Cardiovasular Lecture (Exam 3) Flashcards
Nitric Oxide (NO)
cellular signaling molecule involved in many physiological processes, including dilation or arterioles
-1 of 3 endothelium-derived vasodilators blood flow regulators at rest and during exercise
Cardiovascular Drift
an increase in heart rate during exercise to compensate for a decrease in stroke volume. This compensation helps maintain a constant cardia output
-decrease in SV and a parallel increase in HR
Endothelium
innermost layer of the intima
For cardiovascular drift, when SV decreases:
skin blood flow increases
plasma volume decreases (sweating)
venous return/preload
Maximal Heart Rate (HRmax)
the highest heart rate value attainable during an all-out effort to the point of exhaustion
- 1 beat per year decreases
- estimated HRmax = 208 - (0.7 x age in years)
Normal RHR
- the heart rate at rest, averaging 60 to 80 beats/min
- Trained RHR: as low as 30 to 40 beats/min
- Due to an increase in vagal tone for PSNS
Steady-State HR
the optimal heart rate for meeting circulatory demands at a submaximal intensity
- point of plateau
- if intensity increases, so does steady-state HR
- adjustment to new intensity takes 2 to 3 minutes
- is the basis for simple exercise tests hat estimate aerobic fitness and HRmax
Systolic blood pressure (SBP)
highest arterial blood pressure, resulting from ventricular systole
- top number : 110/*
- ~110 - 120 mmHg
Ventricular Systole
contraction of the heart muscles
SBP normal response to exercise
increase in SBP is proportional to exercise intensity
- 120 mmHg at rest
- > 200 mmHg in trained individuals
- 240-250 mmHg in highly trained individuals
Diastolic blood Pressure (DBP)
lowest arterial pressure, resulting from ventricular diastole
-bottom number: */70
~70 - 80 mmHg
Ventricular Diastole
resting phase of the heart
-heart refills with blood
DBP normal response to exercise
slight decrease or slight increase at max exercise
Sympathetic Nervous System relationship to the heart
-increases HR and force contraction because of stress by releasing of norepinephrine (neurotransmitter)
-carries impulses to SV, AV nodes to increase:
rate of depolarization of SA node
conduction speed
-Increases HR above intrinsic HR
determines HR during physical activity and emotional stress
max HR: 250 bpm
Parasympathetic Nervous System relationship to the heart
-reaches heart through the vagus nerve (vagal tone)
-decrease HR and force of contraction by release acetylcholine
-can slow it as low as 20-30 bpm
-carries impulses to SV, AV nodes to:
cause hyperpolarization of cells, resulting in slower depolarization and decreased HR and contraction
-Decreases HR below intrinsic HR
intrinsic HR: 100 bpm
normal RHR: 60-100 bpm
elite endurance athletes: 35 bpm
Stroke Volume
volume of blood pumped in 1 heartbeat -most blood ejected during systole -end-diastolic volume -end-systolic volume SV(mL/bpm) = EDV - ESV
End Diastolic Volume (EDV)
volume of blood in ventricle before contraction
End Systolic Volume (ESV)
volume of blood in ventricle after contraction
Ejection Fraction
proportion of blood pumped out of the left ventricle each beat
Total Volume of Blood per min: EF (%) = SV / EDV
Contractility
the strength and vigor of the heart’s contraction during systole
Cardiac Output
the volume of blood pumped out by the heart per minute
Q• = HR x SV
-increases with increased intensity
Normal Values for Cardiac Output
resting: Q ~5 L/min
untrained: Qmax ~20 L/min
trained: Qmax 40 L/min
Resting a-vO2diff value
~6 mL O2 / 100 mL blood
Max exercise a-vO2diff value
~16 to 17 mL O2/100 mL blood
a-vO2diff (mL O2 / 100 mL blood)
represents the extent to which oxygen is extracted from the blood as it passes through the body
VO2 = Q• x (a-v- )O2 difference
VO2 = HR x SV x (a-v- )O2 difference
Fick Equation
represents the relationship of the body’s oxygen consumption (VO2) to the arterial – venous oxygen difference (a-vO2diff) and cardiac output (Q)
Sinoartrial (SA) node
Initiates contraction signal (pacemaker)
- contracts w/o neural stimulation with an intrinsic HR of ~ 100 bpm
- pacemaker cells on posterior wall of right atrium (RA)
- stimulates RA, LA contraction
Atrioventricular (AV) node
Built in delay of .13 seconds allowing atria to contract before ventricles
- located in right arterial wall near center of heart
- contracts w/o neural stimulation with an intrinsic HR of ~40 bpm
AV bundle (bundle of his)
relays signals to right and left ventricles
- travels along interventricular septum
- sends signals towards apex of heart
Pirkinje Fibers
sends signals throughout right and left ventricles with 6x faster transmission
stimulate LV, RV contraction
Estimating HRmax equation
208 - (0.7 x age in years)
