Prob.Sess8 (mult choice) - In a lab class you have been...

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Unformatted text preview: In a lab class you have been studying ionic concentrations in body fluids, and using appropriate samples you have determined the following concentrations for three physiologically important ionic s oecies: ionic s . ecies __EI_EE __IE-Ifl ——EI_E] __E_Efl Consider the numerical values in your data: (a) [ion]in is likely to refer to the concentration of the ion inside capillaries. (b) [ion]out is likely to refer to the concentration of the ion in lymph. (c) The equilibrium potential for Na+ is expected to be -61 mV, which would produce an inward driving force on Na+ at typical values of neuronal Vrest. (d) You must have made a mistake in your measurement of [K+]out, because it is never this high in a normal healthy adult human being. The Goldman-Hodgkin-Katz equation: (a) Will simplify to the Nernst equation if a membrane is permeable to only one ionic species. For example, if the membrane is permeable to only Ca2+, the Goldman-Hodgkin-Katz eguation will become the Nernst equation for Ca +. (b) Helps us to understand the basis of Vrest. (c) Allows us to calculate the driving force for each individual ionic species that contributes to a multi-ionic current. (d) Can be correctly used only when dV/dt = 0. have an axon in the periphery. (a) Third order neurons in the pain sensory pathway. (b) Post-ganglionic sympathetic neurons. (c) Spinal motor neurons. (d) Pyramidal tract neurons. Skeletal muscle fibers: (a) Each contain a single nucleus. (b) Contain fragments of the organelle called sarcoplasmic reticulum. (c) Contract when [Ca2+]cytophsm increases. (d) Produce force only when they can shorten. Consider the different skeletal muscle fiber types: (a) Red muscle fibers get their color from myoglobin, an 02-binding protein within the cytoplasm of the fibers, and are slow to fatigue. (b) White muscle fibers contain no myoglobin and produce a lot of force per cross-sectional area. (c) Some fibers within the biceps muscle contract isometrically, whereas others contract isotonically. (d) White fibers have large motor units; red fibers have small motor units. Cardiac output would decrease if: (a) Stroke volume decreased, with no other change. (b) Heat rate dropped, with no other change. (c) Parasympathetic activity onto the contractile fibers increased. (d) The level of circulating epinephrine increased. In the circulatory system: (a) Deoxygenated blood flows through the pulmonary veins. (b) AV valves are pushed shut by pressure developed by ventricular contraction; these valves prevent backflow of blood from the ventricles into the atria. (c) Venous valves are pushed shut by pressure developed by atrial contraction; these valves prevent backflow of blood from the atria into the great veins. (d) Arterial pressure is always greater than venous pressure. Venous return to the heart increases: (a) If cardiac output increases. (b) When large skeletal muscles contract rhythmically producing the “muscle pump” effect. (c) If total peripheral resistance increases in a person who is lying flat on his back. (d) During each exhalation, caused by changes in intrathoracic pressure. If you were recording an electrocardiogram: (a) Giving the person a dose of Sudaphed® (synthetic epinephrine, sold as a nasal decongestant) would decrease the time between QRS complexes. (b) You would infer that during the S-T segment (the time from the end of the QRS complex to the beginning of the T wave), all ventricular contractile fibers would be repolarizing. (c) The T wave masks atrial repolarization because the ventricles are so much bigger than the atria. (d) You would be recording the transmission of electrical signals through the conducting system within the heart. At mile 17 in a marathon race (marathons are 26.2 miles longr (a) You would expect the athlete’s pulse pressure to be elevated because working muscles require more 02. (b) You would expect the athlete’s diastolic pressure to be unusually low because local factors released by the working fibers in the large muscles of the leg would reduce total peripheral resistance. (c) You would expect the athlete to be relying primarily on white muscle fibers in leg muscles. (d) You would expect the flow of blood to the biceps and triceps to be higher than normal due to an increase in circulating ephinephrine. Osmolarity: (a) Indicates the total number of solute particles in a solution; one liter of a 1 Osmolar solution contains Avagadro’s number of solute particles. (b) Indirectly indicates the partial molar fraction of water in the solution: a high osmolarity indicates a low partial molar fraction of water. (c) Of 10 mM CaClz is 20 mOsm. (d) Of 300 mM fructose is 300 mOsm. During normal nephron function: (a) Blood enters the nephron by absorption from the glomerular capillary into Bowman’s capsule. (b) Glucose is freely filtered into the nephrons, and about 65% of the filtered glucose is reabsorbed along the proximal tubule. (c) Na+lK+ ATPase molecules are selectively inserted into the serosal membrane of nephron epithelial cells. (d) Some solutes cross the wall of the nephron through the paracellular pathway, and others cross through the transcellular pathway. You are volunteering at a 24-hour veterinary emergency practice, and a distraught woman has just brought in a 12 kilogram dog that has become increasingly lethargic over the past 24 hours and now is very unresponsive. You are doing the initial examination. You already know the following: a normal dog’s body temperature is just slightly higher than a human’s, a normal dog’s blood pressure is about equal to human blood pressure, a normal dog’s plasma volume is about the same percent of body weight as in a human, and a normal dog’s hematocrit is between about 40% and 55%. (a) You measure a blood pressure of 100/60, so you should conclude that the blood pressure is normal. (b) You take a sample of blood and measure a hematocrit of 30%. You should conclude that this dog is dehydrated. (c) You inject 100 mg of Evans blue, wait 15 minutes, and then withdraw a sample of blood. You spin out the cells and measure the concentration of Evans blue in the plasma. It is 5 mglliter. You should conclude that the plasma volume is abnormally low. (d) You measure the dog’s body temperature and find that it is 44°C. You should conclude that there is no sign of fever. ...
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