chapter 20:heart

What does the pulmonary circuit do?

It carries blood to the lungs for gas exchange.

What does the systemic circuit do?

It carries blood to the rest of the body.

What do arteries do?

They carry blood away from the heart.

What do veins do?

They carry blood to the heart.

What are capillaries for?

connects veins & arteries to allow for gas and nutrient exchange

What is the pericardium?

The sac that surrounds the heart.

What is the visceral pericardium?

The layer touching the heart’s surface.

What is the parietal pericardium?

The outer layer of the pericardial sac.

What is the pericardial cavity?

The space with fluid that reduces friction.

What is the epicardium, and what’s it made of?

The outer heart layer (same as visceral pericardium)

mesothelium + connective tissue

What is the myocardium, and what’s it made of?

The thick, muscular middle layer that pumps

muscles, nerves, and blood vessels,

What is the endocardium, and what’s it made of?

The inner lining of the heart chambers

endothelium + connective tissue

What is special about cardiac muscle cells?

They are branched, striated, single‑nucleus, and connected by intercalated discs.

Where is the base of the heart?

At the top.

Where is the apex of the heart?

At the bottom point.

What are auricles?

Ear‑like extensions of the atria.

What does the coronary sulcus separate?

groove between Atria and ventricles.

What does the interventricular sulcus separate?

groove between right and left ventricles.

What does the right atrium do?

Receives deoxygenated blood from the body thru the vena cava’s

What does the right ventricle do?

Pumps deoxygenated blood to the lungs.

What valve is between the right atrium and ventricle?

The tricuspid valve.

What valve leads to the pulmonary trunk?

The pulmonary semilunar valve.

What does the left atrium do?

Receives oxygenated blood from the lungs via pulmonary veins.

What does the left ventricle do?

Pumps oxygenated blood to the body.

What valve is between the left atrium and ventricle?

The bicuspid (mitral) valve.

What valve leads to the aorta?

The aortic semilunar valve.

What do coronary arteries do and how does the blood enter?

Supply oxygen to the atria/ventricles

thru aortic elastic rebound

What do coronary veins do?

Carry deoxygenated blood away from the heart muscle.

What do conducting cells do?

Control and coordinate the heartbeat.

What do contractile cells do?

Produce the force to pump blood.

What does the SA node do and where is it found?

Acts as the pacemaker and sets heart rate

right atrium

what does the internodal pathway do

connect the SA/AV node and pass the signal to the atrial contractile cells

What does the AV node do and where is it?

Delays the signal so the atria can contract first

in the floor of right atrium

What does the atrioventricular bundle do?

Carries the signal down the interventricular septum.

What do bundle branches do?

Carry the signal down the septum and send it to the moderator band to contract papillary muscles

What do Purkinje fibers do?

Spread the signal through the ventricles and cause contraction from apex to base.

What happens during depolarization of contractile cells?

Fast sodium channels open and sodium moves in (contraction).

What happens during the plateau phase?

Sodium channels close fast, and calcium enters slowly, keeping the cell contracted.

What happens during repolarization?

Potassium exits the cell, making the inside negative again and restoring resting membrane potential.

What is the absolute refractory period?

A time when no second stimulus can trigger a response.

What is the relative refractory period?

A stronger stimulus can trigger a response.

What does the P wave represent?

Atrial depolarization ( contraction)

What does the QRS complex represent?

Ventricular depolarization ( contraction)

What does the T wave represent?

Ventricular repolarization (relaxing)

What happens during atrial systole?

Atria contract and finish filling the ventricles.

What happens during ventricular systole?

Ventricles contract and push blood out.

What happens during ventricular diastole?

Ventricles relax and fill with blood.

What causes the first heart sound (S1)?

AV valves closing; start of ventricular systole

What causes the second heart sound (S2)?

Semilunar valves closing; start of ventricular diastole

What is cardiodynamics

movements during cardiac cycle

What is End Diastolic Volume (EDV)?

The amount of blood in a ventricle at the end of filling.

What is End Systolic Volume (ESV)?

The amount of blood left in a ventricle after it contracts.

What is stroke volume?

The amount of blood pumped out per beat (EDV − ESV).

What is cardiac output?

The amount of blood pumped by a ventricle in one minute (SV × HR).

What does acetylcholine do to heart rate?

Slows it down.

What does norepinephrine do to heart rate?

Speeds it up.