
They are considered granular or granular depending on whether they contain conspicuous chemical-filled cytoplasmic granules
What are the 3 types of granular leukocytes?
Neutrophil - smallest granules, evenly distributed, they have an acidic (red) or basic (blue) stain, 2-5 lobe nucleus
Eosinophil - large, uniformed-sized granules that have a red-orange acidic stain, 2 lobe nucleus
Basophil - round, variable-sized granules have blue-purple basic stain, 2 lob nucleus
What are the 2 types of agranular leukocytes?
Lymphocyte - nucleus stain dark and is round or slightly indented while the cytoplasm stains sky blue, they vary in sizes and the large the more cytoplasm, increased size indicated viral infections/autoimmune deficiency
Monocyte - kidney shaped nucleus and cytoplasm is blue-grey and has a foamy appearance, they wanted into blood/tissue and become macrophages
What is the difference between fixed and wandering macrophages?
Fixed - they reside in a particular tissue
Wandering - they roam the tissues and gather at sites of infection/inflammation
Describe major histocompatibility (MHC) antigens
WBCs and other nucleated cells have MHC proteins protruding from their membranes
They cell identity markers are unique to each person (except MZ twins)
Leukocytosis vs. leukopenia
Leukocytosis - A normal and adaptive increase in WBCs above 10,000ul in the presence of stressors
Leukopenia - abnormally low level of WBCs (below 5,000ul) which may be caused by radiation or chemotherapeutic agents
Describe emigration
It is the way WBCs leave the blood stream - they roll along the endothelium stick to it, and then squeeze between endothelial cells
Once granular leukocytes leave the bloodstream they never return but lymphocytes continually recirculate
What is chemotaxis?
Chemicals that area released by microbes and inflamed tissues that attract phagocytes that ingest bacteria and dispose of dead matter
How do neutrophils carry out phagocytosis?
They engulf a pathogen and unleash several chemicals to destroy the pathogen
Chemicals include lysozyme, strong oxidants, and defensins (proteins)
What is the significance of high and low blood cell counts of the following WBC’s?
Neutrophils Lymphocytes Monocytes Eosonphils Basophils
Neutrophils: high = bacterial infections/stress; low = radiation exposure/drug toxicity
Lymphocytes: high = viral infeactions/leukemia; low = prolonged illness/HIV
Monocytes: high = viral/fungal infections/TB; low = bone marrow suppression
Eosonphils: = allergic reaction/parasitic infection; low = drug toxicity/stress
Basophils: allergic reaction/leukemia; low = pregnancy/ovulation/stress
What is the origin and function of platelets?
Under the influence of thrombopoietin, myeloid cells develop into megakarocyte colony-forming cells that develop into precursor cells called megakaryoblasts, that transform into meagakaryoctes what have has many fragments, each enclosed by a plasma membrane called a platelet
They form a platelet plug in hemostasis; release chemicals that promote vascular spasm and blood clotting and live 5-9 days
What is the clinical significant of a complete blood count (CBC)?
CBC is a test that screens for anemia and various infections
It includes counts of RBCs, WBCs, platelets, heatocrit, differential WBC count
Describe the 3 mechanisms that contribute to hemostasis
- Vascular spasm - the smooth muscles in the walls of damaged arteries/arterioles contract to reduce blood loss for several minutes/hours
- Platelet plug formation - platelet adhesion (platelets stick to damaged blood vessel); platelet release reaction (adhesion activates platelets and they extend projections allowing them to interaction with each other and they liberate ADP, 5-HT, thromboxane A2); platelet aggregation (ADP makes other platelets sticky and they adhere to the originally activated platelets), this aggregation forms a plug
- Blood clotting - the process of gel formation of the blood is called clotting or coagulation
What is serum?
When gel separates form the liquid, the liquid is serum - blood plasma minus clotting proteins
Define hemorrhage
The loss of a large amount of blood from the vessels
Hemostsisi is a sequence of responses that stops bleeding to prevent hemorrhage
Define thrombosis
Clotting of an undamaged blood vessel
What are coagulation factors?
Calcium ions, several inactive enzymes synthesized by hepatocytes and released into bloodstream, as well as various molecules associated with platelets or released by damaged tissues
They are identified by roman numerals
What are the 3 stages of clotting?
- The extrinsic and intrinsic pathways lead to the formation of prothrombinase
- Prothrombinase converts prothrombin (plasma protein from liver) into the enzyme thrombin
- Thrombin converts soluble fibrinogen into insoluble fibrin which forms the thread of the clot
What is the difference between the extrinsic and intrinsic pathway of blood clotting?
Extrinsic - occurs rapidly in response to tissue trauma, tissue factor (TF) or thromboplastin leaks into the blood from cells outside the blood vessels and in the presence of Ca2+ it activated clotting factor X which initiates the formation of prothrombinase
Intrinsic - occurs more slowly in response to blood trauma, where endothelial cells come in contact with collagen fibres which activates collating factor XII which imitates a sequence that eventually activates clotting factor X to form prothrombinase. Additionally activated platelets release phospholipids and Ca2+ that activate factor X.
What is the common pathway in blood clotting?
The formation of prothombinase marks the beginning of the common pathway
prothombinase and Ca2+ catalyze the conversion of prothrombin to thrombin, which in the presence of Ca2+ converts fibrinogen which is soluble to loos fibrin which is non-soluble
Thrombin also activates factor XIII which strengthens and stabilizes the fibrin threads into a sturdy clot
Thrombin has 2 positive feedback loops: thrombin accelerates formation of prothrombinase which accelerates the production of more thrombin; thrombin activates platelets, which reinforces their aggregation and the release of phospholipids
What is clot retraction?
Consolidation or tightening of the fibrin clot, slowly pulling the edges of the damaged vessel closer together
What role does vitamin K play in clotting?
Although not involved in actual clot formation, it is required for the synthesis of 4 clotting factors
Thus vit. K deficiency is associated with uncontrolled bleeding
What is the fibrinolytic system?
It dissolves small, inappropriate clots and dissolves clots at site of damage once it is repaired
Dissolution of a clot is called fibrinolysis
Define plasminogen
It is an inactive plasma enzyme that is incorporated into the clot that can be activated into plasmin by thrombin, activated factor XII, and tissue plasminogen activator
Once activated, it can dissolve the clot by digesting fibrin threads and inactivating substances
List and describe anticoagulants
An anticoagulant can delay/supress/prevent blood clotting
Antithrombin - blocks the action of XII, X, and II
Heparin - produced by mast cells and basophils that combines with antithrombin and increases its effectiveness in blocking thrombin
Activated protein C (APC) - inactivates the 2 major clotting factors not blocked by antithrombin
