heart chapter 20 Flashcards
how many layers are there in the heart wall and what are they
3
epicardium- outer layer/visceral layer
myocardium- thick, middle, muscular layer
endocardium- lines the heart chambers
how many layers does that serous percardium have and what are they
2
parietal layer - outer layer
visceral later- inner wall aka epicardium
what are the vessels of the coronary circulation?
LCA + RCA ( and the 2 major branches they divide)
great cardiac vein and middle cardiac vein
LCA (Left coronary artery) divides 2 major branches ___
a. anterior interventricular artery
b. circumflex artery
RCA (right coronary artery) divides 2 major branches ___
a. right marginal artery
b. posterior interventricular artery
where do cardiac veins join at?
coronary sinus
where does the coronary sinus empty blood into?
right atrium
what are the 2 cardiac veins of the coronary circulation?
great cardiac vein (anterior)
middle cardiac vein (Posterior interventricular)
what does the coronary circulation help the heart meet?
metabolic demands and 5 % of circulating blood flows through this
how many valves does the heart have and name them
4 valves
1. tricuspid
2. bicuspid/mitral
3. pulmonary valve
4. aortic valve
what is the valve between atrium and ventricle?
AV
(atrioventricular valve)
what are the valved between the exit of each ventricle
semilunar valves
what are the 2 semilunar valves and where are they
- pulmonary valve right ventricle to pulmonary trunk
- aortic valve
left ventricle to aorta
what are the 2 AV valves
- right AV which was 3 cusps (tricuspid)
- Left AV which has 2 cusps (bicuspid/mitral)
what are cardiocytes and how are they connected to eachother
cardiac muscle cells which are connected by intercalated discs
- autorhythmic
- has 1 central nucleus
what are intercalated discs composed of
interdigitating folds, mechanical junctions, electrical junctions
describe skeletal muscle contraction + its refractory period
action potential in muscle is brief and ends as a contraction (twitch)
twitch contraction is short
refractory period ends before peak tension develops
twitches summate and tetanus occurs
describe cardiac muscle contraction + its refractory period
action potential is prolonged and period of active muscle cells contraction is extended.
refractory period continues until relaxation is well under way so summation does not occur nor do tetanic contractions
what happens if heart is in tetany?
it could not pump blood
what is the cardiac cycle?
period between the start of 1 heartbeat and beginning of the next
systole (systolic)
chamber contraction
- higher #
diastole (diastolic)
chamber relaxation
- lower #
what are the 2 phases the cardiac cycle can be divided into in each chamber of the heart?
systole and diastole
describe the cardiac cycle SIMPLIFIED
heart beat (contraction) followed by relaxtion
basically atria contracts then ventricles contract then relaxation occurs again
cardiac cycle IN DETAIL
when cardiac cycle begings all 4 chambers are relaxed then ventricles are partially filled with blood
- atrial systole - atria contracts ; completely filling relaxed ventricles with blood then atrial systole ends
- atrial diastole begins + continues until the start of next cardiac cycle
what are the two phases inbetween the end of atrial systoles and beginning of ventricular systole?
- ventricular systole 1st phase - isovolumetric contraction
- ventricular systole 2nd phase is ventricular ejection
describe isovolumetric contraction
ventricular contraction pushes AV valves closed but not enough pressure is created to open semilunar valves (not open yet)
describe ventricular ejection
this is when the semilunar valves are open ( ventricular pressure rose and exceeded pressure in the arteries) and blood is ejected out of ventricle then ventricular distole begins until next cardiac cycle
heart rate (HR)
of beats/min
what is the normal range of a HR
60 - 100 bpm
tachycardia
resting HR above 100bpm
bradycardia
resting HR below 60bpm
cardiac output (CO)
amount of blood pumped by left ventricle in 1 min
- evaluates peripheral blood flow / effciency
- determined by stroke volume and heart rate
stroke volume
amount of blood pumped out of left ventricle in 1 heart beat
Heart rate (HR) x Stroke volume (SV) = ____
cardiac output (CO)
EDV (end diastolic volume)
amount of blood that fills ventricles after relaxing / filling phase
ESV (end systolic volume)
amount of blood left over in a ventricle after ventricles contract
preload
amount of myocardial stretching at end of diastolic volume (EDV)
afterload
contractile tension ventricles must produce to open semilunar valves
filling time
duration of ventricular diastole
what two factors influencing stroke volume?
EDV and ESV
at normal venous return, increase HR results in increase or decrease EDV?
decreased EDV and filling time is decreased (ventricular diastole)
low HR results in high EDV meaning
more time to fill ventricles with blood
greater the EDV larger the ____ and greater the_____
larger preload and greater stroke volume
greater the afterload, longer the period of ____
isovolumetric contraction
increase isovolumetric contraction leads to shorter period of _____ and larger ____
shorter period of ventricular ejection and larger ESV = low SV
do you want afterload to be high or low? and why
low because then there is shorter period of isovolumetric contraction so then theres not a lot of pressure being built up to eject blood later
what is the sequence of the cardiac conduction system.
- SA node / sinoatrial -pacemaker that determines rate
- AV node- electrical gateway to ventricles
- AV bundle (of HIS)- connects the atria and ventricles
- Bundle branches- impulses thru IV septum
- purkinje fibers - depolarize ventricle cells
detail cardiac conduction system
- heart beat starts with action potential started from SA node (cardiac pacemaker)
- AV node then generates impulses / stimulus to the
3.AV bundle which is the only electrically connected thing between atria and ventricles
- av bundle leads to R/L bundle branches.
- purkinje fiber depolarize ventricular myocardial cells that trigger ventricular systole.
parasympathetic neurons release ACh, ACh stands for
acetylcholine
when parasympathetic neurons release ACh, does HR slow down or speed up
HR decreases
ACh słóws rate of spontaneous depolarization
NE is released from sympathetic neurons, what is the sympathetic system
fight or flight
parasympathetic is relaxation
does NE increase or decrease rate of depolrization? and what does it do to heart rate and repolarization?
NA increases rate of depolarization
- shortens repolarization
- increase HR
ECG (electrocardiogram) is used to
measure hearts electrical activity
p wave
SA node signal spreading to atria and depolarizing them
QRS complex
signal from AV node spreading through ventricles and depolarizing them
T wave
ventricular repolarization immediately before diastole
atrial repolarization is obscured/ hidden by what
the QRS complex
describe the fetal blood flow in detail… this allows blodo to bypass lungs
- deoxygenated blood flows from fetus to placenta via umbilical arteries
2.oxygenated blood flows from placenta to fetus via umbilical vein which then
- drains into ductus venosus of liver which then empties blood from the umbilical vein and live into IVC
- forman ovale lets most blood pass from right atrium to left atrium then to the aorta
- blood flows from right ventricle to pulmonary trunk then through ductus arteriosus to aorta
prior to birth, lungs are collapsed, that means blood bypasses what circuit?
pulmonary circuit
umbilical arteries are branches of the
internal iliac arteries of the fetus
(fetal blood flow) deoxygenated blood flows from fetus to placenta via
umbilical arteries
(fetal blood flow) oxygenated blood flows from placenta to fetus via
umbilical vein
(fetal blood flow) umbilical vein drains into the ____ of the liver
ductus venous
(fetal blood flow) ductus venous empties blood from umbilical veing and liver veins into ___
IVC
(fetal blood flow) foramenn ovale lets most blood pass from ___ atrium to ____ atrium
right atrium to left atrium then to aorta
(fetal blood flow) blood flows from R ventricle to pulmonary trunk then through ______ to aorta
the through ductus arteriosus to the aorta
fetal blood flow changes at birth
1st breath at birth make lungs inflate then the blood rushes to pulmonary vessels then the foramen ovale closes with pressure change then theres an increase of O2 levels making ductus arteriosus to close
ventricular septal defect
opening in septum separating left and right ventricles
- wall isnt fully closed
- allowing for deoxygenated and oxygenated blood to mix
patent foramen ovale
foramen ovale is not closed
- blood recirculates through pulmonary circut
- blood doesnt enter left ventricle
- left to right shunt
patent ductus arteriosus
blood is forced into systemic circuit through ductus arteriosus
- right to left shunt
- ductus not closed
atrioventricular septal defect
atria and ventricles are incompletely separated
transposition of great vessels
aorta connected to right vent.
pulmonary artery is connected to left vent.
tetralogy of fallout
circulatory defects
1. pulmanory trunk is narrow
- IVS is incomplete
- large right vent. and thicken ventricles
hearts 2 upper chambers are called
R/L atria
hearts 2 lower chambers are called
R/L ventricles
what do the atrias do
receive blood returning to heart
- thin wall
what do the ventricles do
eject blood into arties for circulation
BUT the left vent. pumps blood to ENTIRE body
which ventricle is thicker
left vent.
what are the 2 major division of the cardiovascular system
- pulmonary circuit
- systemic circuit
pulmonary circuit
supplied by right half of heart
carries oxygen POOR blood to lungs
returns oxygenated blood to heart
systemic circuit
supplied by left half of heart
supplies oxygenated blood to all body tissues
returns oxygen poor blood to heart
flow of blood in heart in detail (adults)
- blood enters RA from superior and inferior venae cavae
- blood then flows thru right AV valve into right vent.
- pulmonary valve opens from right vent. contraction making blood go through it
- blood enter pulmonary trunk and is distributed by R/L pulmonary arteries to the lungs where it loads O2 and unloads CO2
- blood returns to lungs by pulmonary veins to left atrium and flows through left AV valve into left vent.
- contraction of left ventricle forces aortic valve open and blood goes thru here into aorta
- aorta sends blood all over, unloading O2 and loading CO2
how does blood return back to the heart?
via venae cavae
