30 Questions
What type of cell is responsible for producing the myelin sheath?
Schwann cell
What is a characteristic of the action potential of skeletal muscle?
It spreads inwards to all parts of the muscle
What is required for contraction in smooth muscle?
Calmodulin
What is the role of tropomyosin in skeletal muscle?
Covering up the actin binding sites of myosin at rest
How does neostigmine improve muscular weakness?
It blocks the action of acetylcholine esterase
How many oxygen molecules are carried by one Hb molecule?
4
What is the characteristic of the S.A node that makes it the pacemaker of the heart?
Its natural leakiness to Na+
What is the duration of the absolute refractory period in the heart?
It lasts till cardiac contraction
During which phase of the cardiac cycle does the first heart sound occur?
Isovolumetric contraction
Which of the following vessels does not have sympathetic control?
Cerebral vessels
What is the main component of the blood-brain barrier?
Astrocytes
What is the effect of stimulating the sympathetic nerves on the heart?
It produces a positive bathmotropic effect
What is the primary cause of CO2 bubbles formation?
Due to increase in barometric pressure
What is the normal value of FEV1 in an adult?
80%
Which gas is most important in maintaining alveolar ventilation?
Carbon dioxide
What is the primary indication for hyperbaric oxygen therapy?
Gas gangrene
What is the effect of high altitude on alveolar PO2 and PCO2?
Decrease in PO2, decrease in PCO2
What is the primary function of surfactant in the lungs?
To reduce surface tension
Where is a diastolic murmur typically loudest?
Apex of the heart
What causes the 's' wave in ECG to be below the isoelectric line?
Change in direction of the impulse when the ventricles are getting depolarized
Which of the following is least likely to cause hypertension?
Chronically increased secretion of thyroid gland
What happens to lymph flow from the foot when an individual rises from the supine to standing position?
It increases
What determines the pressure in the radial artery?
The rate of discharge in sympathetic nerve fibers to the arm
Why is the 'T' wave in ECG above the isoelectric line?
Change in the direction of repolarization from the wave of depolarization
What is the effect of negative G on the eye?
Temporary blinding with redout
What happens to airway resistance in asthama?
It increases
What is the effect of decreased PCO2, decreased H+, and increased PO2 on breathing?
Hypoventilation
At what tidal volume is the Herring-Breuer inflation reflex activated in human beings?
Above 1 liter
What is the characteristic of total vital capacity in scoliosis?
It is decreased
What is the incorrect pairing of enzyme and substrate?
Erythropeptidase-polypeptides
Test your knowledge of the physiology of muscles and the nervous system with this quiz. Questions cover topics such as the myelin sheath, action potential, and muscle contraction.
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