Exam 4: Chapter 14 Flashcards
what does the heart do?
generate pressure to push blood
what do the atria do?
receive blood from veins and push it to the ventricles
what do the ventricles do?
receive blood from the atria and push it to the arteries
are atria and ventricles ever contracted at the same time?
NO!
what do arteries do?
push blood AWAY from the heart
what do veins do?
push blood TO the heart
which is higher in O2, arteries or veins? what are the two exceptions?
arteries: HIGH O2 (except the pulmonary artery)
veins: LOW O2 (except the pulmonary vein)
what is the order of blood circulation of the heart? (start with right atria)
- right atria
- right ventricle
- pulmonary artery
- lungs
- pulmonary vein
- left atria
- left ventricle
- aorta
- systemic tissues
- inferior & superior vena cava
where does the coronary circulation branch off of? where does it go to?
branches off the aorta and goes to the right atria
-circulates blood in the heart
what is the pathway of the right coronary artery (RCA)?
- aorta
- RCA
- capillaries that go to right side of heart
- coronary veins
- coronary sinus
- right atria
what is the pathway of the left coronary artery (LCA)?
- aorta
- LCA
- LAD and circumflex branches
- capillaries that go to the left side of the heart
- coronary veins
- coronary sinus
- right atria
is coronary circulation high or low in O2?
high
what is the hepatic portal system?
connects blood supply of the digestive tract and liver
-does NOT go back to the heart
what are the three functions of the circulatory system?
-transport materials entering the body (O2, H2O, nutrients)
-transport materials from cell to cell (immune cells, hormones)
-transport materials leaving the body (waste, heat, CO2)
what is the pericardium?
membrane that encases pericardium fluid b/w the heart
what is the myocardium?
contractile cells of heart
-BULK of the heart
what are the two main categories of valves in the heart?
atrioventricular valves
semilunar valves
what are the two atrioventricular valves? where are they?
tricuspid (Right atrium -> Right Ventricle)
bicuspid (Left atrium -> Left Ventricle)
what are the two semilunar valves? where are they?
pulmonary valve (Right Ventricle -> Pulmonary Artery)
aortic valve (Left Ventricle -> Aorta)
what do the chordae tendineae and the papillary muscles do to ensure 1-way flow?
chordae attach to papillary in the AV valves
-prevent them from inverting
what are some features of cardiac muscles?
-small, uninucleate
-contain cell junctions called intercalated disks
-contain gap junctions
-large t-tubules
-less developed SR than skeletal muscle
what two things create flow?
pressure gradients
resistance
blood flows from areas of (high/low) pressure to areas of (high/low) pressure?
high -> low
what is hydrostatic pressure?
fluid not moving, force equal in all directions
as fluid moves, what happens to pressure over distance?
pressure decreases
-due to energy lost as friction
what is pressure gradient?
the pressure b/w each end
as pressure gradient increases, what happens to flow?
flow increases
as resistance increases, what happens to flow?
decreases
what three factors impact resistance?
length
viscosity
radius
what happens to resistance as length increases?
resistance increases
what happens to resistance as viscosity (thickness) increases?
resistance increases
what happens to resistance during vasodilation?
resistance decreases (radius increases)
what is velocity in relation to the blood?
how fast blood is moving in a period of time
-distance traveled
what two factors impact velocity?
flow rate
cross-sectional area
what happens to velocity as flow rate increases?
velocity increases
what happens to velocity as cross-sectional area increases?
velocity decreases
-narrower the vessel = faster the velocity
what is stroke volume?
volume of blood pumped by one ventricle during a contraction
(mL/beat)
what is the equation to determine stroke volume?
SV = EDV - ESV
(EDV is usually bigger)
EX: 135 - 65 = 70
what happens to the force of contraction as stroke volume increases?
force of contraction increases
(FRANK STARLING LAW)
what is ejection fraction? what is the equation for it?
the % fo EDV ejected with one contraction
EF = (SV / EDV) *100
should be above 50%
EX: (70/135) * 100 = 51.9%
what is cardiac output?
volume of blood pumped by one ventricle in a given period of time
what two factors impact cardiac output?
stroke volume
heart rate
what is the equation for cardiac output?
CO = SV * HR
should be around 5L/beat (5000mL/beat)
EX: 70*70 = 4900 mL/beat
what three factors impact EDV?
skeletal muscle pump
respiratory pump
sympathetic NS
how does the skeletal muscle pump impact EDV?
muscles contract which compresses the veins
-causes the blood to go back to the heart and increase EDV
how does the respiratory pump impact EDV?
pressure drops in thoracic cavity that creates a pressure gradient
-causes the blood to go back to the heart and increase EDV
how does the sympathetic NS impact EDV?
NE binds to alpha receptors to cause vasoconstriction
-causes the blood to go back to the heart and increase EDV
what two factors impact HR?
sympathetic NS
parasympathetic NS
how does the parasympathetic NS impact HR?
ACh binds muscarinic receptors
-causes K+ to exit, blocks Ca2+
-hyperpolarization = slower HR
how does the sympathetic NS impact HR?
NE binds beta1 receptors
-causes Na+ and Ca2+ to enter
-depolarization = faster HR
what do ionotropic agents do?
impacts force of contraction or contractibility
what do positive ionotropic agents do to force of contraction?
increase force of contraction
what do negative ionotropic agents do to force of contraction?
decrease force of contraction
how do Catecholamines (E & NE) cause increase in force of contraction?
- E & NE bind to beta1 receptors
- cAMP messenger system activated
3a. phosphorylates Ca2+ channels to increases Ca2+ release from ECF
3b. phosphorylates phospholambin to increase Ca2+ release from SR and increase Ca2+ removal to be used - overall makes the duration of contraction quicker
what are the steps of cardiac muscle contraction?
- AP travels through gap junctions of pacemaker cells
- AP causes depolarization along plasma MB of contractile cell
- AP goes to T-tubule
- voltage-gated Ca2+ channels open
- Ca2+ enters from ECF
- triggers RyR channels on SR to release more Ca2+
- Ca2+ bind troponin
- tropomyosin moves
- cross bridge froms
- contraction
what are the three steps of cardiac muscle relaxation?
- Ca2+ unbind troponin
- Ca2+ ATPase pumps Ca2+ back into SR
- NCX antiporter exchanges the Ca2+ for Na+ (Na+ IN, Ca2+ OUT)
what happens to force as sarcomere length increases?
force of contraction increases
what is preload?
stretching the heart must overcome to fill the heart with blood
-prior to contraction
what is afterload?
force needed to push blood out to the arteries
-needs EDV & arterial resistance
what is the RMP like in contractile cells?
-90mV
what happens in the depolarization phase in contractile cells?
RAPID
-Na+ channels open (large Na2+ entry)
what happens at the peak in contractile cells?
Na+ channels close
K+ channels open (K+ exits)
Ca2+ channels open (Ca2+ enters)
what happens at the plateau phase in contractile cells?
due to Ca2+, it creates an elongated absolute refractory period
-allows for no summation or twitch overlap
what happens at the repolarization phase in contractile cells?
Ca2+ channels close
K+ channels are still open
what is the RMP like in pacemaker cells?
unstable and never comes to rest
-around -60mV
what happens during the depolarization phase in pacemaker cells?
SLOW
-I(F) channels open = net Na+ entry
-some Ca2+ channels open
what happens during at threshold in pacemaker cells?
rapid Ca2+ entry (many channels open)
what happens at peak in pacemaker cells?
Ca2+ channels close
K+ channels open (K+ exits)
what happens during the repolarization phase in pacemaker cells?
K+ exits
what are some differences b/w skeletal muscle and cardiac muscle?
skeletal: somatic NS, cranial & spinal input, Ca2+ from ECF
cardiac: autonomic NS, no NS input, Ca2+ from ECF & SR
action potentials in ____ cells sends it’s depolarizations thru gap junctions to ____ cells to coordinate contraction
pacemaker cells -> contractile cells
what is the electrical conduction pathway of the heart?
- SA node
- AV node (creates the AV delay, allows for completion of atrial contraction)
- AV bundle
- bundle branches
- purkinje fibers (wrap around base of ventricles)
the electrical conduction pathway contracts ventricles ___ to ___
bottom (apex) –> top (base)
what does the P-wave represent on an ECG?
atrial depolarization
-getting ready to contract
-SA node fires and goes to contractile cells
what does the PR segment represent?
atrial contraction
-goes through AV node and AV bundle
-AV delay!!
what does the QRS complex represent?
ventricle depolarization
-getting ready to contract
what does the T wave represent?
ventricular repolarization
-ventricles are getting ready to relax
what does the ST segment represent?
ventricle contraction
what does the TP segment represent?
electrically quiet
-neither are contracting
what does the RR segment represent?
one complete heartbeat
what does the QT interval represent?
ventricular depolarization and repolarization
what does the PR interval represent?
atrial depolarization and the start of repolarization
what is a normal HR?
60-100 bpm
what is it called when HR is above 100?
tachycardia
what is it called when HR is below 60?
bradycardia
systole
contraction
diastole
relaxation
what are the five step of the cardiac cycle?
- active filling
- isovolumic ventricular contraction
- ventricular ejection
- isovolumic ventricular relaxation
- passive filling (late ventricular diastole)
what occurs during active filling? (diastole or systole, AV valves, semilunar valves, volume, pressure)
atria contract
ventricle relax
AV valves open
semilunar closed
ventricular volume increasing
pressure stays the same
EDV measurement!!
what occurs during isovolumic ventricle contraction? (diastole or systole, AV valves, semilunar valves, volume, pressure)
atria relax
ventricle contract
all valves closed (LUB)
volume stays the same
pressure increases
what occurs during ventricular ejection? (diastole or systole, AV valves, semilunar valves, volume, pressure)
atria relax
ventricle contract
AV valves closed
semilunar open
volume decreases
pressure is starting to decrease
ESV measurement
what occurs during isovolumic ventricular relaxation? (diastole or systole, AV valves, semilunar valves, volume, pressure)
atria relax
ventricle relax
all valves closed (DUB)
volume stays the same
pressure decreases
what occurs during passive filling / late ventricular diastole?
atria relax
ventricle relax
AV valves open
semilunar valves closed
volume increases
pressure is the same
where on the ECG represents active filing?
right after the P-wave
where on the ECG represents isovolumic ventricular contraction?
right after QRS complex
where on the ECG represents ventricular ejection?
T-wave
where on the ECG represents isovolumic ventricular relaxation?
right after the T-wave
where on the ECG represents passive filling?
right before the P-wave
