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Cardiac Muscle Physiology Lab Report

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Group 3: Linzy Dioguardi, Drew Christerson, Kaitlyn Vander Putten, Teryn Wheeler, Callie Womack Shahang Derakhshan Human Physiology Lab 21 September 2017 Lab 4: Cardiac Muscle Physiology 1. There are many electrical changes and movement of ions during membrane polarization in a cardiac action potential. The following is an overview of the five main phases of an action potential: Phase 4 is the resting phase in which is the beginning and ending phase. It takes place at -90mv due to a constant outward leak of potassium. Sodium and calcium channels are closed at resting phase. Phase 0 is the depolarization phase and is similar to that of depolarization in a neuron action potential. Sodium channels begin to open and an increase of sodium moves …show more content…

L-type calcium channels stay open with a small constant current while the potassium channels remain closed. The countercurrents are electrically balanced during this phase. Phase 3 is the repolarization phase where the membrane potential falls to negative values. Potassium channels that began to open during the 1st and 2nd phases allow a significant amount of potassium out of the cell. The calcium channels then close, reducing the influx of calcium into the cell. Repolarization occurs until resting potential is reached, entering back into phase 4. 2. Cardiac muscle cells are very unique in comparison to skeletal muscle cells. There are two different types of cardiac muscle cells that make up the heart. The predominant of these cells is the contractile cells, which make up roughly 99% of the heart itself. These muscles are responsible for the mechanical process of filling and emptying the heart. The second and debatably most important type of cardiac muscle cells are the auto rhythmic cells. These cells make up the conductile network that allow the heart to function independently of the nervous system. These cells are responsible for generating the action potential that initiates a contraction within the heart muscles and allow us to have a …show more content…

Potassium is a fundamental protein the body needs for continuing a steady, rhythmic heartbeat. Too much or too little potassium can lead to a heart attack, or even death, due to how significant it is to the body. The potassium-sodium ion pumps maintain the concentration gradient by regulating the concentration of each ion inside and outside of the cell. Cells, nerves, muscles and the heart all rely on the potassium-sodium concentration gradient to function accurately. Normally, potassium is higher in concentration on the outside of the cell; whereas sodium is higher in concentration on the inside of the cell. Potassium chloride is one of the main components during lethal injections because of its ability to quickly and easily stop the heart. When a large amount of potassium enters the bloodstream, it rushes inside the cells and rapidly reverses the concentration gradient. When the concentration gradient is reversed, the resting electrical potential of the heart dramatically drops and cells are unable to repolarize. Depolarized cells will cause sodium channels to become inactive and cells will not be able to fire action potentials. When cells are unable to fire, the heart is unable to contract and will stop beating while in

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