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 causes hypertension where diastolic blood pressure is increased which increases the afterload. Because of this, the stroke volume decreases.
b. Massive bleeding
During massive bleeding, the body detects the decrease in blood pressure, causing it to increase heart rate and contractility to maintain the perfusion to vital organs, increasing the cardiac output.
c. the drug dopamine
When dopamine is taken, dopamine exhibits positive chronotropic and inotropic effects on the myocardium which results in an increased heart rate and contractility. Because of this, the cardiac output increases.
d. Running a sprint
Running a sprint increases the cardiac output because the body needs more oxygen to produce the energy to run. Because of the need for more oxygen, the heart rate increases (increases the cardiac output) to deliver more blood throughout the body.
e. Hyperthryoidism with increased secretion of thyroid hormones
Hyperthyroidism causes an increased preloid accompanied by low systemic vascular resistance, and increased heart rate which increases the cardiac output.
f. Massive myocardial infarction (cardiac tissue death)
During myocardial infarction, the cardiac output decreases because
g. Hypothermia
Hyopothermia causes a decrease in arterial blood pressure which in turn decreases cardiac output.
h. Emotional distress
Emotional distress causes an increase in heart rate because of the stress hormones released which in turn increases the cardiac ouput.