Lab 2

Question 1

Draw the 3 leads, label them, and their charges

Answer 1

Do it

Question 2

How do you determine the reflection a signal will produce on the EKG

Answer 2

Opposite charges going at each other –> positive deflection
Trace a 90 degree angle from tip and tail of vector to lead, that provides direction
If going completely away from lead–> flat line

Question 3

Electrical and mechanical events of heart during systole

Answer 3

Ventricles contract and pump blood out of the heart, atria are relaxing. Starts with closure of AV valves and ends with closure of semilunar valves.
Depolarization

Question 4

Electrical and mechanical events of heart during diastole

Answer 4

Ventricles relax and fill with blood from atria, atria are contracting. Starts with the closure of semilunar valves and ends with the closure AV valves.

Question 5

Path of electric conduction through heart

Answer 5

SA node –> AV node –> AV bundle –> Bundle branches –> purkinje fibers

Question 6

Calculate instant HR from EKG

Answer 6

60 / time from R-R peak

Question 7

Calculate avg HR from EKG

Answer 7

QRS complexes in 15 second period * 4

Question 8

Why does QRS complex have largest amplitude

Answer 8

the ventricles have the largest amount of myocardium that gets depolarized and the strongest contraction.

Question 9

Why do athletes have lower resting HR

Answer 9

They have a larger stroke volume (stronger heart) so need less contractions to get the same amount of circulation

Question 10

Resting Heart rate variation

Answer 10

60-100 bpm
The more fit a person is the lower the resting HR
Men typically have lower resting HR

Question 11

When is the first heart sound

Answer 11

After the QRS complex

Question 12

What causes lub sound, specifically

Answer 12

The lub sound is the closing of AV valves. The ventricles are depolarized which causes contraction. The contraction increases the pressure in the ventricle. The blood pushes back on the AV valves and they close.

Question 13

When is the second heart sound

Answer 13

After the T wave

Question 14

What causes dup sound, specifically

Answer 14

The dup sound comes after the t wave because the ventricle repolarizes which causes relaxation. There is no more blood in the heart so pressure decreases. The valves must close to prevent backflow of blood into the ventricles from the arteries.

Question 15

P wave

Answer 15

Atrial depolarization

Question 16

QRS complex

Answer 16

Ventricular depolarization

Question 17

T wave

Answer 17

Ventricular repolarization

Question 18

Why does QRS appear before lub sound

Answer 18

It is the depolarization, and the ventricles much depolarize to push blood onto AV valves for them to close. The depolarization causes the contraction that pushes against the valves

Question 19

Why does T occur before dup

Answer 19

The ventricles must repolarize first in order to relax