Overview of CV system

What is the primary purpose of the cardiovascular system?

Rapid transport of substances (oxygen, nutrients, hormones, drugs, water), removal of waste products, temperature regulation, and distribution of hormones.

Where is the heart located?

Behind the sternum, in front of the spine, between the lungs, enclosed within the pericardium.

What are the two layers of the pericardium?

Parietal pericardium (outer) and visceral pericardium (inner).

What are the functions of the pericardium?

Protection, stabilisation, and lubrication of the heart.

What fills the pericardial cavity?

Serous fluid.

What are the three layers of the heart wall from outer to inner?

Epicardium, myocardium, endocardium.

Which layer of the heart is primarily responsible for contraction?

Myocardium.

Which chamber receives blood from the superior and inferior vena cava?

Right atrium.

Which chamber pumps blood into the pulmonary artery?

Right ventricle.

Which chamber receives oxygenated blood from the pulmonary veins?

Left atrium.

Which chamber pumps blood into the aorta?

Left ventricle.

What structure separates the right and left sides of the heart?

Septum.

What is the correct order of blood flow through the pulmonary circulation?

Right atrium → Tricuspid valve → Right ventricle → Pulmonary valve → Pulmonary artery → Lungs → Pulmonary veins → Left atrium.

What is the correct order of blood flow through the systemic circulation?

Left atrium → Mitral valve → Left ventricle → Aortic valve → Aorta → Body tissues → Vena cavae → Right atrium.

Which veins carry oxygenated blood?

Pulmonary veins.

Which arteries carry deoxygenated blood?

Pulmonary arteries.

What are the atria primarily responsible for?

Receiving blood.

What are the ventricles primarily responsible for?

Distributing blood.

What is the tricuspid valve?

The atrioventricular valve between the right atrium and right ventricle.

How many leaflets does the tricuspid valve have?

Three.

What is the mitral valve?

The atrioventricular valve between the left atrium and left ventricle.

How many leaflets does the mitral valve have?

Two.

What structures attach AV valve leaflets to papillary muscles?

Chordae tendineae.

What is the function of the chordae tendineae?

Prevent valve prolapse and help keep AV valves closed during ventricular contraction.

Where is the aortic valve located?

Between the left ventricle and the aorta.

Where is the pulmonary valve located?

Between the right ventricle and the pulmonary artery.

What type of valves are the aortic and pulmonary valves?

Semilunar valves.

Why are semilunar valves called semilunar?

Their cusps are crescent-shaped.

How do heart valves open?

Passively when pressure behind the valve exceeds pressure ahead of it.

How do heart valves close?

When pressure behind the valve falls below pressure ahead of it.

When does the mitral valve open?

When left atrial pressure exceeds left ventricular pressure.

When does the aortic valve close?

When left ventricular pressure falls below aortic pressure.

What is ventricular contraction called?

Systole.

What is ventricular relaxation called?

Diastole.

Do the atria contract simultaneously?

Yes, approximately.

Do the ventricles contract simultaneously?

Yes, approximately.

How much blood do the ventricles normally eject relative to each other?

Equal volumes.

What is stroke volume (SV)?

The volume of blood ejected by a ventricle with each beat.

What is heart rate (HR)?

The number of heart beats per minute.

What is cardiac output (CO)?

The volume of blood ejected by one ventricle per minute.

What is the equation for cardiac output?

CO = SV × HR.

A patient has a stroke volume of 70 mL and a heart rate of 60 bpm. What is their cardiac output?

4200 mL/min (4.2 L/min).

What is a typical adult stroke volume?

70–80 mL.

How does cardiac output change during strenuous exercise?

It can increase approximately 4–5 fold.

Which organ receives disproportionately high blood flow due to its excretory role?

Kidneys.

Approximately what percentage of oxygen does cardiac muscle extract from coronary blood flow?

65–75%.

Define blood flow.

The volume of blood flowing through a vessel per minute (mL/min).

Define blood pressure.

The force per unit area exerted on vessel walls by blood, expressed in mmHg.

Define resistance.

The opposition to blood flow through vessels.

What provides the driving force for blood flow?

A pressure gradient.

According to Darcy's law, what determines flow?

Pressure difference divided by resistance.

State Darcy's law.

Q = (P1 − P2) / R.

What happens to resistance as vessel diameter decreases?

Resistance increases.

How are resistances combined when vessels are connected in series?

They are added together.

Why is systemic vascular resistance relatively high?

Because blood must pass through many narrow arterioles and capillaries connected in series.

How does pulmonary vascular resistance compare to systemic vascular resistance?

It is much lower.

What are the two main ways to increase blood flow to an organ?

Increase driving pressure or decrease vascular resistance.

How is local blood flow usually regulated?

By changing vascular resistance.

Which blood vessels primarily regulate local vascular resistance?

Small arteries and arterioles.

Why can severe bradycardia cause dizziness and syncope?

Reduced cerebral perfusion due to insufficient cardiac output.

What happens if blood becomes stationary?

It coagulates, wastes accumulate, and oxygen is depleted.

Why are septal defects associated with reduced systemic oxygenation?

They allow abnormal mixing/shunting of blood between circulations.

Which circuit oxygenates blood?

Pulmonary circulation.

Which circuit delivers oxygenated blood to tissues?

Systemic circulation.

True or False: Blood must complete the pulmonary circuit before re-entering the systemic circuit.

True.

True or False: Both circulations begin and end at the heart.

True.

What is the moderator band and where is it found?

A structure in the right ventricle near the apex that helps prevent overdistension.

Which heart chamber has the thickest myocardium?

Left ventricle.

Which valve lies between the left atrium and left ventricle?

Mitral valve.

Which valve lies between the right atrium and right ventricle?

Tricuspid valve.

Which valve lies between the left ventricle and aorta?

Aortic valve.

Which valve lies between the right ventricle and pulmonary artery?

Pulmonary valve.