Question 1

How could vasoconstriction affect cardiac output?

Accepted Answer

Vasoconstriction increases the resistance to flow. This is called an afterload. It is like a pump having to pump water up a steep hill; it won't pump as well as on flat land.

Question 2

Does psuedophedrine cause vasoconstriction of coronary arteries?

Accepted Answer

Yes you can call spasm of the corner arteries avoid this with significant coronary disease.

Question 3

Does a cigarette cause coronary artery vasoconstriction? if yes, wouldnt this cause a angina if you started exercising?

Accepted Answer

Cigarettes are associated with coronary artery vasoconstriction.  This constriction could cause angina if combined with exercise in some people, but it would not do so in everyone.  Much of the response would be based on the underlying health of the heart and coronary arteries.

Question 4

Does nicotine cause a big vasoconstriction effect on coronary arteries? if any how long does it last? surely body would override to myocardium needs?

Accepted Answer

Here's an article  witch will answer most of your questions:
http://content.onlinejacc.org/article.aspx?articleid=1121737
Just like the body can't override the effects of cyanide gas

Question 5

When could cardiac output decrease?

Accepted Answer

Cardiac output is related to the heart rate, and volume of blood the heart can pump with each heart beat.  A low cardiac output occurs when the pump function of the heart is compromised by an event such as a heart attack or when the blood volume is reduced by and event such as dehydration, or bleeding.

Question 6

Can you tell me how could an increased cardiac output help exercise?

Accepted Answer

During exercise, the muscles burn more oxygen for fuel. Increasing cardiac output increases the amount of oxygen carried by the blood  to the tissues.

Question 7

How could hypertension affect cardiac output?

Accepted Answer

It can cause the heart muscle to get thick and stiff so that it does not relax and fill up with blood properly. It could also cause the heart muscle to become weak so that it does not squeeze or contract as forcefully. These are called diastolic dysfunction (too thick) or systolic dysfunction (weak and flabby).

Question 8

Why doesn't tachycardia always affect cardiac output?

Accepted Answer

is stroke volume times heart rate. if stroke volume goes down more than heart rate goes up, cardiac output won't increase. stroke volume depends on preload (filling of the heart), afterload (resistance to flow), and contractility (how much the heart pumps for how much it is filled. For instance, if the heart rate goes up but the the heart doesn't have time to fill, output won't increase.

Question 9

How could hyperthyroidism affect cardiac output?

Accepted Answer

Cardiac output describes the amount of blood pumped through the heart in 1 minute.  Two effects of high thyroid levels are an increased heart rate (more beats per minute) and an increased stroke volume (more blood per beat). These combine to increase the the cardiac output..  However, at some point, the increased work can cause the heart to fail, and the cardiac output will fall.

Question 10

What could increase cardiac output?

Accepted Answer

Basically an increase in demand for oxygen by the body. This may be physiological (exercise) or pathological (sepsis - infection - fever) or increased metabolism (hyper active thyroid gland - hyperthyroidism) or abnormal conducts (shunting of blood).

How could vasoconstriction affect cardiac output