Anatomy and Physiology

    Cardiovascular System
    Through which structures does the electrical signal that produces contraction travel once it is initiated by the heart’s pacemaker?
    The signal that initiates contraction emanates from the SA node, but there is no sino-atrial bundle.
    Author: rikazzz Comment
    Electricity
    When can electrical microshock occur? When:
    Microshock refers to electrocution by a current above about 100 μA if delivered by a conductor that has penetrated the skin. Currents less than this are probably not fatal. If the current greater than 100 mA is applied to the exterior of the skin, it is called microshock. Choice D is referring to external defibrillation.
    Author: rikazzz Comment
    Muscles
    During muscle cell contraction, what happens because of Ca++ binding to troponin?
    Troponin causes tropomyosin (which covers the binding site of actin) to be shifted away.
    Author: rikazzz Comment
    Measurement, Errors, Data and Unit Conversion
    Which of the following units is NOT part of the Australian Metric System of units?
    Pascal (Pa) is the SI unit for pressure.
    Author: rikazzz Comment
    Reproductive System
    What is the function of progesterone?
    Progesterone prepares the uterus lining for pregnancy (and causes the number of peg cells in the fallopian tube to increase).
    Author: rikazzz Comment
    Cardiovascular System
    Consider Pascal’s principle. If the heart exerts a pressure of 120 mmHg on the blood in the aorta, where else in the body will the blood pressure be 120 mmHg?
    Resting BP is usually measured while the subject is seated. In this posture, the brachial artery is at the level of the heart. Hence gravity will not affect the BP in the brachial artery. In a standing person, gravity would increase the BP in the legs. BP in the capillaries and vena cava is not comparable to BP in the aorta.
    Author: rikazzz Comment
    Respiratory System
    One of the reasons that the mixture of gases in the air contained in the alveoli of the lungs differs from atmospheric air is that alveolar air is:
    Alveolar air is saturated with water vapour, and this has a partial pressure greater than the PP of water in atmospheric air. Alveolar air and atmospheric air are at the same pressure except when inhalation and exhalation is occurring, so if water is in greater proportion within the alveoli (than in the atmosphere), then the other gases must be in lesser proportion.
    Author: rikazzz Comment
    Muscles
    Smooth muscle cells may be described by which of the following?
    Smooth muscle is not striated, and it is involuntary and has one nucleus.
    Author: rikazzz Comment
    Muscles
    One of the following muscle names refers to a superficial muscle that lies between the ribs. Which one is it?
    “Costa” refers to rib. There are internal intercostal muscles, so the external intercostals are more superficial. The muscles in choices B and C lie on the femur and radius bones, respectively.
    Author: rikazzz Comment
    Cardiovascular System
    By what means does an electrical signal travel from the atria to the ventricles? Via:
    The conduction system of the heart passes the electrical signal via the AV node to the AV bundle (also known as the bundle of His) in the interventricular septum.
    Author: rikazzz Comment