Professor Jill McMillin
G150/PHA1500 Section 08 Structure and Function of the Human Body May 30, 2010
The Cardiovascular and Muscular Systems
Organ system is a group of organs that work together to perform a certain task. Humans have a variety of systems due to the complexity of the species' organism. The human body consists of biological systems, that consist of organs, that consist of tissues, that consist of cells and connective tissue. Although an organ has a specific function, organs also function as part of a group. The organ system is the organizational unit by which medicine is studied, diseases are generally categorized, and treatments are planned.
Homeostasis is self-regulation of a biological system in balance. The Cardiovascular homeostasis is the process by which the functioning of the cardiovascular system is maintained at a level of functional efficiency appropriate to the conditions that each behavior requires. The system consists of the heart and blood vessels and their main task is to ensure optimal blood flow in different organs. Accomplishes this task using a fixed volume of blood, about 6-8% of body weight. That is, a 70 kg body weight is between 5.0 and 5.5 l of blood. Muscular homeostasis is capable of maintaining a normal body temperature somewhere between 37° C and 38° C even if the external temperature varies between 16° C and 54° C. When the body is at rest, body heat is generated primarily by the liver, heart, brain, and endocrine glands but when the muscles are active they generate many times the heat produced by these organs.
The cardiovascular system includes the heart and the blood vessels. The heart pumps blood, and the blood vessels channel and deliver it throughout the body. Arteries carry blood filled with nutrients away from the heart to all parts of the body. The blood is sometimes compared to a river, but the arteries are more like a river in reverse. Arteries are thick-walled tubes with a circular covering of yellow, elastic fibers, which contain a filling of muscle that absorbs the tremendous pressure wave of a heartbeat and slows the blood down. This pressure can be felt in the arm and wrist - it is the pulse. Eventually arteries divide into smaller arterioles and then into even smaller capillaries, the smallest of all blood vessels. One arteriole can serve a hundred capillaries. Here, in every tissue of every organ, blood's work is done when it gives up what the cells need and takes away the waste products that they don't need. Now the river comparison really does apply. Capillaries join together to form small veins, which flow into larger main veins, and these deliver deoxygenated blood back to the heart. Veins, unlike arteries, have thin, slack walls, because the blood has lost the pressure which forced it out of the heart, so the dark, reddish-blue blood which flows through the veins on its way to the lungs oozes along very slowly on its way to be reoxygenated. Back at the heart, the veins enter a special vessel, called the pulmonary arteries, into the wall at right side of the heart. It flows along the pulmonary arteries to the lungs to collect oxygen, then back to the heart's left side to begin its journey around the body again. The circulatory system is an organ system that passes nutrients (such as amino acids and electrolytes), gases, hormones, blood cells, etc. to and from cells in the body to help fight diseases and help stabilize body temperature and pH to maintain homeostasis. This system may be seen strictly as a blood distribution network, but some consider the circulatory system as composed of the cardiovascular system, which distributes blood, and the lymphatic system, which distributes lymph. While humans, as well as other vertebrates, have a closed Cardiovascular system (meaning that the blood never leaves the network of arteries, veins and capillaries), some invertebrate groups have an...