Homeostasis 2 COPY Flashcards
<p>Homeostatic reflexes are represented by reflexes which may be..?</p>
<p>Neural</p>
<p>Hormonal</p>
<p>What do the mechanisms of homeostasis maintain?</p>
<p>O2and CO2</p>
<p>Waste and ions</p>
<p>Blood pressure and blood volume</p>
<p>Nutrient level</p>
<p>What percentage of body weight does water make up?</p>
<p>60%</p>
<p>Why is homeostatic regulation of water crucial?</p>
<p>Because water affects the concentration of everything else</p>
<p>How is water regulated?</p>
<p></p>
<p>Input by thirst mechanism</p>
<p>Output by regulation of kidney function</p>
<p>Other processes which are not regulated towards water balance, such as sweating which is for temperature regulation</p>
<p>What three compartments is water split between?</p>
<p>Intracellular fluid (ICF)</p>
<p>Interstitual fluid (ISF, fluid between cells)</p>
<p>Plasma (fluid component of blood)</p>
<p></p>
<p>ISF and plamsa make up extracellular fluid (ECF)</p>
<p>How does water move between compartments?</p>
<p>Water can move through all three compartments freely, but movement is subject to forces such as osmosis</p>
<p>How does fluid pass from ECF and ICF</p>
<p>Crosses the cell membrane</p>
<p>How does fluid move between plasma and ISF?</p>
<p>Crosses the capillary wall</p>
<p>Explain the permeability of the cappilary wall?</p>
<p>Permeable to everything except plasma proteins</p>
<p>Explain the permibility of the cell membrane?</p>
<p>Selective permeability</p>
<p>What is the ratio of water distribution across the compartments?</p>
<p>1/3 in ECF and 2/3 in ICF</p>
<p>How is water distributed in ECF</p>
<p>80% in ISF</p>
<p>20% in plasma</p>
<p>What do proportions of water vary with?</p>
<p>Sex and age</p>
<p>Woman and older people have higher proportions of fat than muscle (70% of muscle is water whereas 10% of fat is water)</p>
<p>Why is plasma described as the dynamic component of the ECF?</p>
<p>Because it is continuously moving through vessels by the pumping action of the heart</p>
<p>What nutrients does plasma exchange with ISF through the cappilary wall?</p>
<p>O2</p>
<p>Glucose</p>
<p>Ions</p>
<p>CO2</p>
<p>Urea</p>
<p>Can exchange take place through large vessels like arteries?</p>
<p>No because the walls are too thick for exchange to take place</p>
<p>Is the composition of blood and ISF the same?</p>
<p>Yes, apart from plasma proteins which are too large to pass through the cappilary wall</p>
<p>What is the dilution principle?</p>
<p>c = m/V</p>
<p>What can the dilution principle be used to measure?</p>
<p></p>
<p>Body fluids</p>
<p>What should be remembered when using the dilution principle?</p>
<ol> <li>c = m/V becomes V = m/c</li> <li>Only plasma can be sampled, so only compartments which plasma is a component of can be measured directly</li> <li>The nature of barriers which seperate compartments is crucial in determining the test substance</li></ol>
<p>What components can be measured directly?</p>
<ol> <li>Plasma volume (measure plasma protein using dye)</li> <li>ECF (something that crosses cappilary wall but not the cell membrane like24Na+</li> <li>Total body water, TBW (water because no barriers, use heavy water D2O)</li></ol>
<p>What compartments can be calculated indirectly?</p>
<p>ISF and ICF</p>
<p>ISF = ECF - PV</p>
<p>ICF = TBW - ECF</p>
<p>What do you need to remember when calculating fluid levels?</p>
<p>To subtract any secretions or metabolism</p>
<p>Why is the composition of the ECF very different from the ICF?</p>
<p>Because the cell membrane acts as a selective barrier</p>
<p>How do ion concentrations of the ECF compare to the ICF?</p>
<p>More Na+and Cl-outside the cell</p>
<p>More K+inside the cell</p>
<p>Why must large concentration gradients of ions be maintained?</p>
<p>For nerve function</p>
<p>What does hyper mean?</p>
<p>Greater than normal</p>
<p>What does hypo mean?</p>
<p>Less than normal</p>
<p>What does aemia mean?</p>
<p>In the blood</p>
<p>What does uria mean?</p>
<p>In the urine</p>
<p>What does 'glyc' mean?</p>
<p>Relates to glucose</p>
