Chapter 18 - The Heart Flashcards
the cardiovascular system is made up of
the heart and blood vessels
what makes up the circulatory system
the heart, blood vessels, and blood
what are the two divisions of the circulatory system
pulmonary circuit and systemic circuit
pulmonary circuit
brings blood to the lungs to be oxygenated
the pulmonary circuit pumps blood from which side of the heart
right
arteries
move blood away from the heart
what gases are exchanged in the lungs through the pulmonary system
CO2 out, O2 in
way of deoxygenated blood and oxygenated blood in the pulmonary system
deoxygenated blood is pumped by the right side of the heart into the lungs, oxygenated blood arrive on the left side of the heart
systemic circuit
delivers oxygenated blood to the body via systemic arteries
the systemic circuit pumps blood from which side of the heart
left
way of oxygenated and deoxygenated blood in the systemic circuit
oxygenated blood is pumped by the left side of the heart through the body, then deoxygenated blood returns to the right side of the heart
atria
veins that receive blood returning to the heart from the body
location of atria
two superior chambers of the heart
the right atrium receives blood from circulation, the left atrium receives blood from circulation
right atrium receives blood from systemic circulation, left atrium receives blood from pulmonary circulation
ventricles
pump blood into arteries
ventricles are located
in the two inferior chambers of the heart
the right ventricle pumps blood into , the left ventricle pumps blood into
the right ventricle pumps blood into the pulmonary artery, the left ventricle pumps blood into the aorta
flow of blood through the right side of the heart
- Deoxygenated blood arrives at the right atrium via systemic veins
- Right Atrium pumps blood to the right ventricle
- Right Ventricle pumps blood to pulmonary artery then the lungs and body
two main systemic veins
superior and inferior cava
flow of blood through the left side of the heart
- oxygenated blood arrives at the left atrium via pulmonary arteries
- Left atrium pumps blood to the left ventricle
- Left ventricle pumps blood into the aorta and systemic circulation of the body
function of heart valves
ensure the one way flow of blood
when do heart valves open
due to the pressure gradient created by heart beats
Atrioventricular Valves ensure blood flow from to .
from the atria to the ventricles
right AV valve is also called
tricuspid valve
left AV valve is also called
bicuspid or mitral valve
why do AV valves stay closed
to prevent backflow when ventricles contract
chordae tendineae
attach AV valves to floor of ventricles, attach to papillary muscles
blood flow
vein to atrium to ventricle to artery
semilunar valves are between
ventricles and great arteries
pulmonary semilunar valves are between
right ventricle and pulmonary artery
aortic semilunar valve is between
left ventricle and aorta
semilunar valves only open upon
ventricular contraction
cardiac cycle
one complete cycle of contraction and relaxation of all four heart chambers
the heartbeat lasts approximately
1 second
systole
cardiac contraction
diastole
cardiac relaxation
general reference to systole/diastole of the heart means
the ventricles
which chambers drive the cardiac cycle
ventricles
in ventricular diastole, blood flows from
atria to ventricles
AV valves close when
blood pressure in ventricles push them close
the first heart sound occurs
when AV valves close
in Ventricular systole, blood flows
into arteries
in ventricular diastole, pressure increases/decreases
decreases
in ventricular systole, pressure increases/decreases
increases
Semilunar valves are pushed open when
ventricles contract
semilunar valves close when
the blood pressure in arteries push them closed
the second heart sound occurs
when the blood pressure in arteries push semilunar valves closed
what sound does S1 make
lub
what sound does S2 make
dub
the third heart sound occurs
when the mitral valve opens and blood hits the wall of the left ventricle
what sound does S3 make
ta
the third heart sound is only heard
in people under 30
what phases of the cardiac cycle occur in ventricular diastole
ventricular filling and isovolumetric relaxation
what phases of the cardiac cycle occur in ventricular systole
ventricular ejection and isovolumetric contraction
three phases of ventricular filling
rapid ventricular filling, diastasis, atrial systole
end-diastolic volume
volume of blood in each ventricle at the end of atrial systole
end-diastolic volume amount
130 mL
in what phase of the cardiac cycle does the atria first relax
isovolumetric contraction
in what phases of the cardiac cycle does ventricles depolarize
isovolumetric contraction
why do ventricles not yet eject blood in isovolumetric contraction
blood pressure in arteries is too high to open the Semilunar valves
in what phase of cardiac contraction does the ventricles fully contract
ventricular ejection
in what phase of the cardiac cycle do semilunar valves open
ventricular ejection
ventricular ejection phases
rapid ejection and reduced ejection
end systemic volume
amount of blood left after ventricular ejection
what is stroke volume
the amount of blood ejected from the ventricles
how is end-systolic volume calculated
EDV-SV
end systolic volume releases how much blood?
60 mL
which phase of the cardiac cycle is the longest
ventricular ejection
in which phase of the cardiac cycle do ventricles begin to expand
isovolumetric relaxation
in what phase of the cardiac cycle do semilunar valves close
isovolumetric relaxation
ventricles receive the same/a different amount of blood
the same
cardiomyocytes
cardiac muscle cells
characteristics of cardiomyocytes
short cells, involuntary, striated, single nuclei, branched, fibrosis repair, joined by intercalated discs
striation
regular arrangement of thick and thin filaments
interdigitating folds
folds interlocking with the folds of adjoining intercalated discs
interdigitating folds allow for
increased contact surface area between cardiomyocytes
types of junctions between cardiomyocytes
desmosomes and gap junctions
desmosomes in cardiac muscle
prevent cardiomyocytes from pulling apart
gap junctions in cardiomyocytes
assist in depolarization of ventricles and simultaneous contraction of entire myocardium
cardiac muscle uses what type of metabolism
aerobic respiration
why is aerobic respiration used in cardiac muscle
high myoglobin, glycogen, and mitochondria content
cardiac conduction system
coordinates the heartbeat pathways that travel through the myocardium
steps of cardiac conduction
SA node, Atria, AV node, AV bundle, subendocardial conduction network
the internal pacemaker is the
SA node
location of the SA node
right atrium, near superior vena cava
the right side of the heart receives blood from the circuit and sends blood to the circuit
systemic, pulmonary
the left side of the heart receives blood from the circuit and sends blood to the circuit
pulmonary, systemic
electrical signals are prevented from reaching ventricles from the atria because of
a fibrous skeleton
the electrical gateway to the ventricles is the
AV node
the AV node is located within
the interatrial septum
the AV bundle is also called
bundle of His
the AV bundle branches or is one
branches
subendocardial conduction network
nerve-like projections from the apex into the ventricles
cardiomyocytes pass electrical signals through
gap junctions
in which phase of the cardiac conduction system does the ventricles contract
subendocardial conducting network
cardiac rhythm
rate at which heart beats
sinus rhythm
normal HR triggered by SA node
sinus rhythm fires every
0.8 sec
sinus rhythm heart rate
70-80 bpm
sinus rhythm functions best when under the influence of
the vagus nerve
ectopic focus
region of spontaneous firing other than the SA node
nodal rhythm
heart rate generated by AV node
nodal rhythm heat rate
40-50 bpm
pacemaker potential
gradual depolarization of SA node
RMP of pacemaker potential
-60 mV
SA node Action potential steps
threshold voltage reached, voltage gated Ca and Na channels open, depolarization, repolarization
threshold voltage of SA node action potential
-40 mV
depolarization voltage of SA node AP
0 mV
cardiomyocytes RMP
-90 mV
cardiomyocytes AP start with
SA node stimulation
phases of AP in cardiomyocyte
depolarization, plateau phase, repolarization
cardiomyocyte depolarization voltage
30 mV
Plateau Phase
contraction sustained in cardiomyocyte by expelling blood from chamber
longest phase of cardiomyocyte AP
plateau phase
purpose of the absolute refractory period for cardiomyocytes
allows for complete contraction and relaxation
heart rate
number of heart beats per minute
cardiac output
volume of blood ejected by one ventricle per minute
cardiac output formula
HR x SV
stroke volume
amount of blood pumped by ventricle with each heartbeat
cardiac reserve
difference between max and resting Cardiac Output
tachycardia
fast HR
tachycardia bpm
over 100 bpm
bradycardia
slow HR
bradycardia bpm
under 60 bpm
chronotropic agent
factor that changes HR
positive chronotropic
raises HR
negative chronotropic
lowers HR
preload
amount of tension in ventricular myocardium just before contraction
more ventricular stretch causes more which cause more
tension, contraction
preload increases/decreases SV
increases
frank starling law
SV is proportional to end-diastolic volume
contractility
how hard the myocardium contract for a preload
contractility increases/decreases SV
increases
inotropic agents
factors of contractility
positive inotropic agents
increased contractility by increased Ca
negative inotropic agents
decreased contractility by decrease Ca
afterload
sum of all forces opposing ejection of blood from ventricle
afterload increases/decreases SV
decreases
main cause of afterload
high BP in arteries
