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Learning Objectives
By the end of this chapter the student will be able to:
List the main functions and components of the cardiovascular system.
Describe the circuitry of the cardiovascular system.
Construct the physical features of the heart and blood vessels and explain the significance of each in its function.
Determine the approximate percentage of the blood volume found in the cardiovascular system.
Indicate how pressure, blood flow velocity and wall tension differ in the various types of blood vessels.
Describe the relationship between blood flow, pressure, and resistance.
Explain the difference between laminar and turbulent blood flow and their significance.
Compare resistance in series to resistance in parallel and their significance.
Describe the blood pressure profiles throughout the systemic and pulmonary vasculature.
Explain the concept of compliance in the blood vessels and the effects of aging on the compliance and consequently on blood pressure.
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The main function of the cardiovascular system is to deliver oxygenated blood and nutrients to all the tissues of the body and to remove the deoxygenated blood and waste products from the body. The heart acts as an efficient and durable pump that on average beats 100,000 times per day and ejects over 7000 liters of blood per day without a conscious effort on our part. Also, the blood vessels, measuring approximately 60,000 miles in length, act as pipes that are connected to this pump (ie, the heart) in such a way that allows a constant flow of blood to all parts of the body. The blood flow is highly adjustable according to the tissues’ need and activity. However, in a few organs, such as the kidneys and lungs, the blood flow serves additional functions. The kidney, for example, receives much more blood flow than its metabolic requirements mainly due to its excretory function to eliminate waste products from the body.
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There are multiple variables that regulate the blood vessels which are critical to maintain their function. The most important ones are blood flow, blood pressure, and vessel resistance. How they are regulated and related to each other are important in hemostasis and survival. In this chapter we will discuss in some detail the overall circuitry of the body and how it is regulated. In addition, how its parameters work separately, and how they are connected and dependent on each other. Furthermore, we will briefly address the effects of the aging process on blood pressure and its variables.
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Functions of the Cardiovascular System
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To deliver oxygenated blood and nutrients to the tissues, and remove deoxygenated blood and waste products (the main function)
To help maintain several homeostatic functions such as:
Arterial blood pressure
Body fluid balance
Body temperature
Adaptation during various stress conditions (eg, hemorrhage, exercise, and changes in posture)
To transport hormones from the endocrine glands to their target sites
To protect ...