Cardiac System Flashcards
characteristics of cardiac muscle
smaller than skeletal muscle
one nucleus per cell fiber
higher mitochondrial density
fewer t tubules
intercalated disks
join adjacent cardiac muscle cells
gap junction
transmits action potentials to cells
functional syncytium
all cells work together
calcium induced calcium release
excitation induced entry of a small amount of Ca2+ through voltage gated cell membrane where Ca2+ channels trigger the opening of Ca2+ release channels in the sarcoplasmic reticulum, inducing a larger release of Ca2+
what do the right and left atriums do?
collect blood
what do the right and left ventricles do?
pump blood
process of blood flow in the heart
superior/inferior vena cava
right atrium
tricuspid valve
right ventricle
pulmonary valve
pulmonary artery
lungs
pulmonary vein
left atrium
bicupsid valve
left ventricle
aortic valve
aorta
rest of body
why is the left side of the heat bigger?
it pumps blood to the rest of the body
atrial septal defect
hole in the septum
mixing of oxygenated and deoxygenated blood
can cause hypoxia due to hypoxemia
ventricular septal defect
hole in he ventricular area
mixing oxygenated and deoxygenated blood
can cause hypoxia due to hypoxemia
transportation of the great vessels
pulmonary artery attached to left ventricle and aorta is attached to the right ventricle or transposed
stenotic
valve doesn’t open all the way (pooling)
prolapse
valve doesn’t close all the way (regurgitating)
mitrovalve prolapse
valve doesnt close all the way and blood regurgitates back to the left atrium
pathway of the conduction system
SA node
AD node and bundle of His
send action potential to ventricles
R+L bundle branches
purkinjie fibers
systole
the period of contraction and emptying
diastole
the period of relaxation and filling during the cardiac cycle
isovolumic contraction period
same volume, increase pressure because contracting, blood can’t enter because valve closed
rapid ejection period
blood leaves ventricle rapidly because aortic valve opens and decrease ventricular volume
slow ejection period
blood exiting but at a slower rate, less step slop in ventricular volume
ejection fraction
determine is strong or weak heart, proportion of blood that is pumped out
stroke volume
the amount of blood pumped out of each ventricle withe ach contraction
endistolic volume
volume of blood at the end of diastole, max amount of blood
ensystolic volume
least amount of blood in ventricle
cardiac output
HR x SV
isovolumetric relaxation period
same volume, aortic valve closes, av valve open
slow filling period
ventricles fill with blood
endothelium
thin, inner layer of epithelial tissue that lines the entire circulatory system
myocardium
middle layer, cardiac muscle and bulk of the heart wall
epicardium
thin, external layer that covers the heart
funny channel
opens to allow Na+ to enter (usually Na+ leaves)
goes toward threshold
t-type channel
transient and allows Ca2+ to enter
L-type channel
Ca2+ enters
K+ channels
K+ exits because positive charges inside and like charges repel
Frank-Starling Law of the Hert
the heart normally pumps out during systole the volume of blood returned during diastole; increased venous return results in increased SV
EDV increases SV because stronger contraction with more optimal length
inotropic
heart contracts with greater force (positive ionotropic), contracting with less force (negative inotropic)
chronotropic
how fast the heart is beating
increase HR (positive) and decrease HR (negative)
how to increase cardiac output
- optimal length tension relationship
- more Ca2+ leaves SR
- more Ca2+ affinity
sympathetic nervous system effect
increases the rate of depolarization to threshold
increases the heart rate
increases contractility and strengthens contraction
promotes the secretion of epinephrine, a hormone that augments sympathetic nervous system actions
parasympathetic nervous system effects
decreases the rate of deplorization to the threshold
decreases heart rate
decreases contractibility and weakens contraction
sympathetic nervous system pathway
sympathetic neurotransmitter norepinephrine binds with a beta-adrenergic receptor is coupled to a stimulatory G protein that accelerates the CAMP pathway in the target cells
parasympathetic nervous system pathway
acetylcholine released from the vagus nerve binds to a muscarinic cholinergic receptor and is coupled to an inhibitory G protein that reduces activity of the CAMP pathway
blood pressure
how much pressure is exerted against the wall of the blood vessels
K+ permeability
hyperpolarizes SA node
resting potential starts farther away from the threshold
SA node reaches threshold and fires less frequently, decreasing the heart rate
beta blocker
decreases blood pressure and lower heart rate
diuretic drug
decreases blood pressure and decreases blood volume and decreases stroke volume
Speed of cardiac excitation rules
- atrial excitation and contraction should be complete before the onset of ventricular contraction
- excitation of cardiac muscle fibers should be coordinated to ensure that each chamber contracts as a unit to pump efficiently
- the pair of atria and pair of ventricles should be functionally coordinated so that both members of the pair contract simultanously
interatrial pathway
extends from SA node within right atrium to left atrium
both atria become depolarized to contract simultanously
internodal pathway
extends from SA node to AV node
action potential must pass through AV node to go to ventricle
pressure volume loop steps
- av valve opens
- passive ventricular filling occurs and volume increases considerably and pressure increases slightly as blood enters
- atrial contraction completes ventricular filling. end diastolic volume is reached at end of this phase
- av valve closes
- isovolumetric ventricular contraction occurs. volume remains constant, pressure increases remarkably
- aortic valve opens
- stroke volume of blood is ejected. as blood leaves, volume decreases considerably as pressure peaks, then falls more slowly until end-systolic volume is reached at the end of this phase
- aortic valve closes
- isovolumetric ventricular relaxation occurs. volume remains constant, pressure falls sharply
sympathetic nervous system
improve effectiveness by increasing HR, decreasing the delay between atrial and ventricular contraction, decreasing conduction time throughout the heart, indicating the force of contraction, and speeding up the relaxation process, so more time is available for filling
parasympathetic nervous system
decreases heart rate as ach slows HR by increasing K+ permeability of peace maker in SA node by binding with muscularine cholinergic receptors that are coupled directly to ach regulated K+ channels by a G protein that opens K+ channels
