Post-lecture activity (Week 10)

ESCOSURA, Clinen L._Post-lecture activity (Week 10): The Cardiovascular System

ESCOSURA, Clinen L._Post-lecture activity (Week 10): The Cardiovascular System

by Clinen Escosura -
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POST-LECTURE ACTIVITY

THE CARDIOVASCULAR SYSTEM

1. Adequate cardiac output is necessary in order to supply oxygen and other nutrients to all body tissues. Cardiac output is influenced by stroke volume and heart rate. Factors affecting the stroke volume includes PRELOAD, CONTRACTILITY and AFTERLOAD.

In the following conditions, indicate what factor/s influence the cardiac output: PRELOAD, CONTRACTILITY, AFTERLOAD, HEART RATE. Explain the why the factor/s affects cardiac output in 1 to 2 sentences.

a. High blood pressure

  • High blood pressure affects the heart in a variety of ways, including increased stiffness and decreased compliance. This can lead to a buildup of left ventricular hypertrophy and diastolic dysfunction, which in turn can cause an increase in myocardial rigidity.

b. Massive bleeding

  • The heart's response to massive bleeding  is governed by an increase in sympathetic nervous system activation and a decrease in both preload and afterload. Because venous return will be diminished, there is less blood available to fill into the atrium.

c. the drug dopamine

  • The hemodynamic effect of dopamine is dose dependent. A low dose results in dilation of renal and splanchnic vessels, enhancing diuresis. Moderate doses enhance cardiac contractility and heart rate, while high doses increase afterload due to peripheral vasoconstriction.

d. Running a sprint

  • When running, your body may need up to four times its normal cardiac output from the left ventricle in order to supply oxygenated blood to your muscles. As a result, the left ventricle's afterload and preload decreased significantly.

e. Hyperthyroidism with increased secretion of thyroid hormones

  • Hyperthyroidism can cause hemodynamic changes; T3 increases erythropoietin production, which leads to an increase in red cell mass. Thus, increases blood volume and preload and contractility.

f. Massive myocardial infarction (cardiac tissue death)

  • Cardiac Tissue death is quite common and is associated with a reduction in cardiac output due to decreased contractility and an increase in afterload.

g. Hypothermia

  • Hypothermia decreases contractility by slowing metabolism and reducing oxygen needed by tissues, ultimately allowing the heart and brain to withstand short periods of interrupted or reduced blood flow.

h. Emotional distress

  • When experiencing emotional distress, the body releases catecholamines such as epinephrine and norepinephrine, which cause the heart rate and blood pressure to increase. This increase in cardiac output leads to a greater total amount of blood pumped by the heart each minute.

 

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