Losing appetite, receiving bad grades, hiding in her room,
The cardiac cycle consists of two phases; a period where the heart muscle is relaxed, called <u>diastole</u>, and a period of contraction, called <u>systole</u>.
These are then divided into four stages. These are;
1.<u>Ventricular Filling Period (VPF)</u>
2. <u>Isovolumetric Contraction Period (ICP)</u>
3. <u>Ventricular Ejection Period (VEP)</u>
4.<u> Isovolumetric Relaxation Period (IRP)</u>
At rest, cardiac diastole lasts for approximately 0.5 seconds, and cardiac systole lasts approximately 0.3 seconds to complete. However, during exercise, when the heart rate is increased the time period of <u>diastole</u> , especially, is reduced.
<span>When a person smokes a cigarette, the body responds immediately to the chemical nicotine in the smoke. Nicotine causes a short-term increase in blood pressure, heart rate, and the flow of blood from the heart. It also causes the arteries to narrow. Carbon monoxide reduces the amount of oxygen the blood can carry. This, combined with the effects produced by nicotine, creates an imbalance in the demand for oxygen by the cells and the amount of oxygen the blood is able to supply.
So the answer is D. increased heart rate</span>
