Anatomy and Physiology

    Cardiovascular System
    Which layer in the walls of blood vessels is responsible for their ability to vasoconstrict and vasodilate?
    The tunica media of a blood vessel has most of the smooth muscle. It is tempting to choose “tunica muscularis”, but a layer with that name does not exist.
    Author: rikazzz Comment
    Nervous System
    Which structure is involved in controlling eye movement?
    The superior colliculi receive input from the lateral geniculate nuclei. The inferior colliculi receive auditory sensation.
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    Cells and Tissues
    The combination of a sugar and a base is given the general term of:
    A nucleotide is formed from a nucleoside and a phosphate group.
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    Biomechanics
    What is the purpose of “counterbalancing” in manual handling? To:
    Counterbalancing involves placing the centre of gravity to one side of the base of support so that the gravitational pull on your body assists in moving the patient.
    Author: rikazzz Comment
    Ionising Radiation
    If a thickness of 7.35 mm of lead can absorb half of the 1 MeV gamma photons that enter the lead, then what fraction of gamma rays will be absorbed by twice this thickness (i.e. 14.7 mm)?
    Since half of the gamma photons are absorbed by 7.35 mm Pb, then that is the “half-value layer”. A second half-value layer placed after the first one would again absorb half of the photons that emerge from the first slab of lead. This would leave half of a half, that is, one quarter emerging from the second half-value layer. Hence ¾ have been absorbed.
    Author: rikazzz Comment
    Cardiovascular System
    In which organs would continuous, fenestrated and sinusoid capillaries, respectively, be found?
    The blood supply to the brain has continuous capillaries (in the blood- brain barrier), the SI has fenestrated capillaries (to facilitate absorption of digestion products) and the liver has sinusoids.
    Author: rikazzz Comment
    Chemistry for Physiology
    Which of the four IV solutions below is hypotonic?
    As 0.9% NaCl is isotonic, and 0.45% is less than 0.9%, it must be hypotonic (and there is only one best correct answer!). A is “4% and a fifth” while B is “3.3% and a third”.
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    Cardiovascular System
    Colloid osmotic pressure:
    Plasma proteins (also known as colloids) are responsible for the colloid osmotic pressure of blood.
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    Cardiovascular System
    Which of the following is NOT used as a unit of pressure?
    Millilitres of water is a volume and is not a form of pressure unit.
    Author: rikazzz Comment
    Chemistry for Physiology
    Given that 1 mol of Na+Cl− has a mass of 58.5 g, what would be the concentration of particles when 0.9 g of Na+Cl− is dissolved in 100 ml of water?
    The number of moles in 0.9 g = 0.9 g/58.5 g/mol = 0.0154 mol of Na+Cl−. However NaCl separates into ions when dissolved, so that there will be 0.0154 mol of Na and 0.0154 mol of Cl; hence 0.0308 osmol of particles = 30.8 mosmol per 100 ml. In 1 L, the number of moles would be ten times greater, so 300 mosmol/L (is closest).
    Author: rikazzz Comment