physio exam 2- Cardiovascular overview and electrical activity

What is the normal pacemaker of the heart?

SA node

What is the basic blood flow path through the heart and lungs?

Body → right heart → lungs → left heart → body

Which chamber receives blood returning from the body?

Right atrium

Which chamber pumps blood toward the lungs?

Right ventricle

Which vessel carries blood from the right ventricle toward the lungs?

Pulmonary artery

Which chamber receives blood returning from the lungs?

Left atrium

Which chamber pumps blood into the systemic circulation?

Left ventricle

Which vessel receives blood from the left ventricle?

Aorta

Which side of the heart pumps to the pulmonary circulation?

Right side

Which side of the heart pumps to the systemic circulation?

Left side

What valve lies between the right atrium and right ventricle?

Tricuspid valve

What valve lies between the left atrium and left ventricle?

Mitral valve

What valve leads from the right ventricle into the pulmonary artery?

Pulmonary valve

What valve leads from the left ventricle into the aorta?

Aortic valve

What sequence is listed under cardiac pump function?

SA node → action potential transmission → AV node → contraction → stroke volume

What does stroke volume represent?

Blood ejected by a ventricle per beat

What does Q represent in the vascular circuit?

Blood flow

What is the equation for cardiac output?

CO = HR × SV

What does cardiac output represent on the aortic flow slide?

Average blood flow

What are the units of cardiac output?

L/min

What is the main delivery function of systemic blood flow?

Deliver O2 to cells

What aortic blood pressure value is given in the lecture?

120/80 mmHg

What is systolic pressure?

The higher arterial pressure during systole

What is diastolic pressure?

The lower arterial pressure during diastole

What is pulse pressure?

Systolic pressure minus diastolic pressure

What is the equation for pulse pressure?

PP = PS − PD

What is the equation for mean arterial pressure?

MAP = PD + 1/3 PP

What does ΔP represent in the vascular circuit?

Perfusion pressure

What is the equation for vascular resistance?

R = ΔP/Q (flow)

What two major mechanisms control the vascular circuit?

ANS control and local control

What quantity is associated with vascular compliance on the slide?

Change in volume ΔV

How are the right and left sides of the heart described as pumps?

Two pulsatile pumps in series

What pressure pattern does each cardiac pump have?

Low-pressure input and high-pressure output

Where does the left ventricle pump blood?

Into the aorta

How are the organs supplied by the left ventricle arranged?

In parallel

Where does the right ventricle pump blood?

Into the pulmonary artery

What organ is supplied by the pulmonary artery?

The lung

What determines the amount of blood flow to an organ?

Perfusion pressure and vascular resistance

How does blood flow compare through organs or vessels arranged in series?

They receive the same blood flow

What organ is given as an example of networks arranged in series?

Kidney

How are vessels of the same type generally arranged within organs?

In parallel

What vessel type is given as an example of parallel vessels?

Capillaries

What is the vessel sequence from arterial to venous side?

Aorta → artery → arteriole → terminal arteriole → capillary → venule → vein → vena cava

What structure initiates coordinated electrical activity of the heart?

Sinoatrial node

Where does the SA node action potential spread next?

To the AV node and then ventricular pathways

What does the coordinated electrical activity ultimately cause?

Cardiac depolarization and ventricular contraction

What is bradycardia?

Heart rate below 60 beats/min

What is tachycardia?

Heart rate above 100 beats/min

What does Bachmann's bundle do?

Carries the impulse to the left atrium

What are internodal tracts?

Conduction pathways from the SA node toward the AV node

What does LBB stand for?

Left bundle branch

What does RBB stand for?

Right bundle branch

What is the main conduction pathway after the AV node?

Bundle of His → right and left bundle branches → Purkinje fibers

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 the full cardiac depolarization sequence?

SA node fires → impulse spreads through right atrium via internodal tracts and to left atrium via Bachmann’s bundle → atria depolarize → impulse reaches AV node → travels through Bundle of His → right and left bundle branches → Purkinje fibers → ventricular muscle depolarizes;

What is the direction of ventricular depolarization across the wall?

Endocardium → epicardium

What is the direction of ventricular repolarization across the wall?

Epicardium → endocardium

Which ventricular myocytes repolarize first?

The last myocytes to depolarize

What is phase 0 of the fast-response cardiac action potential?

Rapid upstroke and depolarization

What is phase 1 of the fast-response cardiac action potential?

Early partial repolarization

What is phase 2 of the fast-response cardiac action potential?

Plateau

What is phase 3 of the fast-response cardiac action potential?

Repolarization

What is phase 4 of the fast-response cardiac action potential?

Resting potential

What does an inward current generally cause?

Depolarization

What does an outward current generally cause?

Repolarization

What Na+ currents are listed in the lecture?

Fast Na+ and funny (SA node) Na+

What Ca++ currents are listed in the lecture?

L type and T type

What does L type Ca++ mean?

Long-lasting Ca++ current

What does T type Ca++ mean?

Transient Ca++ current

What delayed outward rectifier K+ currents are listed?

Ks Kr and Kur

What inward rectifier K+ currents are listed?

K1 KAch and KATP

What is Kto?

Transient outward K+ current

What helps maintain a stable membrane potential in fast-response cells?

IK1

What is the approximate threshold for the fast-response action potential?

About −65 mV

What happens to fast Na+ activation gates at threshold?

They open

What happens to Na+ inactivation gates during the upstroke?

They begin to close

What current produces the rapid fast-response upstroke?

Fast inward Na+ current

Why does the fast Na+ current diminish?

Na+ inactivation gates close

What membrane potential is reached near the peak of the fast response?

About +20 mV

When do voltage-gated slow Ca++ channels begin to open?

After depolarization during the plateau

What happens to some Na+ gates around −50 mV?

They reset

What happens to K+ current during repolarization?

It increases

What happens to Ca++ current during repolarization?

It declines

What combination drives repolarization in fast-response cells?

Increasing K+ current and declining Ca++ current

What is the relative refractory period?

A period of reduced excitability during repolarization

How can adjacent cardiac cells help depolarize a cell?

They draw charge and make Vm less negative

What type of action potential occurs in pacemaker cells?

Slow-response action potential

Which phases are absent from the slow-response pacemaker action potential?

Phases 1 and 2

What is the pacemaker membrane potential near the start of phase 4?

About −60 mV

What happens to funny Na+ channels near −60 mV?

They open and slowly leak Na+ inward

What does funny Na+ entry do to membrane potential?

Slowly makes it less negative

At what voltage do T type Ca++ channels open?

Around −55 mV

What happens when T type Ca++ channels open?

More positive ions enter slowly

What is the pacemaker threshold potential?

About −40 mV

What happens at −40 mV in pacemaker cells?

L type Ca++ channels open

What causes pacemaker depolarization after threshold?

Ca++ influx through L type channels

What happens around +30 mV in pacemaker cells?

L type Ca++ channels close and K+ channels open

What causes pacemaker repolarization?

K+ leaves the cell