AP II- Chapter 17 The Heart

Rank from the first to the last steps to describe the correct order of events of a cardiac contractile cell action potential. Refer to the graph of a contractile cell action potential as you rank the events

1.) Rapid depolarization phase: voltage-gated Na+ channels activate and Na+ enter, rapidly depolarizing the membrane 2.) Initial Repolarization phase: Na+ channels are inactivated and some K+ channels open; K+ leak out, causing a small initial depolarization 3.) Plateau phase: Ca2+ channels open and Ca2+ enters as K+ exit, prolonging the depolarization 4.) Repolarization phase: Na+ and Ca2+ channels close as K+ continue to exit, causing repolarization

Heart tissue dies during a myocardial infarction (MI), and a person's survival and recovery depend on the extent of cell death and the chamber(s) involved. In which chamber would the loss of function be most damaging to survival?

Left Ventricle - The left ventricle loss of function would be most damaging because it provides enough pressure of blood to send to the rest of the body.

The aortic valve opens at __________.

The aortic valve opens when the pressure in the ventricle rises above aortic pressure.

Which of the following happens immediately after the P wave?

The artria contract - After the atrial depolarization (P wave), the atria contract, allowing them to empty and causing the ventricles to reach their EDV.

Blood from the systemic circuit returns to the heart via the __________.

Venae Cavae - The two veins that drain the majority of the systemic circuit are the superior and inferior venae cavae.

Which of these is not a feature of cardiac muscle tissue? a. non-striated b. involuntary c. branched d. intercalated discs

a. non-striated - Cardiac muscle tissue has visible striations caused by the overlap of myofilaments.

What vessel delivers oxygenated blood to systemic capillaries for gas exchange?

aorta

The P wave on an electrocardiogram (ECG) represents the depolarization of cells in the:

atria

Which hormone decreases cardiac output by decreasing blood volume and preload?

atrial natriuretic peptide (ANP)

Which of the following vessels carries oxygenated blood? a. pulmonary artery b. pulmonary trunk c. pulmonary vein d. superior vena cava

c. pulmonary vein

Autorhythmicity in the heart is the responsibility of:

cardiac pacemaker cells.

What largely determines preload?

end-diastolic volume (EDV)

Rheumatic fever is a complication of untreated strep throat and the biggest cause of valve disorders. It can cause a condition caused aortic regurgitation in which the aortic semilunar valve is damaged and blood flows backwards into the:

left ventricle - When the aortic semilunar valve is insufficient, blood will flow back into the left ventricle instead of forward into the systemic circuit. Other reasons for aortic regurgitation include severe hypertension, congenital malformations of the valve, and aortic stenosis.

The pulmonary circuit involves blood flow from the heart to the:

lungs

The apex of the heart is __________.

inferior

What characteristic differentiates cardiac muscle cells from skeletal muscle cells?

intercalated discs

What surface groove separates the right and left ventricles?

interventricular sulcus

Unlike skeletal muscle action potentials, cardiac muscle action potentials __________.

involve calcium voltage-gated channels - The plateau phase of the cardiac action potential is due to the opening of calcium ions channels.

The left ventricle is the chamber with the thickest wall, because:

it has to generate enough pressure to pump blood throughout the entire systemic circuit - The left ventricle generates about five times more pressure than the right ventricle, and a lot more pressure than the atria, which only need to pump blood down into the ventricles.

How will the cardiac output change if you double the heart rate but reduce the stroke volume by one-half?

it will not change - The cardiac output will remain the same, because CO = HR × SV = 2HR × SV/2.

The left side of the heart receives blood returning from the:

pulmonary circuit - The left side of the heart receives oxygenated blood returning from the lungs via the pulmonary veins.

What vessel(s) deliver oxygenated blood to the left atrium?

pulmonary veins

What normally serves as the pacemaker of the entire heart?

sinoatrial (SA) node

What two values are needed in order to calculate cardiac output (CO) for a ventricle?

stroke volume (SV) and heart rate (HR)

The vessels that deliver oxygen to the tissues of the body are part of the __________.

systemic circuit

Right ventricular heart failure prevents the right ventricle from efficiently plumping blood into the pulmonary circuit, thus creating a backup of blood into the right atrium and the:

systemic veins - During right ventricular failure blood backs up into the vena cavae and systemic circuit, often causing systemic or generalized edema.

Afterload is described as:

the force the ventricles must overcome to eject blood into their respective arteries.

The aortic valve closes when __________.

the pressure in the left ventricle falls below aortic pressure - The aortic valve closes to prevent backflow of blood into the ventricle.

The valve located between the right atrium and the right ventricle is the:

tricuspid AV valve - The tricuspid valve prevents backflow from the right ventricle into the right atrium when the ventricle contracts.

What valve prevents the backflow of blood from the right ventricle into the right atrium?

tricuspid valve

The right atrium receives blood from the:

vena cavae - The superior and inferior vena cavae return deoxygenated blood from the systemic circulation to the right atrium.

During what phase does blood flow from the ventricles into the pulmonary trunk and aorta?

ventricular ejection phase