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About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium. All 11 are necessary for life. The remaining elements are trace elements, of which more than a dozen are ...
The sarcoplasmic reticulum (SR) is a membrane -bound structure found within muscle cells that is similar to the smooth endoplasmic reticulum in other cells. The main function of the SR is to store calcium ions (Ca 2+). Calcium ion levels are kept relatively constant, with the concentration of calcium ions within a cell being 10,000 times ...
The muscular system is an organ system consisting of skeletal, smooth, and cardiac muscle. It permits movement of the body, maintains posture, and circulates blood throughout the body. [1] The muscular systems in vertebrates are controlled through the nervous system although some muscles (such as the cardiac muscle) can be completely autonomous ...
abducts, intorts, and depress eye. right medial, superior, and inferior recti (superior and inferior oblique muscles are the synergists) 2. 1. oblique, inferior. head, extraocular (left/right) orbital surface of maxilla, lateral to lacrimal groove. laterally onto eyeball, deep to lateral rectus, by a short flat tendon.
The body contains three types of muscle tissue: (a) skeletal muscle, (b) smooth muscle, and (c) cardiac muscle. On the anterior and posterior views of the muscular system above, superficial muscles (those at the surface) are shown on the right side of the body while deep muscles (those underneath the superficial muscles) are shown on the left ...
The carbonic anhydrases (or carbonate dehydratases) (EC 4.2.1.1) form a family of enzymes that catalyze the interconversion between carbon dioxide and water and the dissociated ions of carbonic acid (i.e. bicarbonate and hydrogen ions). [ 1 ] The active site of most carbonic anhydrases contains a zinc ion.
Bicarbonate buffer system. Carbon dioxide, a by-product of cellular respiration, is dissolved in the blood, where it is taken up by red blood cells and converted to carbonic acid by carbonic anhydrase. Most of the carbonic acid then dissociates to bicarbonate and hydrogen ions. The bicarbonate buffer system is an acid-base homeostatic mechanism ...
Human thermoregulation. As in other mammals, human thermoregulation is an important aspect of homeostasis. In thermoregulation, body heat is generated mostly in the deep organs, especially the liver, brain, and heart, and in contraction of skeletal muscles. [ 1 ] Humans have been able to adapt to a great diversity of climates, including hot ...