THE CARDIOVASCULAR SYSTEM

The Heart

Q 1 The heart is a cone-shaped muscular organ located within the thoracic cavity. Its apex rests on the diaphragm and its base is at the level of the second rib. The coronary arteries that nourish the myocardium arise from the aorta.

The coronary sinus empties into the right atrium. Relative to the role of the heart chambers, the atria are receiving chambers, the ventricles are the discharging chambers. Membrane that lines the heart and forms valve flaps is called the endocardium.

Outermost layers of the heart is called epicardium. Fluid that fills the pericardial sac acts to decrease friction during heart activity. Heart muscle, myocardium, composed of specialized type of muscle tissue called cardiac muscle.

Q 2 From right atrium through tricuspid valve to the right ventricle through the pulmonary semi-lunar valve to the pulmonary trunk to the right and left pulmonary arteries, to the capillary beds of the lungs, to the right and left pulmonary veins to the left atrium of the heart

. . . through the mitral (bicuspid) valve, to the left ventricle through the aortic semilunar valve, to the aorta, to the systemic arteries, to the capillaries of the body tissues, to the systemic veins, to the superior vena cava and inferior vena cava which enter the right atrium of the heart.

A – vessels serving head and upper limbs B – vessels serving trunk and lower limbs C – vessels serving viscera D – pulmonary circulation E – pulmonary “pump” F – systemic “pump”

Q 3 1 – rt atrium 2 – lft atrium 3 – rt ventricle 4 – lft ventricle 5 – sup v c 6 – inf v c 7 – aorta 8 – pulm trunk 9 – lft pulm a 10 – rt pulm a 11 – rt pulm v 12 – lft pulm v 13 – coronary cir 14 – apex 15 – Ligmentosum arteriosum Q 3

Q 4

Q 5 The contraction of the ventricles is referred to as systole and the period of ventricular relaxation is called diastole. The monosyllables describing heart sounds during the cardiac cycle are lub-dup. The first heart sound is a result of closure of the atrio-ventricular valves; closure of the semi-lunar valves causes the second heart sound. The heart chambers that have just been filled when you hear the first heart sound are the ventricles, and the chmabers that have just emptied are the atria. Immediatley after the second heart sound, the atria are filling with blood, and the ventricles are empty. Abnormal heart sounds, or murmurs, usually indicate valve problems.

Q 6, part 2 1 – SA (sino-atrial) node 2 – AV (atrio-ventricular) node 3 – AV bundle 4 – bundle branches 5 – Purkinje fibers 6 – pulmonary valve 7 – aortic valve 8 – mitral (bicuspid) valve 9 – tricuspid valve Q 6, part 2

Q 6 – part 1 A – 6 B – 7 C – 8 D – 9 E – 9 F – 8 G – 1 H – 2

Q 7 1 – recording of the electrical activity of the heart 2 – period during which the atria are depolarizing 3 – period during which the ventricles are repolarizing 4 – period during which the ventricles are depolarizing, preceding their contraction 1 – electrocardiogram 2 – P wave 3 – T wave 4 – QRS wave

Q 7 – cont. 5 – abnormally slow HB, below 60 beats/minute 6 – condition which heart is uncoordinated and useless as a pump 7 – abnormally rapid HB, over 100 beats/minute 8 – damage to the AV node, totally or partially releasing vent from control of SA node 9 – chest pain, from ischemia of myocardium 5 – bradycardia 6 – fibrillation 7 – tachycardia 8 – heart block 9 – angina pectoris

Q 8

Q 9 In CO = HR x SV CO is Cardiac Output HR is Heart Rate SV is Stroke Volume For the normal resting heart, the value of HR is about 75 beats/minute and the value of SV is 70mL/beat. The normal average adult cardiac output is 5250mL/minute. The time for the entire blood supply to pass through the body once each minute.

According to Starling’s law of the heart, the critical factor that determines force of heartbeat, or stroke volume, is the degree of stretch of the cardiac muscle just before it contracts. Consequently, the force of heartbeat can be increased by increasing the amount of blood returned to the heart.

Q 10 Factors the increase cardiac output by influencing heart rate or stroke volume. Epinephrine Thyroxine Fear Exercise Activation of the sympathetic nervous system Low blood pressure Fever

Q 11 1 – The resting heart rate is fastest in adult life. 2 – Because the heart of the highly trained athlete hypertrophies, its stroke volume decreases. 3 – If the right side of the heart fails, pulmonary congestion occurs. 4 – In peripheral congestion, the feet, ankles, and fingers become edematous. 5 – The pumping action of the healthy heart ordinarily maintains a balance between cardiac output and venous return. Q 11 1 – fetal 2 – rate of contraction 3 – left 4 – true 5 – true

Q 12 – term that does not belong 1 – left side of heart 2 – P wave 3 – AV valves opened 4 – aortic semi-lunar vlave 5 – tricuspid valve 6 – heart block