bio 211 lecture exam 2

During a cardiac cycle, how many of the four chambers contract at any one time: 2

2

In an ECG, the P wave is generated when the:atria depolarize A. ventricles depolarize B. atria depolarize C. atria repolarize D. ventricles repolarize E. Purkinje fibers initiate an impulse B. atria depolarize

B. atria depolarize

During exercise, blood flow to skeletal muscles increases. What other blood flow changes occur: Blood flow to coronary vessels increases, and flow to abdominal organs decreases.

Blood flow to coronary vessels increases, and flow to abdominal organs decreases.

Cardiac output is usually expressed in: Liters per minute.

Cardiac output equals the heart rate multiplied by stroke volume

Low blood pressure may cause the net hydrostatic pressure of a capillary to be less than normal. This will result in a(n) Decreased net filtration: Decreased

Decreased

A drug that decreases calcium levels in a muscle cell and thereby lowered the number of cross bridges formed during the heart's contractions would be: Negative inotropic agent

Negative inotropic agent

Which segment of the ECG reflects the plateau phase of ventricular muscle cells' action potentials:S-T segment

S-T segment

In a ECG, what does the T wave represent: ventricular repolarization as the heart rests and prepares to contract again.

The T wave of the ECG represents ventricular repolarization as the heart rests and prepares to contract again.

Sympathetic innervation of the heart: a,c a: increases the heart rate b: decreases the heart rate c: increases the force of contractions d: decreases the force of contractions e: has no effect on contraction force a, c

a,c

The plateau phase of an action potential:allows cardiac muscle cells to contract and then relax without locking up.

allows cardiac muscle cells to contract and then relax without locking up.

Blood pressure is highest in the arteries closest to the heart and lowest in the __veins__. arteries closest to the heart; veins

arteries closest to the heart; veins

The membrane of a contractile cardiac muscle cell contains:fast voltage-gated sodium channels and slow voltage-gated calcium channels. a: fast voltage-gated sodium channels and fast voltage-gated calcium channels. b: fast voltage-gated sodium channels and slow voltage-gated calcium channels. c: slow voltage-gated sodium channels and slow voltage-gated calcium channels. d: slow voltage-gated sodium channels and fast voltage-gated calcium channels.

b: fast voltage-gated sodium channels and slow voltage-gated calcium channels.

Cardiac output is the amount of blood that is pumped:by a single ventricle in one minute.

by a single ventricle in one minute.

What is the sequence of events in the transmission of an impulse through the heart muscle? a: AV node b: AV bundle c: SA node d: Through the atria e: Through the ventricles f: Bundle branches g: Purkinje fibers

c, d, a, b, f, g, e

For the repolarization phase of an SA nodal cell action potential: calcium channels close and potassium channels open.

calcium channels close and potassium channels open.

cardiac reserve is: The difference between resting and maximal cardiac output.

cardiac reserve The difference between resting and maximal cardiac output.

Which type of muscle cell exhibits a longer refractory period: cardiac/muscle

cardiac/muscle

Atrial contraction occurs just before: isovolumetric contraction a: isovolumetric relaxation. b: atrial relaxation and ventricular filling. c: ventricular ejection. d: isovolumetric contraction. d.

d

Vagal tone refers to the ____decreasing_______ of the heart rate below its inherent rhythm by _parasympathetic___________ stimulation:decreasing, parasympathetic

decreasing, parasympathetic

During the plateau phase of a cardiac muscle cell's action potential, the membrane stays:depolarized as potassium exits and calcium enters.

depolarized as potassium exits and calcium enters.

As with action potentials in other types of cells, the repolarization of cardiac muscle cells involves the:exit of potassium through voltage-gated channels.

exit of potassium through voltage-gated channels.

Arteries carry blood toward the heart:false

false

The atrial reflex relies upon chemoreceptors to detect stretch in the atrial wall:False

false

The membrane of a contractile cardiac muscle cell contains: fast voltage-gated sodium channels and slow voltage-gated calcium channels.

fast voltage-gated sodium channels and slow voltage-gated calcium channels.

Cardiac output equals the:heart rate multiplied by stroke volume.

heart rate multiplied by stroke volume.

What are the cell-to-cell contacts of the cardiac muscle fibers called: intercalated discs.

intercalated discs.

Peripheral resistance is __[directly/inversely]__ proportional to the frictional resistance of blood flow through the vessels.

inversely

the shutting of the semilunar valves occurs during which phase: isovolumetric relaxation

isovolumetric relaxation

Large doses of certain stimulants can lead to dangerous increases in heart rates. Such a stimulant is a: positive chronotropic agent

positive chronotropic agent

once SA nodal cell reaches threshold, the depolarization phase occurs during which:potassium moves out through fast voltage gated channels

potassium moves out through fast voltage gated channels

Opening and closing of the heart valves is caused by: pressure gradients.

pressure gradients.

It is the contraction of the atria during atrial systole that completes the filling of the ventricles while the ventricles are in diastole: True.

true

Normally, the left and right ventricles eject the same amount of blood:True

true