Cardiovascular Physiology and Blood Flow Dynamics

Flashcards covering heart anatomy, blood flow pathways, cardiac output calculations, medical abbreviations like EF and MAP, and the physics of blood flow and lung zones.

Where does deoxygenated blood from the body first empty into the heart?

The right atrium.

What is the specific valve between the right atrium and the right ventricle and why is it named so?

The tricuspid valve, named for having three little leaflets that prevent the backflow of blood.

What causes the heart sounds (the thump) heard through a stethoscope?

The closing of the heart valves due to the pressure building up from the volume of blood emptying into the ventricles.

Trace the blood flow from the right ventricle into the left atrium.

Blood is pumped from the right ventricle through the pulmonic valve into the pulmonary artery, goes to the lungs to be oxygenated, and returns to the left atrium via the four pulmonary veins.

What is the unusual characteristic of pulmonary arteries and pulmonary veins compared to the rest of the systemic circulation?

The pulmonary arteries are deoxygenated and the pulmonary veins are oxygenated, which is the opposite of the rest of the body.

What are the definitions of systole and diastole?

Systole is contraction (the squeeze) and diastole is relaxation.

What is the definition of cardiac output ($Q$) and what is the normal value per minute?

Cardiac output is the total blood ejected from the ventricles each minute. A normal value is about $5\,L/min$.

What is stroke volume ($SV$) and what three factors determine it?

Stroke volume is the volume of blood ejected from the ventricles during each contraction. It is determined by preload, afterload, and contractility.

What is the normal range for an ejection fraction ($EF$) and how is it measured?

The normal range is $55\%$ to $70\%$, and it is measured using an echocardiogram.

What is preload and how does it relate to the Frank-Starling mechanism?

Preload is the stretching of the cardiac myocytes at the end of diastole ($EDV$). According to the Frank-Starling mechanism, the greater the stretch (preload), the greater the force of contraction, up to a point.

Which catheter is used to measure preload and what is the specific measurement term?

A pulmonary artery ($PA$) catheter, also known as a Swan-Ganz, which measures the pulmonary capillary wedge pressure ($PCWP$).

What is afterload?

The resistance against which the ventricles must pump to eject blood.

How do arterioles contribute to the circulatory system?

Arterioles are known as resistance vessels; they have muscular smooth walls that regulate systemic blood pressure and the distribution of blood flow.

What are the primary factors that increase systemic vascular resistance ($SVR$)?

Factors include vasoconstriction (due to plaque, clots, or tumors), increased blood viscosity (polycythemia), and the length of the vessel.

Where is the vasomotor center located?

In the medulla oblongata of the brain stem.

What is the function of baroreceptors, and where are they located?

Baroreceptors are stretch receptors sensitive to pressure changes located in the carotid bodies and the aortic arch.

Which cranial nerves provide innervation for the baroreceptors?

The glossopharyngeal nerve ($CN\,IX$) innervates the carotid bodies and the vagus nerve ($CN\,X$) innervates the aortic arch.

What is the formula for Mean Arterial Pressure ($MAP$)?

$$MAP = \frac{Systolic + 2 \times Diastolic}{3}$$

What is the normal range for $MAP$ and at what level does organ failure become a risk?

The normal range is $80$ to $100\,mmHg$. Organ failure becomes a risk when it drops below $60\,mmHg$.

What are the characteristics of the systemic versus pulmonary circulatory systems?

The systemic system is high pressure and high resistance, while the pulmonary system is low pressure and low resistance.

How does blood flow distribution differ between the apex and the base of a lung in an upright position?

Due to gravity, the base of the lung has significantly more blood flow (perfusion) than the apex.

What characterizes Zone 2 in the three-zone model of the lung?

Zone 2 is the middle portion where ventilation is equal to perfusion ($V = Q$).