Lab 5

Question 1

Components of a typical ECG

Answer 1

• p wave = represents the depolarization of the atria
• PR segment= during which the impulses spreads through AV node and the AV bundle into the right and left bundle branches
• QRS interval = represents when the interventricular septum begins depolarization
• ST segment = when ventricles are contracting (when cells are in their plateau phase of AP)
• T wave = electrical activity associate with ventricular repolarization

Question 2

Describe the effects of exercise on components of the ECG

Answer 2

• Heart rate increased after exercise
• blood pressure increases after exercise
• the interval between max p wave and QRS decreased in length
• the magnitude of the p wave increased
• interval between QRS and T wave shortened
• QRS and ST segments shifted to the right

Question 3

Determine blood pressure using a manual sphygmomanometer

Answer 3

• obtain a stethoscope
• wrap the cuff around the subjects arm just above the elbow
• palpate the brachial artery to ensure correct placement of cuff and stethoscope
• place the earpieces of the stethoscope in your ears and place the diaphragm over the brachial artery pulse point in the antecubital fossa.
• close the valve on the side of the rubber bulb and inflate the cuff to approximately 150 mmHg or until no pulse is detected
• open valve slightly to allow slow controlled deflation of the cuff and listen carefully for pressure sounds
• the pressure at which these sounds are first detected are called systolic pressure (make a note of this value)
• the point at which no sound can be detected is recorded as diastolic pressure

Question 4

Relate systolic and diastolic pressures to events of the cardiac cycle

Answer 4

• Systolic pressure is the pressure in the arteries at the peak of ventricular contraction. (When the heart beats to pump blood out)
• diastolic pressure is the pressure during ventricular relaxation(when the heart relaxes after contraction)

Question 5

Describe the effect exercise on blood pressure

Answer 5

Exercise can increase blood pressure but the results are temporary

• exercises increases systolic blood pressure
• diastolic blood pressure will have no change or a slight decrease after exercise

Question 6

Describe how to calculate percent change

Answer 6

BP after exercise - BP before exercise / BP before exercise x 100

Question 7

Central tendency

Answer 7

Describes the tendency of data to cluster around certain values, and may be measured in diff ways, including mean, median and mode

Question 8

Mean

Answer 8

Sum of all values/ sample size

Question 9

Median

Answer 9

-Value above or below which half the values lie
-if even number of values take the mean of the 2 median values
-to find median values must be in order from lowest to highest
Practice

Question 10

Mode

Answer 10

Most freq occurring value

Question 11

Variability

Answer 11

The measure of how dissimilar values are . The range of data set is the simplest measure of variability

Question 12

Range

Answer 12

Lowest # to highest #

Ex ( 51-97 )

Question 13

List some factors that can affect heart rate

Answer 13

• exercise
• drugs
• stress
• biological conditions (heart problems)
• medications
• body temperature

Question 14

Explain why TP time is shorter after exercise

Answer 14

Because the heart is beating faster

Question 15

PR interval

Answer 15

Reflects time from start of atrial depolarization to start of ventricular depolarization

Question 16

TP

Answer 16

The region between ventricular repolarization and atrial depolarization