During the rapid ejection phase of the cardiac cycle, which ONE of the following
ID: 83775 • Letter: D
Question
During the rapid ejection phase of the cardiac cycle, which ONE of the following statements is INCORRECT? Select one: The aortic pressure is rising. The ventricular pressure approaches its maximum X This is not the incorrect statement. The ventricular pressure does reach its maximum during the rapid ejection phase. The ventricular volume is at its lowest. The aortic valve is open. The mitral valve is closed. Your answer is incorrect. The major mechanism controlling the diameter of arteries in the skin is: Select one: accumulation of metabolic waste products extracellular CO2 concentration myogenic X This option is incorrect. Sympathetic nerve activity is the most important controller of blood flow in the skin. Myogenic mechanisms, extracellular K concentration and accumulation of metabolic waste products also contribute, but are less important in controlling the diameter of cutaneous vessels. sympathetic nerve activity extra cellular K concentrationExplanation / Answer
Q1. During the rapid ejection phase of the cardiac cycle, which ONE of the following statements is INCORRECT?Answer: The ventricular volume is at its lowest.
During the rapid ejection phase of the cardiac cycle the ventricular volume does drop but actually reaches its lowest point during the reduced ejection phase.
Q2. The major mechanism controlling the diameter of arteries in the skin is:
Answer: sympathetic nerve activity.
It is very important because it act as a controller of blood flow in the skin.
Q3. Which ONE of the following is true of the ventricular filling phase of the cardiac cycle?
Answer: Ventricular pressure is less than aortic pressure.
When the pressure of ventricular is less then the aortic pressure is much higher.
Q4. According to Fick’s law, which ONE of the following would NOT be a factor in diffusion of a substance across the capillary wall?
Answer: Hydrostatic (blood) pressure in the capillary.
To control filtration or absorption of water into or from capillaries the Hydrostatic pressure in capillaries is very important, however, it has no role in determining diffusion of solutes as defined by Fick’s Law.
Q5. The major mechanism controlling coronary artery diameter is:
Answer: accumulation of metabolic waste products
Metabolic hypermia is the key mechanism to enhance the coronary blood flow, i.e., the dilation of coronary resistance arteries by accumulated metabolic waste products.
Q6. Which ONE of the following statements about an action potential generated from a sinus nodal fibre is INCORRECT?
Answer: The unstable baseline can be partly attributable to a progressive decrease in Ca2+ permeability.
Opening of T (transient) channels is responsible for the unstable baseline can be partly attributable to a small progressive increase (not decrease) in Ca2+ permeability
Q7. Which ONE of the following statements is INCORRECT? Increased sympathetic nervous system activity to the sinoatrial node:
Answer: Decreases the slope of the spontaneous depolarization of these action potentials
Increased SNS activity would increase the slope of spontaneous depolarisation allowing threshold to be reached more quickly.
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