USMLE Step 1 Physiology Review 54 11 Cardiovascular Physiology Intro (1 of 3)

USMLE Step 1 Physiology Review 54 11 Cardiovascular Physiology Intro (1 of 3)

 

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Begin 54 11 Cardiovascular Physiology Intro (1 of 3) Transcription

The next section will be cardiovascular physiology.  Okay, we’ll start with the function of the cardiovascular system.

What does the cardiovascular system distribute?

  • It distributes oxygen and substrate to all body cells as well as hormones to distant sites.

What does the cardiovascular system collect?

  • It collects waste products and carbon dioxide for excretion.

What does the cardiovascular system control?

  • It controls blood flow to the skin and extremities to enhance or retard heat loss to the environment.

What three blood components does the cardiovascular system deliver in its aid of the body’s defense mechanisms?

  • It delivers antibodies, platelets and leukocytes to affected areas of the body.

Okay, now for some questions about the components of the cardiovascular system, and then we’ll summarize these two small sections.

What are the four components of the cardiovascular system? List them in terms of flow from origin to return. Please pause the tape.

  • First, the heart; second, the arteries; third, microcirculation, which includes capillaries; fourth the veins.

What is the purpose of the heart?

  • It provides the driving force for the cardiovascular system.

What is the purpose of the arteries?

  • They are the distribution channels to the organs.

What is the purpose of the microcirculation component?

  • It provides a region of exchange between the cardiovascular system and the tissues.

What is the purpose of the veins?

  • They serve as the reservoirs of blood and channels of collection to return the blood to the heart.

Student Doctor, please pause the tape and summarized the function and the components of the cardiovascular system discussed thus far.

  • The cardiovascular system distributes oxygen and substrates to all body cells as well as hormones to distances sites. It collects and carbon dioxide for excretion. The cardiovascular system controls blood flow to the skin and extremities to enhance or retard heat lost to the environment. The cardiovascular system aids the body’s defense mechanisms by delivering antibodies, platelets and leukocytes to affected areas of the body. The four components of the cardiovascular system are the heart, which provides the driving force, the arteries which are the distribution channels to the organs, the microcirculation, including the capillaries, which provides an exchange region, and the veins, which serve as reservoirs of blood and channels of collection to return the blood to the heart.

Okay, now we are going to talk about the heart as a pump.

The heart is two pumps in series that are connected by the pulmonary and systemic circulations. Each side of the heart has two values that maintain a one way flow of blood.

What are the two types of values that each side of the heart has?

  • Atrioventricular and semilunar values

What do the atrioventricular values separate?

  • The atria from the ventricles.

Is the right AV Value the tricuspid of mitral value?

  • Tricuspid. By the way, AV is short for atrioventricular.

What kind of value is the left AV Value?

  • It is the mitral value.

When do these values open?

  • They open during ventricular relaxation to allow blood to fill the ventricles.

What is another term for ventricular relaxation?

  • Diastole.

During ventricular contraction, these values close to prevent what?

  • To prevent back flow or regurgitation of blood from the ventricles into the atria.

What is another term for ventricular contraction?

Systole.

What kind of valves are the aortic and pulmonary values?

  • They are semilunar values.

During systole or ventricular contraction, what happens to the semilunar valves?

  • They open to allow the ventricles to eject blood into the arteries.

When do the semilunar valves close?

  • They close during diastole or ventricular relaxation.

What purpose do they serve when closing during diastole?

  • They prevent the back flow of blood into the ventricles.

Student Doctor, please pause the tape and summarize the information discussed this far on AV valves and semilunar valves.

The heart is two pumps in series that are connected by the pulmonary and systemic circulations. Each side of the heart has two valves, an atrioventricular valve and a semilunar valve, that maintain a one-way flow of blood. The atrioventricular valve separates the atria from the ventricles. The right AV valve is the tricuspid valve. The left AV value is the mitral valve. These valves open during ventricular relaxation, or diastole, to allow blood to fill the ventricles. During ventricular contraction, or systole, these valves close to prevent back flow regurgitation of blood from the ventricles into the atria.  The semilunar valves are the aortic and pulmonary valves. During systole, the semilunar valves open to allow the ventricles to eject blood into the arteries. The semilunar valves close during diastole to prevent the back flow of blood into the ventricles.

This completes this section on electrophysiology.

****END OF TRANSCRIPTION****

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