The heart of a resting adult beats 72 times in a minute…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
The heart of a resting adult beats times in a minute. Each beat pumps of blood.
- How many times does the heart beat in an hour?
- How many times does it beat in a day of ?
- How much blood does it pump in a day, in litres?
Need a reminder? The key ideaShow
Muscular tissue is made of long cells called fibres that contract and shorten. Skeletal muscle is attached to bones, and its fibres are striated, long, cylindrical, unbranched and multinucleate. It is voluntary. Smooth muscle lies in the walls of internal organs such as blood vessels, the stomach and the intestine. Its cells are spindle shaped with one nucleus and no stripes. It is involuntary. Cardiac muscle forms the wall of the heart. Its cells are striated and branched, and they are joined end to end by intercalated discs with gap junctions, so that they contract as a unit. It is involuntary. The output of the heart is the rate times the stroke volume.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. Rate beats in a minute. Stroke volume .
Plan. Count the beats first. Then multiply by the volume of one beat.
Step 1. An hour. beats.
Step 2. A day. beats.
Step 3. Blood in a day. . In litres: .
Answer: beats; beats; .
Check. At rest the output is about in a minute. And , which is close to the answer.
Discussion (0)
Log in to join the discussion.
Loading…