PHYSIO: Ch.14 pt.2 - Blood, Heart, Circulation

The ventricles completely empty when they contract in systole.

 

True

 

False

False (resulting in EDV)

A medication that blocks the calcium channels in the heart muscle would cause a decrease in heart rate.

 

True

 

False

True

The __________ conducts impulses from the AV node to the bundle branches, which lead to the Purkinje fibers.

 

AV valve

 

ventricular septum

 

AV bundle

 

SA node

AV Bundle (SA node goes SA→ AV)

Within the blood vessels, valves are found in the __________.

 

arteries

 

capillaries

 

arterioles

 

veins

veins (have least amt. of pressure so needs valves to push blood through)

The action potential of non-pacemaker cells is due to the __________.

 

inward diffusion of Na⁺

 

inward diffusion of Ca²⁺

 

inward diffusion of K⁺

 

outward diffusion of K⁺

inward diffusion of Na2+ (just like pacemaker cells)

Closure of the atrioventricular valves occurs at the end of diastole/beginning of systole.

 

True

 

False

True (“lub” of ventricular systole - “dub” of ventricular diastole ~ SL valves closed)

Which of the following statements about cardiac muscle cells is FALSE?

 

the resting membrane potential of autorhythmic cells is maintained by sodium and potassium If channels

 

in autorhythmic cells, at threshold, calcium flows into the cell

 

contractile cells have a resting membrane potential of -85mV

 

when contractile cells are stimulated by nearby cells, sodium flows into the cell

 

only autorhythmic cells are repolarized by potassium efflux

only autorhythmic cells are repolarized by potassium efflux (autorhythmic cells and contractile cells can both be repolarized)

In a complete AV node block, __________.

 

no signals pass into the ventricles

 

the atria will be paced by the SA node

 

the ventricles contract due to ectopic pacemakers

 

All of the choices are correct.

All of the choices are correct.

Myocardial cells exhibit a plateau phase instead of quickly repolarizing. This is due to __________.

 

inward diffusion of calcium through slow Ca²⁺ channels

 

inward diffusion of sodium through fast Na⁺ channels

 

inward diffusion of potassium through voltage-gated K⁺ channels

 

outward pumping of sodium by the Na⁺/K⁺ pump

inward diffusion of calcium through slow Ca2+ channels (slow as to avoid tetanus)

The period of time when the atria relax is called:

 

atrial diastole

 

atrial systole

 

ventricular diastole

 

ventricular systole

atrial diastole

Ventricular fibrillation __________.

 

occurs when the ventricles contract in a rapid, coordinated manner

 

is not life threatening

 

occurs when the ventricles contract in a rapid, uncoordinated manner

 

is induced by defibrillators

occurs when the ventricles contract in a rapid, uncoordinated manner (hence defibrillators needed to reset heart)

The period of time when the ventricles relax is called:

 

atrial diastole

 

atrial systole

 

ventricular diastole

 

ventricular systole

ventricular diastole

What causes the semilunar valves to close?

 

Higher pressure in the ventricles than in the atria

 

Higher pressure in the aorta and pulmonary trunk than in the ventricles

 

Higher pressure in the atria than in the ventricles

 

Higher pressure in the ventricles than aorta and pulmonary trunk

higher pressure in the aorta and pulmonary trunk than in the ventricles (all valves closed)

Which of the following statements about cardiac muscle cells is FALSE?

 

the resting membrane potential of autorhythmic cells is maintained by sodium and potassium If channels

 

in autorhythmic cells, at threshold, calcium flows into the cell

 

contractile cells have a resting membrane potential of -85mV

 

when contractile cells are stimulated by nearby cells, potassium flows into the cell

 

both autorhythmic and contractile cells are repolarized by potassium efflux

when contractile cells are stimulated by nearby cells, potassium flows into the cell (No, NA+ channels are opened similar to Autorhythmic)

The action potential of cardiac pacemaker cells is caused by __________.

 

inward diffusion of Na⁺

 

inward diffusion of Ca²⁺

 

inward diffusion of K⁺

 

outward diffusion of K⁺

inward diffusion of Ca2+

Resistance to blood flow is controlled most by:

 

arteries

 

arterioles

 

veins

 

venules

arterioles

Which type of an AV node block occurs when no atrial waves can pass through the AV node?

 

First-degree

 

Second-degree

 

Third-degree

 

Fourth-degree

third-degree

Which of the following statements about excitation-contraction coupling of myocardial cells is TRUE?

 

calcium influx from the ECF happens before influx from the SR

 

the major source of calcium in is from the SR

 

the sliding filament mechanism is the same as for skeletal muscle

 

all of the above are TRUE

all of the above are TRUE

The lymphatic system is responsible for all of the following EXCEPT:

 

transport of ISF/lymph

 

transport of fat from GI tract to blood

 

resistance to disease

 

transport of blood

transport of blood

End diastolic volume is the volume of blood in the:

 

ventricles after ventricular diastole

 

ventricles after ventricular systole

 

atria after atrial diastole

 

atria after atrial systole

ventricles after ventricular diastole

The __________ are the last part of the electrical conducting system of the heart.

 

SA node

 

AV bundle

 

Bundle of His

 

Purkinje fibers

Punkinje fibers

The T wave of the ECG represents atrial repolarization.

 

True

 

False

False (ventricular depolarization)

If the __________ were not properly functioning, congestion in the venous system would be an expected sign.

 

tricuspid valve

 

bicuspid valve

tricuspid valve

Failure of the SA node to depolarize would result in an ECG __________.

 

lacking a T wave

 

lacking a QRS complex

 

lacking a P wave

 

that is isoelectric

lacking a P wave

Which of the following statements about cardiac muscle cells is FALSE?

 

The resting membrane potential of autorhythmic cells is maintained by sodium and potassium If channels

 

In autorhythmic cells, at threshold, calcium flows out of the cell

 

contractile cells have a resting membrane potential of -85mV

 

when contractile cells are stimulated by nearby cells, sodium flows into the cell

 

both autorhythmic and contractile cells are repolarized by potassium efflux.

in autorhythmic cells, at threshold, calcium flows out of the cell

During isovolumetric ventricular contraction, ventricular pressure is __________.

 

increasing

 

decreasing

 

unchanged

increasing

Briefly describe the structure of the heart (chambers, ,circulation path, valves)

• 2 atria + 2 ventricles separated by septa

• Pulmonary (deoxygenated): R.ventricle → lungs → L.Atrium

• Systemic (oxygenated): L.Ventricle →Tissues → R.Atrium

• AV(tricuspid + bicuspid/mitral) + SL valves (pulmonary/aorta)

What is the purpose of the valves? How do they function?

Valves prevent the backflow of blood.

AV:

opens when: Atria pressure > Ventricle Pressure; closes inversely

SL:

opens when: Ventricle pressure > Arteries pressure; closes inversely

Define: diastole; systole; end diastolic volume; end systolic volume

Diastole: relaxation

Systole: Contraction

EDV: volume of blood in ventricles after atrial systole (blood before being ejected AKA preload)

ESV: volume of blood in ventricles at the end of ventricular systole and is never 0 (AKA afterload)

Define: isovolumetric contraction, isovolumetric relaxation

Isovolumetric contraction: no blood moving, both valves closed, and ventricles contracted. Ventricular pressure is increasing.

Isovolumetric relaxation: no blood moving, both valves closed, and ventricles relaxed

What causes the heart sounds?

“Lub” = closure of the AV valves

“Dub” = closure of the SL valves

Describe the excitation of autorhythmic cells of the heart. How does the ANS affect excitation? 

Autorhythmic cells:

• RMB potential more permeable to Ca influx → more positive, sets rhythm of heartbeat

ANS only influences, does not control.

SNS: NE/E speeds up

PSNS: AcH slows down generation, helps hyperpolarize through K+ channels

Describe the excitation of contractile cells of the heart.  How is contraction accomplished in contractile cells? What is the significance of the long plateau phase?

Contractile cells are stimulated by nearby cells through intercalated discs/electrical synapse.

Na+ channels open to depolarize cells, letting the Ca+ influx slowly to cause a long refractory period. K+ efflux to repolarize.

The significance of a plateau phase with contractile cells is to prevent tetanus.

List the structures, in order, of the conduction pathway of the heart (5 total)

SA Node → AV node → AV Bundle of His → R/L Bundle branches → Purkinje Fibers @ bottom

Describe the typical ECG output. What is the name of each wave and what does each wave signify?

P: Atrial Depolarization

QRS: Ventricular Depolarization

“lub”

T: Ventricular Repolarization

“dub”

What types of vessels are considered: distributing; conducting, resistance, exchange ?

Distributing: Muscular arteries (push blood to organs)

Conducting: Elastic arteries (push blood forward)

Resistance: Arterioles (modify resistance to flow by vasoconstriction/dilation)

Exchange: capillaries