Cardiovascular Flashcards
Permitting the exchange of nutrients and gases between the blood and tissue cells is the primary function of
capillaries
The fact that the left ventricle of the heart is thicker than the right ventricle reveals that it
pumps blood against a greater resistance and pressure
Which of the following is NOT part of the intrinsic conduction system of the heart?
atrioventricular (AV) valve
Purkinje fibres
sinoatrial (SA) node
atriventricular bundle
atrioventricular (AV) node
The atrioventricular (AV) valve is not part of the intrinsic conduction system of the heart.
Which chambers of the heart contain oxygenated blood?
left atrium and ventricle
Isovolumetric contraction ________
refers to the short period during ventricular systole when the ventricles are completely closed chambers
The Frank-Starling Law states that, if other factors are constant, a ________
a higher end-diastolic volume (EDV) will produce a higher stroke volume (SV).
________ is a faster than normal heart rate.
Tachycardia
________ control blood flow into the ventricles.
The atrioventricular (AV) valves
The structure dividing the two atria of the heart is called the
atrial septum
The anatomy of the intrinsic conduction system causes contraction of the ventricles to begin at the apex and move superiorly. Why is this important?
because the Purkinje fibers conduct action potentials away from the heart apex.
How does a high heart rate affect stroke volume?
A high heart rate reduces the end diastolic volume (EDV) and stroke volume (SV), because there is less time for ventricular filling.
What is the effect of high blood pressure on cardiac output?
High blood pressure increases afterload and reduces cardiac output (CO).
What is the primary role of the parasympathetic division of the autonomic nervous system in regulating heart rate
The parasympathetic division normally inhibits the heart, keeping it beating at a slower rate than it would be on its own
What is an effect of epinephrine, norepinephrine, and thyroxine?
increase contractility
What is the structural difference between arteries and veins in the context of their tunica media thickness?
Arteries have a thicker tunica media than veins.
What component of veins allows them to function as a volume reservoir and hold a large volume
high compliance
Vein have a:
- Large radius
- Low resistance
- Less smooth muscle with little myogenictone
- Less elastin so little recoil
What are the three blood vessels - describe
- Arteries: carry blood AWAY from the heart (mostly oxygenated, not always!)
- Capillaries: exchange of gases, nutrients & waste products between blood & tissues
- Veins: return blood TOWARD the heart (mostly de-oxygenated, not always!)
Discuss principles underlying blood pressure measurement
technique
Can be measured indirectly using
sphygmomanometer
▪ Korotkov sounds are heard when pressure is released slowly.
▪ Sounds heard when determining blood
pressure are Systolic pressure (– Pressure when sounds first occur as blood starts to
spurt through artery) and dystolic (Pressure when sounds disappear because artery no longer constricted; blood flowing freely_
▪ Sounds are distinct from heart sounds
associated with valve closure
Describe how the cardiovascular system responds during aerobic exercise. In your response, describe what happens to the heart, absolute cardiac output, the distribution of cardiac output, mean arterial pressure and total peripheral resistance.
During aerobic exercise, the cardiovascular system responds by increasing heart rate, and stroke volume.
As a result, cardiac output is increased to deliver more oxygen to the working muscles.
It redistributes blood flow to prioritize the active tissues and muscles, decreases blood flow to non-essential organs (digestive system)
and it modulates mean arterial pressure by increasing as a result of cardiac output and total peripheral resistance is decreased to maintain overall cardiovascular function.
These adjustments help support increased physical activity and maintain the body’s metabolic needs.
What is the difference in lumen size between arteries and veins, and why do these differences exist in their structures
Arteries have smaller lumens than veins, a characteristic that helps to maintain the pressure of blood moving through the system
Veins have a larger lumen. Veins withstand a much lower pressure from the blood that flows through them. Their walls are considerably thinner and their lumens are correspondingly larger in diameter, allowing more blood to flow with less vessel resistance.
What component of arteries allows them to function as a pressure reservoir and maintain the onward flow of blood during ventricular diastole?
Elastin
What is the function of baroreceptors in the aortic arch and carotid arteries
Chemoreceptors in the aortic arch and carotid arteries detect changes in blood pressure.
Chemoreceptors, specifically baroreceptors, located in the aortic arch and carotid arteries, play a crucial role in detecting changes in blood pressure and providing feedback to help regulate and maintain blood pressure within a normal range. These receptors help the body respond to changes in blood pressure by regulating heart rate and vascular tone.
How many circuits does the cardiovascular system have?
Pulmonary & systemic
Which system has the highest pressure?
Systemic
How many chambers does the heart have?
Four
2 x atrium (Left & Right)
2 x ventricles (Left & Right)
Which chamber is the most muscular?
Left ventricle
How many valves does the heart have?
2 x atrioventricular valves (tricuspid & bicuspid)
– 2 x semilunar valves (pulmonary & aortic)
Why are valves important
To stop backflow of blood
What is stroke volume
Stroke volume is end diastolic pressure - end systolic pressure.
It represents the volume of blood pumped out of ventricle during each systolic cardiac contraction.
Discuss how an increase in venous return increases cardiac output.
By increasing the venous pressure gradient, which increases preload and, therefore, cardiac output by the Frank-Starling mechanism.
Describe the structure of the cardiac muscle and how this structure helps in
spread of action potentials through the heart
All cardiac muscle cells are electrically linked to one another, by intercalated discs which allow the action potential to pass from one cell to the next.
Describe the spread of excitation through the heart
The excitation signal travels to: Your atria (top heart chambers), telling them to contract. The atrioventricular (AV) node, delaying the signal until your atria are empty of blood. The bundle of His (center bundle of nerve fibers), carrying the signal to the Purkinje fibers.
Describe excitation-contraction coupling in the cardiac muscle
Excitation-contraction (E-C) coupling refers to the series of events that link the action potential (excitation) of the muscle cell membrane (the sarcolemma) to muscular contraction.
What factors ensure continued & uninterrupted unidirectional
flow of blood through the systemic circulation?
Valves maintain direction of blood flow
Provide labels for A, B and C of a normal ECG trace and describe each event
P Wave - depolarisation of the atria
QRS wave - depolarisation of the ventricular, leading to contraction of ventricles
T wave = repolarization of the ventricle
The mechanical phases of the cardiac cycle are ventricular filling, isovolumetric contraction, ventricular ejection, and isovolumetric relaxation.
a) For each phase, describe the pressure differential between relevant heart chambers or vessels, and
consequent opening or closure of atrioventricular (AV) and semilunar (SL) valves.
Ventricular filling: Blood flows from the vena cava and pulmonary veins into the right and left atria respectively, before flowing directly into the ventricles. The ventricles fill with blood at a steadily decreasing rate, until the ventricles’ pressure is equal to that in the veins.
Isovolumetric contraction: The isovolumetric contraction causes left ventricular pressure to rise above atrial pressure, which closes the mitral valve and produces the first heart sound. The aortic valve opens at the end of isovolumetric contraction when left ventricular pressure exceeds aortic pressure.
Ventricular ejection: When the heart contracts, it pumps out — ejects — blood from the two lower heart chambers, called ventricles. When the heart relaxes, the ventricles refill with blood.
Isovolumetric relaxation: The ventricular pressures drop below the diastolic aortic and pulmonary pressures (80 mmHg and 10 mmHg respectively), the aortic and pulmonary valves close producing the second heart sound (point d). This marks the beginning of diastole.
Ventricular filling is comprised of TWO (2) phases. List and describe these TWO (2) phases
Rapid Ventricular Filling: The initial and rapid filling of the ventricles
Diastasis: The ventricles continue to fill, although at a slower rate, as atrial pressure remains higher than ventricular pressure.
