Cardiovascular physiology lab Flashcards
First heart sound
Produced at the beginning of systole when the atrioventricular (A-V) valves close and the semilunar (S-L) valves open. This has a lower pitched tone, called the “lub” sound of the heartbeat
Second heart sound
Occurs during the end of systole and is produced by the closure of the S-L valves, the opening of the A-V 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
Third heart sound
Occurs during the rapid filling of the ventricles after the A-V valves open and is probably produced by vibrations of the ventricular walls
Fourth heart sound
Occurs at the time of atrial contraction and is probably due to the accelerated rush of blood into the ventricles
Auscultation
To listen to. In this case, we are listening to the heart and studying the sounds of the heart from vibrations produced when the heart valves close and the blood rebounds against the ventricular walls or blood vessels
Stethoscope
Instrument used to listen to heart sounds
Phonocardiogram
The vibrations producing the heart sounds can be visually displayed through the use of a heart sound microphone and physiological recorder to produce a phonocardiogram
Auscultatory areas
The 4 areas on the chest where the sounds from each valve can be heard most clearly. 2 are on either side of the sternum at the level of the third rib, one is on the left side of the sternum at the level of the sixth rib, and the fourth is at about the same level but more lateral.
Blood pressure
The pressure exerted by the blood against the vessel walls, the arterial blood pressure being the most frequently measured pressure and the most useful. It provides us with information on the heart’s pumping efficiency and the condition of the systemic blood vessels
Systolic blood pressure
The highest pressure in the artery- produced during the heart’s contraction (systolic) phase. Normal for a 20-year-old male is 120mm Hg. Systolic blood pressure indicates the force of contraction of the heart.
Diastolic blood pressure
The lowest pressure in the artery- produced during the heart’s relaxation (diastolic) phase. Normal for a 20-year-old male is 80mm Hg. The diastolic blood pressure indicates the condition of the systemic blood vessels (for instance, an increase in the diastolic pressure indicates a decrease in vessel elasticity)
Pulse pressure
The difference between the systolic and diastolic pressures. Normal value 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 is 96-100mm Hg. The mean blood pressure is a function of two factors–cardiac output (C.O.) and total peripheral resistance (TPR)
Mean blood pressure equation
Cardiac output times total peripheral resistance. Cardiac output equals heart rate times stroke volume
Peripheral resistance depends on (2)
The diameter of the blood vessels and the viscosity of blood
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 also called the auscultatory method. The auscultatory method has been found to be fairly close to the direct method in the pressures recorded; usually the systolic pressure is about 3-4 mm lower than that obtained with the direct method
Palpatory method of measuring blood pressure
Older and less accurate. You palpate (feel) the pulse as pressure is applied to the artery. The systolic pressure recorded with the palpatory method is usually around 5mm Hg lower than that obtained using the auscultatory method.
Sphygmomanometer
An instrument that applies pressure to the artery in the indirect blood pressure measurement methods. It consists of an inflatable rubber bag (cuff), a rubber bulb for introducing air into the cuff, and a mercury or anaeroid manometer for measuring the pressure in the cuff.
Where is blood pressure measured?
The brachial artery of the upper arm. In addition to being a convenient position for taking measurements, it has the added 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. This allows us to correlate B.P. with heart activity.
What is a major disadvantage of the palpatory method?
It can’t be used to measure diastolic pressure
Korotkow sounds
The 4 phases of sound changes when measuring blood pressure using the auscultatory method
Phase 1 of korotkow sounds
Appearance of a fairly sharp thudding sound which increases in intensity during the next 10mm Hg of pressure drop. The pressure when the sound first appears is the
systolic pressure.
Phase 2 of korotkow sounds
The sounds become a softer murmur during the next 10-15 mm Hg drop in pressure.
Phase 3 of korotkow sounds
The sounds become louder again and have a sharper thudding quality during the next 10-15 mm Hg of pressure drop
Phase 4 of korotkow sounds
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.
Blood pressure varies with a person’s (3)
Age, weight, and sex
How does blood pressure vary with age and sex?
Below the age of 35 women generally have a B.P. 10 mm Hg lower than that for men. However, after 40-45 years of age, a woman’s B.P. increases faster than does a man’s. The old rule of thumb of 100 plus your age is still a good estimate of what your systolic pressure
should be at any given age. After the age of 50, however, the rule is invalid.
What causes the increase in blood pressure with age?
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.
Cold pressor test
A test used to demonstrate the effect of a sensory stimulus (cold) on blood pressure
What are the normal and hypertensive responses to the cold pressor test?
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.
Diving bradycardia
Some members of each class of tetrapods are able to remain under water for prolonged periods. When animals are submerged, they use oxygen more efficiently and make cardiovascular adjustments. One adjustment is bradycardia, which is associated with a reduction of circulation to all regions of the body except certain vital areas such as heart tissue and the brain. Humans have a more poorly developed diving response, but it can still be observed.
The Harvard step test
This test consists of measuring the endurance in stepping up and down a bench 20 inches high (16 inches for women) and the pulse reaction to this exercise. It measures general endurance (not strength, cardiovascular or muscular endurance).
What do Harvard step test scores indicate?
Below 55 indicates poor physical condition, with above 90 being excellent
Tuttle’s pulse ratio
Defined as the total number of pulse beats counted for one minute
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 two-minute period of recovery immediately after exercise. The cardiovascular efficiency of a person is determined by the amount of exercise required 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.
Norms for the Tuttle pulse-ratio test
Boys 10-12: 33 steps
Boys 13-18: 30 steps
Adult man: 29 steps
Adult woman: 25 steps
How do exercise and postural changes affect pulse and blood pressure?
Sitting/standing from laying down increases heart rate and blood pressure and running increases both of them even more.
Are you vasodilated during exercise?
Depends on which blood vessels you’re referring to. Blood vessels going to skeletal muscle will be dilated, while blood vessels going to organs like the stomach will be constricted.
From which direction is a vein refilled?
Veins are refilled by the blood distal to the point of pressure. This is why veins are emptied when pushing proximally but not distally.
S1
Number of steps of first test, tuttle pulse ratio
S2
Number of steps of second test
S0
Number of steps required to obtain a 2.5 ratio
r1
Pulse ratio for S1
r2
Pulse ratio for S2
