Heart Flashcards
Where can you find the heart in the human body?
superior to diaphragm, medial cavity of thorax, enclosed in mediastinum
Where on the heart is the point of maximum intensity (where contractions are strongest)?
apex
Why are contractions the strongest at the bottom of the heart?
to prevent blood from pooling
What is the name of the membrane that covers the heart?
pericardium
what are the two layers of the pericardium?
fibrous + serous
What is the fibrous layer of the pericardium composed of?
protiens/fibers (e.g. collagen)
Which layer of the pericardium is double layered and filled with fluid?
serous
What is the name of the cavity where serous fluid is found?
pericardial cavity
Which layer of the serous pericardium is closest to the heart?
visceral
Which layer of the serous pericardium is farthest from the heart?
parietal
What is the name of the condition when the serous pericardium gets inflamed and causes a buildup of fluid?
pericarditis
What are the three layers of heart tissue?
epicardium, myocardium, endocardium
which layer of the heart is contractile?
myocardium
What anchors the muscle cells of the myocardium?
connective tissue made up of collagen and elastin
What is the name of the layer that lines the heart chambers?
endocardium
What type of cells make up the endocardium?
simple squamous epithelial
Why is the endothelium smooth?
help with blood flow through the heart chambers
What separates the left and right atria?
interatrial septum
What separates the left and right ventricles?
interventricular septum
Where does the left atria receive blood from?
lungs (pulmonary)
where does the right atria receive blood from?
body (systemic)
Why do the atria have weaker contractions?
they just need to get the blood into the ventricles and gravity helps with that
What is the job of the ventricles?
expel blood into the arteries
Why do the ventricles have stronger contractions?
they have to move the blood further (through the arteries)
Why do ventricles have thicker walls than atria?
their contractions are stronger
Where does blood from the left ventricle go to?
to the body via aorta
Where does blood from the right ventricle go?
to the lungs via pulmonary artery/trunk
Which direction is blood found in an artery going?
away from the heart
Which direction is blood found in a vein going?
back towards the heart
Which major vessel brings blood to the right atrium?
vena cava –> inferior = from body
superior = from the brain
Which major vessel brings blood to the left atrium?
pulmonary viens
pathway of blood:
right atrium > tricuspid valve > right ventricle > pulmonary sl valve > pulmonary artery > lungs > pulmonary vien > left atrium > mitral valve > left ventricle > aortic sl valve > aorta > body > vena cava (repeat)
What is coronary circulation?
blood flow to and from the myocardium
What is the job of coronary arteries?
deliver nutrient to the myocardium
What is the job of the coronary viens?
take away waste form myocardium
Another name for a heart attack…
myocardial infarction
How does blood move through the heart?
pressure gradients (area of high pressure to low pressure)
What is the job of valves?
prevent backflow
What is the name of the valves between atrium/ventricles?
atrioventricular valves
What is the name of the valves between ventricles and arteries?
semilunar valves
Name of right av valve…
tricuspid
Name of left av valve…
mitral
name of right sl valve..
pulmonary sl valve
Name of left sl valve…
aortic sl valve
what is the name of the structure that keeps av valves shut during ventricular contractions?
chordae tendinae
Where do the chordae tendinae attach?
valves and papillary muscles
What happen to persons heart rate is a valve is leaking + why?
it goes up due to inefficient pumping
What is the ‘lub’ heart noise indicating?
av valve closing
What is the ‘dub’ heart noise indicating?
sl valve closing
What does a heart murmur indicate?
turbulent blood flow (can be caused by a valve that doesn’t fully open)
What carries electrical current/action potentials?
sarcolemma
Where are cardiac muscle cells found?
myocardium
Name three features of cardiac muscle cells:
1) intercalated discs/striations
2) gap junctions between cells
3) packed with desmosomes for strength
What is the purpose of gap junctions in cardiac muscle cells?
allow AP and ions to pass between cells
Why is cardiac muscle called a functional syncytium?
they’re a coordinated, functional unit because of an electrical link
Define action potential:
rapid and predictable change in ion distribution
What are the three types of cardiac muscle cells?
pacemaker cells, contractile cells, conducting cells
Which cardiac muscle cell can make their own AP?
pacemaker cells
Can pacemaker cells contract?
nopeeee
Which cardiac muscle cells carry AP from pacemaker cells?
conducting cells
Which cells contract in response to action potential and make up a majority of the myocardium?
contractile cells
Does the contraction occur in atria or ventricles first?
atria
What is threshold?
cell reached a voltage where an AP can occur (point of no return )
What is depolarization?
cell become more +
What is repolarization?
cell becomes more negative
What is membrane potential?
unequal distribution of charged molecules on either side of the plasma membrane
What is pacemaker potential?
a depolarization event that causes a cell to reach threshold
Which ion enters the cell during depolarization?
Na+
Which ion enters the cell after threshold is reached?
Ca2+
Which ion leaves the cell during repolarization?
K+
Do pacemaker cells ever rest?
no, they are always depolarizing or repolarizing
What are the three locations in the heart you can find pacemaker cells?
1) Sinoatrial nodes
2) atrioventricular nodes
3) purkinje fibers
Which node in the heart is ‘dominant’?
SA node
If the SA node fires at 80 action potentials/minute, what is your heart rate?
80 BPM
What division of the nervous system helps the heart slow down?
parasympathetic nervous system
What division of the nervous system helps the heart rate increase?
sympathetic nervous system
What is the parasympathetic effect?
slowing down the amount of time it takes to reach threshold
What hormones can increase heart rate?
adrenaline and TH
What is tachycardia?
resting heart rate above 100 BPM
What is bradycardia?
resting heart rate below 60 BPM
How does AP move through the atria?
freely and quickly
What does the AP go through to get to the ventricles?
internodal pathway
What are the parts of the internodal pathway?
AV node, bundle of His, purkinje fibers
Where do the purkinje fibers take the AP?
from the apex up the ventricular walls
AP pathway through the heart:
SA node > atria (freely) > AV node > bundle of HIS > purkinje fibers > ventricles
What is an arrhythmia?
irregular conduction of AP which leads to irregular heart beats
What is heart block?
AP can’t pass from atrium to ventricles
How do you treat heart block?
insert a pacemaker
When producing an AP in the myocardium, what are the three phases?
1) Depolarization
2) Plateau
3) Repolarization
What is happening during the depolarization phase (AP in myocardium)?
Na+ channels open and close quickly
What is happening during the plateau phase (AP in myocardium)?
Ca2+ and K+ channels are open
The influx of which ion causes contraction?
Ca2+
Which ion has to do with the cross bridge cycle?
Ca2+
What is happening during the repolarization phase (AP in myocardium)?
Ca2+ and K+ channels close to end the action potential
Does a pump or channel facilitate active transport?
pump (channel is passive)
What is an EKG/ECG?
a measurement of all electrical activity in the heart at a given moment
What is happening in the heart when a P wave is shown?
cells in the atria are depolarizing
What is happening in the heart when the QRS complex shows up?
cells of the atria are repolarizing and the ventricles are depolarizing
When does atrial contraction occur (on an ECG)?
the PR segment
What is happening in the heart when the T wave is shown?
ventricles are repolarizing
When does ventricular contraction occur (on an ECG)?
the ST segment
What is the cardiac cycle?
all events associated with blood flow from the heart
What is systole?
the contraction phase
What is diastole?
the relaxation phase
What is happening in the first phase of the cardiac cycle?
Both the atria and ventricles are in diastole, AV Valves open, SL valves closed, passive filling of both chambers
What is happening during the second phase of the cardiac cycle?
atrial systole, ventricular diastole, AV valves open, SL valves closed, final 20% of blood enters ventricles, EDV is reached
What is happening during the 3a phase of the cardiac cycle?
isovolumetric contraction phase, ventricle starts contracting, no blood movement yet, atria enter diastole, all valves are closed (pressure in ventricles goes up)
What is happening in the 3b phase of the cardiac cycle?
ventricular ejection, AV closed, SL open, blood goes into arteries due to pressure gradient
What is happening during the fourth phase of the cardiac cycle?
Isovolumetric relaxation, ventricles enter diastole, all valves are closed, ESV reached
What is stroke volume and how can you calculate it?
the amount of blood that leaves the heart during ventricular ejection; SV=EDV-ESV
What is the wiggers diagram?
a big graph that allows us to track electrical events, mechanical events, and flow all in one place (three different y axis, time on x)
What is the order in which the valves open/close as shown on the wiggers pressure diagram?
AV close, SL open, SL close, AV open
What is cardiac output? (& how do you calculate it)
volume of blood that goes through the heart in a minute
CO=HR x SV
Why do more fit people have a higher stroke volume?
exercise builds cardiac muscle which allows more blood to get pumped out
What is cardiac reserve?
the difference in cardiac output between rest and maximum intensity
What are the three way to change cardiac reserve?
1) change stroke volume
2) increase efficiency
3) lower afterload
What is the Frank-Starling Law of the Heart?
the SV is dependent on EDV so as EDV increases, the contractions become more effeincient and when more blood is ejected the ESV goes down… together, a lower ESV and higher EDV lead to a higher SV
What is afterload?
pressure the ventricles have to overcome to expel blood
Why does a higher blood pressure lead to a higher resting heart rate?
when the arterial pressure goes up, the SL valves aren’t open for as long (refer to wiggers diagram) which leads to a decrease in SV so to keep the amount of blood ejected to your body the same, the HR goes up to compensate
