Week 1 formative quiz questions Flashcards
What is plasma pH proportional to?
hint: think bicarbonate and carbonic acid conc.
Plasma pH is proportional to bicarbonate ion conc. divided by carbonic acid conc. (or CO2 levels as you can substitute CO2 for carbonic acid and get the same effect in terms of movement of pH
Are all pathological process naturally occuring?
No, as pathological processes can occur unnaturally, for example following traumatic injury or iatogenic (caused by healthcare) harm
Ribosomes are involved in what process?
Protein synthesis
What % of the human body is water?
60%
Is the entry of sodium ions to a nerve cell during an action potential positive or negative feedback? Why?
This is a good example of positive feedback as when a nerve cell is stimulated the cell membrane becomes permeable to sodium. Entry of sodium to the nerve cell causes the nerve cell membrane to become even more permeable to sodium thus more sodium enters and so on. This “chain reaction” is termed positive feedback
Will a SATURATED fatty acid have the maximum or minimum number of double bonds?
Minimum, A saturated fatty acid has no double bonds.
Amphipathic molecules have what two parts?
Water loving (hydrophilic) and water repellent (hydrophobic)
does more double bonds present in the fatty acids of a cell membrane make the membrane more or less flexible?
Double bonds increase the flexibility of a fatty acid chain
True or false: plasma makes up less than a third of intracellular volume?
True. Plasma accounts for about 3L of the 14L that is extracellular fluid (11L is interstitial fluid)
True or false: When you eat a sugary donut, merely the presence of food in your stomach stimulates the release of insulin from the pancreas prior to the glucose being absorbed across the gut wall. This is an example of negative feedback
False. This is instead an example of a feedforward mechanism. Blood glucose conc. has not yet increased but the body pre-empts an increase due to the presence of food in the stomach and promotes the release of insulin to minimise the disturbance to blood glucose levels when the glucose is absorbed
True or false: A rise in buffer concentration will result in a fall in pH
False. A rise in buffer conc. will increase pH. Remember the henderson hasselbalch equation which describes the relationship between buffer and pH. Simply put pH is proportional to buffer conc. divided by protonated buffer concentration so as buffer conc. goes up, pH goes up and vice versa
True or false: intracellular fluid volume can be measured directly
False. We can only directly measure the volume of fluid compartments of which plasma is a component because we only have access to the plasma (via veins) to inject the marker and sample the diluter marker after equilibration. Plasma is not a component of ICF. However ICF is a component of TBW, so if we measure TBW using heavy water and measure ECF using radiolabelled Na (remember plasma is a component of both ECF and TBW) we can calculate ICF indirectly by subtracting ECF from TBW
True or false: Phosphate ions are the main buffering agents in plasma
False. Bicarbonate ions are the main buffering agents in plasma. Phosphate ions buffer intracellular fluid
True or false: The nucleic acid base adenine is only found in DNA
False. Adenine is found in both DNA and RNA. All base pairs except Thymine are found in DNA and RNA. The RNA base pair for adenine is uracil
True or false: Bicarbonate and phosphate ions are the major buffer systems in the body
True. Theses two ions form the main buffering agents that help maintain body fluid pH at 7.4
True or false: The GMC develops postgraduate training programmes and exams
False. The royal colleges do this, and they are approved by the GMC. The GMC is the regulatory body for medicine in the UK
True or false: Having a drink of water when you are thirsty is an example of a feedforward mechanism
False. This is instead an example of negative feedback. Your homeostasis of water is already disturbed causing you to feel thirsty and seek water. By drinking water you remove the trigger that caused the thirst, thus removing the thirst response = negative feedback