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23 Cards in this Set
- Front
- Back
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How many leaders of blood does the heart pump per minute?
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5 liters of blood per minute.
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About how big is the adult heart?
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About the size of a closed fist.
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How much of the heart located to the left of the midline?
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About 2/3rds.
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What pushes the heart valves open?
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A forward pressure gradient.
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What pushes the valves closed?
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A backward pressure gradient.
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What is the loose-fitting baglike structure that encloses the heart?
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The pericardial sac.
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What is the pacemaker of the heart?
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The S-A node
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What is the S-A node composed of?
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P-cells, aka the pacemaker cells of the S-A node
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What do p-cells/ pacemaker cells have a constant permeability of the membrane to?
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Sodium ions.
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Where is the sinoatrial node (SA node or pacemaker)?
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within the posterior wall of the right atrium, near the opening of the superior vena cava
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Where to rhythmical impulses originate?
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Rhythmical impulses originate in the SA node and spread throughout the atria.
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What is the first half of the pacemaker a result of?
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The first half of the pacemaker potential is a result of:
1. an opening of funny (If) channels, 2. closure of outward K+ channels |
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What is the second half of the pacemaker?
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The second half of the pacemaker potential is the opening of T-type Ca+ channels.
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What happens once threshold is reached?
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Once threshold is reached there is an opening of the L-Ca+ channels (long lasting Ca+ channels).
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What is the falling phase a result of?
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The falling phase is a result of the opening of K+ channels.
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Where is the ventricular node located?
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within the lower right interatrial septum
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How long is an impulse delayed in the AV node?
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about a tenth of a second, this allows the atria to contract before ventricular contraction
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Where does the atrioventricular bundle originate?
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it originates int he AV node, and divides into two bundle branches extending to the papillary muscles and lateral walls
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Where do purkinje fibers originate?
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Purkinge fibers originate from the right and left branches, extending to the papillary muscle and lateral walls of the ventricles
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What does nodal tissue of the conduction system do?
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Generates and rapidly conducts impulses through the heart
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What do EKG's measure?
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(Electrocardiogram) rhythmical atrial and ventricular contrations
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What type of control of conduction is there in the heart?
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intrinsic system
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What factors may alter the heartbeat rate?
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1. Sympathetic and parasympathetic impulses
2. Hormones 3. body temperature 4. exercise 5. emotions |
