Lab 5 - intro to cardiovascular physics Flashcards
L5 Sec A: What is the objective?
investigate the heart sounds and their correlation to cardiac cycle events
L5 Sec A: what are the normal sounds of the heart? How would you hear them? what causes them?
-heard with a stethoscope at the second right, second left, and 5th left intercostal space
-lub-dup…lub-dup…
-due to turbulent backwash of blood in the chambers of the heart:
lub: closure of AV valve at beginning of ventricular systole. ventricles contract causing blood to backflow onto the AV valve causing it to bulge into the atria.
dup: closure of the semi-lunar valves (aortic and pulmonary) after ventricular systole. back-surge of blood from the valves causes vibrations.
L5 Sec A: what is the setup and results for this section?
heart sounds.
-setup: in a quiet environment examiner places the “bell” of the stethoscope on the 5th intercostal space (lub) and 2nd intercostal space (dub)
-results:
longer pause after the dub.
pulse felt after the dub (after ventricular systole)
L5 Sec B: what is the objective for this section? how will it be accomplished?
Determine Blood pressure using the indirect auscultatory method. within 10% of values measured directly from the artery. this is is done by observing “Korotkoff sounds “ from blood flow when a sphygmomanometer (pressure cuff) is applied
L5 Sec B: describe the setup for this section.
- blood pressure determination
- sphygmomanometer is applied to upper arm of a sitting subject. air is pumped causing the pressure (140-160mmHg) to cut off blood flow through the brachial artery.
- pressure is gradually released (2-3 mmHg/heartbeat), causing blood to squirt through the artery with each systole/beat causing a rhythmic sound (1st Korotkoff sound). as pressure is released blood low returns to normal laminar flow, the sounds ceases (2nd Korotkoff sound).
- repeat after subject lays down for 10 mins and again when the subject stands up.
what does a sphygmomanometer consist of?
- compression bad surrounding by an un-yeilding cuff for application pressure of the arm
-an inflation bulb for creating pressure in the system - manometer to measure pressure
- valve to deflate the system in a controlled manner
L5 Sec B: describe the normal and abnormal results for this section
- determining blood pressure
- Normal: 120/80 mmHg
-abnormal: 160/95 mmHg or more on three different occasions separated by hours or days = high blood pressure
What is the difference between systolic and diastolic pressure?
-systolic pressure: the pressure reading in the cuff when the 1st Korotkoff sound is heard (normal: 120mmHg). represents the work done by the left ventricle (to pump deoxy blood up and out of the heart)
-diastolic pressure: the pressure reading in the cuff when the 2nd Korotkoff sound is heard (normal: 80mmHg). indicates the health of the arteries because it is the minimum/regular pressure they are subject to (laminar flow)
what is the meaning of pulse pressure? what is a normal pulse pressure?
-the difference between systolic and diastolic pressure
-normal: 120 (systolic) - 80 (diastolic) = 40 mmHg
L5 Sec C: what is the objective for this experiment?
use and electrocardiogram (ECG/EKG) to measure cardiac output at various body positions and after exercise.
what is cardiac output? What is are normal and abnormal cardiac outputs due to?
- cardiac output: the measure of how well the heart is delivering blood to the circulatory system.
- indicates cardiovascular health
normal: increase is Q in healthy individual usually from increase HR
abnormal but highly fit/healthy: increases in Q likely due to increased stroke volume
abnormal: reduced output. due diseases like hypertension, cardiomyopathy, and heart failure
abnormal: increased output due to sepsis and infection
Q: Liters of blood ejected from the left ventricle in a minute
describe what happens to intrathoracic pressure during breathing
Decreases during inspiration and increases during expiration .
how to you measure/calculate cardiac output
- clinical: MRI, Doppler ultrasound, impedance cardiography, and thermodilution techniques.
- cardiac output (Q) L= heart rate (HR) beat/minstroke volume (SV) L/beat
Normal: (4.2 - 21.6 L/min) = (60-180 b/m)(70-120mL/b)
what influences cardiac output?
- O2 metabolism (primary): oxygen demand of cells. increased metabolism = increased cardiac output.
- circulatory system changes: blood vessel diameter changes via vasoconstrictors (VP) that decreased lumen diameter, increasing blood pressure, and increasing cardiac output.
- respiratory cycle: breathing affects intrathoracic pressure (decrease during inhale, increase during exhale). increased intrathoracic pressure causes ventricle volume to decrease during diastole, decreasing cardiac output. decreased intrathoracic pressure during exhale causes ventricle to fill with more blood, increasing cardiac output
what is stroke volume? how do you calculate it?
SV = EDV - ESV
SV: stroke volume. the difference between the volume of blood that fills the left ventricle at the end of diastole (EDV) and the volume of blood remaining in the ventricle after it contracts (ESV)
EDV: end diastolic volume.
ESV: end systolic volume.
L5 C what equipment is needed for this section?
- BP-220 non-invasive blood pressure transducer (fancy sphygmomanometer)
- PPG-320 Pulse transducer
- stethoscope
- laptop
- iWorx kit
- sphy
what is a supine position?
laying down on one’s back with face up and palms down.
What is an important safety note when using the sphygmomanometer?
do not leave cuff inflated for more than 20 seconds. do not release pressure any slower than 5mmHg/sec
L5 C (E1-E4) results and data analysis
- Pulse channel: regular pulse that flatlines when cuff is inflated. as pressure is slowly released from the cuff pulse comes back weak and the quickly returns to normal with no pressure
- Blood pressure channel: flatline until pressure increases in cuff then step increase with each pump until flatline at top of peak. as pressure is released, gradual decline.
- Heart Rate: relatively steady until steep drop at peak cuff pressure, then shoots back up
- data analysis:
systolic & diastolic blood pressure: cursors at the peak of the first returning HR (systole) and at the peak of the first returned to normal heart beat (diastolic). Record the BP of these cursors in the analysis window using the BP panel (T1 systolic and T2 diastolic)
average Heart rate: place one cursor at the peak of the heart beat amplitude 10 seconds after diastole. Record the mean value in the analysis window of the HR channel - use these values to calculate:
Stoke volume (SV, ml/beat) = 101 + (0.5Systolic) = (1.09Diastolic) - (0.61*age) - Use the recorded HR and calculated SV to calculate:
Cardiac output (ml/min) = SV (ml/beat) * HR (bpm) - repeat for subject sitting, standing, sitting after 30secs after exercise, sitting 60s after exercise, sitting 90s after exercise, and sitting 120s after exercise). record all values in table 5.1
How do the Systolic and diastolic pressures vary between reclining, exercising and resting at various times, sitting, and standing positions?
lowest while lying down, highest 30 sec after exercise
How do the heart rates of the subject in the sitting, reclining, exercising and resting at various times, and standing position compare?
lowest while reclining. increases from sitting to standing. highest 30 sec after exercise
How do the cardiac outputs of the subject in the reclining, sitting, exercising and resting at various times, and standing positions compare?
increases with increased activity. decreases with more rest time between exercise
Does stroke volume or heart rate have a greater impact on cardiac output?
HR has a higher impact on cardiac output
L5 D: objective?
students will explore reflex brachy cardia/the diving reflex by determining normal resting HR, Hr while holding breath, and HR while holding their breath in cool water.
