24 Questions
What happens to the impulses that originate at the SA node during atrial contraction?
They are delayed for about 0.1 second before spreading to the heart apex
What is the function of the bundle branches and Purkinje fibers?
To conduct signals from the AV node to the ventricular walls
What is the role of the parasympathetic division in regulating heart tempo?
It slows down the pacemaker
What is the effect of an increase in body temperature on heart rate?
It increases heart rate by about 10 beats per minute
What is the role of epinephrine in regulating heart rate?
It speeds up the pacemaker
What happens to the atria during atrial contraction?
They contract in unison
What is a characteristic of some cardiac muscle cells?
They can contract and relax repeatedly without any signal from the nervous system
Where is the pacemaker located in vertebrates?
In the wall of the right atrium, near where the superior vena cava enters the heart
What is the function of the sinoatrial node?
To set the rate and timing of cardiac muscle cell contractions
What is the purpose of an electrocardiogram (ECG or EKG)?
To measure the electrical activity of the heart
What is special about the impulses produced by the sinoatrial node?
They are similar to those produced by nerve cells
What is the term for the cluster of autorhythmic cells that sets the rate and timing of cardiac muscle cell contractions?
Sinoatrial node
Where in the heart does the heartbeat originate?
In the cardiac muscle cells
What allows impulses from the SA node to spread rapidly within heart tissue?
Gap junctions
What is recorded by electrodes placed on the skin in an electrocardiogram?
Electrical currents
What is the shape of the graph representing the stages in the cardiac cycle?
Complex waveform
What is unique about the rhythmic contractions of autorhythmic cardiac muscle cells?
They can contract and relax repeatedly without any signal
In which vertebrates is the pacemaker located in the nervous system?
Arthropods
What is the primary function of the AV node?
To delay the impulses from the SA node
What happens to the heart rate when the body temperature increases?
It increases by about 10 beats per minute for every 1°C increase
What is the primary function of the bundle branches and Purkinje fibers?
To conduct signals from the AV node to the ventricular walls
What is the result of the sympathetic division stimulating the pacemaker?
An increase in heart rate
What is the primary function of the SA node?
To generate impulses
What is the result of the parasympathetic division stimulating the pacemaker?
A decrease in heart rate
Learn about the autorhythmic cardiac muscle cells in vertebrates and how their contractions are coordinated in the intact heart. Understand the origin of the heartbeat and the role of the nervous system in cardiac function. Explore the rhythmic contractions of cardiac tissue in a laboratory setting.
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