W6 PPT- Physiology- The Cardiovascular System PDF

9/21/2023 The Cardiovascular System FOX, CHAPTERS 13 &14 © STANBRIDGE UNIVERSITY 2023 1 1  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 2 2 ...

9/21/2023 The Cardiovascular System FOX, CHAPTERS 13 &14 © STANBRIDGE UNIVERSITY 2023 1 1  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 2 2  9/21/2023 Location of the heart Located in the thoracic cavity Between the lungs Slightly to the left of midline Apex (bottom tip) of the heart points to the left side © STANBRIDGE UNIVERSITY 2023 3 3  9/21/2023 Location of the Heart in the Thorax Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 4 4  9/21/2023 Heart Basics Size – size of a fist; less than a pound Location – generally between 2nd rib and 5th intercostal space, rests on superior diaphragm; 2/3rds of mass on left side Enclosed in pericardium: double walled sac Heart is “The Pump” the primary source of movement of blood in circulation © STANBRIDGE UNIVERSITY 2023 5 5  9/21/2023 Layers of the Heart Wall © STANBRIDGE UNIVERSITY 2023 6 6  9/21/2023 Heart Basics Heart wall – three layers ◦ Epicardium – outer most layer –squamous cells, serous membrane (contains coronary arteries and its main branches send branches to myocardium) and part of the serous pericardium ◦ Myocardium – middle layer – mainly cardiac cells; this is the layer that contracts ◦ Endocardium – inner most layer – endothelium resting on thin connective tissue Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 7 7  9/21/2023 Pericardium Peri = around / Pericardium = around the heart Pericardium – tough membrane fibroserous double walled sac Pericardium has two layers with a potential space in between ◦ Fibrous pericardium – protects heart acts as shock absorber ◦ Serous pericardium: parietal layer (outer) and visceral layer (against heart, called epicardium) Pericardial Fluid – lubricates surfaces allows heart to move freely during contractions (between parietal and visceral layers of serous pericardium © STANBRIDGE UNIVERSITY 2023 8 8  9/21/2023 Heart Chambers are separated by walls called septa (septum = singular form) Interatrial Septum – separates the two atria Interventricular Septum – separates the two ventricles © STANBRIDGE UNIVERSITY 2023 9 9  9/21/2023 Heart (Marieb, 2019) © STANBRIDGE UNIVERSITY 2023 10 10  9/21/2023 Divisions of the Heart Heart is a double pump Right side pump and a left side pump Right side pumps deoxygenated blood to the lungs Left side pumps oxygenated blood to the body © STANBRIDGE UNIVERSITY 2023 11 11  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 12 12  9/21/2023 Divisions of the Heart Heart is a hollow muscle with 4 chambers Marieb, 2019 In order of blood flow, the chambers 1. Right Atrium 2. Right Ventricle 3. Left Atrium 4. Left Ventricle © STANBRIDGE UNIVERSITY 2023 13 13  9/21/2023 Frontal Section of the Heart Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 14 14  9/21/2023 Heart Valves Each heart chamber is separated from the others by one-way valves Valves allow blood to flow in one direction They prevent backflow (regurgitation) There are 4 valves 1.Right Atrioventricular (AV) valve 2.Pulmonary semilunar valve 3.Left Atrioventricular (AV) valve 4.Aortic semilunar valve © STANBRIDGE UNIVERSITY 2023 15 15  9/21/2023 Heart Valves Heart valves slam shut like double Marieb, 2019 doors They are stopped from going any further by tiny tendons that anchor them Tiny tendons called Cordae Tendineae –Tricuspid and Mitral valves © STANBRIDGE UNIVERSITY 2023 16 16  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 17 17  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 18 18  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 19 19  9/21/2023 Heart Valves Right AV valve = Tricuspid valve (because it has 3 cusps or flaps) Left AV valve = Mitral valve ◦ Named after a miter, the 2-sided pointed hat worn by a bishop Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 20 20  9/21/2023 Anatomy of Ventricles Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 21 21  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 22 22  9/21/2023 AV (tricuspid and mitral) valves: Open (Marieb, 2019) © STANBRIDGE UNIVERSITY 2023 23 23  9/21/2023 AV valves: Closed (Marieb, 2019) © STANBRIDGE UNIVERSITY 2023 24 24  9/21/2023 Semilunar (pulmonic and aortic) Valves: Open (Marieb, 2019) © STANBRIDGE UNIVERSITY 2023 25 25  9/21/2023 Semilunar Valves: Closed Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 26 26  9/21/2023 Heart Sounds Marieb, 2019 “lub” ◦Closure of the atrioventricular valves ◦Tricuspid (right) ◦Mitral (left) “dub” ◦Closure of semilunar valves ◦Pulmonary ◦Aortic © STANBRIDGE UNIVERSITY 2023 27 27  9/21/2023 “The Pump” Order of Progression Right Side Left Side 1.Superior/Inferior Vena Cava 1.Pulmonary veins 2.R atrium 2.L atrium 3.Tricuspid valve 3.Bicuspid/mitral valve 4.R ventricle 4.L ventricle 5.Pulmonary Semilunar valve 5.Aortic semilunar valve 6.Pulmonary artery 6.Aorta 7.Pulmonary circuit (Lungs – 7.Systemic circuit aveoli – exchange CO2 for O2) © STANBRIDGE UNIVERSITY 2023 28 28  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 29 29  9/21/2023 Myocardium (Heart Muscle) Cardiac muscle cells are slightly striated (contract by sliding filament mechanism) Cardiac muscle cells have intercalated disks between each cell ◦ Attaches adjacent cells to each other ◦ Allows rapid transfer of electrical signals between cells © STANBRIDGE UNIVERSITY 2023 30 30  9/21/2023 Cardiac Muscle Cells Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 31 31  9/21/2023 Cardiac Muscle Cells Mitochondria: 25-30% of cell volume, therefore highly resistant to fatigue Shape of cells: short, fat, branched, interconnected Each cell/fiber: 1-2 centrally located nuclei Intercellular spaces: loose connective tissue matrix with many capillaries Connects to a fibrous skeleton which provides something for cells to exert force on © STANBRIDGE UNIVERSITY 2023 32 32  9/21/2023 Intercalated Discs, Desmosomes, and Gap Junctions of Cardiac Cells Intercalated discs: where plasma membranes of cardiac cells interlock Desmosomes: in intercalated discs, prevent adjacent cells from separating during contraction Gap junctions: in intercalated discs, allow ions to pass from cell to cell → transmit current throughout heart (functional syncytium= heart acts as single coordinated unit) © STANBRIDGE UNIVERSITY 2023 33 33  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 34 34  9/21/2023 The Heart’s Conduction System Cardiac muscle is stimulated to contract by a wave of electricity flowing through the cells Action potential is generated by specialized tissue Two “nodes” of specialized tissue ◦ Sinoatrial Node (SA Node) – The Pacemaker (fastest depolarization rate) ◦ Atrioventricular Node (AV Node) - slows impulse conduction between atria and ventricles (pause) ◦ Allows time for contracting atria to fill ventricles with blood before the lower chambers contract Bundle of His – transition from AV node before splitting into the Purkinje fibers Right and left bundle branches (in intervertebral septum running towards apex) Purkinje Fibers – rest of septum, apex, and ventricular wall © STANBRIDGE UNIVERSITY 2023 35 35  9/21/2023 Electrical Conduction in the Heart SA node electrical impulse that begins the heartbeat (pacemaker) Both atria contract (atrial depolarization) Electrical impulse reaches the AV node – slows impulse down – allows ventricles to fill Travels rapidly from AV node to the AV bundle (aka bundle of His) Bundle of His to right and left bundle branches in interventricular septum towards heart apex From bundle branches to the Purkinje fibers who deliver the signal to the muscle walls of the ventricles The ventricles then contract (ventricular depolarization) © STANBRIDGE UNIVERSITY 2023 36 36  9/21/2023 Action Potentials in the Heart 1% of cardiac cells are auto-rhythmic (automaticity) 1. Depolarization opens few fast voltage-gated Na+ channels in sarcolemma → Na+ into cell → positive feedback cycle → opens many Na+ channels → reverse membrane potential/ rising phase of action potential Na+ channels inactive ending phase © STANBRIDGE UNIVERSITY 2023 37 37  9/21/2023 Action Potentials in the Heart 2. Depolarization down T-tubules → allows Calcium to enter from extracellular space (about 10-20% needed) “slow Calcium channels” → causes sarcoplasmic reticulum (SR) to release Calcium into sarcoplasm through Calcium channels (80% needed); -Depolarization continues due to Calcium → causes plateau in action potential (AP) tracing -few potassium (K+) channels also open -if Calcium channels open, muscles contract © STANBRIDGE UNIVERSITY 2023 38 38  9/21/2023 Action Potentials in the Heart 3. Repolarization: Calcium channels inactivated and K+ voltage-gated channels open → K+ out of cell → restore membrane potential -Calcium pumped into extracellular space and SR © STANBRIDGE UNIVERSITY 2023 39 39  9/21/2023 Action potentials of cardiac cells (Marieb, 2019) © STANBRIDGE UNIVERSITY 2023 40 40  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 41 41  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 42 42  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 43 43  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 44 44  9/21/2023 Variations in Heart Rates Bradycardia – slow HR (less than 60 bpm) Tachycardia – fast HR (more than 100 bpm) An artificial pacemaker can be implanted under the skin A wire sends a regular signal into the heart to maintain a normal rhythm © STANBRIDGE UNIVERSITY 2023 45 45  9/21/2023 Electrical Cardiac Cycle Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 46 46  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 47 47  9/21/2023 ECG and Electrical Conductivity For the following slides with pictures of the heart: Depolarization is Yellow Repolarization is Red © STANBRIDGE UNIVERSITY 2023 48 48  9/21/2023 ECG ECG has three waves 1. P wave (0.8 s) ◦ Represents atrial depolarization ◦ Initiates atrial contraction ◦ Occurs when impulse travels from SA node to AV node ◦ Diastolic phase Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 49 49  9/21/2023 ECG: at AV node (Marieb, 2019) © STANBRIDGE UNIVERSITY 2023 50 50  9/21/2023 QRS Complex 2. QRS complex (0.8 s) ◦ Represents ventricular depolarization ◦ Initiates ventricular contraction ◦ Atrial repolarization not shown Marieb, 2019 ◦ Systolic phase © STANBRIDGE UNIVERSITY 2023 51 51  9/21/2023 ECG: Ventricular Depolarization is Complete (Marieb, 2019) © STANBRIDGE UNIVERSITY 2023 52 52  9/21/2023 T wave 3. T wave (0.16 s) ◦ Represents ventricular repolarization ◦ Recovery following ventricular depolarization © STANBRIDGE UNIVERSITY 2023 53 53  9/21/2023 ECG Ventricular Repolarization is Complete (Marieb, 2019) © STANBRIDGE UNIVERSITY 2023 54 54  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 55 55  9/21/2023 Cardiac Output Heart can adjust its strength and speed Cardiac Output (CO) is the amount of blood pumped by each ventricle in 1-minute Stroke Volume (SV) is the amount of blood pumped with each beat Heart Rate (HR) is the speed of contractions HR x SV = CO © STANBRIDGE UNIVERSITY 2023 56 56  9/21/2023 Increasing Cardiac Output Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 57 57  9/21/2023 Blood Supply to the Myocardium Heart needs its own supply of blood Coronary arteries supply blood to the myocardium Right and left coronary arteries branch off the Aorta and feed blood to the heart Used blood drains into the coronary sinus which then drains into the right atrium Arterial supply to heart varies a lot between individuals © STANBRIDGE UNIVERSITY 2023 58 58  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 59 59  9/21/2023 Cardiovascular Vessels © STANBRIDGE UNIVERSITY 2023 60 60  9/21/2023 Systemic Circulation: Heart-> aorta -> artery-> arteriole-> capillary-> venule->vein-superior/inferior vena cava> heart Arteries Veins Arterioles Venules Capillaries Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 61 61  9/21/2023 Two Major Highways Arteries—ALWAYS carry blood away from the heart; in systemic circulation, carry O2-rich blood * Aorta—largest artery Arterioles—smallest arteries Veins—ALWAYS returns blood to the heart; in systemic circulation carry O2-poor blood * Vena cava—largest veins in the body * Venules—smallest veins © STANBRIDGE UNIVERSITY 2023 62 62  9/21/2023 Systemic Circulation Overview Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 63 63  9/21/2023 Pulmonary Circulation Overview (Marieb, 2019) © STANBRIDGE UNIVERSITY 2023 64 64  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 65 65  9/21/2023 Arteries and Veins Arteries Veins Carry blood away from heart Carry blood to heart Thick walls Carries waste by products Higher blood pressure Large diameter lumens Artery lining does not contract Thinner walls Artery lining folds (during Lower blood pressure constriction) Vein lining contracts More elastic Valves © STANBRIDGE UNIVERSITY 2023 66 66  9/21/2023 Arteries and Veins Veins Near The Heart Arteries Near The Heart Inferior Vena Cava Pulmonary Artery Superior Vena Cava Aorta Pulmonary Vein Coronary Artery Coronary Sinus -pulmonary artery carries blood -pulmonary vein carries blood away from the heart toward the heart -blood is oxygen-poor as it heads -blood is oxygen-rich because it comes from the lungs toward the lungs © STANBRIDGE UNIVERSITY 2023 67 67  9/21/2023 Arterial System Elastic Arteries: pressure reservoirs to maintain fairly constant blood flow and to reduce the pressure on arterial walls, located closer to the heart Muscular arteries: more distal, more active in vasoconstriction and less capable of stretching, deliver blood to specific body organs Arterioles: varying sizes; determine blood flow into capillary beds © STANBRIDGE UNIVERSITY 2023 68 68  9/21/2023 Venous System Venules: very porous, right after capillary beds, vary in size Veins: larger lumens and thin walls to accommodate large blood volume ◦ Blood reservoirs: can hold up to 65% of body’s blood at one time Valves: prevent back flow of blood Venous sinuses: coronary sinus and dural venous sinus © STANBRIDGE UNIVERSITY 2023 69 69  9/21/2023 Venous Return 1. Skeletal muscle contraction 2. One-way valves 3. Respiratory movements 4. Sympathetic venoconstriction: smooth muscle constricts under sympathetic control Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 70 70  9/21/2023 Generalized Structure of Arteries, Veins, and Capillaries Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 71 71  9/21/2023 Photomicrograph of a cross section of muscular artery and the corresponding vein Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 72 72  9/21/2023 Capillary Structure (Marieb, 2019) © STANBRIDGE UNIVERSITY 2023 73 73  9/21/2023 Generalized capillary structure Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 74 74  9/21/2023 Capillary Exchange of Respiratory Gases and Nutrients 1. Lipid soluble molecules (ex. respiratory gases) diffuse through membrane 2. A. Small water-soluble solutes (ex. a.a., sugars) pass through fluid filled intercellular capillary clefts B. Or fenestrations 1. Some larger molecules (ex. proteins) actively transported © STANBRIDGE UNIVERSITY 2023 75 75  9/21/2023 Generalized Capillary Transport Mechanisms Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 76 76  9/21/2023 Continuous Capillary Least permeable Most common Ex. skin, muscle Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 77 77  9/21/2023 Fenestrated Capillary Large fenestrations increase permeability Areas of active absorption or filtration ex. kidney and small intestine Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 78 78  9/21/2023 Sinusoid Capillary Most permeable; allows even blood cells to pass Occurs in livers, bone marrow, spleen, adrenal medulla Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 79 79  9/21/2023 Blood Flow through Capillaries Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 80 80  9/21/2023 Two Kinds of Pressure In Capillaries Hydrostatic pressure (HP): ◦ Blood pressure ◦ Due to fluid pressing against a boundary ◦ From capillary (cHP) and interstitial fluid (iHP) Osmotic pressure (OP): ◦ Following concentration gradient ◦ From capillary (cOP) and interstitial fluid (iOP) © STANBRIDGE UNIVERSITY 2023 81 81  9/21/2023 Two Kinds of Pressure In Capillaries ◦Overall: more fluid out than in ◦Lymphatic system collects fluid and leaked proteins (in interstitial tissue) and returns then into the circulation ◦At arterial end → fluid net out ◦At venous end → fluid net in © STANBRIDGE UNIVERSITY 2023 82 82  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 83 83  9/21/2023 Blood Vessels and Lymphatic System (Marieb, 2019) © STANBRIDGE UNIVERSITY 2023 84 84  9/21/2023 Baroreceptor (stretch receptor) Reflexes to Help maintain blood pressure homeostasis Located in carotid sinuses in internal carotid arteries, aortic arch, walls of most major arteries of the neck and thorax © STANBRIDGE UNIVERSITY 2023 85 85  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 86 86  9/21/2023 Marieb, 2019 © STANBRIDGE UNIVERSITY 2023 87 87  9/21/2023 Direct and Indirect Hormonal Renal Control of Blood Pressure (Marieb, 2019) © STANBRIDGE UNIVERSITY 2023 88 88  9/21/2023 Blood Pressure Blood flow in arteries: ◦ Systolic pressure —highest arterial pressure from ventricular contraction ◦ Pressure in aorta is higher than in distal arteries so blood moves to the distal arteries ◦ Diastolic pressure —lowest aortic pressure during diastole ◦ Walls of aorta and other elastic arteries recoil to keep the blood moving forward Sphygmomanometer - blood pressure cuff Measured in millimeters of mercury (mmHg) © STANBRIDGE UNIVERSITY 2023 89 89  9/21/2023 Atherosclerosis Small patchy thickenings that make the arterial walls thicker and stiffer → hypertension If into the opening of the artery → can cause arterial spasms or blood clot → close opening One type of arteriosclerosis © STANBRIDGE UNIVERSITY 2023 90 90  9/21/2023 Atherosclerosis Risk factors: High lipid blood levels, hypercholesterolemia, smoking, hypertension, diet with a lot of saturated and trans fats One type of arteriosclerosis Exercise can increase HDLs which moves cholesterol from vessel walls to the liver © STANBRIDGE UNIVERSITY 2023 91 91  9/21/2023 Arteriosclerosis -Any proliferative or degenerative change to the arteries, reducing elasticity -Affected arteries not able to stretch and recoil in response to blood pressure → hypertension © STANBRIDGE UNIVERSITY 2023 92 92  9/21/2023 Cardiovascular System Blood (Marieb, 2019) © STANBRIDGE UNIVERSITY 2023 93 93  9/21/2023 Functions of Blood 1.Transportation ◦ Gases [O2 & CO2] ◦ Nutrients [electrolytes, vitamins, etc.] ◦ Waste [urea, drugs, etc.] ◦ Hormones [insulin, estrogen, etc.] 2.Regulation ◦ buffers in the blood to maintain pH ◦ blood proteins maintain osmotic pressure ◦ carries heat to the surface- “blushing” 3.Protection ◦ transports immune cells and antibodies ◦ carries coagulation factors that stop bleeding © STANBRIDGE UNIVERSITY 2023 94 94  9/21/2023 Blood 1.Plasma [the liquid portion] 2.Formed Elements a) Red Blood Cells (Erythrocytes) b) White Blood Cells (Leukocytes) c) Platelets (Thrombocytes) Marieb, 2019 Plasma (55% of whole blood) Buffy coat: leukocyctes and platelets (