Lec Exam 4: Heart

Why must blood stay in motion?

To maintain homeostasis and exchange nutrients, gases, and wastes.

What organ keeps blood moving?

The heart.

How many times does the heart beat per day?

About 100,000 times.

What is the normal cardiac output range?

5-30 liters per minute.

What is the size of the heart?

About the size of a clenched fist.

How many chambers does the heart have?

Four.

Name the heart chambers.

Right atrium, right ventricle, left atrium, left ventricle.

What does the pulmonary circuit do?

Carries deoxygenated blood to lungs and returns oxygenated blood.

What does the systemic circuit do?

Carries oxygenated blood to body and returns deoxygenated blood.

What is the pericardium?

Membrane surrounding the heart.

What is pericarditis?

Inflammation of the pericardium.

What are the three layers of the heart wall?

Epicardium, myocardium, endocardium.

What is the epicardium?

Outer layer of heart (visceral pericardium).

What is the myocardium?

Muscle layer responsible for contraction.

What is the endocardium?

Inner lining of heart and valves.

What is the cardiac muscle energy source?

Aerobic respiration.

Why does cardiac muscle have many mitochondria?

Needs lots of energy for constant contraction.

Does cardiac muscle need nervous input?

No, it can contract on its own.

What are the functions of the fibrous skeleton?

Supports valves, distributes force, prevents overexpansion, separates chambers.

What does the superior vena cava drain?

Head, neck, upper body.

What does the inferior vena cava drain?

Lower body.

What does the coronary sinus do?

Returns blood from heart muscle to right atrium.

What enters the right atrium?

Deoxygenated blood from body.

What separates the atria?

Interatrial septum.

What is the name of the right AV valve?

Tricuspid valve.

What separates the ventricles?

Interventricular septum.

What is the function of the pulmonary valve?

Prevents backflow into right ventricle.

Where does blood go after the right ventricle?

Pulmonary trunk → lungs.

What enters the left atrium?

Oxygenated blood from lungs.

What is the name of the left AV valve?

Mitral (bicuspid) valve.

Which chamber has the thickest wall?

Left ventricle.

Why is the left ventricle the thickest?

Needs high pressure for systemic circulation.

What is the function of the aortic valve?

Prevents backflow into left ventricle.

Where does blood go after the left ventricle?

Aorta → body.

What is stroke volume?

Blood pumped per beat.

What determines cardiac output?

Heart rate × stroke volume.

Why does a fetus bypass the lungs?

Lungs not functional before birth.

What is the function of the foramen ovale?

Shunt from right atrium to left atrium.

What is the function of the ductus arteriosus?

Bypasses pulmonary circuit.

What is the function of the ductus venosus?

Bypasses liver.

What is the problem with patent ductus arteriosus?

Ductus doesn't close → breathing issues, cyanosis.

What supplies the heart muscle?

Coronary circulation.

Where do coronary arteries originate?

Ascending aorta.

What does the right coronary artery supply?

Right atrium, ventricles, conduction system.

What does the left coronary artery supply?

Left atrium and left ventricle.

What is myocardial infarction?

Heart attack from blocked artery.

What is bypass surgery?

Rerouting blood around blocked artery.

What causes the 'lubb' sound?

AV valves closing.

What causes the 'dupp' sound?

Semilunar valves closing.

What is the cardiac cycle?

One full heartbeat cycle.

What is systole?

Contraction phase.

What is diastole?

Relaxation phase.

What is the top number in blood pressure?

Systolic.

What is the bottom number in blood pressure?

Diastolic.

What controls heart rhythm?

Electrical conduction system.

What is the SA node?

Pacemaker of heart.

Where is the SA node located?

Right atrium near superior vena cava.

What is the effect of acetylcholine on the heart?

Slows heart rate.

What is the effect of norepinephrine on the heart?

Increases heart rate.

What is bradycardia?

Slow heart rate.

What is tachycardia?

Fast heart rate.

What is an ECG?

Recording of heart electrical activity.

What does the P wave represent?

Atrial depolarization.

What does the QRS complex represent?

Ventricular depolarization.

What does the T wave represent?

Ventricular repolarization.

What is arrhythmia?

Abnormal heart rhythm.

What is a premature ventricular contraction?

Extra heartbeat not controlled by SA node.