ABCT2326 CVS 2019.pdf

Chapter 19 - 21 Cardiovascular System 1 Functions and Components of the Circulatory System -I heart blood blood vessel 2 Today’s Lecture Composition of blood Blood vessels Struct...

Chapter 19 - 21 Cardiovascular System 1 Functions and Components of the Circulatory System -I heart blood blood vessel 2 Today’s Lecture Composition of blood Blood vessels Structure of heart and functions The conduction system #ET -Si SA action potential 正在載入⋯ Myocardial action potential Heart function test ECG Cardiac cycle 3 Circulatory System acid g Incose , fatty Transportation of respiratory gases, delivery of nutrients and hormones, and waste removal. lurea cor) , Temperature regulation, clotting, and immune function. Include cardiovascular and lymphatic systems Heart pumps blood thru cardiovascular system Blood vessels carry blood from heart to cells and back En ( , hir capillaries, venules, veins & arterioles, Includes arteries, 1A FATE Lymphatic system picks up excess fluid filtered out in capillary beds and returns it to veins 24 Its lymph - nodes are part of immune system :-I his 4 Composition of the Blood 正在載入⋯ 5 Composition of Blood Total blood volume is about 5L Consists of formed elements (cells) Ex - most of formed elements Red blood cells (RBCs) comprise % of RBCs in centrifuged blood sample = hematocrit Asfix T , Hematocrit is 36-46% in women; 41-53% in men plasma (fluid part) (90 %) straw-colored liquid consisting of H2O and dissolved solutes Includes ions, metabolites, hormones, antibodies Nat k+ , clotting blood The form ↑. Fibrinogen serves as clotting factor Converted to fibrin THE E Serum is fluid left when blood clots # 7  15) Formed Elements - RBCs and WBCs Are erythrocytes (RBCs) and leukocytes (WBCs) RBCs are flattened biconcave discs XX) E Shape provides increased surface area for diffusion Lack nuclei and mitochondria > short survival days (120 days) - Each RBC contains 280 million hemoglobin molecules Carry or or cor) About 300 billion RBCs are produced each day /produced by bone (against the infection) #Fi Lecture 1 46. p. 8 Formed Elements - Platelets (thrombocytes) X Are smallest of formed elements, lack nucleus, are not true cells Are fragments of megakaryocytes from bone marrow Constitute most of mass of blood clots Survive 5-9 days fragment of membrane well deliver untrient. 02. removal of cor 9 Blood Vessels 10  Structure of Blood Vessels ↓ Innermost layer of all vessels is the endothelium E // Capillaries are made of only endothelial cells middle outer Arteries and veins have 3 layers called tunica externa, media, and M interna inside tunica 正在載入⋯ Externa is connective tissue ~ Media is mostly smooth muscle to contract the blood vessel Connective Interna is made of endothelium, basement membrane, and tissues elastin 17 A flat (thin cell ↓ Easier for untriention delivery major component of basement membrane Collage blood flowing musclecell Contraction of Smooth rely on 11  deoxygenated oxygenated : red. dark bright red & Smooth muscle Basement membrane A protective layer composed of collagen, laminin, heparan sulfate, and glycosaminoglycan one layer of the cell (flat cell) Vrecievenutrient from tissue. 12 * Arteries Carry blood away from heart Large arteries are muscular and elastic Contain lots of elastin #3 44 : TE Tippressures EE ( withstand high Expand during EY systole and recoil during diastole Helps maintain smooth blood flow during diastole Small arteries and arterioles are muscular Provide most resistance in circulatory system 13  Capillaries Networks between arteries and veins Exchange dissolved gases, nutrients, wastes between blood and tissues thin Provide extensive surface area for exchange Blood flow through a capillary bed is ZE5537A1 determined by state of precapillary sphincters of arteriole supplying it Precapillary sphincters are rings of smooth muscle that regulate the flow of blood through capillaries They help to control the location of blood flow to where it is needed 14 15 Types of Capillaries In continuous capillaries, endothelial cells are tightly joined together Have narrow intercellular channels that permit exchange of molecules-smaller than proteins - Present in muscle, lungs, adipose tissue A Sti Fenestrated capillaries contain “windows”, or pores, that penetrate the endothelial lining. Allow rapid exchange of water and solutes between blood and interstitial fluid - Present in brain, endocrine organs (e.g. hypothalamus), intestinal tract, kidneys. # O 16  Veins Carry blood to heart Contain majority of blood in circulatory system Very compliant (expand readily) Contain very low pressure (about 2mm Hg) revent Insufficient to return blood Pbackflow of the to heart pressure blood vein blood in In , Blood is moved toward heart by contraction of surrounding skeletal muscles (skeletal muscle pump) E ALL 42TA And pressure drops in chest during breathing 1-way venous valves 17 ensure blood moves only toward heart.  toward heart An Introduction to the Cardiovascular System Pulmonary circulation is path of blood from right ventricle through lungs and back to heart Systemic circulation is path of blood from left ventricle to body and back to heart Rate of flow through systemic circulation = flow rate through pulmonary circuit 18 Figure 20-1 An Overview of the Cardiovascular System. PULMONARY CIRCUIT SYSTEMIC CIRCUIT Pulmonary arteries Systemic arteries Pulmonary veins Systemic veins Capillaries Capillaries in head, in lungs neck, upper limbs ↓ Ak Right atrium Left atrium Right descending aorta. ventricle Left ventricle Capillaries in trunk and lower limbs 7 P  Pulmonary and Systemic Circulations Blood coming↓ from tissues F enters superior and inferior vena cavae which empties into right atrium, then goes to right ventricle which pumps it S through pulmonary arteries to lungs Oxygenated blood from lungs passes through pulmonary veins to left atrium, then to left ventricle which pumps it through aorta to body Pulmonary circulation moves blood between the heart and lungs. It transports deoxygenated blood to the lungs to absorb oxygen and release carbon dioxide. The oxygenated blood then flows back to the heart. Systemic circulation moves blood between the heart and the rest of the body 20 Structure of the Heart 21  Structure of the Heart Heart Wall: Il Epicardium (Outer Layer) # F Visceral pericardium ~ Covers the heart * //kA. Myocardium (Middle Layer) allow heart to contract Muscular wall of the heart Concentric layers of cardiac muscle tissue fin. Yes Atrial myocardium wraps around great vessels Two divisions of ventricular myocardium 1. Nettright. Il Endocardium (Inner Layer) Simple squamous epithelium Figure 20-4a The Heart Wall. Myocardium Pericardia Parietal l pericardium (cardiac muscle tissue) cavitytiny Dense fibrous layer Cardiac muscle cells Areolar Connective tissues tissue Mesothelium Artery Vein Endocardium Epicardium Endothelium (visceral Areolar pericardium) tissue Mesothelium Areolar fibre Heart wall tissue a A diagrammatic section through the heart wall, showing the relative positions of the epicardium, myocardium, and endocardium. The proportions are not to scale; the thickness of the myocardial wall has been & greatly reduced. ↑A Structure of the Heart Cardiac Muscle Tissue Intercalated discs All in ( Interconnect cardiac muscle cells /DILIAR Intercalated discs Secured by desmosomes 2 Linked by gap junctions japB delivery of La. Convey force of contraction TE IEUXITE to 2 Propagate action potentials beat : cell muscle is need energy many cardiac 1 Intercalated discs are specialised junction between cardiac muscle fibers (cardiomyocyte)that allow for rapid electric transmission,called an action potential,and nutrient exchange. Intercalated discs are important because they allow for the cells in our heart to beat as one Figure 20-5a Cardiac Muscle Cells. Cardiac muscle cell Mitochondria Intercalated disc (sectioned) Nucleus Cardiac muscle cell (sectioned) Bundles of myofibrils Intercalated discs a Cardiac muscle cells Figure 20-5b Cardiac Muscle Cells. Intercalated disc Gap junction one cell to another Z-lines bound to 2 opposing plasma = membranes Desmosomes - & b Structure of an intercalated disc Figure 20-5c Cardiac Muscle Cells. Structure of the Heart Characteristics of Cardiac Muscle Cells 1. Small size 2. Single, central nucleus 3. Branching interconnections between cells 4. Intercalated discs Intercalated discs Cardiac muscle tissue c ↳ produce Atp (energy) to. beat (compare to skeletal muscle cell) C unique structures  Structure of the Heart Heart has 4 chambers 2 atria (singular: atrium) receive blood from venous system 2 ventricles pump blood to arteries BEE 2 sides of heart are 2 pumps separated by muscular septum body Revere capillaries. tissue 02 a upper , Aortic arch : low high & & C pressure pressure To APTR or gives - pulmonal S recieves Co2 in lung Lung F a # A "ThY heart muscle : thicknessof value T & TR > T pal - blood to one of the coronary ↳ as need to pump =Fin v arteries blocked # get BE whole body O ↓ connect tricuspid and I heart attack bimspid values to the (lack of 02) & bottom of the ventricles lower body , tissue capillaries , gives Co or revieves 28 Figure 20-4b The Heart Wall. Atrial musculature 正在載入⋯ Ventricular musculature b Cardiac muscle tissue forms concentric layers that wrap around the atria or spiral within the walls of the ventricles. Structure of Heart continued Between atria and ventricles is layer of dense connective tissue called cardiac (fibrous) skeleton which encircle the heart valves and bases of pulmonary truck and aorta - structurally and functionally separate ventricles and atria electrically insulate the ventricular cells from atrial cells. ventricleand atrium will not contract at the same time , ↳ EEP IFEE SEED HTC EN - 30 Structure of Heart continued Structural Differences between the Left and Right Ventricles ventricle - Right ventricle wall is thinner, develops less pressure than left A - Right ventricle is pouch-shaped, left ventricle is round Left ventricle Right ventricle high l sure pressure a A diagrammatic sectional view through the heart, showing the relative thicknesses of the two ventricles. Notice the pouchlike shape of the right ventricle and the greater thickness of the left ventricle. Figure 20-7b Structural Differences between the Left and Right Ventricles. Right Left ventricle ventricle Dilated Contracted b Diagrammatic views of the ventricles just before a contraction (dilated) and just after a contraction (contracted). Atrioventricular Valves Fi only one way blood flow Blood flows from atria into ventricles thru 1-way atrioventricular (AV) valves & Between right atrium and ventricle is tricuspid valve Between left atrium and ventricle is bicuspid or mitral valve 33 Semilunar Valves * As Seminlunar valves including pulmonary and aortic valves prevent the backflow of blood from pulmonary arteries and aorta into right and left ventricles, respectively. 34 Functions of the valves Opening and closing of valves results from pressure differences 5) High pressure of ventricular contraction is prevented from everting AV valves by contraction of papillary muscles which are connected to AVs by chorda tendinea During ventricular contraction blood is pumped through aortic and pulmonary semilunar valves Close during relaxation E ② O 35 Figure 20-8a Valves of the Heart (Part 1 of 2). Transverse Sections, Superior View, Atria and Vessels Removed POSTERIOR Cardiac Left AV (bicuspid) skeleton valve (open) RIGHT LEFT VENTRICLE VENTRICLE Re la xe d ve ntr Right AV icl (tricuspid) valve (open) es Aortic valve (closed) Pulmonary ANTERIOR valve (closed) a When the ventricles are relaxed, the AV valves are open and the semilunar valves are closed. The Aortic valve closed chordae tendineae are loose, and the papillary muscles are relaxed. Figure 20-8a Valves of the Heart (Part 2 of 2). Frontal Sections through Left Atrium and Ventricle Pulmonary veins LEFT ATRIUM Re Left AV (bicuspid) la valve (open) xe d Chordae Aortic valve ve (closed) tendineae (loose) ntr Papillary muscles icl (relaxed) es LEFT VENTRICLE (relaxed and filling with blood) a When the ventricles are relaxed, the AV valves are open and the semilunar valves are closed. The chordae tendineae are loose, and the papillary muscles are relaxed. Figure 20-8b Valves of the Heart (Part 1 of 2). Right AV Cardiac Left AV (tricuspid) valve skeleton (bicuspid) valve (closed) (closed) LEFT Co RIGHT VENTRICLE VENTRICLE ntr act in g ve ntr icl value es semilular Aortic valve (open) Pulmonary valve (open) b When the ventricles are contracting, the AV valves are closed and the semilunar valves are open. In the Aortic valve open frontal section notice the attachment of the left AV valve to the chordae tendineae and papillary muscles. Figure 20-8b Valves of the Heart (Part 2 of 2). Aorta LEFT Co ATRIUM ntr Aortic sinus Left AV (bicuspid) act valve (closed) in Aortic valve g (open) Chordae tendineae (tense) ve ntr Papillary muscles icl (contracted) es Left ventricle (contracted) b When the ventricles are contracting, the AV valves are closed and the semilunar valves are open. In the frontal section notice the attachment of the left AV valve to the chordae tendineae and papillary muscles. The Conducting System 40  The Conducting System Cardiac Physiology Two types of cardiac muscle cells 1. Conducting system Initiates and distributes electrical impulses that stimulate contraction Controls and coordinates heartbeat 2. Contractile cells 12 STEA PE Produce contractions that propel blood cardiac muscle cell The Conducting System Q The Cardiac Cycle B e Begins with action potential at SA node - ② ⑤ - Transmitted through conducting system see Produces action potentials in atrin X & cardiac muscle cells rentries (contractile cells)  The Conducting System Structures of the Conducting System Sinoatrial (SA) node – wall of locatio right atrium Atrioventricular (AV) node – junction between atria and ventricles Conducting cells – throughout myocardium The Conducting System P Conducting Cells Interconnect SA and AV nodes Distribute stimulus through I Ca myocardium In the atria Internodal pathways In the ventricles AV bundle and the bundle branches The Conducting System – SA node The Sinoatrial ↳ (SA) Node In posterior wall of right atrium Contains pacemaker cells ↳REM Connected to AV node by internodal pathways Begins atrial activation (Step 1)  tin Interculateddiv Action prential paremaker cells & ( takes for longer j. Cardian muscle cell transmit Allow signals to -ve ve  The Conducting System – Pacemaker potential * Ep Prepotential Also called pacemaker potential Resting potential of conducting cells Gradually (spontaneously) depolarizes toward threshold SA node depolarizes first, establishing heart rate Simulated/ Depolarization + Extracellular 2111- Intercellular k 90 a kkt Nat + Nat Nat Nat L S - MA -30 : + 110 Extracellular Nat Nat Nat Nat 111 = closed Intercellular + 40k + k - + Resting potential - MA To : - MA : Intercellular - Extracellular  from paremaker cell (short Pacemaker Potential continued Membrane voltage begins at around -60mV and gradually depolarizes to -40mV threshold contract Intercellular ↑ e Spontaneous depolarization is cartin out caused by Na+ flowing through channel that opens when hyperpolarized (HCN channel) & no - Ho At threshold voltage-gated Ca2+ repolarization negative H less channels open, creating upstroke and contraction relaxation - depolarize v Repolarization is via opening of Conce of K : voltage-gated K+ channels 5/ > /) Hyperpolarization ve more - 3 40mV Action potential - 48 resting potential  The Conducting System – From SA node to AV node contain parema initiate electrical impulse Action potentials from SA node spread through atrial / B LB1. myocardium via gap junctions But need special pathway to ventricles because of non- conducting fibrous tissue AV node 1324 Lintmmis AV bundle (bundle of His) send electrical impulse. send another pass SAnode- > Contractional atria. > - Ar modeis Arbundle contraction - of ventricle SA node heartbeats and control heart rate Initiate 49 The Conducting System – AV Node The Atrioventricular (AV) Node In floor of right atrium Receives impulse from SA node (Step 2) - Delays impulse (Step 3) Atrial contraction begins (short for artium contraction The Conducting System – AV bundle The AV Bundle In the septum Carries impulse to left and right bundle branches Which conduct to Purkinje fibers (Step 4) E EF STE And to the moderator band Which conducts to papillary muscles The Conducting System – Purkinje Fibers Purkinje Fibers Distribute impulse through ventricles (Step 5) Atrial contraction is completed Ventricular contraction begins Ensure the ventricle is completely contracted The Conducting System – from cardlar muscle. Myocardial Action Potentials kt and caltchannel open Nat channel. open call in Myocardial cells have resting ki out at out , Nat in membrane potential of –90 mV & less negative Depolarized to threshold by action potentials originating in SA node less-re less-re Inside more - ve # Upstroke occurs as voltage-gated Na+ channels open negative place. Ensureback to origin Membrane potential rapidly spontaneously I declines and stays for 200-300 upwards ( go msec (plateau phase) TE Plateau results from balance between slow Ca2+ influx and K+ efflux -O long. => O Cardiac muscle cells cannot respond more negative Repolarization due to opening of ⑤ ensures complete long refractory period extra K+ channels before another contraction and relaxation 53 action potential initiate. 54  EA Refractory Periods Refractory Period Absolute refractory period Long - Cardiac muscle cells cannot respond Relative refractory period Short Response depends on degree of stimulus Timing of Refractory Periods Length of cardiac action potential in ventricular cell 250–300 msec 30 times longer than skeletal muscle fiber F Long refractory period prevents summation and tetany 55 z 56  Lab Electrocardiogram (ECG or EKG) A recording of electrical events in the heart Obtained by electrodes at specific body locations Abnormal patterns diagnose damage  Electrocardiogram (ECG or EKG) Features of an ECG P wave Atria depolarize URT QRS complex Ventricles depolarize 42 STE T wave Ventricles repolarize 3 Fe relax. -re of the P–R interval From start of atrial depolarization To start of QRS complex Q–T interval From ventricular depolarization To ventricular repolarization Electrocardiogram (ECG or EKG) Cardiac Cycle 60 Cardiac Cycle Is repeating pattern of contraction and relaxation of heart Systole refers to contraction phase Diastole refers to relaxation phase Both atria contract simultaneously; ventricles follow 0.1-0.2 sec later 61  Cardiac Cycle continued # 3 * ERFAY - ↑ End-diastolic volume is volume of blood in ventricles at - > relax end of diastole 42Th ↑ Stroke volume is amount of blood ejected from ventricles during systole End-systolic volume is amount of bloodeleft in ventricles at-end of systole contract 422T Frank-Starling Law: proportional stroke volume increases as the end-diastolic volume increases (increased blood volume will stretch ventricular wall force of contraction increases) Y U2TBDT in ventricle ↓ : i ↓ blood volume 4 62 Cardiac Cycle continued Heart Sounds S1 tricuspid value & bicuspid value Loud sounds Produced by AV valves when they're shut S2 Loud sounds pulmonary & aortic Produced by semilunar valves when they're shut 63 Figure 20-18b Heart Sounds. out the heart 12 0 pump Semilunar Semilunar valves open valves close 9 0 Aorta Pres sure (mm 6 Hg) 0 Left ventricle 42TA 3274 Left AV valves AV valves 3 atrium close open 0 0 S 1 S S 2 S S Heart sounds 4 3 4 “Lubb” “Dupp ” b The relationship between heart sounds and key events in the cardiac cycle