Lab 5 - intro to cardiovascular physics

Question 1

L5 Sec A: What is the objective?

Answer 1

investigate the heart sounds and their correlation to cardiac cycle events

Question 2

L5 Sec A: what are the normal sounds of the heart? How would you hear them? what causes them?

Answer 2

-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.

Question 3

L5 Sec A: what is the setup and results for this section?

Answer 3

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)

Question 4

L5 Sec B: what is the objective for this section? how will it be accomplished?

Answer 4

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

Question 5

L5 Sec B: describe the setup for this section.

Answer 5

• 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.

Question 6

what does a sphygmomanometer consist of?

Answer 6

• 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

Question 7

L5 Sec B: describe the normal and abnormal results for this section

Answer 7

• 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

Question 8

What is the difference between systolic and diastolic pressure?

Answer 8

-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)

Question 9

what is the meaning of pulse pressure? what is a normal pulse pressure?

Answer 9

-the difference between systolic and diastolic pressure
-normal: 120 (systolic) - 80 (diastolic) = 40 mmHg

Question 10

L5 Sec C: what is the objective for this experiment?

Answer 10

use and electrocardiogram (ECG/EKG) to measure cardiac output at various body positions and after exercise.

Question 11

what is cardiac output? What is are normal and abnormal cardiac outputs due to?

Answer 11

• 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

Question 12

describe what happens to intrathoracic pressure during breathing

Answer 12

Decreases during inspiration and increases during expiration .

Question 13

how to you measure/calculate cardiac output

Answer 13

• 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)

Question 14

what influences cardiac output?

Answer 14

1. O2 metabolism (primary): oxygen demand of cells. increased metabolism = increased cardiac output.
2. circulatory system changes: blood vessel diameter changes via vasoconstrictors (VP) that decreased lumen diameter, increasing blood pressure, and increasing cardiac output.
3. 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

Question 15

what is stroke volume? how do you calculate it?

Answer 15

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.

Question 16

L5 C what equipment is needed for this section?

Answer 16

• BP-220 non-invasive blood pressure transducer (fancy sphygmomanometer)
• PPG-320 Pulse transducer
• stethoscope
• laptop
• iWorx kit
• sphy

Question 17

what is a supine position?

Answer 17

laying down on one’s back with face up and palms down.

Question 18

What is an important safety note when using the sphygmomanometer?

Answer 18

do not leave cuff inflated for more than 20 seconds. do not release pressure any slower than 5mmHg/sec

Question 19

L5 C (E1-E4) results and data analysis

Answer 19

• 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

Question 20

How do the Systolic and diastolic pressures vary between reclining, exercising and resting at various times, sitting, and standing positions?

Answer 20

lowest while lying down, highest 30 sec after exercise

Question 21

How do the heart rates of the subject in the sitting, reclining, exercising and resting at various times, and standing position compare?

Answer 21

lowest while reclining. increases from sitting to standing. highest 30 sec after exercise

Question 22

How do the cardiac outputs of the subject in the reclining, sitting, exercising and resting at various times, and standing positions compare?

Answer 22

increases with increased activity. decreases with more rest time between exercise

Question 23

Does stroke volume or heart rate have a greater impact on cardiac output?

Answer 23

HR has a higher impact on cardiac output

Question 24

L5 D: objective?

Answer 24

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.

Question 25

L5 D equipment and setup

Answer 25

• laptop
  -IXTA-ROAM data acquisition kit
• PPG-320 pulse transducer (for finger)
• pan of water at 5, 15, 25 degrees Celsius
  -USB cable

Question 26

which animals exhibit efficient O2 use for diving?

Answer 26

• sperm whales/whales
• alligators
• some avian and terrestrial reptiles
• some amphibians
• seals

Question 27

what are methods of O2 conservation for diving? How do they work?

Answer 27

• selective peripheral vasoconstriction: ensures O2 delivered to high priority organs (heart, brain, and adrenal glands). Other organs survive on O2 stores. constriction of peripheral blood vessels results in increase blood pressure so balanced by reduced cardiac output via….
• bradycardia: lowered HR reduces the cardiac output of diving animals

Question 28

True or False: humans do not exhibit a diving reflex. Explain.

Answer 28

FALSE.
humans do exhibit a diving reflex (selective peripheral vasoconstriction, apnea & brachy cardia) but it cannot be utilized for long term survival in cold water. The reflex is nowhere near as long as in diving mammals as it lasts only 2-3 minutes max

Question 29

Who is Dr. Martin Niemeroff. What was his hypothesis? Was this hypothesis confirmed by research?

Answer 29

hypothesis: young, skinny humans can survive being submerged in cold waters for up to an hour due to the rapid drop in core temperature.
not supported by research

Question 30

L5 D E1 heart rate at rest. describe the procedure and results for this exercise

Answer 30

• procedure: PPG320 pulse transducer is placed and secured to the subjects volar (pad) surface of the finger. record the pulse for 1 minute while the subject sits comfortably.
• data analysis: find a good section of 20 sec pulse data (top panel). bottom panel shows HR data (normal respiratory sinus arrythmia cycle). place cursors on either side of 2 breath cycles. record the min, max, and mean values for these numbers on the table.

Question 31

what is apnea? when does it occur?

Answer 31

occurs when a person stops breathing. occurs in humans during the dive reflex so that no water is taken into the lungs.

Question 32

L5 D E2 heart rate & apnea. describe the procedure and results for this exercise

Answer 32

• procedure: PPG320 pulse transducer is placed and secured to the subjects volar (pad) surface of the finger. record the pulse for 1 minute while the subject holds their breath for as long as possible. record for an additional 30 sec after subject resumes breathing.
• data analysis: pulse data (top panel). bottom panel shows HR data (normal respiratory sinus arrythmia cycle). place cursors on the point where subject began holding their breath and after breathing resumed. record the min, max, and mean values for these numbers on the table.

Question 33

L5 D E3 heart rate during the diving reflex. describe the procedure and results for this exercise

Answer 33

• procedure: PPG320 pulse transducer is placed and secured to the subjects volar (pad) surface of the finger. record the pulse for 1 minute while the subject submerges their face in 25 degrees C water. repeat with water at 15 degrees C and 5 degrees C.
• data analysis: pulse data (top panel). bottom panel shows HR data (normal respiratory sinus arrythmia cycle). place 1 cursor at the point the subject submerged their face and the other cursor 5 seconds later. repeat for the final 5 seconds of submersion repeat for other temps
  record the min, max, and mean values for these numbers on the table.

Question 34

what happens to the subjects HR as their face is submerged in 25, 15, and 5 degree C water

Answer 34

heart rate decreases with increasing water temperature.

Question 35

what causes the subjects HR to change when the face is submerged in cold water

Answer 35

the face and nose becoming wet triggers bradycardia (slowed HR)

Question 36

How does the human dive reflex help a person who falls into cold water?

Answer 36

selective peripheral vasoconstriction decreases blood flow to and from the limbs. preserving the core temperature of the body where vital organs are. the heart, brain, and adrenal glands are given O2 over other organs as well.

Question 37

L5 E: circulation (procedure, data analysis, results)

Answer 37

• procedure:
• analysis:
• results:

Question 38

define hyperemia

Answer 38

an increase in the amount of blood flow to an organ or another part of the body

Question 39

what is the function of valves in veins and capillaries

Answer 39

• protect capillaries of the lower limbs by dividing the long column of blood in the veins (from the feet up to the heart) into many segments. this is done to overcome the effect of gravity/pressure on these capillaries
• prevent backflow of blood

Question 40

what 2 factors help promote circulation of the veins?

Answer 40

• respiratory pump: pressurizes great veins with each breath. inhalation increase pressure in the thoracic cavity via the movement of the diaphragm with increases the pressure in the abdominal cavity. this alternating pressure on the inferior vena cava forces blood towards the trunk
• skeletal muscle pump: rhythmic movement of skeletal muscle contraction causes opening of the valves assisting blood flow from the limbs to the heart

Question 41

do veins remain empty when blood is physically pushed up a blocked vein?

Answer 41

YES, backflow is prevent by respiratory and skeletal muscle pumps via valves

Question 42

define hyperemia. what are the three types of hyperemia ? provide an example of each

Answer 42

• hyperemia: more blood than normal going to tissues (veins) or organs
  active/arterial: blood flow to an area of the body is increased due to increased demand in that area (e.g., build up of lactic acid or other waste products, swollen ankles after running)
• passive/venous: blood flow to an area is blocked resulting in the accumulation of arterial blood (e.g., applying a tourniquet to ones arm to make veins of lower limb bulge)
• reactive: application of cold object (icepack) applied to an area causes dilation of blood vessels after removal, promoting blood flow (and increasing healing of injuries)