Chapter 8 Flashcards
The Cardiovascular Responses
to Acute Exercise is:
Increases blood flow to working muscle
The Cardiovascular Responses
to Acute Exercise is:
-Involves altered heart function, peripheral circulatory adaptations to:
- Heart rate
- Stroke volume
- Cardiac output
- Blood pressure
- Blood flow
- Blood
The resting heart rate (rhr)
untrained rhr:
trained: rhr:
60-80
30-40
Resting heart rate is Affected by
neural tone, temperature, altitude
Anticipatory response:
HR ↑ above RHR just before start of exercise
-________ ↓
-_______&, ______ ↑
- Vagal Tone
- Norepinephrine, epinephrine
Heart Rate During Exercise is Directly _____ to exercise intensity
proportional
Maximum HR (HRmax): highest HR achieved in ]
all-out effort to volitional fatigue
Maximum Heart rate (hr max)
- Highly reproducible
- Declines slightly with age
- Estimated HRmax = _____ – age in years
- Better estimated HRmax = ___– (0.7 x age in years)
- 220
- 208
Steady-state HR: point of plateau, :
optimal HR for meeting circulatory demands at a given submaximal intensity
Steady-state HR:
- If intensity ↑, so does _____
- Adjustment to new intensity takes __to__ min
- The more intense, the longer to
- steady-state HR
- 2-3
- achieve
Steady-state HR basis for simple exercise tests that estimate
aerobic fitness and HRmax
Stroke Volume (SV) ↑ With ↑ intensity up to __ to ___% V•O2max
- Beyond this, SV plateaus to ____
- Possible exception: elite endurance athletes
- 40-60
- exhaustion
SV during maximal exercise ≈ double
standing SV
SV during maximal exercise only slightly higher than
supine sv
Supine EDV > ______
standing EDV
Factors That Increase Stroke Volume:
- ↑ Preload:
- ↑ Contractility:
- ↓ Afterload:
↑ Preload: end-diastolic ventricular stretch
– ↑ Volume of ______returned to heart
– ↑ Stretch (i.e., ↑ EDV) → ↑ contraction strength
Frank-Starling mechanism
venous blood
↑ Contractility: inherent ventricle property
– _________ or ________→ ↑ contractility
Independent of EDV (↑ ejection fraction instead)
↑ Norepinephrine or epinephrine
↑ Preload at lower intensities → ↑ SV
– ↑ Venous return → ↑ EDV → ↑ _____
-preload
Increase in HR → ↓ filling time → slight ↓ in EDV → ↓ _____
Stroke Volume SV
↑ ________ at higher intensities → ↑ SV
Contractility
↓ Afterload via vasodilation → ↑ _______
SV
Q=
HR x SV
↑ With ↑ intensity, plateaus near
V•O2max
Normal values of cardiac output:
Resting Q• ~__ L/min
Untrained Q•max ~__ L/min
Trained Q•max __ L/min
- 5
- 20
- 40
Q•max a function of
body size and aerobic fitness
Calculation of tissue O2 consumption depends on blood flow, O2 extraction
V•O2 =
V•O2 = Q• x (a-v- )O2 difference
V•O2 = HR x SV x (a-v- )O2 difference
During endurance exercise, mean arterial pressure (MAP) increases
- Systolic BP ↑ proportional to _____
- Diastolic BP slight ↓ or slight ↑ (at max exercise)
-exercise intensity
MAP = Q• x ______
total peripheral resistance (TPR)
MAP = Q• x total peripheral resistance (TPR)
-Increased MAP from increased Q• helps to increase blood flow
-During prolonged steady-state endurance exercise, MAP due to TPR ↓ slightly
-Vasoconstriction blunted by
______
-sympatholysis
Rate-pressure product =
HR x SBP
Resistance exercise → _________
Up to 480/350 mmHg
More common when using Valsalva maneuver
periodic large increases in MAP
↑ Cardiac output → ↑ ______
available blood flow
Blood Flow Redistribution Must redirect ↑ blood flow to
areas with greatest metabolic need (exercising muscle)
Sympathetic vasoconstriction shunts blood away from ______
- Splanchnic circulation (liver, -pancreas, GI)
- Kidneys
less-active regions
Local vasodilation permits additional blood flow in exercising muscle
- Local VD triggered by metabolic, endothelial products
- Sympathetic vasoconstriction in muscle offset by _______
- Local VD > neural VC
-sympatholysis
As temperature rises, skin VD also occurs
– ↓ Sympathetic VC, ↑______
Permits heat loss through skin
sympathetic VD
Cardiovascular Drift is Associated with
↑ core temperature and dehydration
SV drifts ↓
Skin blood flow ___
Plasma volume ↓ (sweating)
Venous return/preload ↓
↑
during cardiovascular drift:
HR drifts _ to compensate (Q• maintained)
↑
(a-v- )O2 difference (mL O2 / 100 mL blood)
- Arterial O2 content – mixed venous O2 content
- Resting: ~___ mL O2 / 100 mL blood
- Max exercise: ~___ to __ mL O2/100 mL blood
- 6
- 16-17
Mixed venous O2 ≥___ mL O2 / 100 mL blood
- Venous O2 from active muscle ____
- Venous O2 from inactive tissue > active muscle
- Increases mixed ______
4
~0 mL
venous O2 content
↓ Plasma volume → hemoconcentration
Fluid percent of blood ____, cell percent of blood ____
Hematocrit increases up to __% or beyond
decrease, increase
50
Net effects of hemoconcentration
- Red blood cell concentration ↑
- Hemoglobin concentration ↑
- O2-carrying capacity ↑
Cardiovascular responses to exercise complex, fast, and finely tuned
- First priority: maintenance of ________
- —Blood flow can be maintained only as long as BP remains _____
- —Prioritized before other needs (exercise, thermoregulatory, etc.)
- blood pressure
- Stable
Immediate ↑ in ventilation
- Begins before ____
- Anticipatory response from ______
- muscle contractions
- central command
Gradual second phase of ↑ in ventilation
-Driven by _______
– ↑ CO2, H+ sensed by ______
- chemical changes in arterial blood
- chemoreceptors
Ventilation increase proportional to ______
At low-exercise intensity, only _______↑
At high-exercise intensity, _____ also ↑
- metabolic needs of muscle
- Tidal Volume
- Rate
Ventilation recovery after exercise delayed
- Recovery takes several ______
- May be regulated by _______
- minutes
- blood pH, PCO2, temperature
Dyspnea (shortness of breath)
- Common with poor aerobic fitness
- Caused by inability to adjust to high_______
- Also, fatigue in ______
- blood PCO2, H+
- respiratory muscles
Hyperventilation (excessive ventilation)
-Anticipation or anxiety about exercise
– ↑ PCO2 gradient between alveoli (___ mmHg), blood (__ mmHg)
– ↓ Blood PCO2 → ↑ blood pH → ↓ drive to breathe
-40 & 15
Valsalva maneuver: potentially dangerous but accompanies certain types of exercise
- Closed ____
– ↑ ______ P (bearing down)
– ↑ _______P (contracting breathing muscles)
- glottis
- Intra-abdominal
- Intrathoracic
Valsalva maneuver:
High pressures collapse great veins → ↓
venous return → ↓ Q• → ↓ arterial blood pressure
Ventilation matches:
metabolic rate
Ventilatory equivalent for O2
- V•E/V•O2 (_____________)
- Index for control of breathing properly matched to _________
- (L air breathed / L O2 consumed / min)
- to body’s demand for oxygen
Ventilatory threshold is the:
-Associated with lactate threshold and ↑ PCO2
Point where L air breathed > L O2 consumed (50% to 75% VO2 max)
Ventilation normally not limiting factor
- Respiratory muscles account for __% of V•O2, __% of Q• during heavy exercise
- Respiratory muscles very______
- 10
- 15
- fatigue resistant
Airway resistance and gas diffusion normally not
limiting factors in normal, healthy individuals exercising at sea level
Restrictive or obstructive respiratory disorders can
limit performance in patients
Exercise-induced arterial hypoxemia (EIAH) by ________ (40%-50% of elite endurance athletes)
-High Q•, high rate of blood flow through lungs, not sufficient time for saturation with oxygen
ventilation-perfusion mismatch
Metabolic processes produce H+ → ↓ ___
ph
H+ + buffer →
H-buffer
At rest, body slightly alkaline
7.1 to 7.4
Higher pH =
alkalosis
During exercise, body slightly acidic
6.6 to 6.9
Lower pH =
acidosis
Physiological mechanisms to control pH
-Chemical buffers: _______, ____, ______, _______
– ↑ Ventilation helps H+ bind to _______
-Kidneys remove H+ from ____, excrete H+
- bicarbonate, phosphates, proteins, hemoglobin
- bicarbonate
- buffers
Active recovery facilitates pH recovery
Passive recovery: __ to __ min
Active recovery: __ to __ min
- 60-120
- 30-60
