Cardiovascular System

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McMaster University
Danny M.Pincivero

Chapter 19 – Blood What are the functions of blood? 1. Transport of gases, nutrients, and waste products 2. Transport of processed molecules 3. Transport of regulatory molecules 4. Regulation of pH and osmosis 5. Maintenance of body temperature 6. Protection against foreign substances 7. Clot formation -------------------------------------------------------------------------------------------------------------------- - What is blood composed of? 1. Plasma (55%) - Proteins (7%) - Water (91%) - Other solutes 2. Buffy Coat - Platelets - WBC’s 3. Formed Elements (45%) - RBC’s -------------------------------------------------------------------------------------------------------------------- - What is plasma and what is it composed of? - Plasma is the liquid part of blood - Colloid: contains suspended substances o Water (91%) o Proteins, ions, nutrients, waste products, gases, regulatory substances (9%)  Proteins • Albumins: most abundant (58%) o Osmotic pressure, transports FAs • Globulins (38%) o Transports lipids, carbohydrates, hormones, ions, and antibodies • Fibrinogen (4%) o Blood clotting What are the formed elements composed of?  Red Blood Cells (erythrocytes) o Bioconcave discs, no nucleus, or mitochondria o Contain hemoglobin (protein) transports O and CO 2 2 o Converts CO 2nd H O2to H C2 3  White Blood Cells (leukocytes) o Granulocytes: large granules; have multi-lobed nuclei  Neutrophils, eosinophils, basophils o Agranulocytes: small granules and nuclei that are not lobed  Lymphocytes and monocytes  Platelets (thrombocytes) o Cell fragment o Form platelet plugs, release chemicals necessary for blood clotting -------------------------------------------------------------------------------------------------------------------- - How are the components of blood formed? • Hematopoiesis: process of blood cell production - Post-birth: red bone marrow, lymphatic system • Stem Cells: all formed elements derived from single population hemocytoblast o Proerythroblasts  red blood cells o Myeloblasts  neutrophils, basophils, eosinophils o Lymphoblasts  lymphocytes o Monoblasts  monocytes o Megakaryoblasts  platelets -------------------------------------------------------------------------------------------------------------------- - What are the components and transport functions of RBC’s?  Components - 1/3 hemoglobin - 2/3 lipids, ATP, and carbonic anhydrase  Transport functions o Oxygen (2 atoms, 2 ways to transport) 1. 98% bound to hemoglobin 2. 1.5% dissolved in plasma o Carbon dioxide (3 atoms, 3 ways to transport) 1. 23% bound to hemoglobin 2. 7% dissolved in plasma 3. 70% as H 2O 3 o H+ 1. Generated from carbonic anhydrase reaction • Hemoglobin: quaternary protein structure (4 components) – 1 O and 4 2 hemoglob2n o Oxyhemoglobin, deoxyhemoglobin, carbaminohemoglobin What is erythropoisis? - Production of RBC’s • Erythropoietin: hormone (produced by kidney) stimulates RBC production o Approx. 4 days  Stimulus? Low blood O 2 o  blood O > stimulates kidneys >  erythropoietin production >  RBC production 2 >  blood O 2 - More RBC’s = greater O car2ying capacity - Darbepetin alfa-albuin is a drug used to treat anemia by boosting the body’s natural mechanism for making RBC’s -------------------------------------------------------------------------------------------------------------------- - How are RBC’s naturally broken down? 1. Globin - Protein - Recycles into amino acids 2. Heme - Iron removed and recycled - Stored in liver, spleen, and bone marrow 3. Iron-free heme - Converted to bilirubin - For the liver, intestines, and kidney -------------------------------------------------------------------------------------------------------------------- - What is the function of WBC’s and how are they transported? - Serve to protect the body against microorganisms and remove dead cells and debris o Nucleated, have no hemoglobin 1. Ameboid: pseudopods (“false foot”) 2. Diapedesis: cells become thin, elongate, and move either between or through endothelial cells of capillaries 3. Chemotaxis: attraction to and movement toward foreign materials or damaged cells - Pus: accumulation of dead white cells and bacteria - Injured-diseased cells release chemoattractants (cytokines, proteins) What are the 5 different types of WBC’s? (NoBLaME) 1. Neutrophils (60-70%) - Phagocytise bacteria - Secrete lysozyme (enzymes metabolize bacteria) - Pro-inflammatory… muscle injury 2. Basophils (0.5-1%) - Inflammation and allergic response of tissues - Produces histamine (vasodilation and bronchial constriction) - Produces heparin (inhibits blood clotting) 3. Lymphocytes (20-25%) - Produced in red bone marrow, proliferates in lymphatic tissue - Produces antibodies 4. Monocytes (3-8%) - Become macrophages after 3 days - Phagocytic cells - Increases with chronic infection 5. Eosinophils (2-4%) - Active in allergic reactions - Destroy inflammatory chemicals like histamine (reduces inflammation) - Release chemicals that help destroy tapeworms, flukes, pinworms, and hookworms -------------------------------------------------------------------------------------------------------------------- - What are platelets? - Cell fragments pinched off from megakaryocytes in red bone marrow - Surface glyoproteins and proteins allow adhesion to other molecules (ie collagen) - Important in preventing blood loss o Platelet plugs: accumulation of platelets at blood vessel “breaks” o Promoting formation and contraction of clots Chapter 20 – Heart What are the functions of the heart? 1. Generate blood pressure - Transfer of energy - Pressure (force/ surface area) - Actin-myosin interactions, change in blood vessel diameter 2. Routing blood - 3 circulations: pulmonary, systemic, coronary 3. Ensuring one-way blood flow - Valves (preventing blood flow) 4. Regulating blood supply - Changes in contraction rate and force match blood delivery and changing metabolic needs -------------------------------------------------------------------------------------------------------------------- - Define the parts of the heart.  Pericardium: pericardial sac o Fibrous Pericardium: tough fibrous outer layer o Serous Pericardium: thin, transparent, inner layer  Parietal Pericardium: lines the fibrous outer layer  Visceral Pericardium: covers heart surface • The two are continuous and have a pericardial cavity between them filled with pericardial fluid  Heart Wall 1. Epicardium: serous membrane; smooth outer surface of heart 2. Myocardium: middle layer composed of cardiac muscle cell and responsibility for heart contracting 3. Endocardium: smooth inner surface of heart chambers • Pectinate Muscles: muscular ridges in auricles and right atrial wall • Trabeculae Carnae: muscular ridges and columns of inside walls of ventricles Describe coronary circulation as related to the arteries (aorta)?  Right CoronaryArtery: extends to posterior aspect of heart o Posterior interventricular artery > posterior and inferior portions of heart o Right marginal artery > lateral wall of right ventricle  Left Coronary Artery: posterior and inferior aspects of heart o Circumflex artery > posterior wall o Left marginal artery > lateral wall of left ventricle o Anterior interventricular artery > anterior heart -------------------------------------------------------------------------------------------------------------------- - Describe coronary circulated as related to the veins.  Great Cardiac Vein: drain left side of heart  Small Cardiac Vein: drains right margin of heart  Coronary Sinus: large venous cavity, empties into the right atrium -------------------------------------------------------------------------------------------------------------------- - What is the function of valves and what is the difference between the main 2 valves? - Valves ensure one-way flow of blood • Antrioventricular Valves (AV Valves) o Leaf-like cusps attached to papillary muscles by tendons (chordae tendineae) o Right has three cusps (tricuspid) and left has two cusps (bicuspid, mitral) • Semilunar Valves: right (pulmonary); left (atrial) o Cups filled = valve closed (and vice versa) -------------------------------------------------------------------------------------------------------------------- - What is the difference between a relaxed and a closed left ventricle?  Relaxed LV o Bicuspid valve open, aortic valve closed = LV filling  Contracted LV o Bicuspid valve closed, aortic valve open = LV empyting -------------------------------------------------------------------------------------------------------------------- - Describe the skeleton of the heart. - Consists of plate of fibrous connective tissue between atria and ventricles - Fibrous rings around valves to support - Serves as electrical insulation between atria and ventricles - Provides site for muscle attachment What is the heart? - Elongated, branching cells containing 1-2 centrally located nuclei - Contains actin and myosin filaments • Intercalated Disks: specialized cell-cell contacts - Cell membranes interdigitate - Desmosomes hold cells together - Gap junction allow the movement ofAPs The heart is an electromechanical organ • Mechanical: cardiac cells contract, produce force, and generate mechanical energy - Causes blood to move • Electrical: signals (APs) causing the cells to contract • Electromechanical Delay: difference in time onsets between electrical stimulus (AP) and mechanical response (force production) -------------------------------------------------------------------------------------------------------------------- - What is the electrical pathway of the heart? SANode: contains nodal cells (pacemaker) - APs spread to atria  AV Node: nodal cells, small time delay, slow conduction  AV Bundle: extension into interventricular septum  R & LBundle Branches: faster conduction  Purkinje Fibers: fastest conduction to ventricles -------------------------------------------------------------------------------------------------------------------- - Describe the electrical properties of a skeletal muscle. Resting State:  extracellular Na ,  intracellular K + 1.Depolarization - Na influx + + Na channels open, K channels start opening 2.Repolarization - K efflux Na channels closed, K channels open Na /K ATPase restores ion gradient Describe the electrical properties of a cardiac muscle. Resting State:  extracellular Na and Ca ++ +  intracellular K 1. Depolarization - Na influx Na open, Ca start to open, K closed 2. Early Repolarization - Ca ++ influx + ++ + Na closed, Ca open, some K opening 3. Late Repolarization K efflux (K channels open) -------------------------------------------------------------------------------------------------------------------- - How does the SANode relate to autorhythmicity? • Autorhythmicity: self-generatingAPs in regular time intervals 1.Pacemaker Potential + - Na “leakage” into cell causes resting membrane potential to move towards threshold - inside, more positive + - K channels closing 2. Depolarization Phase ++ + - Ca open, K closed • Fast K closing: K removed from extracellular space sooner • Slow K closing: K stays in extracellular space longer o Keeps cells hyperpolarized
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