9. The Cardiovascular System PDF

9. The Cardiovascular System Course Human Anatomy & Physiology Status Complete Materials 9. The Cardiovascular System - Slides Textbook Chapter 11 & 12...

9. The Cardiovascular System Course Human Anatomy & Physiology Status Complete Materials 9. The Cardiovascular System - Slides Textbook Chapter 11 & 12 Table of Contents Blood Plasma (55%) Formed Elements (45%) Homeostasis (Blood Clotting) Plasma Platelets Osmotic Pressure Fibrin Heart Circuits External Features of Heart Heart Wall & Pericardium Cardiac Muscle Internal Features of Heart 9. The Cardiovascular System 1  Path of Blood through the Body Valves Atrioventricular (AV) Valves Semilunar (SL) Valves The Heartbeat Heart Sounds Action Potential of Cardiac Muscle Cell The Conducting System Electrocardiogram (ECG) The Cardiac Cycle Wiggers Diagram Cardiac Output (CO) Compensation Autonomic Innervation of Heart Blood Vessels Blood Vessel Structure Arteries Veins Capillaries Capillary Bed Dynamics Blood Flow Dynamics Pressure in the Circuit Summary of Changes in Circuit Blood Pressure (BP) Regulation Peripheral Resistance (pR) Auto-, Neural and Endocrine Regulation Lymphatic System Circulation Blood Structure: is a fluid connective Functions: tissue Transport: respiratory gases, Cells: RBC, WBC and platelets nutrients, wastes, hormones, heat Ground substance: Plasma Regulation: pH & ion composition and volume of 9. The Cardiovascular System 2  No extracellular fibers but has blood controls IF the potential to make fibers in Plasma ↔ IF (interstitial hemostasis fluid) Fibrinogen: soluble Protection: circulating protein that can polymerize forming fibrin Immune defense: (role of WBC & antibodies) Fibrin: insoluble fiber that forms a mesh that traps Hemostasis: blood clotting activated platelets and & platelet activation RBCs forming temporary plug and stopping blood flow Plasma (55%) Plasma: fluid portion of blood composed of 92% water and dissolved solutes Serum: plasma minus fibrin (no clotting) Dissolved solutes: Ions (Electrolytes), Organic Nutrients & Wastes, Dissolved Proteins Dissolved Proteins: Albumin, Globulins, Fibrinogen, Regulatory Proteins Plasma proteins are synthesized by the liver 9. The Cardiovascular System 3  Formed Elements (45%) 9. The Cardiovascular System 4  Formed Elements: Cells & Cell fragments including WBC, RBC & platelets White blood cells or Leukocytes: Function: part of immune response of body are true cells with distinctive nuclei Red blood cells or Erythrocytes: Function: carry respiratory gases: O2 and CO2 are not true cells due to lack of nucleus & organelles Platelets or Thrombocytes: are cytoplasmic pieces involved in blood clotting Hematocrit or Packed Cell Volume: percentage of blood volume occupied by formed elements in relation to whole blood Indicator of oxygen carrying capacity of blood because cell fraction is 99.9% RBC Obtained by centrifugation of whole blood Average value is 45% (Males: 47%, Females: 42%) Homeostasis (Blood Clotting) Blood Homeostasis: Processes that stop loss of blood in damaged vessels dependant on platelets and soluble proteins (clotting factors) Plasma Osmotic Pressure Plasma in equilibrium with Osmotic Pressure: indication of interstitial fluid force of osmotic water movement or pressure that must be applied to 9. The Cardiovascular System 5  ion composition of interstitial prevent osmotic movement across fluid controlled by composition a membrane of plasma Is due to plasma proteins Ion composition of plasma Is aprox. 25mmHg regulated by kidneys Interstitial fluid: between 0-5 IF contains essential, no, or little mmHg because negligible protein amounts of proteins Circulating plasma proteins never leave circulation and play role in Fibrin osmotic pressure of blood Fibrin: insoluble fiber that forms a mesh that traps activated platelets and RBCs Forms temporary plug and stops blood flow Formed by the polymerization of fibrinogen (a soluble circulating blood protein) Formation is triggered by wound signals Platelets Platelets: cell membrane bound cytoplasmic pieces containing chemicals Activated by abnormal changes in surroundings Release clotting factors and other chems Swell and stick together Formed by shedding of a megakaryocyte: a fusion of many cells i.e. is multinucleate Along with fibrin, mesh forms a temporary plug in hemostasis (stopping of bleeding) 9. The Cardiovascular System 6  Heart Function: Pumps blood into 2 circuits in sequence through vessels Location: mediastinum cavity of the thorax Pericardium: double serous membrane forming pericardial sac (parietal) and epicardium (visceral) Position: just off the midline, rotated to the left anterior to descending aorta, esophagus, Vagus nerve and thoracic duct dorsal to sternum 9. The Cardiovascular System 7  Circuits Heart Pumps Blood into Two Circuits in Sequence: 1. Pulmonary circuit: Right side pumps to and from the lungs to pick up oxygen and unload carbon dioxide 2. Systemic circuit: Left side pumps to and from the tissues of the body to deliver nutrients and oxygen and pick up wastes including CO2 3. Coronary circuit: supplies blood to heart Three Kinds of Blood Vessels 1. Arteries: efferent vessels a. Carry blood away from heart and carry it to the capillaries 2. Capillaries: connects arteries and veins a. Site of exchange area between blood and cells 3. Veins: afferent vessels a. Receive blood from capillaries and carry it back to the heart Two Sets of Pumping Chambers in Heart (carry equal volumes) 1. Right atrium: Receives systemic blood 2. Right ventricle: Pumps blood to lungs (pulmonary) 3. Left atrium: Receives blood from lungs 4. Left ventricle: Pumps blood to organ systems (systemic) External Features of Heart 9. The Cardiovascular System 8  Heart Wall & Pericardium 1. Endocardium: Simple Squamous Endothelium + Loose Connective Tissue for frictionless surface 9. The Cardiovascular System 9  2. Myocardium: Cardiac Muscle Tissue + Fibrous Skeleton Fibrous skeleton: Skeleton of Collagen and Elastic fibers that supports the valves and electrically isolates Atria & Ventricles 3. Epicardium (Visceral Pericardium): Simple Squamous Epithelium + Loose Connective Tissue a. inner layer of the pericardium (serous Muscle spirals around heart membrane) 4. Pericardial cavity: contains serous fluid 5. Parietal Pericardium: reinforced with dense fibrous connective tissue a. forms a protective sac attached to diaphragm Cardiac Muscle Cardiac Muscle Cells: Parallel elongated muscle cells that are striated and mono- nucleated with intercalated discs and some branching Spiral arrangement of muscle around ventricals: allows ventricular 9. The Cardiovascular System 10  contraction to squeeze blood upward from the apex They contract as a unit because of: Intercalated discs or gap junctions: sieve-like connection between cells Pores allow ions to pass from one cell to the next coupling the cells electrically Prolonged Action Potential: produces longer contraction Automaticity or Conducting system: ensures heart can contract independent of NS Internal Features of Heart Coronal section of heart 9. The Cardiovascular System 11  Right Ventrical: Cresent shaped shorter pulmonary circuit produces a lower pressure to pump Thinner Wall Left Ventrical: Circular longer systemic circuit produces a higher pressure to Cross-section of heart pump Thicker Wall 1. Vena cava (Superior & Interior): Path of Blood through the Venous blood enters Body 2. Right atrium: Collects venous blood 3. Tricuspid AV valve: between right atria and ventricle 4. Right ventricle: Pumps venous blood 5. Pulmonary semilunar valve: between right ventricle and pulmonary trunk 6. Pulmonary trunk and arteries: Venous blood exits 7. Lung capillaries: blood oxygenates 8. Pulmonary veins: Arterial blood enters 9. Left atrium: Collects arterial blood 10. Bicuspid (Mitral) valve: between left atria and ventricle 11. Left ventricle: Pumps arterial blood 9. The Cardiovascular System 12  12. Aortic semilunar valve: between left ventricle and aorta 13. Aorta (Ascending & Descending): arterial blood exits 14. Arteries: carry oxygenated blood 15. Tissue capillaries: cells oxygenate, blood deoxygenates Relaxed vs Contracted Ventricals 16. Veins: carry deoxygenated blood 17. Vena cava (Superior & Interior): Venous blood enters Valves Valves: ensure one way flow, prevents Stenosis: the narrowing of the backflow valves Types of Valves: Prolapse: cords or papillary muscle no longer hold flaps Atrioventricular Valves (Tricuspid & taut Bicuspid) i.e. regurgitation or Semilunar Valves (Pulmonary & inefficiency Aortic) Atrioventricular (AV) Valves 9. The Cardiovascular System 13  Location: are found between the atria and ventricles. Tricuspid AV valve: on the right side Bicuspid or Mitral AV valve: on the left Structure: consists of flaps, chordae tendinea, papillary Closes: pressure due to volume of muscles blood from filling of ventricle is Tricuspid AV valve: 3 flaps greater in ventricles than atria Bicuspid or Mitral AV valve: 2 flaps Opens: pressure due to volume of blood in ventricles is less than in atrium Semilunar (SL) Valves 9. The Cardiovascular System 14  Location: found between ventricles and vessels Pulmonary SL valve: on right side Aortic SL valve: on left side Structure: Consist of 3 cup-like flaps Function: cups fill with back flow of ejected blood in vessel sealing the opening (like a parachute filling with air) Open: due to increasing pressure Close: backflow of ejected blood created by muscle contraction fills cusps (pressure in vessels (pressure in ventricles exceeds exceeds pressure in ventricle) pressure in vessels) The Heartbeat Heart Sounds 9. The Cardiovascular System 15  Cause: turbulence in blood caused by closing of a valve Lub: closing of AV valves Marks end of diastole and beginning of ventricular systole Dup: closing of SL valves Marks end of systole and beginning of diastole Pause: ventricular diastole Murmurs: imbalance of blood flow Obstructed blood creates turbulence (incompetent valve) Action Potential of Cardiac Muscle Cell The Conducting System 9. The Cardiovascular System 16  Conducting System: an electrical system of specialized cardiac cells that: self-excite or depolarize (automaticity) distribute action potential establishes heart rate referred to as automaticity SA node: located in right atrium establishes heart rate of 70-80 bpm is the pacemaker because it depolarizes at a faster rate AV node: located between atrium & ventricles in right ventricle creates a delay allowing the atria and ventricles to contract separately if SA node does not function, forms a heart rate of 40-60 bpm and will replace as pacemaker Heart rates established can be modified by ANS, hormones, drugs Atria and ventricles are electrically isolated by fibrous skeleton Signal is distributed to ventricles by: Bundle of HIS or AV Bundle: is in the AV septum 9. The Cardiovascular System 17  Bundle branches: right and left located in the septum Purkinje Fibers: located in ventricles Electrocardiogram (ECG) P wave: depolarization of the atria QRS complex: repolarization of the atria and depolarization of ventricles T wave: repolarization of the ventricles PQ(R) interval: atrial systole SA node to bundles or AV node delay: Atria and ventricles are electrically insulated connected only by AV node ST segment: ventricular systole TP interval: ventricular diastole (TQ not TP) 9. The Cardiovascular System 18  The Cardiac Cycle The Cardiac Cycle: one complete cycle of the pumping of blood through the heart involves Systole: contraction phase & Diastole: relaxation phase Phases: 1. Atrial systole 2. Atrial diastole 3. Isovolumetric ventricular systole 4. Ventricular systole ejection 5. Early ventricular diastole 9. The Cardiovascular System 19  6. Late ventricular diastole Wiggers Diagram a. SL Valves Open b. SL Valves Close c. AV Valves Close d. AV Valves Open e. Blood exits Ventrical f. Blood enters Ventrical Cardiac Output (CO) Cardiac Output: the amount of blood pumped by each ventricle in one minute CO = SV × HR (ml/min) HR = heart rate SV = Stroke volume: the volume pumped out with each beat SV = EDV-ESV EDV = End diastolic volume: maximum volume at the end of relaxation ESV= End systolic volume: minimum volume at the end of contraction 9. The Cardiovascular System 20  CO depends on Preload (stretch or venous return) and Postload (squeeze/CO) Regulating Factors: 1. Monitored by chemoreceptors (H+,CO2) and baroreceptors (BP) of the carotid and aortic sinus 2. Modified by ANS (sympathetic or parasympathetic nervous systems) 3. Stretch reflexes of heart wall: Atrial reflex & Frank Starling Principle (stretch of SA node also increases SA node depolarization) 4. Hormones: epinephrine, thyroxin, glucagon 5. Other chemicals: ions, nicotine, caffeine 6. Age, gender, exercise, body temperature Congestive Heart Failure: pumping efficiency is low and does not meet tissue needs caused by: Coronary atherosclerosis BP Myocardial infarcts: dead cardiac cells Dilated cardiomyopathy Pulmonary congestion 9. The Cardiovascular System 21  Peripheral congestion Stenosis (the narrowing of the valves) Prolapse valve (insufficiency or incompetence resulting in regurgitation) Compensation Pathologies of CV system can result in: increase in afterload: aortic stenosis or arteriosclerosis Increase in contractility: increase thickness of myocardium (damage of heart or valves) Increase in preload: exercise, increase blood volume, regurgitation from valve failure 9. The Cardiovascular System 22  Autonomic Innervation of Heart Receptors Chemo & Baroreceptors of carotid & aortic sinuses Carotid artery: blood going to brain (glossopharyngeal n.) Aorta: blood going to body (Vagus nerve) Stretch Receptors of atria and ventricle (Frank Starling Principle) Afferent Path: Vagus nerve Control Center: Medulla (modifies heart rate and contractility) Cardioinhibitory center (Parasympathetic) Cardioacceleratory center (Sympathetic) Efferent Paths: From Inhibitory center: Vagus nerve (parasympathetic path) From Accelerator center: via sympathetic pathways Effectors: SA node & Cardiac Muscle Blood Vessels Function: Delivery routes for blood 9. The Cardiovascular System 23  Types of Blood Vessels: 1. Arteries: Efferent vessels (carry blood away from the heart) 2. Veins: Afferent vessels (return blood to the heart) 3. Capillaries: Sites of exchange (gases, nutrients, waste) Path of Blood Flow: Heart → Arteries → Arterioles → Capillaries → Venules → Veins → Heart Blood Distribution: Pulmonary Circuit: 10% Heart: 5% Arterial System: 15% Capillaries: 5% Venous System: 65% Blood Vessel Structure 9. The Cardiovascular System 24  Three Layers of Vessel Walls: 1. Tunica Interna (Intima): Simple squamous epithelium 2. Tunica Media: Smooth muscle Regulates vessel diameter (vasoconstriction/dilation) 3. Tunica Externa (Adventitia): Dense irregular connective tissue with elastic fibers Maintains high pressure Arteries Veins 9. The Cardiovascular System 25  Characteristics: Characteristics: High-pressure vessels Low-pressure vessels with high volume capacity Deliver blood to tissues Return blood to the heart Structure: Act as blood reservoirs Thick walls (65% of blood volume) More muscle and elastic fibers Structure: Small lumens Thin walls No valves Less muscle and elastic Branching vessel structure fibers Types: Larger lumens 1. Elastic Arteries: Maintain high Valves present to prevent pressure for delivery backflow 2. Muscular Arteries: Deliver blood to Merging vessel structure organs; vasoconstriction by the sympathetic nervous system Venous Return 3. Arterioles: Regulate blood flow to Small pressure drop tissues and blood pressure; One-way valves Vasoconstricts in response to Sympathetic NS, hormones or local Merging vessels/large controls lumens 9. The Cardiovascular System 26  Muscular pump: skeletal muscle contraction Arteries and Veins serve the same area and lie side squeeze thin walled by side vessels Respiratory pump: pressure changes in thoracic cavity Capillaries Function: are exchange vessels for tissues Exchange Mechanisms: Diffusion and osmosis Filtration through gaps and pores Structure: Smallest diameter (RBC size) Single layer of simple squamous epithelium Key Structures: 9. The Cardiovascular System 27  Precapillary Sphincters: Capillary Bed Dynamics ring of smooth muscle that Push Out: force due to hydrostatic regulate flow pressure or BP Anastomosis: Path that Arteriole end= 35mmHg Bypasses bed Venule end= 18mmHg Characteristics: Pull In: force due to blood osmotic Large surface area due to pressure; is a constant = 25mmHg branching Pressure Changes in Capillary Bed: Lower pressure Arteriole End: Net outward Constant, slow flow (no pulse) movement (35-25 = 10 mmHg) Types: vary in permeability Venule End: Net inward (leakiness) movement (18-25 = -7 mmHg) 1. Continuous: No gaps or pores; found in the blood-brain barrier 2. Fenestrated: Few gaps and pores; found in most tissues 3. Sinusoidal: Large gaps and pores; found in lymphatic tissue and bone marrow Blood Flow Dynamics 1. Pressure Gradient: Blood flows from high to low pressure due to resistance Flow (Q) = P2 ​ − P1 /R ​ Q = CO Pressure (P) = Hydrostatic pressure exerted on vessel walls Resistance (R): Sum of frictional forces 2. Factors Affecting Resistance: Blood Viscosity: Constant, depends on RBC count and osmolarity 9. The Cardiovascular System 28  Vessel Length: Constant Vessel Diameter: Variable; inversely proportional to resistance (smaller radius = higher resistance); called peripheral resistance (pR) Turbulence: created by irregular walls from injury or disease Pressure in the Circuit Pulse: the pressure changes in heart cycle pulse drops in arterioles i.e. pR Pressure: is maintained by arteries ensuring delivery Pressure drops throughout the circuit: Aorta: Systolic 120 mmHg, Diastolic 80 mmHg Capillaries: 35-18 mmHg Summary of Changes in Circuit a. Vessel diameter: & d. Flow Veins: 18-2 mmHg (vena cava) velocity: to 0 mmHg (right atrium) a. Decreases in arteries due to branching b. Increases in veins due to merging b. Cross-Sectional Area: a. constant in arteries & veins because branching & merging does not change total diameter (i.e. branching x2) b. increases rapidly in capillaries due to high degree of branching (i.e branching x7-9) 9. The Cardiovascular System 29  c. Average Blood Pressure: drops through out the circuit Blood Pressure (BP) Regulation BP is maintained within a narrow range 1. BP Formula: BP = CO × pR = SV x HR x pR = (EDV - ESV) × HR × pR BP is hydrostatic pressure: the pressure of a fluid exerted on vessel walls CO (Cardiac Output): SV × HR SV (Stroke Volume): is the result of the force of contraction; = EDV - ESV EDV= venous return: venoconstriction (Sympathetic NS), blood volume (kidneys), exercise (muscular and respiratory pumps) ESV= contractility of the heart (calcium/Sympathetic NS) Frank Starling Principle: more in = more out (stretch reflex/optimal overlap length for max. crossbridge formation) HR is heart rate (SA node: Sympathetic/Parasympathetic) pR= afterload; vasoconstriction of the arterioles 2. Factors Increasing BP: Increased CO (venous return, HR, contractility) Increased blood volume (aldosterone, ADH) Increased peripheral resistance (vasoconstriction) 3. Factors Decreasing BP: Decreased CO or blood volume Vasodilation (ANP, histamine) 9. The Cardiovascular System 30  Peripheral Resistance (pR) Vasodilation Vasoconstriction ANP Ag II Inflammation factors (histamine Endothelial factors (wound and prostaglandins) factors) Nitrous oxide Local factors (low metabolic activity i.e. cells do not need Local factors (high metabolic nutrients or O2) activity) Auto-, Neural and Endocrine Regulation Short Term Mechanism involve the ANS & hormones (E, ADH, Ag II) that alter CO 9. The Cardiovascular System 31  Long Term Mechanisms involve the hormones acting on kidney altering blood volume (BP). Hormones include: Ag II, EPO, ADH, A, ANP Local Conditions (autoregulation) reflect the metabolic activity of the tissue: i.e. levels of O2, CO2 and H+ in tissues. Low O2, high CO2, high H+& Lactate, increase in temperature reflect high metabolic activity and cause vasodilation. Lymphatic System Functions: Immune defense (lymphocytes, phagocytes) Fluid balance (drains excess interstitial fluid into blood) Transports dietary lipids and lipid soluble vitamins (A, D, E, K) Lymph: fluid found in the vessels, similar to interstitial fluid except has less protein Lymphocytes: Cells of immune system; found in nodes and organs Lymph Nodes: Filter lymph Organs: Thymus, spleen, bone marrow 9. The Cardiovascular System 32  Lymph Capillaries: larger diameters, closed at one end, flat, irregular, thinner walls, Leaky with one-way valves Lymph Vessels: One- way system; ends in right lymphatic & thoracic ducts; Resemble veins but thinner with more valves Circulation is one way drainage system: starts in tissues and ends at the venous system Thoracic or left lymphatic duct merges with the left subclavian vein Receives lymph from the upper right side of body Right lymphatic duct merges with the right subclavian vein left side of head, arm and left chest and rest of body below the ribs 9. The Cardiovascular System 33