Cardiovascular system Cardiovascular control during exercise Mgr. Tereza Brůžová Cardiovascular system 1.Functions 2.Heart and cardiovascular system a)Anatomy b)Heart rate c)Cardiac cycle d)Intrinsic conduction system e)ECG f)Blood pressure g)Blood distribution 3.Cardiovascular system and exercise a)Useful terms b)Responses vs adaptations c)Parameters 4.Blood a)Hematocrit, viscosity b)Functions c)Hemoglobin 1. Cardiovascular system and its functions §A pump – the heart §A system of channels – the blood vessels §A fluid medium – blood Heart organ with solid fill Shape Description automatically generated with low confidence Shape Description automatically generated What are the roles of the heart and the vessels? A.Delivery (e.g., oxygen and nutrients) B. B.Removal (e.g., carbon dioxide, lactate, other waste products) C. C.Transportation (e.g., hormones) D. D.Maintenance (e.g., body temperature, pH) E. E.Prevention (e.g., infection—immune function) 1. Cardiovascular system and its functions 2a) Heart anatomy https://www.gettyimages.com/detail/illustration/anatomy-of-heart-interior-frontal-section-royalty-f ree-illustration/188057943 2a) Heart anatomy Key points §The two atria receive blood into the heart; the two ventricles send blood from the heart to the rest of the body. § §The left ventricle has a thicker myocardium due to hypertrophy resulting from the resistance against which it must contract. 2b) Heart Rate •Resting heart rates in adults tend to be between 60 and 85 beats/min. However, extended endurance training can lower resting heart rate to 35 beats/min or less. This lower heart rate is thought to be due to decreased intrinsic heart rate and increased parasympathetic stimulation. • What is the average resting heart rate frequency? 2b) Heart Rate •Resting heart rates in adults tend to be between 60 and 80 beats/min. However, extended endurance training can lower resting heart rate to 40 beats/min or less. This lower heart rate is thought to be due to decreased intrinsic heart rate and increased parasympathetic stimulation. • 2b) Cardiac Arrhythmias •BRADYCARDIA – Resting heart rate below 60 beats/min •TACHYCARDIA – Resting heart rate above 100 beats/min •PREMATURE VENTRICULAR CONTRACTIONS (PVCs) – feels like skipped or extra beats •VENTRICULAR TACHYCARDIA – three or more consecutive PVCs that can lead to ventricular fibrillation in which contraction of the ventricular tissue is uncoordinated 2c) Cardiac cycle Diagram Description automatically generated §The event that occurs between two consecutive heartbeats (systole to systole) § §Diastole — relaxation phase during which the chambers fill with blood — 62% of cycle duration § §Systole — contraction phase during which the chambers expel blood — 38% of cycle duration https://en.wikipedia.org/wiki/Cardiac_cycle#/media/File:2027_Phases_of_the_Cardiac_Cycle.jpg Diagram Description automatically generated 2d) Intrinsic Conduction System A pair of black and yellow shoes Description automatically generated with medium confidence 2d) Intrinsic Conduction System Diagram Description automatically generated §Cells of Intrinsic conduction system (ICS) generate their own electrical impulses §Sinoatrial node (SA node) – the pacemaker §it generates electrical impulses the fastest and sets the rhythm for the rest of ICS; heavily controlled §Atrioventricular node (AV node) §AV bundle §Bundle branches §Purkinje fibers (subendocardial conducting network) – contractions of the ventricles https://www.facebook.com/photo/?fbid=497597494434803&set=pcb.497598781101341 2d) Intrinsic Conduction System §Cells of Intrinsic conduction system (ICS) generate their own electrical impulses §Sinoatrial node (SA node) – the pacemaker §it generates electrical impulses the fastest and sets the rhythm for the rest of ICS; heavily controlled §Atrioventricular node (AV node) §AV bundle §Bundle branches §Purkinje fibers (subendocardial conducting network) – contractions of the ventricles Diagram Description automatically generated https://www.facebook.com/photo/?fbid=497597494434803&set=pcb.497598781101341 https://www.youtube.com/watch?v=sysTSvey4Ow&ab_channel=AnatomyHero https://www.frontiersin.org/articles/10.3389/fphys.2020.00170/full 2e) Electrocardiogram (ECG) §Printout shows the heart's electrical activity – can be used to monitor cardiac changes §The P wave – atrial depolarization §The QRS complex – ventricular depolarization and atrial repolarization §ST segment – plateau of action potential, ventricles pump blood §The T wave – ventricular repolarization (diastole) https://www.youtube.com/watch?v=RYZ4daFwMa8&ab_channel=AlilaMedicalMedia https://www.youtube.com/watch?v=v7Q9BrNfIpQ&ab_channel=AlilaMedicalMedia Q – depolarization of the interventricular septum R – depolarization of the main mass of the ventricles S – depolarization at the base of the heart 2f) Blood pressure Shape, arrow Description automatically generated Table Description automatically generated with medium confidence §Systolic blood pressure (SBP) is the highest pressure and diastolic blood pressure (DBP) is the lowest pressure §Mean arterial pressure (MAP) — average pressure exerted by the blood as it travels through arteries §MAP = DBP + [0.333 ´ (SBP – DBP)] § § §Rest Blood Pressure is about 120/80 § §Hypertension: BP = more than 140/90 §Hypotension: BP = less than 90/60 https://medical.andonline.com/systolic-vs-diastolic-blood-pressure/ 2g) Blood distribution A picture containing bubble chart Description automatically generated Diagram Description automatically generated https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4551211/ https://physoc.onlinelibrary.wiley.com/doi/10.1113/JP270593 • 3a) Cardiovascular system and exercise • 3a) Cardiovascular system and exercise 3b) Cardiovascular system and exercise •a) Response vs § §Acute (short-term) §Physiology §Function b) Adaptation § §Chronic (long-term) §Anatomy §Structure 3b) Cardiovascular Response to Acute Exercise •Anticipation of exercise: •Heart rate increases •Adrenalin is released • 3b) Cardiovascular Response to Acute Exercise •During exercise: •Heart rate (HR) increases as exercise intensity increases up to maximal heart rate •Stroke volume (SV) increases up to 40% to 60% VO2max in untrained individuals and up to maximal levels in trained individuals. •Increases in HR and SV during exercise cause cardiac output (Q) to increase •Blood flow and SBP (systolic blood pressure) increase •All result in allowing the body to efficiently meet the increased demands placed on it •Redirection of blood flow – vasoconstriction and vasodilation 3b) Cardiovascular Adaptations to Training §Left ventricle size and wall thickness increase §Resting, submaximal, and maximal stroke volume increases §Maximal heart rate stays the same or decreases §Resting heart rate decreases §Cardiac output is better distributed to active muscles and maximal cardiac output increases §Blood volume increases, as does red cell volume but to a lesser extent §Resting blood pressure does not change or decreases slightly, while blood pressure during submaximal exercise decreases 3c) Resting and Maximum Heart Rate •RHR •Averages 60 to 80 beats/min; can range from 28 to above 100 beats/min •Tends to decrease with age and with increased cardiovascular fitness •Is affected by environmental conditions such as altitude and temperature • •HRmax •The highest heart rate value one can achieve in an all-out effort to the point of exhaustion •Remains constant day to day and changes slightly from year to year •Can be estimated: •HRmax = 220 – age in years or •HRmax = 208 – (0.7 x age) • Arrow: Counter-clockwise curve outline Arrow: Clockwise curve outline https://www.mayoclinic.org/healthy-lifestyle/fitness/in-depth/exercise-intensity/art-20046887#:~:te xt=Subtract%20your%20age%20from%20220,minute%20for%20the%20average%20adult. 3c) Heart Rate and Intensity Arrow: Counter-clockwise curve outline https://www.mayoclinic.org/healthy-lifestyle/fitness/in-depth/exercise-intensity/art-20046887#:~:te xt=Subtract%20your%20age%20from%20220,minute%20for%20the%20average%20adult. 3c) Heart Rate and Training https://www.mayoclinic.org/healthy-lifestyle/fitness/in-depth/exercise-intensity/art-20046887#:~:te xt=Subtract%20your%20age%20from%20220,minute%20for%20the%20average%20adult. 3c) Resting Heart Rate •Decreases with endurance training likely due to more blood returning to heart and changes in autonomic control •Sedentary individuals can decrease RHR by 1 beat/min per week during initial training, but several recent studies have shown small changes of less than 3 beats/min with up to 20 wk of training •Highly trained endurance athletes may have resting heart rates of 30 to 40 beats/min Arrow: Clockwise curve outline https://www.mayoclinic.org/healthy-lifestyle/fitness/in-depth/exercise-intensity/art-20046887#:~:te xt=Subtract%20your%20age%20from%20220,minute%20for%20the%20average%20adult. 3c) Heart Rate During Exercise •SUBMAXIMAL •Decreases proportionately with the amount of training completed •May decrease by 10 to 30 beats/min after 6 months of moderate training at any given rate of work, with the decrease being greater at higher rates of work • •MAXIMAL •Remains unchanged or decreases slightly •A decrease might allow for optimal stroke volume to maximize cardiac output https://www.mayoclinic.org/healthy-lifestyle/fitness/in-depth/exercise-intensity/art-20046887#:~:te xt=Subtract%20your%20age%20from%20220,minute%20for%20the%20average%20adult. 3c) Heart Rate Recovery Period •The time after exercise that it takes your heart to return to its resting rate •With training, heart rate returns to resting level more quickly after exercise •Has been used as an index of cardiorespiratory fitness •Conditions such as altitude or heat can affect it •Should not be used to compare individuals to one another 3c) Heart Rate Recovery Period and Training 3c) Stroke Volume •Determinant of cardiorespiratory endurance capacity at maximal rates of work •Increases with increasing rates of work up to intensities of 40% to 60% of max or higher •May continue to increase up through maximal exercise intensity, generally in highly trained athletes •Magnitude of changes in SV depends on position of body during exercise 3c) Stroke Volume and Intensity 3c) Stroke Volume and Training •Stroke Volumes (SV) for Different States of Training • •Subjects SVrest (ml) SVmax (ml) •Untrained 50-70 80-110 •Trained 70-90 110-150 •Highly trained 90-110 150-220 • 3c) Changes in Q and SV with Increasing Rates of Work 3c) Cardiac Output §Resting value is approximately 5.0 L/min. §Increases directly with increasing exercise intensity to maximal values of between 20 to 40 L/min. §The magnitude of increase varies with body size and endurance conditioning. §When exercise intensity exceeds 40% to 60%, further increases in Q are more a result of increases in HR than SV since SV tends to plateau at higher work rates. 3c) Cardiac Output and Intensity 3c) Cardiac Output and Training 3c) Changes in HR, SV, and Q with Changes in Position and Exercise Intensity 3c) Blood Pressure §Cardiovascular Endurance Exercise §Systolic BP increases in direct proportion to increased exercise intensity §Diastolic BP changes little if any during endurance exercise, regardless of intensity § §Resistance Exercise §Exaggerates BP responses to as high as 480/350 mmHg Graphical user interface Description automatically generated with low confidence 3c) Blood Pressure Responses Heart rate measurements • Measuring Heart Rate Measuring Heart Rate Blood pressure measurements 4. Blood §Connective tissue (the only fluid tissue in the body) §Accounts for approx. 7% of body weight §An adult individual has approx. 5liters of blood §Blood composition §Plasma (55%) §91% water §8% proteins – albumin, globulin (transportation) §1% other molecules §Formed elements (45%) §99% red blood cells (erythrocytes) – carry oxygen §<1% white blood cells (leukocytes) – protect from pathogens §Platelets (<1%) Diagram Description automatically generated with medium confidence Blood placed in a centrifuge Line arrow: Counter-clockwise curve with solid fill * Erythrocytes and platelets do not possess all the typical organelles and they can not divide – they are replaced by stem cells in the bone marrow https://www.khanacademy.org/science/biology/human-biology/circulatory-pulmonary/a/components-of-the -blood https://www.youtube.com/watch?v=yj7bfZKlIp8&t=182s&ab_channel=ProfessorDaveExplains 4a) Blood hematocrit, viscosity §Blood viscosity = thickness of the blood §The more viscous, the more resistant to flow §Higher hematocrits result in higher blood viscosity https://www.khanacademy.org/science/biology/human-biology/circulatory-pulmonary/a/components-of-the -blood 4b) Blood functions §Delivers oxygen to tissues §Delivers nutrients such glucose, amino acids or fatty acids – dissolved in blood or attached to carrier proteins §Transports waste products – CO2, Urea, Lactic acid §Transports hormones §Protects from pathogens (Immunological functions) – white blood cells, Antibodies §Regulates temperature §Buffers and balances acid base homeostasis §Coagulation (to stop bleeding) 4c) Hemoglobin (Hb) Diagram Description automatically generated A picture containing colorful Description automatically generated §Hb comprises 4 globin subunits – two α and two β units §Each globin is attached to a heme b group with an iron atom at the center §Each heme b group can carry one oxygen molecule attached to the iron atom §Hb is present in two forms (influenced by partial pressures and pH) §Relaxed (R) §Tense (T) §Different absorption spectra - used for oxygen levels measurements Heme b group Shape Description automatically generated with medium confidence Various factors such as low pH, high CO[2] and high 2,3 BPG at the level of the tissues favor the taut form, which has low oxygen affinity and releases oxygen in the tissues. Conversely, a high pH, low CO[2], or low 2,3 BPG favors the relaxed form, which can better bind oxygen.^[54] The partial pressure of the system also affects O[2] affinity where, at high partial pressures of oxygen (such as those present in the alveoli), the relaxed (high affinity, R) state is favoured. Inversely, at low partial pressures (such as those present in respiring tissues), the (low affinity, T) tense state is favoured.^[55] Additionally, the binding of oxygen to the iron(II) heme pulls the iron into the plane of the porphyrin ring, causing a slight conformational shift. The shift encourages oxygen to bind to the three remaining heme units within hemoglobin (thus, oxygen binding is cooperative). 4c) Hemoglobin (Hb) Diagram Description automatically generated A picture containing colorful Description automatically generated §Approx. 250 million Hemoglobin molecules per one red blood cell! §100 ml of blood contains ~14-18 g of Hb in men and ~12-14 in women (1 g of Hb combines with 1.34 ml of oxygen) §There are ~20.1 ml of O2 per 100 ml of arterial blood (15 g of Hb x 1.34 ml of O2/g of Hb) in men and ~17.4 ml of O2 per 100 ml of arterial blood (13 g x 1.34) in women §Low iron leads to iron-deficiency anemia, reducing the body’s capacity to transport oxygen—this is more of a problem in women than men Heme b group Shape Description automatically generated with medium confidence Various factors such as low pH, high CO[2] and high 2,3 BPG at the level of the tissues favor the taut form, which has low oxygen affinity and releases oxygen in the tissues. Conversely, a high pH, low CO[2], or low 2,3 BPG favors the relaxed form, which can better bind oxygen.^[54] The partial pressure of the system also affects O[2] affinity where, at high partial pressures of oxygen (such as those present in the alveoli), the relaxed (high affinity, R) state is favoured. Inversely, at low partial pressures (such as those present in respiring tissues), the (low affinity, T) tense state is favoured.^[55] Additionally, the binding of oxygen to the iron(II) heme pulls the iron into the plane of the porphyrin ring, causing a slight conformational shift. The shift encourages oxygen to bind to the three remaining heme units within hemoglobin (thus, oxygen binding is cooperative). Blood KEY POINTS §Blood and lymph transport materials to and from body tissues §Blood is about 55% to 60% plasma and 40% to 45% formed elements (white and red blood cells and blood platelets) §Oxygen travels through the body by binding to hemoglobin in red blood cells §An increase in blood viscosity results in resistance to flow KEY POINTS – Cardiovascular system Vascular system §Arteries §Arterioles §Capillaries §Venules §Veins Carry blood away from the heart Carry blood back to the heart Pulmonary VEINS carry oxygenated blood from the lungs to the heart Pulmonary ARTERIES carry blood with lower oxygen levels to the lungs Vascular system §Arteries §Arterioles §Capillaries §Venules §Veins Blood distribution §Matched to overall metabolic demands §Autoregulation—arterioles within organs or tissues dilate or constrict in response to the local chemical environment §Extrinsic neural control—sympathetic nerves within walls of vessels are stimulated causing vessels to constrict §Determined by the balance between mean arterial pressure and total peripheral resistance Blood Flow Increases with Training §Increased capillarization §of trained muscles (higher capillary-to-fiber ratio) §and in the lungs §Greater opening of existing capillaries in trained muscles §More effective blood redistribution—blood goes where it is needed – vasoconstriction and vasodilation §Blood volume increases Blood Volume and Training §Endurance training, especially intense training, increases blood volume §Blood volume increases due primarily to an increase in plasma volume (increases in ADH, aldosterone, and plasma proteins cause more fluid to be retained in the blood) §Red blood cell volume increases, but increase in plasma volume is higher; thus, hematocrit decreases §Blood viscosity decreases, thus improving circulation and enhancing oxygen delivery §Changes in plasma volume are highly correlated with changes in SV and VO2max Blood and Plasma Volume and Training Let’s try this: •Name a parameter we talked about and answer the following: • 1.Describe chosen parameter in one sentence 2.What is the abbreviation used for this parameter 3.What happens with this parameter with training • •Example: Resting heart rate • 1.Number of heart beats per minute 2.BPM (beats per minute) 3.It decreases 4. • §Resting heart rate §Maximal heart rate §Heart size §Stroke Volume §Cardiac output §Blood flow §Systolic blood pressure §Diastolic blood pressure §Blood volume §Hematocrit §Plasma volume Thank you!