Cardiovascular and pulmonary systems

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Cardiovascular and pulmonary systems
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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

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Today

• Cardiovascular
• System review
• Acute adaptations to exercise
• Chronic adaptations to exercise
• Pulmonary
• System review
• Acute adaptations to exercise
• Chronic adaptations to exercise

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Major Cardiovascular Functions

• Delivers oxygen to active tissues
• Aerates blood returned to the lungs
• Transports heat, a byproduct of cellular
  metabolism, from the bodys core to the skin
• Delivers fuel nutrients to active tissues
• Transports hormones, the bodys chemical
  messengers

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CV system

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

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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

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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

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Heart Rate Regulation

• Cardiac muscle possesses intrinsic rhythmicity
• Without external stimuli, the adult heart would
  beat at about 100 bpm

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Regulation of HR

• Sympathetic influence
• Catecholamine (NE/E)
• Results in tachycardia
• Parasympathetic influence
• Acetylcholine
• Results in bradycardia
• Cortical influence
• Anticipatory heart rate

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CV system during exercise

• Acute Adaptations
• Chronic adaptations

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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

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Cardiovascular Dynamics

• Q HR SV (Fick Equation)
• Q cardiac output
• HR heart rate
• SV stroke volume

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Cardiac Output

• 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

Q HR SV
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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

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Training Adaptations Heart

• Eccentric hypertrophy
• Slight thickening in left
• ventricle walls
• Increases left ventricular
• cavity size
• Therefore increases stroke
• volume

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Cardiac output distribution
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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

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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

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Heart Rate

• Elite athletes have a lower heart rate relative
  to training intensity than sedentary people

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

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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

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Oxygen Extraction

• Training increases quantity of O2 that can be
  extracted during exercise

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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
• ? systolic and diastolic blood pressures
• ? maximal stroke volume
• ? maximal cardiac output
• ? extraction of oxygen

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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

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Pulmonary System
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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

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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

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• 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

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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

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Pulmonary system during exercise
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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

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Spirometry

• Static and Dynamic lung volumes are measured
  using a spirometer

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Static Lung Volumes Page 146 of text
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Dynamic lung volumes

• Depend on Volume of air moved
• and the
• Speed of air movement
• FEV/FVC ratio
• MVV

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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.

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Maximal Voluntary Ventilation

• Breath as hard and fast as you can for 15 seconds
• Multiply by 4
• And you have Maximal Voluntary Ventilation
• MVV-
• Males140-180 Litres
• Females 80-120 Litres
• Elite athletes up to 240 Litres

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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

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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

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Alveolar Ventilation Minute ventilation (TV x
breathing rate) dead space
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Gas exchange
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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

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Oxygen Transport in the Blood

• Combined with hemoglobin In loose combination
  with the iron-protein hemoglobin molecule in the
  red blood cell
• Each Red Blood Cell contains 250 million
  hemoglobin molecules
• Each one can bind 4 oxygen molecules

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CO2 Transport in Blood

• In physical solution
• (7) dissolved in the fluid portion of the blood
• As carbamino compounds
• (20) in loose combination with amino acid
  molecules of blood proteins
• As bicarbonate
• (73) combines with water to form carbonic acid

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Regulation of Pulmonary Ventilation
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Regulation at rest Plasma Pco2 and H
Concentration

• The partial pressure of CO2 provides the most
  potent respiratory stimulus at rest
• H in the cerebrospinal fluid bathing the
  central chemoreceptors provides a secondary
  stimulus driving inspiration

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Ventilatory Regulation During Exercise

• Chemical control
• Po2
• Pco2
• H
• Nonchemical control
• Neurogenic factors
• Cortical influence
• Peripheral influence

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Ventilation in steady rate exercise

• Of oxygen ( V E/ V O2)
• Quantity of air breathed per amount of oxygen
  consumed
• Remains relatively constant during steady-rate
  exercise- 25 L air breathed per 1L o2 consumed at
  55 Vo2 max
• Of carbon dioxide ( V E/ V CO2)
• Remains relatively constant during steady-rate
  exercise

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Ventilatory Threshold

• The point at which pulmonary ventilation
  increases disproportionately with oxygen uptake
  during graded exercise
• The excess ventilation relates to the increased
  CO2 production associated with buffering of
  lactic acid

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Pulmonary adaptations to Exercise
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Adaptations to

• Maximal exercise
• Minute ventilation increases
• Increased oxygen uptake

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Submaximal Exercise

• Ventilatory muscles stronger
• Ventilatory equivalent for oxygen
• ( V E/ V O2) reduces? indicates breathing
  efficiency
• This leads to
• Reduced fatigue in ventilatory muscles
• O2 that would have been used by those muscles can
  be used by skeletal muscle.

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Pulmonary Adaptations

• Increased tidal volume
• Decreased breathing frequency
• Increased time between breaths (Increased time
  for oxygen to get into bloodstream)
• Therefore less oxygen in exhaled air

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Summary

• Need to know
• Cardiac and pulmonary Structure and Function
• Veins/arteries/cappilaries
• Flow of blood through the heart
• Alveoli bronchii etc
• Flow of inspired air and pulmonary exchange
• Acute adaptations to exercise
• Chronic adaptations to exercise