Section 12 (Cardiovascular) Flashcards
What happens if the left ventricular contraction weakens?
Blood backs up into the pulmonary capillaries and causes edema in the lungs
The atria passes __% of the blood they receive into the ventricles passively. The remaining __% is passed actively by the contraction of the atria.
80; 20
Name the heart valves:
- Right atrium to right ventricle
- Right ventricle to pulmonary artery
- Left atrium to left ventricle
- Left ventricle to aorta
- Tricuspid valve
- Pulmonary valve
- Mitral valve
- Aortic valve
How does oxygenated blood supply the myocardium from the coronary arteries?
Oxygenated blood passes through an opening just above the aortic valve to the left main coronary artery and right coronary artery
What does the deoxygenated blood pass through in order to get back to right atrium?
Coronary sinus
In EKG, what does the P-wave indicate?
Depolarization of both atria
In EKG, what does the P-R interval indicate?
Impulse transmission atria to ventricles
In EKG, what does the QRS complex indicate?
Ventricular depolarization
In EKG, what does the S-T segment indicate?
Early phase of reploarization of both ventricles, indicates O2 supply of ventricular myocardium
In EKG, what does the T-wave indicate?
Repolarization of both ventricles, also sensitive to ventricular O2 supply
What is the normal end diastolic volume (S1 sound)?
120 mL
What is the normal end systolic volume (S2 sound)?
50 mL
What is stroke volume (expressed mathematically)?
[End Diastolic Volume] - [End Systolic Volume]
120 mL - 50 mL = 70 mL (resting average)
The amount of blood (mL) pumped from the heart per beat (mL/beat)
Stroke Volume
The amount of blood left in the ventricle at the end of dustily just prior to ventricular contraction
End diastolic volume (EDV)
The amount of blood left in the ventricle just after the heart finishes contracting
End systolic volume (ESV)
The percentage of the end diastolic volume ejected with each systole (contraction)
Ejection fraction
What is the mathematical expression of ejection fraction?
Ejection fraction = ([EDV-ESV]/ [EDV]) OR
EF = [SV]/[EDV]
What two factors primarily affect stroke volume?
- Preload (the stretch placed on the ventricles by the EDV just prior to contraction)
- The actual force or contractility of the myocardial contraction or inotropic effect
The the myocardial contraction force increases; the force of contraction decreases
positive inotropic effect; negative inotropic effect
How does stroke volume change with exercise?
It increases (compared to resting)
How does ejection fraction change with exercise?
It increases (compared to resting)
How does SV change in supine to standing?
It decreases: blood rushes down to LEs, causing a drop in venous return
How does HR change in supine to standing?
It increases to make up for the drop in stroke volume
A change in inotropic state means…
a greater or lesser force of contraction at a given EDV or preload
What causes a positive inotropic effect?
activation of the autonomic nervous system (exercise); increase means contractility increases (positive effect: frank-starling curve)
What happens to myocardial contractility in heart failure?
HF causes weak myocardial contractility (there is a higher end diastolic volume and lower stroke volume)
______ effect involves an upward and left shift of the Frank-Starling curve at a given preload (EDV) or an increased ejection fraction
Positive (during exercise, healthy hearts)
______ effect involves a downward and right shift of the Frank-Starling curve at a given preload (EDV) or a decreased ejection fraction
Negative (occurs in heart failure)
What is the main factor that contributes to a larger maximum cardiac output in trained subjects when compared to untrained?
Stroke volume
Both untrained and trained individual’s SV plates at ____% max
40-50
The cardiac output (Q) at submax workloads in trained individuals is [greater/lesser] than untrained individuals when VO2 is constant.
Lesser; trained have a greater a-VO2 difference, so they are able to use O2 more efficiently than untrained individuals, thus requiring less Q
SV in trained individuals is [greater/lesser] than untrained individuals
Greater AT ALL WORK LOADS!!
The max Q in trained individuals is [greater/lesser] than untrained individuals.
Greater
The amount of blood ejected out of the heart per minute from the left ventricle
Cardiac output (Q)
What are the different ways cardiac output is expresses mathematically
Q (L/min) = HR (bpm) x SV (L/min)
Q = [VO2] / [a-VO2 diff]
VO2 = (Q) x [a-VO2 diff]
Main factor contributing to the larger max Q in trained subjects compared to untrained subjects, is the increase in max _____
SV
What does an increase in Left ventricular preload cause?
Increased SV
Compresses veins in the legs causing blood to be propelled to the heart
Skeletal muscle pump
Inspiration; increased abdominal pressure with a lowering diaphragm, forcing blood toward the hart
Respiratory and abdominal pumps
What does the decreased intrathoracic pressure do to blood circulation cause?
causes a “sucking” up of blood
What contributes to increased venous return during exercise?
- Skeletal muscle pumps
2. Respiratory and abdominal pumps
What pushes blood into the heart?
Expiration; increased intrathoracic volume
During exercises lasting over 30-60 minutes, Q is maintained but SV decreases and HR increases, this is referred to as
Cardiovascular drift
What two mechanical factors affect blood flow?
BP and resistance to blood flow (TSPR)
Q = BP/TSPR
The greater BP, the [greater/ lesser] Q. The greater TSPR the [greater/ lesser] Q
Greater; lesser
Express blood pressure mathematical in terms of Q and TSPR
BP = Q x TSPR
Why does BP increase during exercise when the total systemic peripheral resistance falls during exercise?
The heart needs to pump more blood to gain the same amount of O2 consumption; the heart is very dependent on blood flow where sk. m. is not; Q increases more than the TSPR
During rest the heart consumes ___% of O2 brought in the arterial blood. During exercise the sk. m. consumes __% of the O2 brought in the arterial blood.
70; 77
heart already extracting close to max O2 at rest, to increase O2 delivery to meet the increased myocardial demand for O2 during exercise the heart increases coronary circulation from 250-1000 mL/ min during exercise
HR at a given O2 will be [less/more] in trained than untrained
Less
HR at submax O2 is untrained is [less/more] than trained
More
HR at max O2 is untrained is [less/more] than trained
More; Almost the same but only a little higher
