1.Describe the effects of the sympathetic nerves on cardiac muscle during contraction and relaxation. 2.Define preload,...

1.Describe the effects of the sympathetic nerves on cardiac muscle during contraction and relaxation.

2.Define preload, afterload, and contractility.

3.Describe the spread of excitation from the SA node through the rest of the heart.

4.Red blood cells have a lifespan of 120 days. What happens to the blood cell when it dies? Discuss the locations of death, by-products, and formation of RBC.

5.Describe the process of chemotaxis or emigration.

Expert Solution

1.

Cardiac activity is regulated by cardio augmentor nerve called sympathetic nerve. These nerves run along with vagus to form cardiac nerves and flexes which pass to the heart along with great veins and arteries.
The sympathetic division of ANS provides two sets of accelerated fibers, the vagosympathetic fibers, and cardiosympathetic fibers which function in an emergency.
Norepinephrine is the neurotransmitter of this sympathetic system, that acts on the beta-1 receptor of the myocardium.
These fibers supply atria, SA node, AV node, and ventricles. Stimulation of which causes an increase in heart rate and their force of contraction, meaning contribute towards positive inotropic and chronotropic effects.
Thus it can increase the heart rate and contraction force as it causes more Na and Ca channels in the cardiac cycle to open, thus enhances and quickens the action potential in the heart and force of concentration. These are events that occur during the contraction of cardiac myocytes.
The relaxation of cardiomyocytes by removing Na ions from the muscle fibers to the nerve terminal by active uptake and rest Na is diffused into the bloodstream.

Sydney Mullin answered 1 year ago

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