closed system

Examples of closed system in the following topics:

• Open and Closed Circulatory Systems

  • The circulatory system can either be open or closed, depending on whether the blood flows freely in a cavity or is contained in vessels.
  • In all vertebrate organisms, as well as some invertebrates, this is a closed-loop system in which the blood is not moving freely in a cavity.
  • In contrast to a closed system, arthropods (including insects, crustaceans, and most mollusks) have an open circulatory system.
  • (a) In closed circulatory systems, the heart pumps blood through vessels that are separate from the interstitial fluid of the body.
  • Most vertebrates and some invertebrates, such as this annelid earthworm, have a closed circulatory system.

• Work

  • Work performed by a closed system is the energy transferred to another system that is measured by mechanical constraints on the system.
  • In thermodynamics, work performed by a closed system is the energy transferred to another system that is measured by mechanical constraints on the system .
  • For closed systems, energy changes in a system other than as work transfer are as heat.
  • Heat transfer into a system, such as when the Sun warms the air in a bicycle tire, can increase its temperature, and so can work done on the system, as when the bicyclist pumps air into the tire.
  • However, both can change the internal energy of a system.

• Free Energy and Work

  • The Gibbs free energy is the maximum amount of non-expansion work that can be extracted from a closed system.
  • Gibbs energy is the maximum useful work that a system can do on its surroundings when the process occurring within the system is reversible at constant temperature and pressure.
  • The Gibbs free energy is the maximum amount of non-expansion work that can be extracted from a closed system.
  • The work is done at the expense of the system's internal energy.
  • "Useful" in this case, refers to the work not associated with the expansion of the system.

• Rotational Collisions

  • In a closed system, angular momentum is conserved in a similar fashion as linear momentum.
  • During a collision of objects in a closed system, momentum is always conserved.
  • So rotating objects that collide in a closed system conserve not only linear momentum p in all directions, but also angular momentum L in all directions.
  • After the collision, the arrow sticks to the rolling cylinder and the system has a net angular momentum equal to the original angular momentum of the arrow before the collision.

• Open vs. Closed Stratification Systems

  • In an open class system, people are ranked by achieved status, whereas in a closed class system, people are ranked by ascribed status.
  • Sociologists who study stratification have identified open class systems and compared them to closed class systems.
  • Compared with industrialized open systems, pre-industrial societies have mostly been found to be closed class systems where there is low social mobility.
  • In closed class systems, people tend to be ranked by ascribed status.
  • This fifteenth-century woodcutting illustrates the closed stratification system of the three estates of the French Ancien Régime.

• Caste Systems

  • Caste systems are closed social stratification systems in which people inherit their position and experience little mobility.
  • Caste as a closed social stratification system in which membership is determined by birth and remains fixed for life; castes are also endogamous, meaning marriage is proscribed outside one's caste, and offspring are automatically members of their parents' caste.
  • Some sociologists suggest that caste systems come in two forms: racial caste systems and non-racial caste systems.
  • European societies were historically stratified according to closed, endogamous social systems with groups such as the nobility, clergy, bourgeoisie, and peasants.
  • In parts of Europe, these closed social caste groups were called estates.

• The Systems Viewpoint

  • Systems thinking is an approach to problem solving that considers the overall system instead of focusing on specific parts of a system.
  • Systems thinking is the process of understanding how people and situations influence one another within a closed system.
  • Systems generally contain the following aspects:
  • Practitioners of systems thinking believe that the component parts of a system can best be understood, and best analyzed, in the context of their relationships with other parts of a system .
  • This method is opposed to a reductive framework that attempts to focus closely on a single problem.

• The First Law

  • The 1st law of thermodynamics states that internal energy change of a system equals net heat transfer minus net work done by the system.
  • It is usually formulated by stating that the change in the internal energy of a closed system is equal to the amount of heat supplied to the system, minus the amount of work done by the system on its surroundings.
  • Here ΔU is the change in internal energy U of the system, Q is the net heat transferred into the system, and W is the net work done by the system.
  • So positive Q adds energy to the system and positive W takes energy from the system.
  • W is the total work done on and by the system.

• Comparison of Enthalpy to Internal Energy

  • A thermodynamic system can be any physical system with a well-defined volume in space.
  • Hence, -q means the system loses heat, while +q means a system gains heat.
  • Similarly, +w means work is done on the system, while -w means work is done by the system.
  • In contrast, the internal energies of both open and closed systems can change because they can exchange heat and work with their surroundings.
  • However, in open systems, the pressure of the system and the surroundings has stayed constant.

• Structure and Function of the Muscular System

  • The muscular system is made up of muscle tissue and is responsible for functions such as maintenance of posture, locomotion and control of various circulatory systems.
  • The muscular system is closely associated with the skeletal system in facilitating movement.
  • Both voluntary and involuntary muscular system functions are controlled by the nervous system.
  • Smooth muscle tissue is associated with numerous organs and tissue systems, such as the digestive system and respiratory system.
  • Skeletal muscle of the muscular system is closely associated with the skeletal system and acts to maintain posture and control voluntary movement.