philS 21,22,24 : frog heart

A.via the atrioventricular (AV) node.

Pacemaker cells in the sinoatrial (SA) node produce action potentials and pass them to the ventricular myocytes: A.via the atrioventricular (AV) node. B.directly via gap junctions. C.through nerves. D.none of the other options is correct; the ventricles are not excited by pacemaker cells.

C. gap junctions, which link adjacent atrial myocytes.

The action potential travels from the SA node to the atria via: A.specialized nerves in the heart. B.the blood that travels through the heart. C.gap junctions, which link adjacent atrial myocytes. D.chemical synapses, which link adjacent cardiac myocytes.

B.the atrioventricular (AV) node.

The action potential travels from the sinoatrial (SA) node to the ventricles via: A.the blood in the heart. B.the atrioventricular (AV) node. C.gap junctions that link adjacent myocytes. D.specialized nerves in the heart.

the cardiac cycle.

The rhythmic upward and downward deflections of the upper line on the computer screen indicate: -the other two options are true. -the electrical stimuli delivered to the ventricle. -the cardiac cycle.

A.by a single action potential in a group of muscle fibers.

A single "twitch" contraction of skeletal muscle is produced: A.by a single action potential in a group of muscle fibers. B.spontaneously; no action potentials are required. C.by several action potentials in a group of muscle fibers. D.by a change in the tension in the tendon.

B. norepinephrine on the sinoatrial (SA) node pacemaker cells to increase the heart rate.

The sympathetic nervous system uses: A. norepinephrine on the sinoatrial (SA) node pacemaker cells to slow the heart rate. B. norepinephrine on the sinoatrial (SA) node pacemaker cells to increase the heart rate. C. acetylcholine on the sinoatrial (SA) node pacemaker cells to increase the heart rate. D. acetylcholine on the sinoatrial (SA) node pacemaker cells to slow the heart rate.

the electrical stimuli delivered to the ventricle.

The upward deflection on the lower line of the virtual computer screen indicates: -the electrical stimuli delivered to the ventricle. -the cardiac cycle. -the other two options are true.

yes

Was an extra contraction produced when the stimulus was applied after the ventricle had contracted normally?

No

Was an extra contraction produced when the stimulus was applied to the ventricle during the time when the ventricle was contracting normally?

A. Acetylcholine would decrease blood pressure.

Acetylcholine decreases cardiac output so that blood enters the arteries at a slower rate. If the rate of arterial blood loss is constant, what would acetylcholine do to blood pressure? A.Acetylcholine would decrease blood pressure. B.Acetylcholine would increase blood pressure. C. Acetylcholine would have no effect on blood pressure.

B.Acetylcholine decreases the heart rate.

Acetylcholine is used by the parasympathetic nervous system. Look at your data. What does acetylcholine do to heart rate? A.Acetylcholine does not change the heart rate. B.Acetylcholine decreases the heart rate. C.Acetylcholine increases the heart rate.

B.moves it further from threshold so that action potentials (and heart contractions) take place at a slower rate.

Acetylcholine opens potassium channels in the membrane of the pacemaker cells. In this way, acetylcholine hyperpolarizes the membrane, which: A.moves it closer to threshold so that action potentials (and heart contractions) take place at a faster rate. B.moves it further from threshold so that action potentials (and heart contractions) take place at a slower rate. C. does not change relative to threshold, so has no effect on action potential production and heart contractions.

C.Adrenaline increases the heart rate.

Adrenaline (Norepinephrine) is used by the sympathetic nervous system. Look at your data. What does adrenaline do to heart rate? A.Adrenaline does not change the heart rate. B.Adrenaline decreases the heart rate. C.Adrenaline increases the heart rate.

Adrenaline would increase blood pressure.

Adrenaline increases the rate at which blood enters the arteries. If the rate of blood loss from the arterial system remains constant, what would adrenaline do to blood pressure? A. Adrenaline would have no effect on blood pressure. B.Adrenaline would increase blood pressure. C. Adrenaline would decrease blood pressure.

specialized cardiac cells.

An ectopic beat is produced by: -specialized nerves in the heart. -the autonomic nervous system. -blood flowing through the heart. -specialized cardiac cells.

C. a single action potential in, and a contraction of, all ventricular myocytes.

During the cardiac cycle, a ventricular contraction is produced by: A.many action potentials, which evoke a contraction of all ventricular myocytes. B. a single action potential in, and a contraction of, a FEW ventricular myocytes. C. a single action potential in, and a contraction of, ALL ventricular myocytes. D. many action potentials, which evoke a contraction of some ventricular myocytes.

after the atria contract.

During the normal cardiac cycle, the ventricles contract: -at the same time as the atria contract. -after the atria contract. -before the atria contract.

B.at different times throughout the cardiac cycles.

During this experiment, electrical shocks were applied to the ventricles of the frog heart: A.many times in one cardiac cycle. B.at different times throughout the cardiac cycles. C.at the same time in each cardiac cycle.

C. the ventricle filled with some blood before the extra contraction.

If extra ventricular contractions were produced when the ventricle was relaxing, this means that: A. the ventricle filled with the same amount of blood as normal before the extra contraction. B. the ventricle did not have time to fill with any blood before the extra contraction. C. the ventricle filled with some blood before the extra contraction.

A.The sinoatrial (SA) node

If the time between atrial contractions is independent of experimental manipulation, where is the pacemaker for atrial contractions? A.The sinoatrial (SA) node B.The Purkinje fibers C.The atrioventricular (AV) bundle (or bundle of His) D.The atrioventricular (AV) node

D. depolarizes the cell membrane to threshold.

In the cells of the SA node, the pacemaker potential: A.is another name for the membrane potential of the pacemaker cells. B.is the name given to the action potential that travels through the heart to produce the contraction. C.is another name for the action potentials produced by the pacemaker cells. D.depolarizes the cell membrane to threshold.

B.larger than that produced by the contracting atria.

In this lab, contractions of the heart produced upward deflections of the line tracing. The deflection produced by the contracting ventricle was: A.smaller than that produced by the contracting atria. B.larger than that produced by the contracting atria. C.about the same size as that produced by the contracting atria.

A.Cooling decreases the rate that channels open and close, and slows pacemaker activity and the heart rate.

Ion channels and enzymes are both proteins. If cooling decreases the rate of enzymatic activity, what does cooling do to the rate that channels open and close? A.Cooling decreases the rate that channels open and close, and slows pacemaker activity and the heart rate. B.Cooling increases the rate that channels open and close, and slows pacemaker activity and the heart rate. C.Cooling does not change the rate that channels open and close, slowing pacemaker activity and heart rate.

B.about the same as the time interval between ventricle contractions.

Look at your data. In the first part of the lab, when no thread was tied around the heart, the time interval between atrial contractions was: A.much shorter than the time interval between ventricle contractions. B.about the same as the time interval between ventricle contractions. C.much longer than the time interval between ventricle contractions.

B.Cooling decreases the heart rate.

Look at your data. What is the effect of cooling on heart rate? A.Cooling does not change the heart rate. B.Cooling decreases the heart rate. C.Cooling increases the heart rate.

No

Look at your recording when a stimulus produced an extra ventricular contraction. Was an extra contraction produced when the stimulus was applied before the normal ventricular contraction?

A. longer than the action potential recorded from a skeletal muscle fiber.

The duration of the cardiac action potential is: A. longer than the action potential recorded from a skeletal muscle fiber. B. about the same as the action potential recorded from a skeletal muscle fiber. C.shorter than the action potential recorded from a skeletal muscle fiber. D.varied, so that sometimes it is shorter and sometimes it is longer than the action potential recorded from a skeletal muscle fiber.

the ventricle was relaxing and was filling with blood.

The extra ventricular contractions were produced only when: -the ventricle was contracting. -the atria were contracting. -the ventricle was relaxing and was filling with blood.

B. the heart must relax between contractions to fill with blood.

The heart cannot go into tetanus or "fibrillation" and continue to pump because: A. such a strong contraction would damage the tendons in the heart. B. the heart must relax between contractions to fill with blood. C.too much blood would enter the arteries. D. the blood pressure in the arteries would be too great.

D.directly via gap junctions.

The pacemaker cells in the sinoatrial (SA) node produce action potentials and pass them to atrial myocytes: A.none of the other options is correct; the atrial myocytes are not excited by pacemaker cells. B.via the atrioventricular (AV) node. C.through nerves. D.directly via gap junctions.

B.acetylcholine on the sinoatrial (SA) node pacemaker cells to slow the heart rate.

The parasympathetic nervous system uses: A.norepinephrine on the sinoatrial (SA) node pacemaker cells to increase the heart rate. B.acetylcholine on the sinoatrial (SA) node pacemaker cells to slow the heart rate. C.norepinephrine on the sinoatrial (SA) node pacemaker cells to slow the heart rate. D.acetylcholine on the sinoatrial (SA) node pacemaker cells to increase the heart rate.

All of the other options are true.

The prolonged refractory period following the action potential ensures that: the ventricle does not enter fibrillation. the ventricle has time to relax. the heart can fill with blood before contracting again. All of the other options are true.

open voltage-gated calcium channels.

The prolonged refractory period in the cardiac action potential is produced by: -closed voltage-gated calcium channels. -open voltage-gated potassium channels. -open voltage-gated calcium channels. -open voltage-gated sodium channels.

A.the sinoatrial (SA) node.

The rhythmic contractions of the healthy human heart are initiated by action potentials produced by cells in: A.the sinoatrial (SA) node. B.the brain. C.the autonomic nervous system. D.the atrioventricular (AV) node.

D.The contraction amplitude increases and the cardiac output increases.

What is the effect of adrenaline on the amplitude of each contraction and the cardiac output? A.The contraction amplitude decreases and the cardiac output increases. B.The contraction amplitude increases and the cardiac output decreases. C.The contraction amplitude decreases and the cardiac output decreases. D.The contraction amplitude increases and the cardiac output increases.

B. Cooling decreases the rate of enzymatic action.

What is the effect of cooling on the rate of enzymatic action? A. Cooling increases the rate of enzymatic action. B. Cooling decreases the rate of enzymatic action. C. Cooling does not change the rate of enzymatic action.

A. It was about the same as the time interval between atrial contractions recorded from the pristine heart.

When thread was tied across the sulcus and the atria and ventricle contracted asynchronously, how was the time interval between the atrial contractions altered when compared to that of the pristine heart? A. It was about the same as the time interval between atrial contractions recorded from the pristine heart. B. It was significantly shorter than the time interval between atrial contractions recorded from the pristine heart. C. It was significantly longer than the time interval between atrial contractions recorded from the pristine heart.

B.in the AV node, the AV bundle, or the Purkinje fibers.

When thread was tied across the sulcus and the atria and ventricle contracted asynchronously, the pacemaker for the (slower) ventricle contractions was: A.in the sinoatrial (SA) node. B.in the AV node, the AV bundle, or the Purkinje fibers. C.created by blood as it stretched the wall of the ventricle.

C. the pacemaker for the (less-frequent) ventricle contractions was not in the SA node.

When thread was tied across the sulcus and the atria and ventricle contracted asynchronously: A.the atria and ventricles were excited by the pacemaker in the sinoatrial node. B.only the occasional action potential made its way through the AV node to excite the ventricles. C. the pacemaker for the (less-frequent) ventricle contractions was not in the SA node.

B. It was significantly longer than the time interval between ventricle contractions recorded from the pristine heart.

When thread was tied across the sulcus, how was the time interval between ventricular contractions altered when compared to that of the pristine heart? A. It was about the same as the time interval between ventricle contractions recorded from the pristine heart.Incorrect B. It was significantly longer than the time interval between ventricle contractions recorded from the pristine heart. C. It was significantly shorter than the time interval between ventricle contractions recorded from the pristine heart.

D.showed that the ventricles and the atria were contracting asynchronously.

When thread was tied across the sulcus, the line tracing: A.showed that only the atria were contracting. B.did not change when compared with the tracing from the pristine heart. C.showed that only the ventricles were contracting. D.showed that the ventricles and the atria were contracting asynchronously.

C.It was about the same as the time interval between atrial contractions recorded from the pristine heart.

When thread was tied across the two atria and produced only atrial contractions, how was the time interval between the atrial contractions altered when compared to that of the pristine heart? A.It was significantly longer than the time interval between atrial contractions recorded from the pristine heart. B.It was significantly shorter than the time interval between atrial contractions recorded from the pristine heart. C.It was about the same as the time interval between atrial contractions recorded from the pristine heart.

D.showed that just the atria were contracting.

When thread was tied across the two atria, the line tracing: A.did not change when compared with the tracing from the pristine heart. B.showed that the ventricles and the atria were contracting asynchronously. C.showed that just the ventricle was contracting.Incorrect D.showed that just the atria were contracting.

D.The sinoatrial (SA) node.

Where is the pacemaker for the normal healthy heart? A.The atrioventricular (AV) bundle or bundle of His. B.The Purkinje fibers. C.The atrioventricular (AV) node. D.The sinoatrial (SA) node.