1	Chapter 7 Cardiovascular and Respiratory Anatomy and Physiology: Responses to Exercise
2	The Heart Made up of two pumps: Right side: Pulmonary pump Left side: Systemic pump Each pump has two chambers: An Atrium and a Ventricle
3	Figure 7.1
4	Valves Right Atrioventricular valve is the tricuspid valve Left Atrioventricular valve is called the bicuspid valve These two valves prevent back flow of blood from ventricle to atrium during the contraction of the ventricles called systole.
5	Valves Right semilunar valve is called the Pulmonary Valve Left semilunar valve is called the Aortic Valve These valves keep the blood from flowing backward from the aorta or the pulmonary vein into the ventricles during the relaxation phase of the ventricles called diastole
6	Conduction System 1. Sinoatrial Node (SA Node) Pacemaker – where impulses are initiated 2. Internodal pathways 3. Atrioventricular Node (AV Node) Impulses from the internodal pathways are delayed before the pass into the ventricles 4. AV Bundle (Bundle of His) 5. Left and Right Bundle Branches 6. Purkinje fibers
7	Figure 7.2
8	"The delay in the AV..." The delay in the AV Node is to allow time for the blood to get from the atria to the ventricles before ventricular contraction begins. The Left and Right Bundle branches pass down the septum between the two ventricles, and are fast conducting fibers The impulses travel quickly throughout the ventricles so that all parts of the ventricles contract at nearly the same time. The wave of conduction is down the septum and up the sides of the ventricles
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10	Control of Heart The SA Node normally controls the rhythm of the heart and has a discharge frequency of 60-80 impulses per minute. Sympathetic and Parasympathetic NS both transmit signals to the SA Node, and the atria. The ventricles are supplied only with Sympathetic NS Sympathetic effect is to speed up the heart and the parasympathetic effect is to slow it down. Heart Rate > 100bpm is tachycardia; < 60 bpm is bradycardia
11	Electrocardiogram Electrical activity of the heart is “broadcast” throughout the body and can be picked up by electrodes on the skin. When the electrical signals are amplified and recorded on a scope or chart it is called an electrocardiogram. It is composed of P,Q,R,S and t waves. The P-wave is the depolarization of the atria The QRS-complex is the depolarization of the ventricles The T-wave is repolarization of the ventricles. There is no repolarization wave of the atria visible.
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13	Blood Vessels Arteries – begins with the Aorta and carries blood away from the heart to the systems of the body. Arterioles – Smaller branches of the arteries that have smooth muscle the can constrict or dilate Capillaries – very small BVs that may only allow one red blood corpuscle to pass through, and where oxygen, nutrients, hormones, electrolytes, and other substances pass into the interstitial fluid between cells or directly into the cells Venules – collect blood from the capillaries and converge to form veins, which transmit the blood back to the heart.
14	Circulatory System
15	Pressures in the Blood Vessels
16	Blood Two major functions of blood are: The transport of oxygen from the lungs to the tissues for use in cellular metabolism, The removal of carbon dioxide from the tissues to the lungs. Hemoglobin carries the oxygen in a loose bond, and also is used as a buffer, a regulator of hydrogen ion concentration.
17	Respiratory Anatomy and Physiology The primary function of the respiratory system is the basic exchange of oxygen and carbon dioxide.
18	The Lungs Ambient air passes through the nose, and nasal cavities in order to: Warm Humidify, and Purify the air. Air travels to the lungs via the trachea (1^st generation), bronchii (2^nd generation), bronchioles (additional divisions), and into the alveoli (there are 23 divisions before the air reaches the alveoli)
19	Respiratory System
20	Exchange of Air Air fills the lungs through expansion of the pleural cavity. The lungs are passive and expand and recoil by the upward and downward movement of the diaphragm, and the elevation and depression of the rib cage, which increases the diameter of the chest cavity. Quiet breathing mostly controlled from diaphragm. As the diaphragm contracts it lowers the floor of the pleural cavity creating a negative pressure (vacuum) and the air is drawn into the lungs.
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22	"5." 5. During expiration the diaphragm relaxes; the floor of the pleural cavity rises; the elastic recoil of the lungs, chest wall and abdominal structures compress the lungs and the air is expelled. 6. During heavy breathing the elastic recoil is not enough to expire the necessary amount of air, so the abdominal muscles contribute the extra force to expel the air.
23	Pleural Pressure The pressure between the lung pleura and the chest wall pleura. The pressure is normally slightly negative On inspiration, movement of the ribs outward draws the lungs with it,increasing their volume and causing air to flow into the lungs.
24	Alveolar Pressure Pressure in the alveoli when the glottis is open and no air is flowing in or out. To cause air to flow in, the alveolar pressure must drop below atmospheric pressure To flow out of the lungs the pressure must increase above atmospheric pressure.
25	Exchange of Respiratory Gases Oxygen diffuses from the alveoli into the blood, and carbon dioxide diffuses from the blood into the alveoli through the alveolar capillary membrane At rest and at sea level, the partial pressure of oxygen in the blood is about 100 mmHg, and carbon dioxide is 40 mmHg.
26	Control of Respiration Nervous system controls the rate of ventilation by adjusting the rate and depth of breathing Dorsal respiratory group initiates respiration Ventral respiratory group contributes to increased respiration, causes inspiration or expiration Pneumotaxic center controls rate and pattern of breathing, controls the degree of filling of the lungs. The basic reflex is inspiration. When the lungs expand the stretching of the musculature and tissues turn the inspiration off, unless the drive exceeds the reflex.
27	Cardiovascular and Respiratory Responses to Acute Exercise: Cardiovascular Responses 1. Cardiac Output: Q = Stroke volume X Heart rate 2. Aerobic Exercise increases demand on the heart. Cardiac output increases from about 5 L/min to as much as 20-25 L/min. 3. Stroke volume increases until about 50% of maximum oxygen uptake. After this level Q increases through the increase in HR.
28	Stroke volume Regulated by the end-diastolic volume, the amount of blood that fills the left ventricle during diastole. Hormones, epinephrine and norepinephrine of the sympathetic NS produce increased force and contractility of the left ventrical for greater systolic emptying.
29	Aerobic Exercise More blood returning to the heart and the end-diastolic volume is increased Myocardial fibers become stretched which results in a more forceful contraction and a more complete emptying; Frank-Starling mechanism. The increase in cardiac emptying is an increase in the percentage of blood ejected from the heart per beat; Ejection Fraction At the onset of exercise the sympathetic stimulation causes an increased myocardial contractility and stroke volume.
30	Resistance Exercise The intensity of the effort of the resistance work is important to the acute response of stroke volume Heavy resistance exercise results in no increase in SV, particularly when very high intraabdominal and intrathoracic pressures develop during the lift, reducing venous return, and end-diastolic volume Valsalva maneuver increases these pressures and limits venous return
31	Heart Rate 1. HR increases at the onset of exercise due to a reflex stimulation of the sympathetic nervous system 2. Aerobic Exercise: HR increases linearly as workload increases 3. Maximum HR can be estimated by subtracting a person’s age from 220; a 47 year old would have an estimated HRmax: 220-47 = 173 bpm ± 10-12 beats 4. Resistance exercise can increase HR to maximal levels
32	Oxygen Uptake 1.The amount of oxygen consumed by the tissues 2. Aerobic exercise – amount of oxgyen consumed is related to: Mass of the muscles used Metabolic efficiency Intensity of the exercise 3. Maximal Oxygen Uptake is the greatest amount of oxygen that can be used at the cellular level for the entire body.
33	Maximum Oxygen Uptake The accepted measure of cardiopulmonary fitness. Capacity to use oxygen is related to the ability of the heart and circulatory system transport oxygen and to the ability of the tissues to use it. Resting oxygen uptake is about 3.5 ml/kg/min; this value is defined as 1 MET (Metabolic Equivalent) Normal, healthy individuals range from 25 to 80 ml/kg/min; 7.1 to 22.9 METS
34	Calculation of VO₂ VO₂= Q x a-vO₂ difference Q = cardiac output a-vO₂ difference = arteriovenous oxygen difference (the difference between the oxygen content of the arterial and venous blood) VO₂= HR x SV x a-vO₂ difference = 72 beats/min x 65 ml/beat x 6 mlO₂ /100 ml blood = 281 mlO₂/min Divide by person’s weight in kg to get ml/kg/min
35	Calculation of Cardiac Output Oxygen consumption is determined using an open circuit system a-vO₂ difference is determined by extracting blood from the artery to and vein from the working muscles. Fick equation: Q = VO₂¸ a-vO₂ difference Q = 281 mlO₂/min ¸ 6 mlO₂ /100 ml blood = 4,683 ml blood/min = 4.683 L/min
36	Blood Pressure Systolic BP is used to estimate the pressure exerted against the arterial walls as blood is forcefully ejected during the ventricular contraction (systole) phase. Rate-pressure product = HR x SBP **Used in a clinical setting to establish exercise prescription. Diastolic BP is used to estimate the pressure exerted against the walls when there is no blood forcefully ejected through the vessels.
37	Arterial Pressure Fluctuates from a normal systolic of 120 and diastolic of 80 mmHg. Mean arterial pressure is 1/3 the difference between SBP and DBP + DBP MAP = 1/3(SBP-DBP) + DBP
38	Control of Local Circulation Blood flow is a function of resistance. Less resistance to flow the faster the flow rate, more resistance to flow the slower the flow rate. Factors the increase resistance: reduced diameter of the blood vessels Viscosity of the blood Length of the tube Shunting of blood by vasoconstriction and vasodilation
39	Aerobic Exercise Dilation of local arterioles in the working muscles BF increases, peripheral resistance decreases Constriction of BVs in the viscera Sympathetic NS takeover
40	Resistance Exercise Light weights, many reps similar to aerobic exercise and BF increases, peripheral resistance decreases Heavy weights, increased peripheral resistance, BP increases, BF is retarded through working muscles. BF stops when muscle contracts to about 50-60% of its isometric maximum
41	Respiratory Responses Minute ventilation is the volume of air breathed per minute With aerobic exercise Minute Ventilation increases both with the depth of breathing (0.4 to 1.0 L at rest to 3 of more) and the rate of breathing (12-15 breaths/min to 35-45) to a maximum of 90 to 150 L/min. Ratio of minute ventilation to oxygen uptake is called the ventilatory equivalent and ranges at rest between 20-25 L air to 1 L of oxygen.
42	"4." 4. At higher intensities (45-65% in untrained and 70-90% in trained athletes) breathing frequency increases abruptly, and ventilatory equivalent may rise to 35-40 L air /L O₂ 5. Inspired air fills the: Anatomical dead space (~ 150 ml in young adults and increases with age) Physiological dead space Alveoli
43	Gas Responses Diffusion of oxygen and carbon dioxide across the cell membrane is a function of the concentration (pressure) of the gas. Diffusion results from the movement of gas from high concentration to low. During heavy aerobic exercise the partial pressure of oxygen can reach 3 mmHg and CO₂ can reach 90 mmHg.
44	Figure 7.11
45	Blood Transport of Gases and Metabolic By-Products Oxygen is not readily soluble in fluids; ~ 3ml/L of plasma Remainder in combination with Hemoglobin (Hb) Men have 15-16g Hb/ 100 ml Blood Women have about 14g Hb/ 100 ml Blood 1 gram Hb can carry 1.34 ml O₂ Men carry about 20 ml/ 100 ml Blood; women slightly less
46	Carbon dioxide Produced in the cell and transported out of the cell by diffusion. Blood transports it to the lungs 5% is dissolved in the blood; some is transported via Hb. These are limited. About 70% of the CO₂is in combination with water to form bicarbonate (HCO₃^{- )} Initial step is for CO₂to combine with H₂O to form Carbonic Acid H₂CO₃which is a reversible step facilitated by enzyme Carbonic Anhydrase.
47	"6." 6. Once Carbonic acid is formed it is broken down into H+ ions and bicarbonate. 7. The H+ ions combine with the Hb, buffering the acid. 8. Bicarbonate ions diffuse out of the RBCs into the plasma and Cl^- diffuse into the RBCs 9. Lactic Acid, when it accumulates, forms lactate.
48	Cardiovascular and Respiratory Responses to Aerobic and Resistance Training The Heart Increased Cardiac Output, Q Increased Stroke Volume Decreased HR at rest and submaximal exercise Max HR may decrease slightly Resistance training does not appear to hypertrophy the heart
49	Capillary Supply Increased Capillarization, which decreases the diffusion distance for oxgyen and metabolic substrates. No change in capillary density with high intensity resistance training, but low intensity, high volume may increase capillarization.
50	Ventilation 1. Usually unaffected by training 2. Some training adaptations may be increased tidal volume, and breathing frequency with maximum exercise. Oxygen Extraction 1. Arteriovenous oxygen difference reflects the ability of the muscle to extract oxygen 2. With the increases in mitochondria with aerobic training, more oxygen can be extracted from the blood
51	Blood Lactate 1. Aerobic training delays the onset of anaerobic metabolism, thus the blood lactate levels are lower at the same submaximal exercise levels 2. OBLA occurs at a higher percentage of VO_2max (80-90%) 3. May be due to: a. fiber type b. specific local adaptation to training which reduces the production of LA c. changes in hormone release d. more rapid rate of LA removal
52	External Influences on Cardiorespiratory Response Altitude a. Reduced partial pressure of oxygen b. Increase in ventilation at rest and exercise c. Increase in Q at rest and during submax exercise; HR and and Q can increase 30% TO 50% above sea-level; SV remains constant or slightly less. d. decreased oxygen saturation of blood
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54	"e." e. Changes revert back to sea-level values in about one month. f. Increased hemoglobin and RBCs (5-15%) g. Increased diffusing capacity through alveolar membranes h. Maintenance of acid-base balanceof body fluids by renal excretion of HCO₃^- i. Increased capillarization j. 3-6 weeks to adapt
55	Hyperoxic breathing Breathing oxygen rich gas mixturesduring rest periods may postively affect some aspects of exercise performance. May increase the dissolved oxygen content, but not the Hb saturation very much. Psychological effects are positive
56	Smoking Increased airway restriction Increased fluid secretion Swelling in bronchial tree Paralysis of cilia on surfaces of respiratory tract, and reduction in ability to remove excess fluids and foreign particles Carbon monoxide may impair hemodynamic response to exercise and increased catecholamine release, and binding of CO to Hb.
57	Blood Doping Artificially increasing RBC mass by removing one’s own blood and reinfusing the blood back into the body after the body replaces what was removed. The extra blood could come form someone else. The extra blood could be manufactured in one’s own body with the aid of erythropoietin (EPO), which stimulates RBC production Lasts only a couple of weeks VO_2max may increase 10%
58	Risks of blood doping Increased hematocrit levels increase risks for emoblic events such as stroke, myocardial infarction, deep vein thrombosis, or pulmonary embolism.