Anatomy - Cardiac Output

Module 12

Name the four things that impact Heart Rate

Autonomic NS, hormones, fitness, age

What is role of gap junctions

Action potential propagation between cells

What doesn’t DIRECTLY affect Heart Rate

Blood Pressure

Blood Pressure affects

Cardiac Output

Stroke Volume

Blood pumped from end diastole to end systole

Afterload

Resistance; pressure to push blood into aorta out to body

Preload

Heart stretches during maximum diastole

Contractility

How hard heart squeezes w/every beat

Cardiac Output

Amount of blood pumped over one minute

Heart rate (HR)

How fast heart beats

Lisa comes out of open heart surgery with an ejection fraction of 40% (normal 50 - 70 %). Predict what will happen to Lisa's heart rate as the body tries to maintain cardiac output.

Heart Rate increases

Normal ejection fraction percentage

50-70%

Lower ejection fraction means

Low Stroke Volume

What happens to Cardiac Output when you increase preload

Increase cardiac output due blood amount that enters heart increases (aka More EDV)

What happens to CO when you increase afterload

Decreased Cardiac Output due increased resistance to push blood out of heart

What happens when systemic blood vessel diameter decreases

Decreased CO due to increased peripheral resistance

What happens when contractility is increased

Increased CO due heart squeezing faster

What happens when systemic blood volume decreases

Decreased CO due decreased BV

Heart beats 100 bpm with 100ml EDV with 50ml ESV. What’s heart’s ejection fraction?

50%

Heart beats 100 bpm with 100ml EDV with 50ml ESV. What’s Cardiac Output?

5000ml/min (Divide 5000 by 1000 to get 5 L)

Narrow blood vessels means

Lower Stroke Volume

Ejection Fraction Percentage Formula

Stroke Volume/EDV

Cardiac Output formula

Heart Rate times Stroke Volume

The moderator band prevents ___

too much stretch

What does Hypervolemia (Increased blood volume) do to BLOOD PRESSURE

Increased Blood Pressure due increased blood volume

What does decreased vessel length do to blood pressure

Decreased blood pressure due decreased vessel length

What does Tachycardia (increased HR) do to blood pressure

Increased BP due increased HR

What does vasoconstriction do for blood pressure

increased BP due decreased vessel diameter

Vasoconstriction is regulated by

Autonomic nervous system

Explain Vasoconstriction

circulating blood must move through smaller area under higher pressures. reduced blood flow → resistance increased → higher BP

What does Hyper viscosity Syndrome do to BP

Increased BP due increased viscosity

Vasoconstriction INCREASES

vein’s blood pressure, blood flow AND return of blood to heart!