Question

1. A) What is the trigger for initiating an action potential in a cardiac cell?  

B) What phase or event of an action potential is the trigger for the actual muscle contraction?

2. Why do you believe a defect or blockage in the cardiac conduction system would cause cardiac arrhythmia?

3. A patient is being examined for life-threatening low blood pressure.  Under questioning, the patient admits to having taken Viagra, an erectile dysfunction drug, in spite of already taking high blood pressure medications.  Briefly look up how Viagra works and using that information provide a short rationale for the patient’s very low blood pressure.

4. A) What effect do you predict would occur to blood pressure if the heart is contracting more forcefully?

B) What effect do you predict would occur to blood pressure if the kidneys are retaining more water?

C) What effect do you predict would occur to blood pressure if arterioles throughout the body are dilating?

Answer 1

1.A.ans,The cardiac action potential.The cardiac action potential is a brief change in voltage(membrane potential) across the cell membrane of the heart cells.As this is caused by the movement of charged atoms called ions between inside and outside of the cell, through proteins called ion channels.

1.B.ans,Muscle contraction is describrd by the sliding filament Model of contraction .ACh is the neurotransmitter that binds at the neuro muscular junction(NMJ) to trigger dipolarization,and an action potential travels along the sarcolemma to trigger calcium release from SR.

2.ans,any blockage or defect I don't think so Heart arrythmias or heart rhythm problems feel when electrical impulses that cordinate your heart beats don't work properly,causing your heart to beat too fast or too slow or irregularly.

3.ans,Inspite of already taking high blood pressure medications in low blood pressure life threatening cases Usage of Viagra can contribute to a lowering blood pressure,Causing life threatening problems to the patients.So it should be taken for suited blood pressure condition.

4.ans,If the heart is contracting more forcefully it tends to increase more blood pressure in the arterioles and arteries walls.

4.B.ans,In most cases kidneys can eliminate all waste materials that body produce but when the fluid retention comes it causes the blood pressure and flow to the kidneys.

4.C.ans,Blood in the legs is the fastest away from the heart and it has to flow up to reach it .The heart rate increases ,which increases the hydrostatic pressure against the artery walls.At the same time arterioles dialate in response to the increased exercise .