Lab 10 Answers

Topics: Blood, Heart, Blood pressure Pages: 3 (1148 words) Published: April 10, 2011
Analysis:
1. Explain why blood pressure and heart rate differ when measured in a reclining position and in a standing position. When a person stands, the heart must pump blood against the pull of gravity to reach important areas such as your brain. Veins must work hard to get blood back to your heart. As a person reclines, the heart does not have to pump as hard to reach the same areas, decreasing the blood pressure. Also, a person is usually more relaxed in a reclining position, which slows breathing and heart rate. Less oxygen is needed to support the body. It differs because your heart has to work harder when standing. the blood that reaches your legs has to travel back up through veins in your legs as gravity tries to pull it down. More blood pressure means there wont be as much flow back(veins don't have a lot of blood pressure to begin with). also to prevent back flow there are valves in your veins that close after each pass of blood. Another reason why is because while standing muscles are contracted and using ATP which leads to a need for more blood supply to ensure those muscles continue to contract. When you are in reclining position your muscles are relaxed and your cells aren't using as much ATP.

Yes, you are pumping somewhat against gravity but also:

When you are standing you are using all the small muscles to actually stand. Muscles in your legs and feet are contracting in order to keep you in balance. These muscles need oxygen and thus your heart must pump faster. When reclining, the floor is keeping your body up and you are not using muscles to balance yourself.

2. Explain why high blood pressure can be dangerous to an individual. High blood pressure means that the blood must be pumped harder and faster to get to places. This is usually due to something hindering its passage, probably the large molecules of cholesterol. If the arteries are completely blocked, it can be extremely dangerous and result in a stroke (in...
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