Blood Pressure

With each contraction of the ventricles, blood is forced into the arteries of the body. The force with which the blood is pushing against the artery walls when the ventricles are contracting is known as the systolic pressure. The systolic pressure averages 120 millimeters of mercury (mm Hg). The pressure that results in the arteries when the ventricles are relaxed is known as the diastolic pressure. The diastolic pressure indicates the lowest, constant pressure or strain on the vessel wall. The diastolic pressure averages 80 mm Hg.

Exercise 27.1

Stethoscope Method of Blood Pressure Determination

Materials:

Stethoscope

Sphygmomanometer

1. Wrap the sphygmomanometer cuff around your lab partner's upper arm, which should be resting on the lab table:

2. Make sure the metering valve on the bulb of the sphygmomanometer is closed.

3. Pump up the sphygmomanometer cuff. While watching the sphygmomanometer gauge, inflate the cuff to about 180 mm Hg.

4. Place the bell of the stethoscope just below the sphygmomanometer and midway between the epicondyles of the humerus. At this point, you will be listening to sounds in the brachial artery.

5. Slowly release the air from the sphygmomanometer cuff by loosening the valve on the bulb.

6. While watching the sphygmomanometer gauge, listen for the sound of blood as it passes through the brachial artery. When you hear this sound, note the location of the needle on the gauge. This is the systolic pressure.

7. Continue observing the sphygmomanometer gauge while listening to the sounds through the stethoscope. When you are no longer able to detect a sound, note the location of the needle on the gauge. This is the diastolic pressure.

8. Lab partners should change positions and repeat the above procedure.

9. Record your systolic pressure below.

10. Record your diastolic pressure below.

Exercise 27.2

Figure 27.1 shows a view of the internal anatomy of the heart. Using your textbook as a guide, fill in the labels on the figure.

Figure 27.2 shows an anterior and a posterior view of the heart. Using your textbook as a guide, fill in the labels on the figure.

Exercise 27.3

Study the model of the heart. Identify the following structures on the model: aorta, aortic semilunar valve, apex, base, chordae tendineae, circumflex artery, coronary sinus, inferior vena cava, innominate artery, interventricular septum, left anterior descending artery, left atrium, left common carotid artery, left coronary artery, left pulmonary artery, left subclavian artery, left ventricle, mitral valve, myocardium, opening to the coronary sinus, papillary muscle, pulmonary semilunar valve, pulmonary trunk, right atrium, right coronary artery, right pulmonary artery, right ventricle, superior vena cava, and tricuspid valve.

Exercise 27.4

Identify the following structures on the sheep heart: aortic semilunar valve, apex, base, chordae tendineae, interventricular septum, left atrium, left ventricle, mitral valve, myocardium, papillary muscle, pulmonary semilunar valve, right atrium, right ventricle, and tricuspid valve.

External Structure Sheep Heart

Figure 27.1 Internal Anatomy of the Heart

Aorta Aortic semilunar valve Apex Chordae tendineae Endocardium Epicardium (Visceral pericardium)

Inferior vena cava Innominate artery Interventricular septum Left atrium Left common carotid artery

Left pulmonary artery Left subclavian artery Left ventricle Mitral valve (X2) Myocardium Opening to coronary sinus

Papillary muscle Parietal pericardium Pericardial cavity Pulmonary semilunar valve Pulmonary trunk

Pulmonary veins Right atrium Right pulmonary artery Right ventricle Semilunar valve Superior vena cava

Tricuspid valve (X2)

Figure 27.2 External Anatomy of the Heart

ANTERIOR VIEW: Aortic arch Ascending aorta Great cardiac vein Inferior vena cava Innominate artery

Left anterior descending artery Left atrium Left common carotid artery Left pulmonary artery Left subclavian artery

Left ventricle Marginal artery Pulmonary trunk Right atrium Right coronary artery Right ventricle Superior vena cava

Posterior View Coronary Arteries

POSTERIOR VIEW: Aortic arch Circumflex artery Coronary sinus Inferior vena cava Innominate artery Left atrium Left common carotid artery Left pulmonary artery Left pulmonary veins Left subclavian artery Middle cardiac vein Posterior interventricular artery Right atrium Right coronary artery Right pulmonary artery Right pulmonary veins Superior vena cava

Name the three arteries that originate from the aortic arch.

After blood has passed over the mitral valve, the blood will enter the (4) (chamber).

Name the two layers that make up the covering of the heart.

What structure of the heart is located between the fifth and six ribs and 7 to 9 centimeters left of the midline?

The scientific name for cardiac muscle is (8) .

What is the name of the partition that separates the two ventricles?

Name the two main branches of the left coronary artery.

Name the two large veins that return blood to the heart after the blood has circulated to the various body structures.

Name the two valves of the heart that have chordae tendineae and papillary muscle associated with them.

Give the scientific location of the heart.

Name the three layers that make up the wall of the heart.

Name the four chambers of the heart.

24. _ The constant pressure or strain that an artery must withstand is known as the (24) pressure.

25. _ When using the arm to take a blood pressure, what artery is used?

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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