A world-champion body builder has no more muscles than does a 90-pound person who is physically weak.So what makes him so strong?What other qualities does he need? Muscles are made of thousands of stringy fibers-a number that is fixed during childhood-which contract(收缩)when doing work....
Smooth muscle is also known as a nonstriated muscle because the bands that are seen in skeletal and cardiac muscles are absent. Smooth muscle is seen lining the walls of hollow organs such as the blood vessels, urinary tract, urinary bladder, and other organs such as skin, eye, respiratory ...
A world-champion body builder has no moremusclesthan does a 90-pound person who is physically weak. So what makes him so strong What other qualities does he need Muscles are made of thousands of stringy fibers-a number that is fixed during childhood-which contract(收缩)when doing work. Stre...
Female spotted hyenas are known for their male-like genitalia, high levels of aggression, and dominance over males, characteristics which are attributed to exposure to elevated levels of testosterone in utero. Although the nervous system of spotted hyenas has not previously been examined, one might ...
【解析】A、 一个人总是知道他的肌肉在做什么B、 一个人在不工作的情况下执行简单的动作C、 一个人的肌肉只被用到他们执行的每一个动作所必需的程度根据原文“The muscles of the body are made to move,and they are kept in constant motion,not by conscious effort,but by the intelligent use of ...
You probably know many of the things that you can do with the hundreds of different muscles(肌肉) in your body. But have you ever thought about how the muscles in an animal's body are different from yours? An animal's muscles are made to do the things that are the most important for...
Knowing about the different muscles in your back, how they work, and what you can do to strengthen them will help keep this critical muscle group healthy. What Are Back Muscles? Back muscles are skeletal muscles made up of tiny elastic fibers bound tightly together. They are part of themusc...
A chest is a region at the front of the person's body that is located between the diaphragm and the neck. It protects the internal organs such as the lungs and the heart. It is made up of the breastbone and the ribs cage or the person's thorax....
Exercise makes muscles do what? Grow bigger and stronger Grow smaller and weaker Become less stretchy Become less effective 3 . What are muscles made from? Fat cells Thin strands of iron Thousands of small stretchy fibers Carbohydrates 4 . ...
What are the four main muscles in the leg? The four main muscle groups of the leg are the adductors, quadriceps, hamstrings, and calves. However, it is important to note that these muscle groups are each made up of smaller muscles, and there are also muscles that are not in these grou...