# Circulation in animals

Essay by Vixen-Mayhem May 2008

Diffusion alone is not for transporting chemicals over macroscopic distances in animals ÃÂ for example, for moving glucose from the digestive tract and oxygen from the lungs to the brain of a mammal.

The time it takes for a substance to diffuse from one place to another is proportional to the square of the distance the chemical will travel ÃÂ for example, if it takes 1 second for a given quantity of glucose to diffuse 100 micrometers (10-6) it will take 100 seconds for the same quantity to diffuse /mm.

-To solve this problem, macroscopic organisms have a circulatory system, which ensures that no substance must diffuse very far to enter or leave a cell.

- By transporting fluids throughout the body, the circulatory system functionally connects the aqueous environment of the body cells & the organs that exchange gases, absorb nutrients, & dispose of waste.

Circulatory System(http://www.williamsclass.com)Oxygen Molecule ADVENTUREDiaphragm contracts & air is inhaled into the mouth/nose.

The oxygen molecule is than pushed through the Larynx into the trachea. Oxygen than passes through the bronchiole tubes in the lungs which than passes through bronchioles which defuse through a thin layer of cells called alveoli. This is where gas exchange occurs.

3. Quantum MechanicsFour basic principles of quantum mechanics are:3.1 Physical StatesEvery physical system is associated with a Hilbert Space, every unit vector in the space corresponds to a possible pure state of the system, and every possible pure state, to some vector in the space.[7] In standard texts on quantum mechanics, the vector is represented by a function known as the wave-function, or ÃÂ-function.

3.2 Physical QuantitiesHermitian operators in the Hilbert space associated with a system represent physical quantities, and their eigenvalues represent the possible results of measurements of those quantities.

3.3 CompositionThe Hilbert space associated with a complex system is the tensor product of those associated with the simple systems (in the standard, non-relativistic, theory: the individual particles) of which it is composed.

3.4 Dynamicsa.Contexts of type 1: Given the state of a system at t and the forces and constraints to which it is subject, there is an equation, ÃÂSchrÃÂ¶dinger's equationÃÂ, that gives the state at any other time U|vt> Ã¢ÂÂ |vtÃ¢ÂÂ²>.[8] The important properties of U for our purposes are that it is deterministic, which is to say that it takes the state of a system at one time into a unique state at any other, and it is linear, which is to say that if it takes a state |A> onto the state |AÃ¢ÂÂ²>, and it takes the state |B> onto the state |BÃ¢ÂÂ²>, then it takes any state of the form ÃÂ±|A> + ÃÂ²|B> onto the state ÃÂ±|AÃ¢ÂÂ²> + ÃÂ²|BÃ¢ÂÂ²>.

b.Contexts of type 2 ("Measurement Contexts"):[9] Carrying out a "measurement" of an observable B on a system in a state |A> has the effect of collapsing the system into a B-eigenstate corresponding to the eigenvalue observed. This is known as the Collapse Postulate. Which particular B-eigenstate it collapses into is a matter of probability, and the probabilities are given by a rule known as Born's Rule:prob(bi) = ||2.

There are two important points to note about these two kinds of contexts:ÃÂThe distinction between contexts of type 1 and 2 remains to be made out in quantum mechanical terms; nobody has managed to say in a completely satisfactory way, in the terms provided by the theory, which contexts are measurement contexts, andÃÂEven if the distinction is made out, it is an open interpretive question whether there are contexts of type 2; i.e., it is an open interpretive question whether there are any contexts in which systems are governed by a dynamical rule other than SchrÃÂ¶dinger's equation.

http://plato.stanford.edu/entries/qm/