w9 Flashcards
What is the Visible Human Project
the creation of complete, anatomically detailed, three-dimensional representations of the normal male and female human bodies
goal is to produce a system of knowledge structures that will transparently link visual knowledge forms to symbolic knowledge formats, such as the names of body parts.
How was the Visible Human Project completed
Acquisition of transverse CT, MR and cryosection images of representative male and female cadavers was completed.
The male was sectioned at one-millimeter intervals, the female at one-third of a millimeter intervals.
What are some applications of the Visible Human Project
Simulation of a surgical incisions. Virtual scalpel is haptically interfaced to a real scalpel handle to provide the user with the feel of the cut.
can isolate skeletal, muscular, vascular, etc elements.
allows access to information at the various spatial scales using ontologies (organ, tissue, cells, etc) and web databases that contain models encoded in markup languages (physio, anat, tissue, cell).
what is the goal of modelling physiological systems
to identify the parameters and structure of the system, not to design a system.
Ideally, the input and the output of the physiological system are known and some information about the internal dynamics of the system are already available (essentially a black box).
In many cases, either the input or output is not measurable or observable but is estimated
from remote signals (such as medical image data), and no information about the system is
known.
What is System identification
the process of creating a model of a system and estimating the parameters of the model
what is a quantitative physiological model
a mathematical representation that approximates the
behavior of an actual physiological system.
Physiological systems are almost always dynamic and can be characterized mathematically with differential equations. Approximates the behaviour of an actual physiological system using basic and natural laws.
What is the most important and time consuming task in modelling
The design and execution of experiments is one of the most important and time consuming tasks in modelling.
The best experiment is one that provides data that is highly related to variables used in the model.
what are Qualitative physiological models
describe the actual physiological system without the use of mathematics.
most often used by biologists
what are the goals of physiological modelling
Generation of new knowledge, explaining the
underlying processes that cause the experimental data.
Prediction of observations before they occur
Assistance in designing new experiments
what are the stages of Developing a Model
Conjecture: based on observations from an experiment or a phenomenon
Initial Hypothesis: formed via a mathematical model
Obtain Data: extracted from experiments via data acquisition
Test Hypothesis: testing the model against the data
Modify Hypothesis: update model, carry out additional experiments (e.g. to provide information about previously unobservable variables)
State Solution: a good model can predict future performance well. Usually a statistical test is performed to test the goodness of fit.
How did the introduction of digital computers, programming languages, and simulation software
cause a rapid change in the use of physiological models
allowed inclusion of as much knowledge as possible about the structure and interrelationships of the physiological system without any overriding concern about the number of calculations
what are compartments
When analyzing systems of the body characterized by a transfer of solutes (e.g. a radioactive tracer, a molecule such as glucose, or a gas such as oxygen
or carbon dioxide) from one compartment to another, such as the circulatory and respiratory systems, it is convenient to describe the system as a series of compartments.
what is PET
a functional imaging technique that measures the local concentration of an exogenous radioactive tracer molecule in the target tissue.
Thus, given a time sequence of PET images, one can quantify tracer kinetics in vivo.
The power of PET lies in its molecular specificity. By using a particular radiotracer molecule, one can monitor the interaction of that molecule with the body’s physiological processes. Most diseases are functional in nature and structural changes are secondary.
Describe the behavior of the tracer
The amount of tracer injected is a trace amount that causes no change in the physiology of the organism;
The tracer is in steady state with the endogenous molecule (the molecule that the tracer seeks to emulate, which we call the tracee, such as glucose in the brain). the tracer goes everywhere that the tracee goes.
What is a tracer and describe its role in PET
a “positron-emitting nuclide.”
characterized by its emission of a positive charged particle called positron (positive electron). This positron emission is not naturally occurring, but it requires a device called a cyclotron for the production of positron -emitting nuclides or isotopes. Once emitted, this is followed by a prompt reaction of positrons with surrounding electrons, thus inducing their annihilation. As a consequence of this collision, two high-energy photons called gamma-rays are produced that travels away from the site at almost 180 degrees. These photons are then detected from outside of the patient’s body by the PET scanner.
