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C-11: Chapter 29- Origin of the Heartbeat & Electrical Activity of the Heart
Terms in this set (32)
What is Diastole?
Time when cardiac muscles are relaxed (time for filling heart).
What is Systole?
Time when cardiac muscles are contracted (time for emptying the heart).
Blood moves because of ___ ___.
The blood moves from an area of ___ pressure to an area of ____ pressure.
What is the blood pressure in the aorta?
120mm Hg (max.) & 80 mm Hg (min.)
What is the blood pressure in the vena cava &/ the right atrium?
Around 5-19mm Hg
The pressure difference of the aorta and the vena cava/right atrium moves what?
Blood through the circulatory system
Cardiac muscle is a ____ muscle.
Are attached end to end and they have gap junctions
Cardiac muscle can not go into ____?
Describe the 4 phases of Cardiac Muscle Cell AP
P0- Depolarization...Voltage-gated Na+ Channels
P1- Initial Rapid Repolarization...close Na+ channels and open K+ channels
P2- Plateau Phase.. Opening Voltage-gated Ca2+ channels
P3- Late Repolarization then P4- Baseline.... Close Ca2+ channels and open various potassium channels.
What is the signal that typically tells a cardiac muscle cell (myocyte) to start an AP?
The depolarization coming from the adjacent myocyte.
Myocytes are connected by ____ ____.
There is a conducting system of cardinal cells which initially start AP and help ___ the AP around the ____. These cell comprise abut __% of the amount of myocytes.
Transport; Heart; 1
What parts make up the conducting system?
-Sinoatrial Node (SA Node)
-Atrioventricular Node (AV Node)
-Bundle of His
-Right & Left Bundle Branches
Where are the Sinoatrial Node and Atrioventricular Node found, and the AV node bridges into the ____.
They're found in the Right Atrium; Ventricles
What is the purpose of the conduction system?
To rapidly move AP around the heart to allow muscle fibers to contract together.
Why is there a delay at the AV node?
To let the atrium contract before ventricles thus pushing more blood into the ventricle.
The Pacemaker Action Potential does not have a true ___ ___. The resting potential is ____ rising until it generates another ___ ___.
Resting Potential; Slowly; Action Potential
What are the two types of Voltage gated Calcium Channels?
L Channels & T Channels
What are the channels of the pacemaker cells?
Voltage-Gated Calcium Channels, Potassium Channels, and Sodium Channels.
The Ih channel (a.k.a If channel) is a type of ____ channel.
T Channels (transient calcium channels) are open during the _____ phase.
L Channels are open during ______.
After Repolarization (from potassium channels), the membrane potential is ____ (reaches about ____mV). This triggers the ___ current which brings ____ and ___ into the cells and the membrane potential slowly rises. At about -50mV, the ___ channels open bringing Ca2+ in. At about -40mV, the ___ Ca2+ channels open initiating phase ___ and more rapid _____.
Hyperpolarized; -65; Ih; Na+ & K+; T-type; L-Type; 0; Depolarization
Compare the AP in the Ventricular Myocyte (VM) and the Auto-rhythmic Cells (SA & AV Nodes) in Phase 0.
VM- Voltaged-Gated Sodium Channels
SA & AV: Voltage-Gated Calcium Channels (L-type voltage-gated calcium channels)
Compare the AP in the Ventricular Myocyte (VM) and the Auto-rhythmic Cells (SA & AV Nodes) in Phase 2.
VM: Slow Calcium Channels open (L-type), some potassium channels open
SA & AV: When P1 is reached, calcium channels start closing and potassium channels start opening, so not much of P2.
Compare the AP in the Ventricular Myocyte (VM) and the Auto-rhythmic Cells in Phase 3.
VM: Slow calcium channels close, potassium channels open
SA & AV: Calcium channels have been closing, and potassium channels have been opening
Compare the AP in the Ventricular Myocyte (VM) and the Auto-rhythmic Cells in Phase 4.
VM: Potassium Channels are open (steady)
SA & AV: Potassium Channels slowly close and then have Ih for Na+ followed by T-Calcium Channels start to open. The result is slow depolarization. (SA node closes potassium channels faster than AV node)
When chollingergic vagar stimulation occurs, the nodes are _____. This slows down the ___ firing rate. This occurs by opening a set of _____ channels. The opening of the ____ channels is slowed b/c the ___ current is inhibited (making it longer to reach the threshold levels).
Hyperpolarized; Nodal; Potassium; Calcium; Ih
Describe the Sympathetic Stimulation of the nodes.
Norepinephrine binds to beta one receptors eventually causing the opening of L channels.
An increased temperature can increase the rate of ____ of the SA node. Thus, during a fever, the heart rate may increase producing. ______.
Pacemaker of the heart (stopped here 10/4)
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