Cardiovascular and pulmonary
systems
Mid Session Quiz -25%
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Next week
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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
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
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
Peripheral Vasculature
• Arteries
– Provides the highpressure 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
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
Heart Rate Regulation
• Cardiac muscle
possesses
intrinsic
rhythmicity
• Without external
stimuli, the adult
heart would beat
at about 100
bpm
Regulation of HR
• Sympathetic influence
– Catecholamine (NE/E)
– Results in tachycardia
• Parasympathetic
influence
– Acetylcholine
– Results in bradycardia
• Cortical influence
– Anticipatory heart rate
CV system during exercise
Acute Adaptations
Chronic adaptations
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
Cardiovascular Dynamics
• Q = HR × SV (Fick
Equation)
– Q: cardiac output
– HR: heart rate
– SV: stroke volume
Cardiac Output
• At Rest
– Q = 5 L p/Min
Q = HR × SV
• 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
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
Training Adaptations: Heart
• Eccentric hypertrophy
– Slight thickening in left
ventricle walls
– Increases left ventricular
cavity size
Therefore increases stroke
volume
Cardiac output
distribution
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
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
Heart Rate
• Elite athletes have
a lower heart rate
relative to training
intensity than
sedentary people
Saltin, 1969
Endurance athletes
Sedentary college BEFORE 55 day aerobic training program
Sedentary college AFTER
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
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
Oxygen Extraction
• Training increases quantity of O2 that can
be extracted during exercise
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
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
Pulmonary System
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
• At rest
– Air in  Tracheahumidified 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
Breathing
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
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
Pulmonary system during
exercise
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
Spirometry
• Static and Dynamic
lung volumes are
measured using a
spirometer
Static
Lung
Volumes
Page 146
of text
Dynamic lung volumes
• Depend on Volume of air moved
and the
• Speed of air movement
FEV/FVC ratio
MVV
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.
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
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
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
Alveolar Ventilation =
Minute ventilation (TV x breathing rate) – dead space
Gas exchange
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
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
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
Regulation of Pulmonary Ventilation
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
Ventilatory Regulation During
Exercise
• Chemical control
– Po2
– Pco2
– [H+]
• Nonchemical control
• Neurogenic factors
– Cortical influence
– Peripheral influence
Ventilation in steady rate exercise
• Of oxygen ( V E/ V O2)
– Quantity of air breathed per amount of
oxygen consumed
– Remains relatively constant during steadyrate exercise- 25 L air breathed per 1L o2
consumed at 55% Vo2 max
• Of carbon dioxide ( V E/ V CO2)
– Remains relatively constant during steadyrate exercise
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
Pulmonary adaptations to
Exercise
Adaptations to
Maximal exercise
• Minute ventilation increases
• Increased oxygen uptake
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.
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
Summary
• Need to know
– Cardiac and pulmonary Structure and
Function
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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