To be successful you will make sure you complete diagrams as instructed in the tasks, including proper values on the x & y-axis as well as labeling those

Question

Criteria for Success: To be successful you will make sure you complete diagrams as instructed in the tasks, including proper values on the x & y-axis as well as labeling those. Make sure to label ESV, EDV, aortic and mitral valve opening and closing, and Isovolumetric relaxation and contraction where possible on the diagrams regarding blood volumes and pressure. You also need to make sure to list or provide explanation where necessary or where it is asked in the tasks. A successful submission would be very clear and easy to read and it would be easy to see the differences in pressures and volumes based on the given situations. For submission, you can submit them as a pdf or image from a phone if you are drawing these at home. I also suggest looking at the homework you have completed and the provided examples to help you in completing these tasks. 



1.  Tyreke has been putting himself through a strict diet and exercise regiment. In the last week, he was feeling some irregularity in his heart rate and heart beat. He decided to visit a doctor and found that he was suffering from Hyperkalemia. Use a diagram to explain how Hyperkalemia could impact cardiac pacemaker and contractile cells. Your diagram should show how Hyperkalemia causes changes. Make sure to include the following items at a minimum in the diagram(s):
2. mV (Membrane Potential in millivolts)
3. Na+
4. K+
5. Ca+
6. Slow acting channels
7. Fast acting channels
8. -40mV
9. -60mV
10. -90mV
11. Pacemaker potential
12. Depolarization
13. Repolarization
14. Hyperpolarization
15. Absolute Refractory Period

Answer 1

Below is a detailed explanation of how Hyperkalemia impacts cardiac pacemaker and contractile cells, including the key elements you mentioned.

Hyperkalemia is a condition characterized by elevated levels of potassium (K+) in the blood. This can have significant effects on the electrical activity of the heart, particularly in pacemaker and contractile cells.

Cardiac pacemaker cells are responsible for generating the electrical impulses that initiate and regulate the heartbeat. Contractile cells, on the other hand, are responsible for the actual contraction of the heart muscle.

In a normal situation, the membrane potential of pacemaker cells oscillates between -60mV and -40mV, which is known as the pacemaker potential. When the membrane potential reaches -40mV, voltage-gated calcium (Ca2+) channels (slow-acting channels) open, causing an influx of Ca2+ and leading to depolarization. This depolarization causes the membrane potential to become more positive, reaching around 0mV. Afterward, potassium channels open, allowing K+ to exit the cell, leading to repolarization and bringing the membrane potential back to -60mV.

Contractile cells have a resting membrane potential of around -90mV. When an electrical impulse from a neighboring cell arrives, voltage-gated sodium (Na+) channels (fast-acting channels) open, causing an influx of Na+ and rapid depolarization. The membrane potential becomes more positive, reaching around +30mV. Then, voltage-gated potassium channels open, allowing K+ to exit the cell, and Ca2+ channels close, leading to repolarization. The membrane potential returns to -90mV, and the cell enters a hyperpolarized state, which is the absolute refractory period during which the cell cannot be stimulated again.

In Hyperkalemia, the elevated levels of extracellular potassium (K+) cause the resting membrane potential of both pacemaker and contractile cells to become less negative (closer to 0mV). This can lead to several consequences:

1. Pacemaker cells may reach the threshold for depolarization (-40mV) more quickly, leading to an increased heart rate.

2. Contractile cells may become partially depolarized, reducing the effectiveness of the fast-acting Na+ channels and impairing the cell's ability to depolarize fully. This can lead to a weakened contraction of the heart muscle.

3. The absolute refractory period of contractile cells may be shortened, increasing the risk of arrhythmias.

In summary, Hyperkalemia can impact the normal functioning of cardiac pacemaker and contractile cells by altering their membrane potentials and affecting the opening and closing of ion channels. This can lead to an increased heart rate, weakened contractions, and a higher risk of arrhythmias.