Lecture 2 -- Exam 2 Flashcards
When are all chambers are of the heart relaxed?
late diastole
When does first heart sound happen?
after atrial systole (AV valve closing)
What isovolumic ventricular contration?
when ventricles contract and but not enough force to open semilunar valves open and AV valves are closed
When are all the heart valves closed?
isovolumic ventricular contration
When does the semilunar valves finally open?
ventricular ejection (enough pressure has build up in ventricles)
When does the second heart sound happen?
after ventricular ejection (semilunar valves closing)
What is isovolumic ventricular relaxation?
ventricles are relaxed (low pressure) and semilunar valves close
What are the 5 steps of the cardiac cycle?
- last diastole
- atrial systole
- isovolumic ventricular contration
- ventricular ejection
- isovolumic ventricular relaxation
start again
In a Wigger Diagram, when does electrical events happen relative to the mechanical events?
before mechanical events
What is the first small pressure bump on the Wigger’s Diagram?
atrial contraction (atrial systole / depolarization / P wave)
What is the very tall hump on the Wigger’s Diagram?
ventricular contraction (ventricular systole / depolarization / QRS complex)
What is the reason for the small hump in aorta pressure right BEFORE the ventricles contract on the Wigger’s Diagram?
pressure building in ventricles causes semilunar valves to bulge into aorta
What is the reason for the small hump in aorta pressure right AFTER the ventricles contracr on the Wigger’s Diagram?
elastic recoil of aorta
What is the reason for the small dip in atrial pressure right after the atrium contracts?
AV valves closing
Where on the Wigger’s Diagram does the AV valves close?
(use photo)
A
Where on the Wigger’s Diagram does the AV valves open?
(use photo)
D
Where on the Wigger’s Diagram does the semilunar valves close?
(use photo)
C
Where on the Wigger’s Diagram does the semilunar valves open?
(use photo)
B
What is the first upward curve of volume on the Wigger’s Diagram?
blood entering ventricles
What occurs at the peak of the volume curve on the Wigger’s diagram?
ventricular isovolumic contraction
What is the lowest point on the volume curve on the Wigger’s Diagram?
ventricular isovolumic relaxation
What is diastole?
relaxation
- heart filling with blood
What is systole?
contraction
- heart ejecting blood
What is stroke volume?
volume of blood ejected out of left ventricle every cycle
What is afterload?
the force against which the heart has to contract to eject the blood
What is preload?
initial stretching of the cardiac muscle prior to contraction (due to blood filling ventricles)
What is Frank-starling mechaism of the heart?
heart’s ability to change its contraction force, and therefore stroke volume, in response to changes in venous return
What does the Frank-Starling curve indicate?
left ventricle’s muscle can stretch as pressure/volume increase but only to a certain point the myosin cannot attach to each other for contraction
As end-diastole volume increased the myocardium stretches more which increases/decreases contraction and stroke volume
increase contraction
increase stroke volume
What is contractility?
ability of cardiac muscle cells to develop force at any given length (known as inotropism)
What is inotropism?
ability of heart modify its muscular contractility
Regarding calcium, how does a heart muscle contraction occur?
- action potential allows Ca2+ influx
- Ca2+ enters SR then leaves
- high amounts of Ca2+ in cytosol allows for contraction
Regarding calcium, how does a heart muscle relax after contraction occur?
Ca2+ in cytosol enter SR or is pumped out of cell with opposing Na+ gradient (Na+ entering cell)
How does Ca2+ enter the SR?
@ 2nd action potential
Ca2+ is built up in cytosol PLN unbinds for SERCA2 channel allowing Ca2+ into SR
How does Ca2+ NOT enter the SR at the first action potential?
adenylate cyclase makes cAMP which makes PKA
PKA phosphorylate PLN which inhibits SERCA (Ca2+) channel preventing Ca from entering SR
Why is Ca2+ not allowed to enter SR at first action potential?
need to build up lots of Ca2+ in cytosol first
Once a lot of Ca2+ has entered SR via SERCA channel what happens?
Ca2+ quickly leaves SR and muscle contracts
What are pressure volume loops?
relates changes in pressure to changes in blood volume in heart
On a pressure volume loop, what does A-B mean?
(see image)
ventricles filling
On a pressure volume loop, what does B-C mean?
(see image)
ventricles filling
On a pressure volume loop, what does C-D mean?
(see image)
ventricular isovolumic contraction
On a pressure volume loop, what does D-E mean?
(see image)
ventricles eject blood
On a pressure volume loop, what does E-F mean?
(see image)
pressure falls since ventricles just contracted
On a pressure volume loop, what does F-A mean?
(see image)
ventricular isovolumic relaxation
On a pressure volume loop, where does the mitral valve close?
(see image)
C
On a pressure volume loop, where does the mitral valve open?
(see image)
A
On a pressure volume loop, where does the aortic valve close?
(see image)
F
On a pressure volume loop, where does the aortic valve open?
(see image)
D
On a pressure volume loop, where is the end systolic volume?
(see image)
X axis (A)
On a pressure volume loop, where is the end diastolic volume?
(see image)
X axis (C)
On a pressure volume loop, how do you find the stroke volume?
(see image)
distance from ESV to EDV
If you were to increase the EDV, how would that affect contractility?
increases contractility
If you were to increase contractility , how would that affect venous return?
increase venous return
If you were to increase the contractility, how would that affect stroke volume ?
increase stroke volume
If you were to increase the preload, how would that affect blood ejection?
increase ejection
If you were to increase the preload, how would that affect stroke volume?
increase stroke volume
If you were to increase the preload, how would that affect end-diastole volume?
increase EDV
If you were to increase the afterload, how would that affect stroke volume?
decrease stroke volume
If you were to increase the afterload, how would that affect end-systole volume?
increase ESV
(more blood will be left over after contraction = increased volume)
If you were to increase the afterload, how would that affect blood ejected?
decrease blood ejected
If you were to increase the preload, how would that affect venous return?
increased venous return
Under steady state, cardiac output should = _________ return
venous return
How is heart rate determined?
rate of depolarization
What 2 factors determine stroke volume?
force of contraction (contractility and EDV)
What is mean arterial pressure?
average blood pressure in a patient’s arteries during a single cardiac cycle
How do you calculate MAP (mean arterial pressure)?
diastolic pressure + (pulse pressure) / 3
How do you find pulse pressure?
systolic pressure - diastolic pressure
What 2 ways can blood pressure be regulated?
fast response (via cardiovascular system) and slow response (via kidneys)
Where in the brain is BP controlled?
medulla and hypothalamus
What is the baroreceptor reflex?
primary way BP is regulated
Where are the 2 baroreceptor reflexes located?
carotid sinus
aortic arch
How do the baroreceptors detect changes in BP?
detects bulging of artery not pressure itself
What 3 things on pressure volume loops can be tweaked to change the shape of the loop?
- contractility
- pre-load
- after load
