PHYS Lab Quiz 4

What does an ECG (EKG) measure?

The electrical activity of the heart.

What does the P wave represent?

Atrial depolarization (atria contracting).

What does the QRS complex represent?

Ventricular depolarization (ventricles contracting).

What does the T wave represent?

Ventricular repolarization (ventricles relaxing).

Why is atrial repolarization not visible on the ECG?

It is hidden by the larger QRS complex.

What electrical event triggers mechanical contraction of the heart?

Depolarization.

Where does the heartbeat normally start?

The SA node (sinoatrial node).

Why is the SA node called the pacemaker?

It sets the rhythm of the heart.

What is the function of the AV node?

Delays the electrical signal before it enters the ventricles.

What is the cardiac cycle?

One complete heartbeat including contraction and relaxation.

What is systole?

Contraction phase of the heart.

What is diastole?

Relaxation phase of the heart.

When are the ventricles filling with blood?

During ventricular diastole.

When do the ventricles pump blood out of the heart?

During ventricular systole.

What causes the 'lub' sound (S1)?

Closure of AV valves (mitral & tricuspid).

What causes the 'dub' sound (S2)?

Closure of semilunar valves (aortic & pulmonary).

When does S1 occur in the cardiac cycle?

Beginning of ventricular systole.

When does S2 occur?

Beginning of ventricular diastole.

What happens to heart rate during exercise?

It increases.

What happens to cardiac output during exercise?

It increases.

What happens to systolic blood pressure during exercise?

It increases.

What happens to diastolic blood pressure during exercise?

It usually stays the same or slightly decreases.

Why does heart rate increase during exercise?

Muscles need more oxygen and nutrients.

What happens to blood flow to muscles during exercise?

It increases.

What happens to blood flow to digestive organs during exercise?

It decreases.

What is respiration?

The process of exchanging oxygen and carbon dioxide.

What muscle is primarily responsible for breathing?

The diaphragm.

What happens to the diaphragm during inhalation?

It contracts and moves downward.

What happens to the diaphragm during exhalation?

It relaxes and moves upward.

What happens to lung volume during inhalation?

It increases.

What happens to lung pressure during inhalation?

It decreases.

What is tidal volume (TV)?

Air moved in or out during normal breathing.

What is inspiratory reserve volume (IRV)?

Extra air that can be inhaled after a normal breath.

What is expiratory reserve volume (ERV)?

Extra air that can be exhaled after a normal breath.

What is residual volume (RV)?

Air remaining in the lungs after maximal exhalation.

What is vital capacity (VC)?

Maximum air that can be exhaled after a maximum inhale. VC = TV + IRV + ERV

What is inspiratory capacity (IC)?

Maximum air inhaled after normal exhalation. IC = TV + IRV

What is functional residual capacity (FRC)?

Air left in lungs after normal exhale. FRC = ERV + RV

What is total lung capacity (TLC)?

Total air lungs can hold. TLC = TV + IRV + ERV + RV

What does the small up-and-down pattern on a spirometry graph represent?

Tidal volume.

What does the large peak above tidal breathing represent?

Inspiratory reserve volume.

What does the deep drop below tidal breathing represent?

Expiratory reserve volume.

What portion cannot be measured directly with spirometry?

Residual volume.

What determines airflow in the lungs?

Pressure differences between the lungs and atmosphere.

Air flows from ____ pressure to ____ pressure.

High → Low pressure.

Why does air enter the lungs during inhalation?

Lung pressure becomes lower than atmospheric pressure.

Why does air leave the lungs during exhalation?

Lung pressure becomes higher than atmospheric pressure.

What happens to breathing rate after exercise?

It increases.

What happens to tidal volume during exercise?

It increases.