Week 9 - Study Guide Flashcards by Beautiful !

Definition of Cardiac Output

blood pumped by the ventricle in one minute (minute volume)

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Formula for Cardiac Output

CO = (SV)(HR)

(ml/min) = (ml/beat)(bpm)

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Average heart rate

75 bpm

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Stroke Volume is

amount of blood pumped by each ventricle with each heart beat

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Stroke Volume =

average 70 ml/beats

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what is the AVG CO =

5.35 L/min

for every minute = is nearly the entire blood volume of the body

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Total Blood volume =

5.5 L

Each ventricle pumps equivalent of total blood volume/minute at rest

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Cardiac Reserve =

difference between CO at rest and all-out work

which is allowing us to understand that there is a normal resting cardiacoutput
AND
a large reserve capacity allowing us to increase our activity quite a bit

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Exercise CO =

14-20 L/min

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Hemorrhage CO =

1.5 L/min

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Elite Athletes CO =

30 L/min

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Contraction phase

Systole
pumped volume

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Relaxation phase

Diastole
filled volume

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Formula for Stroke Volume (SV) =

SV = EDV - ESV

when ventricles are full = EDV
when ventricles pump = ESV
SV is the difference

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Dicrotic Notch

closure of the aortic semilunar valve causes temporary increase pressure

blood briefly backflow against the valve.

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Which contraction is the biggest pressure change?

Left ventricular contraction

which alters Left atria and aortic pressure

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Frank-Starling Law

Better fill = Better pumping

Amount of stretching in ventricle prior to contraction

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Factors affecting stroke volume

Frank-Starling Law
Sympathetic nerve activity
Venous return (determines and influences the EDV)

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What do you want in cardiac muscle in regards to sarcomere length?

Want the most stretching, the greatest filling that you can - in order to create the greatest pumping efficiency

The more you stretch - the better the contractile strength.

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Preload

filling or stretching of the ventricles - creating the strength of their contractions

for heart to be effective, preload has to be greater than afterload

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Afterload

Pressure in the artery that the heart has to contract against.

is pressure in vessels applied to backside of semilunar valve,

Has to pump against back pressure of semilunar valves for things like hardening of the arteries, etc.

Increasing afterload =

decreased SV

increased ESV

Sympathetic enhances contractility and relaxation by

enhancing Ca2+ movements

When you are stressed you need more blood which means

Stroke volume rises

Norepinephrine does what

speeds things up

Norepinephrine Release has 3 main effects

1. Makes pacemaker speed up (SA node) 2. Heart beats faster, pause is shorter -- decreases conduction time through AV node 3. heart more reactive - effective pump - gap junctions. increases excitability of entire heart

ACH release does what?

1. Vagus nerve stimulates the heart 2. Decreases heart rate Vagus nerve input is going to slow down the heart - because that is the parasympathetic signal.

Preload > Afterload

your ventricles will be able to pump blood effectively out to the pulmonary circuit and the systemic circuit. Pumping blood out of the heart

Preload = Afterload

your ventricle does not have sufficient pressure to overcome the afterload so- the semilunar valves are not open

Preload < Afterload

Not able to open the semilunar valve. Probably be pushing blood backward. Making sure that any blood that is trying to enter the ventricles is actually backing up

How do you calculate Cardiac Output? What are the average adult values?

CO = (HR)(SV) 5.25 L/min = (70 mL/beat)(75 bpm)

EDV

End Diastolic Value (Volume of blood in ventricle, right before it contracts, i.e. how full it is)

ESV

End Systolic Value (volume of blood in ventricle left over right after it contracts. i.e. indicates how much blood was pumped

Another way to describe preload and afterload

preload is stretch afterload is the opposition the heart works against

Syncope

pass out

Venous return

summary of all the things that help to assure wherever the blood is in the body's system - that it will make it back to the heart to keep the cycle going. **Heart cannot pump what it does not receive**

Return of blood to the heart influences --

stroke volume

Influencing factors of stroke volume

1. Total Blood volume 2. Venous pressure 3. Breathing

EDV dependent on Venous retrun. Did the blood from the veins get back to the heart. Factors that influence this?

**BLOOD VOLUME** (BV) 1. BV goes up when you pee more. that fluid is no longer in the bloodstream (an inverse relationship) **As urine volume goes up - blood volume goes down** meaning - if you BV is down - Venous return will. be down. **TISSUE FLUID VOLUME** 1. Edema (build-up of fluids in the tissues) would cause a blood volume decrease 2. which would then cause a venous return decrease.

Venous return is inversely related to

1. urine output 2. tissue fluid volume more urine volume = less BV more tissue fluid = less BV

What keeps the blood clean and creates urine? (filter)

Kidneys 20% of heart beat foes to kidneys to filter

Build-up of fluid in the tissues

Edema

What happens to the pressure the farther you get away from the heart?

the more the pressure drops

Venoconstriction

The SNS can constrict the muscle in the vein to increase a little bit of pressure to push blood from the vein back to the heart.

Skeletal Muscle Pump

About you voluntarily moving and pushing blood back to your heart. One of the reasons it is important to move around to keep your blood from being stuck in your periphery.

Negative interthoracic pressure - Breathing

1. Ribs will be pushed out 2. Diaphragm contracts and pushes downward 3. Causing a pressure gradient meaning - the pressure in the thoracic cage - actually falls because your diaphragm contracts and pushes down on the abdomen. Meaning - the abdomen has a higher pressure than the thoracic activity. pressure gradient If there is HIGH pressure in the abdomen and LOW pressure in the thoracic cage - BLOOD wants to go from the abdomen back to the heart. REMEMBER 1. Blood wants to go from High pressure to Low pressure

How does this impact venous return? Breathing

Good for Venous return Blood wants to for from high pressure to low pressure

How does this impact venous return? Urine volume

urine volume up venous pressure low

How does this impact venous return? Skeletal muscle activity

skeletal muscle activity up Venous goes up

How does this impact venous return? Edema

Edema goes up Venous pressure goes down Blood volume goes down

How does this impact venous return? Sympathetic Activity

Sympathetic Activity goes up Everything goes up