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

Chapter 8 Flashcards by Zach Leupold

The Cardiovascular Responses

to Acute Exercise is:

Increases blood flow to working muscle

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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

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The resting heart rate (rhr)
untrained rhr:
trained: rhr:

60-80

30-40

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Resting heart rate is Affected by

neural tone, temperature, altitude

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Anticipatory response:
HR ↑ above RHR just before start of exercise
-________ ↓
-_______&, ______ ↑

Vagal Tone

- Norepinephrine, epinephrine

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Heart Rate During Exercise is Directly _____ to exercise intensity

proportional

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Maximum HR (HRmax): highest HR achieved in ]

all-out effort to volitional fatigue

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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)

- 208

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Steady-state HR: point of plateau, :

optimal HR for meeting circulatory demands at a given submaximal intensity

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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

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Steady-state HR basis for simple exercise tests that estimate

aerobic fitness and HRmax

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Stroke Volume (SV) ↑ With ↑ intensity up to __ to ___% V•O2max

Beyond this, SV plateaus to ____
Possible exception: elite endurance athletes

40-60

- exhaustion

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SV during maximal exercise ≈ double

standing SV

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SV during maximal exercise only slightly higher than

supine sv

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Supine EDV > ______

standing EDV

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Factors That Increase Stroke Volume:

↑ Preload:
↑ Contractility:
↓ Afterload:

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↑ Preload: end-diastolic ventricular stretch
– ↑ Volume of ______returned to heart
– ↑ Stretch (i.e., ↑ EDV) → ↑ contraction strength
Frank-Starling mechanism

venous blood

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↑ Contractility: inherent ventricle property
– _________ or ________→ ↑ contractility
Independent of EDV (↑ ejection fraction instead)

↑ Norepinephrine or epinephrine

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↑ Preload at lower intensities → ↑ SV

– ↑ Venous return → ↑ EDV → ↑ _____

-preload

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Increase in HR → ↓ filling time → slight ↓ in EDV → ↓ _____

Stroke Volume SV

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↑ ________ at higher intensities → ↑ SV

Contractility

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↓ Afterload via vasodilation → ↑ _______

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HR x SV

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↑ With ↑ intensity, plateaus near

V•O2max

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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+ → ↓ ___

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