Anatomy and Physiology

    Muscles
    Which of the following is the smallest unit in a muscle?
    Myosin is a molecule, many of which combine to make a thick myofibril.
    Author: rikazzz Comment
    Chemistry for Physiology
    What distinguishes an osmole from a mole?
    Both mole and osmole may be used in reference to ionic compounds (because the atoms of ionic compounds separate into their constituent ions when dissolved), while the atoms within covalent compounds remain as molecules even when dissolved.
    Author: rikazzz Comment
    Ionising Radiation
    What are isotopes? Atoms of the one element whose nuclei:
    The number of neutrons does not affect the nature of the element.
    Author: rikazzz Comment
    Biomechanics
    Which of the following is not an example of a force?
    Inertia is not a force; it is a measure of mass. A measure of inertia of an object is the difficulty of setting the object in motion.
    Author: rikazzz Comment
    Biomechanics
    When two forces of magnitude 6 N and 10 N are added vectorially, what value could the resulting vector NOT have?
    The maximum value that can be obtained by adding two vectors of length 6 and 10 N is 16 N when the vectors are in the same direction.
    Author: rikazzz Comment
    Chemistry for Physiology
    Consider a volume of 100 ml of each of the four solutions below. Which would contain the greatest number of osmoles of dissolved particles? (FYI the atomic masses of H = 1, C = 12, O = 16, Na = 23, Cl = 35.5)
    By adding the masses of the atoms in the formula, we can determine that 1 mol of each substance has a mass of 46 g (for ethanol: 2 × 12 + 6 × 1 + 1 × 16 = 46), 180 g (glucose) and 58.5 g (NaCl). “5%” means 5 g of substance (much less than 1 mol of each substance) is dissolved in 100 ml of solution. An ethanol molecule is much less than half the mass of a glucose molecule, so there are more than twice as many ethanol molecules as glucose molecules in a 5% solution. Hence the ethanol solution has more osmoles than either glucose solution. While NaCl has a greater formula mass than ethanol, NaCl is an ionic substance, so it separates into Na ions and Cl ions when dissolved. This doubling in the number of particles when NaCl dissolves means that choice C contains the greatest number of osmoles. Or by calculation, the number of osmoles in each 100 ml of solution is determined by dividing the mass of dissolved substance by the mass of 1 mol of that substance for 5% ethanol, 5/46 = 0.109; 5% glucose, 5/180 = 0.0278; NaCl, (5/58.5) × 2 = 0.171; and 10% glucose, 10/180 = 0.0556 osmoles per 100 ml.
    Author: rikazzz Comment
    Renal System
    The kidney turns blood into filtrate and then filtrate into urine. Which list has the structures in the correct order of liquid flow from proximal to distal?
    the renal cortex is before the papilla; the efferent arteriole is not part of flow of the filtrate; Bowman’s capsule comes before the loop of Henle.
    Author: rikazzz Comment
    Measurement, Errors, Data and Unit Conversion
    Given that 1 mmHg = 0.133 kPa, how can a systolic BP measurement of 120 mmHg be converted to a measurement in kPa?
    We know that 1 mmHg is the same as 0.133 kPa, so two of them would be 2 × 0.133 = 0.266 kPa. Hence 120 of them would be 120 × 0.133 = 16 kPa.
    Author: rikazzz Comment
    Respiratory System
    Blood entering the capillaries of the alveoli has dissolved CO2 at 46 mm Hg and is separated from air in the alveoli, which contains CO2 at a partial pressure of 40 mm Hg, by the respiratory membrane. What will be the concentration of dissolved CO2 of the blood capillaries leaving the alveoli?
    Carbon dioxide will continue to diffuse from blood across the respiratory membrane into the alveoli, while the concentration gradient exists. The gradient will exist until the dissolved CO2 in the blood in the capillaries falls to 40 mmHg.
    Author: rikazzz Comment
    Nervous System
    Which sequence of ion movements describes the action potential?
    Sodium ions are in high concentration outside the cell (and in low concentration inside the cell). The correct sequence is Na in followed by K out.
    Author: rikazzz Comment