Cardiovascular Physiology Lab Flashcards
Auscultation of the hearts means
to listen to and study the various sounds arising from the heart during its pumping activity
The vibrations producing the sounds can be visually displayed through the use of a heart sound microphone and physiological recorder to produce a
phonocardiogram
1st Heart Sound
Produced at the beginning of systole when the atrioventricular (AV) valves close and the semilunar (SL) valves open. This has a lower pitched tone commonly termed the “lub” sound of the heartbeat
2nd Heart Sound
Occurs during the end of systole and is produced by the closure of the SL valves, the opening of the AV valves, and the resulting vibrations in the arteries and ventricles. Due to the higher blood pressures in the arteries the sound produced is higher pitched. It is commonly referred to as the “dub” sound
3rd Heart Sound
Occurs during the rapid filling of the ventricles after the AV valves open and is probably produced by vibrations of the ventricular walls
4th Heart Sound
Occurs at the time of atrial contraction and is probably due to the accelerated rush of blood into the ventricles
The 4 Major Auscultatory Areas
Aortic Area (aortic SL valve) Tricuspid Area (right AV valve) Pulmonary Area (pulmonary SL valve) Mitral Area (left AV valve)
Blood Pressure
the pressure exerted by the blood against the vessel walls
Where do we most commonly measure blood pressure?
arterial blood pressure
Systolic Blood Pressure
the highest pressure in the artery–produced during the heart’s contraction (systolic) phase
Normal systolic blood pressure for a 20-year old male is
120mm Hg
Diastolic Blood Pressure
the lowest pressure in the artery–produced during the heart’s relaxation (diastolic) phase
Normal diastolic blood pressure for a 20-year old male is
80mm Hg
Pulse Pressure
the difference between the systolic and diastolic pressures
Normal value for pulse pressure is
40mm Hg
Mean Blood Pressure
Diastolic Pressure + 1/3 of the pulse pressure. This is the average effective pressure forcing blood through the circulatory system
Normal value for mean blood pressure is
96-100mm Hg
Formula for Mean BP (mm Hg)
Cardiac Output (ml/min) X Total Peripheral Resistance (TPR units)
Formula for Cardiac Output
Cardiac Output (ml/min) = Heart Rate (beats/min) X Stroke Volume (ml/beat)
Peripheral Resistance depends on
the diameter of the blood vessels and the viscosity of the blood
In general we say that the systolic BP indicates ______ and the diastolic BP reflects _______
systolic = the force of contraction of the heart
diastolic = the condition of the systemic blood vessels
ex: an increase in the diastolic pressure indicates a decrease in vessel elasticity
Direct Method of measuring blood pressure
a cannula is inserted into the artery and the direct, head-on pressure of the blood is measured with a transducer or mercury manometer
Indirect Method of measuring blood pressure
pressure is applied externally to the artery and the pressure is determined by listening to arterial sounds (using a stethoscope) below the point where the pressure is applied
This is called the auscultatory method since the detection of the sounds is termed “auscultation”
Palpatory Method
Older and less accurate method. One simply palpates or feels the pulse as pressure is applied to the artery. You inflate the cuff, note when the pulse is first lost, go a little bit higher and then let air out as you wait for the first pulse which is the systolic blood pressure. The systolic blood pressure recorded with the palpatory method is usually around 5mm Hg lower than that obtained using the auscultatory method. Major disadvantage of this method is that it cannot be used to measure the diastolic pressure
In both indirect methods for blood pressure the instrument we use is
pressure is applied to the artery using an instrument called the sphygmomanometer; consists of an inflatable rubber bag (cuff), a rubber bulb, and a mercury or anaeroid manometer for measuring the pressure
Where is human blood pressure most commonly measured?
in the brachial artery of the upper arm; has the advantage of being approximately the same level as the heart so that the pressures obtained closely approximate the pressure in the aorta leaving the heart. Allowing us to correlate BP with heart activity
Auscultatory Method
pressure cuff is used and stethoscope is used to listen to the changes in sounds from the brachial artery. With no air in the cuff no sounds can be heard. Inflate the cuff beyond systolic pressure so that the artery is completely collapsed and no sounds are heard. Now open the valve and begin to slowly lower the pressure in the cuff
The Korotkow Sounds
Phase 1: Appearance of a fairly sharp thudding sound which increases in intensity during the next 10 mm Hg of pressure drop. The pressure when the sound first appears is the systolic pressure
Phase 2: The sounds become a softer murmur during the next 10-15 mm Hg drop in pressure
Phase 3: The sounds become louder again and have a sharper thudding quality during the next 10-15 mm Hg of pressure drop
Phase 4: The sounds suddenly become muffled and reduced in intensity. The pressure at this point is termed the diastolic pressure. Thus muffled sound continues for another 5 mm Hg pressure drop, after which all sound disappears. The point where the sound ceases completely is called the end diastolic pressure. It is sometimes recorded along with the systolic and diastolic pressures in this manner: 120/80/75
The auscultatory method is usually how far off from the direct method in the pressures recorded?
about 3-4 mm lower than that obtained with the direct method
Difference in BP between Men and Women
Below the age of 35, women generally have a BP 10 mm Hg lower than that for men. However, after 40-45 years of age, a woman’s BP increases faster than does a man’s
Rule of thumb for what your systolic pressure should be
100 plus your age; rule is valid until after the age of 50
Why does BP increase with age
The increase in BP with age is caused largely by the overall loss of vessel elasticity with age, part of which is due to the increased deposit of cholesterol and other lipid materials in the blood vessel walls
When you go from lying down to standing BP should
You may have an initial drop in blood pressure as blood pools but it should increase after your baroreceptors sense it and increase your heart rate
What generally happens to BP during exercise?
During aerobic exercise you should see an increase in BP as your heart rate is increased thereby raising the systolic pressure while keeping diastolic relatively the same
during vigorous exercise you can see a slight drop in BP, then it’ll return to normal after rest
A crude estimate of peripheral resistance equation
TPR = mean arterial pressure / cardiac output
where cardiac output = stroke volume X heart rate
TPRest = [(systolic + 2 diastolic)/3] / [pulse pressure X heart rate]
A normal reflex response in BP to a cold stimulus is
an increase in blood pressure (both systolic and diastolic); In a normal individual the systolic pressure will rise no more than 10 mm Hg, but the rise in a hypertensive individual may be 30 to 40 mm Hg
Explain the test we did when the subject raised their hand and we measured the hand’s height from the heart
lower the arm and observe the filling of the veins on the back of the hand, raise the hand and watch to the point where the veins are just barely collapsed; measure the distance in mm; this will give the atrial pressure in mm of blood. The specific gravity of blood is 1.056 while that of mercury is 13.6. Convert to mm of mercury by dividing by 13.6 and compare with arterial pressure at the level of the heart
What happens when we dunk our faces in icy cold water?
Mammallian dive reflex happens in 3 stages:
1. Bradycardia-is the first response to submersion. Immediately upon facial contact with cold water, the human heart rate slows down 10-25% percent. Slowing the heart rate lessens the need for bloodstream oxygen, leaving more to be used by other organs.
2. Peripheral vasoconstriction
3. Blood Shift
In humans, the mammalian diving reflex is not induced when limbs are introduced to cold water. Mild bradycardia is caused by subjects holding their breath without submerging the face within water.[4] When breathing with face submerged this causes a diving reflex which increases proportionally to decreasing water temperature
Why are children more likely to survive drowning in icy cold waters than adults?
Children have a survival advantage over adults in cold water. Their bodies have a higher surface area-to-volume ratio than adult bodies, so they cool more quickly—the same way that a cupcake just out of the oven cools faster than a sheet cake. They also have the innate ability to absorb more oxygen into their bloodstream than adults do, so, when they go underwater, there is already more oxygen available.
This test consists of measuring the endurance in stepping up and down a bench 20 inches high (16 for women) and the pulse reaction to this exercise. Measures general endurance.
Harvard Step Test
Harvard Step Test
This test consists of measuring the endurance in stepping up and down a bench 20 inches high (16 for women) and the pulse reaction to this exercise. Measures general endurance.
Harvard Step Test Index Formula
Index = Duration of exercise in seconds X 100 / 2 X (sum of the 3 pulse counts in recovery)
Below 55 = poor 55-64 = low avg 65-79 = high avg 80-90 = good above 90 = excellent
Tuttle Pulse-Ratio Test
This test is based on the observation that for the same number of steps, a less fit person will have a relatively higher pulse rate during the 2-minute period of recovery immediately after exercise. Tuttle’s pulse ratio is defined as the total number of pulse beats counted for one minute. The cardiovascular efficiency of a person is determined by the amount of exercise require to obtain a 2.5 pulse ratio. This test appears to be fairly accurate for measuring physical condition in the middle range and has also been found to be useful in the detection of pathological hearts and heart abnormalities
Steps to the Tuttle Pulse-Ratio Test
Subject sits at a chair until pulse is stabilized. Pulse is recorded over 1 minute
Subject makes 20 complete steps (up and down) in 1 minute on a bench 13 inches high (15 steps for females). Record the number of steps completed
Immediately after exercise, the subject sits, and the pulse is counted for 2 minutes
The total pulse for 2 minutes is divided by the resting rate. This is called the first “pulse ratio”
Subject rests until the pulse returns to normal
Subject steps up and down again for 1 minute, making 40 complete steps (35 for women). Record the number of steps
Immediately after exercise, subject sits, pulse is counted again for 2 minutes
The pulse obtained in 2 minutes is divided by the resting pulse. This is called the second “pulse ratio”
Then calculate the number of steps required to obtain a 2.5 pulse-ratio
Formula to record a 2.5 pulse-ratio
S0 = S1 + (S2-S1)(2.5-r1)/(r2-r1)
S1 = the number of steps used in the first test S2 = the number of steps used in the 2nd test S0 = the number of steps required to obtain a 2.5 ratio r1 = the pulse ratio for S1 r2 = the pulse ratio for S2
The established norms for the Tuttle pulse-ratio test are:
boys, ages 10 to 12 years - 33 steps
boys, ages 13 to 18 years - 30 steps
adult man - 29 steps
adult women - 25 steps
