Components of a typical ECG
- 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
Describe the effects of exercise on components of the ECG
- 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
Determine blood pressure using a manual sphygmomanometer
- 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
Relate systolic and diastolic pressures to events of the cardiac cycle
- 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)
Describe the effect exercise on blood pressure
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
Describe how to calculate percent change
BP after exercise - BP before exercise / BP before exercise x 100
Central tendency
Describes the tendency of data to cluster around certain values, and may be measured in diff ways, including mean, median and mode
Mean
Sum of all values/ sample size
Median
-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
Mode
Most freq occurring value
Variability
The measure of how dissimilar values are . The range of data set is the simplest measure of variability
Range
Lowest # to highest #
Ex ( 51-97 )
List some factors that can affect heart rate
- exercise
- drugs
- stress
- biological conditions (heart problems)
- medications
- body temperature
Explain why TP time is shorter after exercise
Because the heart is beating faster
PR interval
Reflects time from start of atrial depolarization to start of ventricular depolarization
TP
The region between ventricular repolarization and atrial depolarization
