Cardiovascular and pulmonary systems

1. Cardiovascular and pulmonary systems

2. Mid Session Quiz -25% • Next week • Will be on WebCT assessments • From 9 am 25/8/08  5 pm 29/8/08 • Multiple choice and matching • Practice test (question types) up now, practice (content) on companion website for text. • Covers all lecture, lab, text and reading materials from weeks 1-5 • Time limit = ½ hour • Grades will be released automatically • Contact me if tech problems

3. Today • Cardiovascular • System review • Acute adaptations to exercise • Chronic adaptations to exercise • Pulmonary • System review • Acute adaptations to exercise • Chronic adaptations to exercise

4. Major Cardiovascular Functions • Delivers oxygen to active tissues • Aerates blood returned to the lungs • Transports heat, a byproduct of cellular metabolism, from the body’s core to the skin • Delivers fuel nutrients to active tissues • Transports hormones, the body’s chemical messengers

5. CV system • Consists of; • Blood ~ 5L or 8% body mass • 55% plasma • 45% formed elements (99%RBC, 1%WBC) • Heart- pump • Arteries- High pressure transport • Capillaries- Exchange vessels • Veins- Low pressure transport

8. Peripheral Vasculature • Arteries • Provides the high-pressure tubing that conducts oxygenated blood to the tissues • Capillaries • Site of gas, nutrient, and waste exchange • Veins • Provides a large systemic blood reservoir and conducts deoxygenated blood back to the heart

10. Blood Pressure • Systolic blood pressure • Highest arterial pressure measured after left ventricular contraction (systole) • e.g., 120 mm Hg • Diastolic blood pressure • Lowest arterial pressure measured during left ventricular relaxation (diastole) • e.g., 80 mm Hg

13. Heart Rate Regulation • Cardiac muscle possesses intrinsic rhythmicity • Without external stimuli, the adult heart would beat at about 100 bpm

14. Regulation of HR • Sympathetic influence • Catecholamine (NE/E) • Results in tachycardia • Parasympathetic influence • Acetylcholine • Results in bradycardia • Cortical influence • Anticipatory heart rate

15. CV system during exercise Acute Adaptations Chronic adaptations

16. Heart rate • At rest- 60-80 bpm • Trained athletes  lower (28-40 bpm) • Pre exercise- anticipatory response • Sympathetic nervous system release N/E and ephedrine • Increases during exercise to steady state

17. Cardiovascular Dynamics • Q = HR × SV (Fick Equation) • Q: cardiac output • HR: heart rate • SV: stroke volume

18. Cardiac Output Q = HR × SV • At Rest • Q = 5 L p/Min • Trained RHR = 50 bpm, SV = 71 • Untrained RHR = 70 bpm, SV = 100 • During Exercise • Untrained- Q = 22 000 mL p/min, MHR = 195 • SV av 113 ml blood p/beat • Trained- Q= 35 000 ml p/min, MHR = 195 • SV av 179 ml blood p/beat

19. Increases in Stroke Volume • Increases in response to exercise • Is ability to fill ventricles, particularly left ventricle • And more forceful contraction to pump blood out • Training adaptations • left ventricle hypertrophy • Increased blood volume • Reduced resistance to blood flow

20. Training Adaptations: Heart • Eccentric hypertrophy • Slight thickening in left ventricle walls • Increases left ventricular cavity size Therefore increases stroke volume

21. Cardiac output distribution

22. Oxygen transport • When arterial blood is saturated with oxygen : • 1 litre blood carries 200 ml oxygen • During exercise • Q = 22L p /min • = 4.4L oxygen per minute • At rest • Q = 5L p/ min • = 1 L oxygen per minute • 250 ml required at rest • Remainder- oxygen reserves

23. Stroke Volume and Cardiac Output • Exercise  increases stroke volume during rest and exercise • Slight decrease heart rate • Increase in cardiac output comes from increased stroke volume

24. Heart Rate • Elite athletes have a lower heart rate relative to training intensity than sedentary people

25. Saltin, 1969 Endurance athletes Sedentary college BEFORE 55 day aerobic training program Sedentary college AFTER

26. Total Blood Volume • * Plasma volume • 4 training sessions can increase plasma volume by 20% • *Increased RBC • - Number of RBC increases, but due to increase in Plasma volume, concentration stays the same

27. Blood Pressure • Aerobic exercise reduces systolic and diastolic BP at rest and during exercise • Particularly systolic • Caused by decrease in catecholamines • Another reason for exercise to be prescribed for those with hypertension • Resistance training not recommended due to acute high BP it causes

28. Oxygen Extraction • Training increases quantity of O2 that can be extracted during exercise

29. Chronic Adaptations to Exercise- Chapter 10 • Cardiovascular adaptations to training are extremely important for improving endurance exercise performance, and preventing cardiovascular diseases. • The more important of these adaptations are, • Size of heart ventricular volumes • total blood volume • - plasma volume • - red cell mass •  systolicand diastolic blood pressures • maximal stroke volume • maximal cardiac output •  extraction of oxygen

30. Factors Affecting Chronic adaptations • Initial CV fitness • Training: • Frequency- 3 x p/week • Only slightly higher gains for 4 or 5 times p/week • Intensity • Most critical • Minimum is 130/ 140 bpm = (av) 50-55% Vo2 max/ 70% HR max • Higher = better • Time • Or duration- 30 min is minimum • Type • Specificity

31. Pulmonary System

33. Pulmonary Structure and Function • The ventilatory system • Supplies oxygen required in metabolism • Eliminates carbon dioxide produced in metabolism • Regulates hydrogen ion concentration [H+] to maintain acid-base balance

34. Breathing • At rest • Air in  Trachea- humidified and brought to body temperature •  divides into 2 branches lungs • Lungs hold 4-6 litres of ambient air- huge surface area • 300 million alveoli • 250 ml oxygen in and 200 ml Carbon dioxide out each minute

35. Inspiration • Ribs rise • Diaphragm contracts (flattens) Moves downward (10cm) • Thoracic volume • Air in lungs expands • Pressure to 5 mm Hg below atmospheric pressure • Difference between outside air and lungs = air is sucked in until pressure inside and out is the same

36. Expiration • Ribs move back down • Diaphragm relaxes (rises) • Thoracic volume • Pressure • Difference between outside air and lungs = air is pushed out until pressure inside and out is the same

38. Pulmonary system during exercise

39. Lung Volumes • Static lung volume tests • Evaluate the dimensional component for air movement within the pulmonary tract, and impose no time limitation on the subject • Dynamic lung volume tests • Evaluate the power component of pulmonary performance during different phases of the ventilatory excursion

40. Spirometry • Static and Dynamic lung volumes are measured using a spirometer

41. Static Lung Volumes Page 146 of text

42. Dynamic lung volumes • Depend on Volume of air moved and the • Speed of air movement FEV/FVC ratio MVV

43. FEV/FVC Ratio • Forced Expiratory Volume • Forced Vital Capacity • Ratio tells us the speed at which air can be forced out of lungs • Normal = 85% FVC can be expired in 1 second.

44. Maximal Voluntary Ventilation • Breath as hard and fast as you can for 15 seconds • Multiply by 4 • And you have Maximal Voluntary Ventilation • MVV- • Males:140-180 Litres • Females: 80-120 Litres • Elite athletes up to 240 Litres

45. Minute Ventilation At Rest • 12 breaths per minute • Tidal volume = 0.5L per breath • = 6 Litres of air breathed p/min During Exercise • 50 breaths p/ minute • Tidal Volume = 2 L per breath • = 100L p/min

46. Alveolar Ventilation • Minute ventilation is just total amount of air • Alveolar ventilation refers to the portion of minute ventilation that mixes with the air in the alveolar chambers • Minute ventilation minus anatomical dead space (150-200 ml)- the air that is in the trachea, bronchi etc

47. Alveolar Ventilation = Minute ventilation (TV x breathing rate) – dead space

48. Gas exchange

49. Gas Exchange in the Body • The exchange of gases between the lungs and blood, and their movement at the tissue level, takes place passively by diffusion