The program simulates experiments designed to demonstrate by
investigation the important characteristics of the transport of
two important nutrients - hexoses and amino acids, in the small
intestine.
Introduction and Methods use a combination of
text and high-resolution graphics to explain the process of carrier-mediated
transport of these nutrients, the everted sac preparation and the
methods used to measure nutrient transport:
· using radiolabelled galactose, glycine and methionine and
a scintillation counting technique;
· measuring the transmural potential difference particularly
for kinetic analysis of the transport system.
Experiments allows the user to collect sample
data from a range of experiments designed to:
· measure the transport of each of these nutrients - Control
experiments;
· demonstrate the Na+ dependence of the transport process
by measuring transport of each nutrient when the mucosal fluid contains
reduced concentrations of sodium ions (NaCl partly replaced with
KCl/tris chloride/choline chloride);
· investigate the mutual interaction of the hexose and amino
acid transport systems by performing a series of experiments (including
a kinetic analysis and calculation of apparent Km and Vmax for the
transport process) to assess whether the interaction is due to competition
for energy or competition at the carrier level.
Students are presented with raw data: weights: wet empty sac; weight
of sac containing 0.5ml Krebs bicarbonate saline; wet weight after
incubation in mucosal fluid containing a nutrient; wet weight of
final empty sac; radioactive counts )cpm, ESR, dpm, blank-corrected
dpm): blank; control sample; serosal sample, gut sample. The data
is based on predictive models of carrier-mediated transport, which
have been verified by experiment. Students collect the data and
use them to calculate transport parameters e.g. mucosal fluid transfer,
total amount of nutrient transferred, final gut concentration and
T/M ratio, in much the same way as they would if they performed
the experiment for real. The program is supported by printed learning
materials in the form of a user's manual, student's and tutor's
notes.
Target Audience: It is aimed at undergraduate students studying
physiology.
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