L. 18 Cardiac Output

What are the 2 phases of the Cardiac cycle?

systole

diastole

What is systole?

when the heart contracts and ejects blood

What is Diastole?

when the heart relaxes and fills with blood

Diastole is 3 times ____ than Systole

longer

What makes up the Systolic phase of the cardiac cycle?

isovolumetric contraction phase

ejection phase

What is the Isovolumetric contraction phase?

heart is contracting and developing force and pressure (all valves are closed → there is no flow of blood into or out of heart)

What is the Ejection phase?

heart has generated enough pressure to push open the semilunar valves

What is the Diastolic phase of the cardiac cycle?

isovolumetric relaxation

rapid filling phase

atrial contraction phase

What is the Isometric revolution?

heart is relaxing (all valves are closed, no flow of blood into or out of the ventricles)

What is the Rapid filling phase?

pressure in ventricles is lower than pressure in atria (AV valves open ventricles start to will with blood)

What is the Atrial contraction phase?

atria contract and “top off” the filling of the ventricles

During which phase of the cardiac cycle is the heart filling?

diastole

Withdrawing/removing parasympathetic activity to the heart will result in what?

increased heart rate, increased contractility

The heart pumps blood to meet the ____ ____ of the body

metabolic demands

What is Cardiac output?

how much blood it pumps out of a single ventricle per beat and how frequently the heart beats

How many pumps does the heart have?

2 (left/right)

What is Stroke volume?

amount of blood pumped out per beat (ml/min)

What is Heart rate?

beats per min (bpm)

What is the Equation for cardiac output?

heart rate x SV = cardiac output

What is Preload?

the stretch the heart muscle before it contracts (how much blood is in the ventricle at the end of diastole)

What is Afterload?

the pressure the heart must over come to open the semilunar valves

What is Cardiac output at rest?

~5 L/min

What is Heart rate at rest?

60-80 bpm

What is Stroke volume at rest?

50-110 mL per beat

What do Positive Chronotropic Agents do?

influences that increase heart rate

What are Examples of positive chronotropic agents?

NE/EPI through B₁ receptors

Thyroid hormones (increases the # of b₁ receptors)

What do Negative Chronotropic Agents do?

factors that decrease heart rate

What are Examples of negative chronotropic agents?

beta blockers

What are Factors that influence stroke volume?

end-diastolic volume (EDV)

inotropic agents

afterload

What is End-Diastolic Volume (EDV)?

how much blood is in the ventricle at the end of diastole (inc EDV → inc SV)

What are Ionotropic Agents?

chemical compound neurotransmitters, hormones, drugs that alter the amount of calcium in the cardiac muscle cell

What is Afterload?

the force or pressure the heart is pumping against

A major factor that determines stroke volume is ____ ____ 

venous return

Venous return determines ____

preload

What does the End Diastolic Volume (EDV) equal to?

amount of blood in the heart at the end of diastole

increased venous return, increased preload = ____ stroke volume (SV)

increased

What is the Frank=Starling Law of the Heart?

EDV increases, greater stretch of heart wall results in the thick and thin filaments moving closes together 

Increased ____ to calcium = ___ force

sensitivity, more

Heart contracts more forcefully when filled with more blood so SV ____

increases

How does an increase in Venous pressure influence Stroke Volume?

more blood in the venous circulation (more blood volume) increases during exercise by muscle and respiratory pump

An increase in ____ blood volume will increase ____ ____ and increase ____ ____

central, venous pressure, venous return

When time to fill increases with slower heart rate what effect will it have on diastole?

increased duration of diastole

What is central blood volume?

volume of blood in the core

What are the skeletal functions when we take a deep breath in?

diaphragm pushes down on our abdominal cavity, which then increases pressures on those vessels

When you’re breathing in what happens to the large veins in your thoracic area?

it opens up the thoracic area which will then drive the flow of blood from the abdominal cavity to the thoracic area

What happens to in the thoracic cavity when we breath out?

increases pressure which causes the blood to be pushed into the heart

What are Ionotropic Agents?

agents that alter the amount of calcium in the cardiac muscle cell

What do Positive Ionotropic Agents do?

inc [Ca⁺] → inc contractility of the heart

What do Negative Ionotropic Agents do?

dec [Ca⁺] → dec contractility of the heart

What are Examples of Positive Ionotropic Agents?

SNS through NE/EPI

thyroid hormones

What do thyroid hormones do as a positive ionotropic agent?

inc B₁ receptors, inc NE/Epi signaling pathway

What are Examples of Negative Ionotropic Agents?

beta blockers, calcium channel blockers

increased after load will ____ stroke volume

reduce

What is High Blood Pressure (hypertension)?

increased afterload due to increased pulmonary or systemic resistance

What is Aortic Stenosis?

pumping blood against a narrower blood vessel

What are factors that Decrease stroke volume?

decreases with blood volume (dehydration, hemorrhage, anemia)

lower end-diastolic volume (lower preload → lower SV)

increase in heart rate (decrease filling time → decrease end-diastolic volume → decrease preload → decrease volume → decrease SV)

What would Increase stroke volume?

increased preload

decreased afterload

decrease heart rate

What would Decrease stroke volume?

decreased preload

increased afterload 

increased heart rate

(T/F) Increased central venous pressure would result in increased stroke volume by decreasing preload

false

How does blood flow in Arteries?

pulsatile (pulsating)

How does blood flow in Veins?

steady

Blood flow can be ____ but sometimes ____

laminar, turbulent

What does Laminar mean?

blood flowing in different rates

What does Turbulent mean?

blood flows like in stream moving very fast