Anatomy and Physiology

    Cardiovascular System
    Why is the myocardium of the right ventricle thinner than that of the left ventricle?
    The RV delivers blood to the lungs which has a relatively low resistance to blood flow. Hence a small pressure will suffice.
    Author: rikazzz Comment
    Nervous System
    Some cells in the body can maintain an electric potential across their cell membrane. How do they do this?
    It is the distribution of ions of different charge on either side of the membrane that determines the membrane potential.
    Author: rikazzz Comment
    Chemistry for Physiology
    What is a definition of an osmole? The amount of substance that:
    Ionic substances (e.g. Na+Cl−) separate into ions when dissolved. Hence a mole of NaCl would produce two osmoles of ions (1 mol of Na ions and 1 mol of Cl ions). Hence half of a mole of NaCl, when dissolved, would result in one osmole of dissolved particles (ions).
    Author: rikazzz Comment
    Cells and Tissues
    Which one of the following terms best describes a phospholipid. It consists of a:
    polar = hydrophilic head of phosphate, which can dissolve in the aqueous extracellular solution because water molecules are polar; non-polar = hydrophobic tails of lipid, which being non-polar, cannot dissolve in aqueous solutions.
    Author: rikazzz Comment
    Chemistry for Physiology
    A buffer solution consisting of H2PO4− (acid) and HPO42− (base), in a ratio of 1:4, maintains the pH at 7.4. What is the ratio of these two components if the pH were to become 8.4 after the addition of more of the basic component of the buffer?
    The pH of a buffer is determined by the ratio of its two components. pH is a logarithmic scale of the hydronium ion concentration of a solution. Hence the ratio must change by a factor of 10 in order for the pH to change by one (i.e. change from 7.4 to 8.4).
    Author: rikazzz Comment
    Chemistry for Physiology
    Which body fluid is at the lowest pH?
    Acids have low pH (less than 7). The stomach contents contain hydrochloric acid secreted by the parietal cells of the gastric glands so typically has a pH of less than 2.0. Urine, while usually acidic, rarely falls below pH of 5.
    Author: rikazzz Comment
    Integument
    Which layer of the integument contains rapidly dividing keratinocytes?
    Stratum germinativum (= stratum basale) implies that germination is happening. In fact new cells are formed here by mitosis to replace those lost from the stratum corneum.
    Author: rikazzz Comment
    The Physics of Waves: Light Waves, Sound Waves and Ultrasound
    Consider an electron that is in its ground state in an atom. When this electron moves to another state in the atom, it is said to have:
    “Ground state” is the state of lowest energy; hence, it can only move to a higher energy state. In this case it is said to be excited.
    Author: rikazzz Comment
    Biomechanics
    The counter-traction force on a patient’s leg is often increased by tilting the bed so that the patient’s head is lower than their feet. Why is this done? Because tilting the bed increases the:
    Unless the bed is tilted, there is no component of the patient’s weight that is parallel to the bed. The force of gravity and the force exerted by the hanging masses do not change.
    Author: rikazzz Comment
    Chemistry for Physiology
    The formula for leucine (an amino acid) may be written as (CH3)2C3H4NH2COOH. How many atoms of each type of element are there in a molecule of leucine?
    The number of atoms immediately follows the symbol for the element as a subscript. A number following a parenthesis multiplies the atoms inside the parenthesis. Hence there are six atoms of carbon (including two inside the parenthesis). By the same reasoning, there are 13 atoms of hydrogen (including 6 inside the parenthesis). An amino acid always has an atom of nitrogen.
    Author: rikazzz Comment