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Cardiac - Week 4
Terms in this set (113)
circulation that supplies blood to all the body except to the lungs
oxygenated blood leaves left heart and go to systemic circulation to deliver oxygen to tissues and take up carbon dioxide (at tissue capillary bed)
flow of blood from the heart to the lungs and back to the heart
deoxygenated blood returns to right heart/pulmonary circulation to take up oxygen and drop off carbon dioxide (at pulmonary capillaries)
contraction phase of the heartbeat
relaxation phase of the heartbeat
The volume of blood ejected from the left side of the heart in one minute.
heart rate x stroke volume
cranial vena cava
a large vein carrying blood from the head, neck and forelimbs, to the right atrium
caudal vena cava
large blood vessel that carries blood back to the heart from the lower extremities and abdominal region
Receives deoxygenated blood from the body
tricuspid (right AV) valve
valve between the right atrium and the right ventricle
pumps deoxygenated blood to the lungs
valve positioned between the right ventricle and the pulmonary artery
pulmonary artery/pulmonary trunk
carries blood from right ventricle to pulmonary arteries
carries oxygenated blood from the lungs to the heart
receives oxygenated blood from the lungs
valve between the left atrium and the left ventricle; bicuspid valve
pumps oxygenated blood to the body
The semilunar valve separating the aorta from the left ventricle that prevents blood from flowing back into the left ventricle.
Physiological purpose of cardiovascular system
it is a muscular pump connected to a vascular circuit
it is a closed system that provides blood flow through all capillary beds of the body
Circulations allows the distribution of what blood components
RBCs, WBCs, platelets, coagulation factors, electrolytes, chemical messengers, fuel (glucose, O2) and waste (CO2) removal.
A horse being exercised with clearly defined superficial veins needs what?
muscular activity creates a lot of heat, and muscles need more energy and need to remove more waste
the body needs regulate blood flow to areas of need in order to deliver O2 and remove CO2, it also needs blood flow to regulate temperature, and preserve blood flow to essential organs like the brain and heart
A dog that has been injured and lost a lot of blood needs what?
delivery of products like platelets to stop bleeding, also needs regulated blood flow like vasoconstriction of reduce flow to site of injury and increase flow to essential organs
deliver blood from heart to tissues
where exchange occurs
return blood to heart
central pump that moves blood forward
What is it called when ventricles are filling?
What is it called when the ventricles are pumping?
Does systole of the atria and ventricles occur at the same time or sequentially?
What are the 4 heart valves?
2 atrioventricular valves
2 semilunar valves
The semilunar valves separate ventricles from ___________-
The atrioventricular valves separate ventricles from ___________
Atrioventricular valves are open for ventricular filling during ___________
The semilunar valves are open for ventricular pumping during ___________
Opening and closing of the valves is driven by what?
Which valves are open during diastole?
tricuspid and mitral
Which valves are closed during diastole?
aortic and pulmonic
Which valves are open during systole?
aortic and pulmonic
Which valves are closed during systole?
tricuspid and mitral
How can an unattached heart still beat?
because of the sinoatrial node and electrical activity involved there
How does the sinus node work
it spontaneously depolarizes which sets heart rate, which is variable
heart does not require conscious control
What are the 2 kinds of muscle cells that make up the spontaneous central muscular pump?
specialized cardiac myocytes and working cardiac myocytes
specialized cardiac myocytes of the cardiac conduction system
sinus node- spontaneous depolarization = excitation
conduction system controls spread of depolarization through the heart, which initiates contraction
working cardiac muscle myocytes
responsible for muscle contraction and pumping of blood
make up most of the atria and ventricles
Specialized conduction system pathway
sinus node depolarization initiates cardiac cycle, atrial depolarization and contraction enhances ventricular filling, AV node (delay) a pause between atrial depolarization and ventricular depolarization to optimize ventricular filling before ventricular pumping starts, ventricular depolarization and contraction results in ventricular pumping
coordinated contraction and relaxation of cardiac chambers results in .....
forward blood flow with each heart beat
What system helps coordinate the series of events that result in forward blood flow?
Circulatory system as two systems in series
right heart/pulmonary circulation and left heart/systemic circulation
Right heart pumps to the _______ circulation
Left heart pumps to the _________ circulation
Example of the importance of two circulations in series
when forward flow is interrupted it may result in congestion (back up of blood in circulation)
if right side has problem and valve is leaking back, it can cause problem pumping into lungs, reducing amount of oxygenated blood getting into tissues
congestion of blood can lead to congestive heart failure
Do right and left ventricles contract at the same time or sequentially?
ventricular pressures during systole
right - 15-30
left - 100-140
ventricular pressures during diastole
right - 2-8
left - 3-12
What is the flow in the heart driven by?
right - 2-8
vessel pressures during systole
pulmonary artery - 15-30
aorta - 100-140
vessel pressures during diastole
pulmonary artery - 4-12
aorta - 40-90
Pressure differences in ventricles during systole and diastole
during diastole the ventricular pressures are similar, but during systole there's a big pressure difference (almost 100 Hg difference)
Which ventricle is thicker and why
left because it needs to pump to more of the body
Which system is higher pressure, systemic or pulmonic?
Systemic arteries are ___________ pressure, systemic veins are ____________ pressure.
List the vessels in order from highest to lowest pressures
systemic arteries, pulmonic veins, pulmonic arteries, systemic veins
What causes the valves of the heart to open and close?
pressure goes up in ventricles and exceeds ventricle next to it
pressure difference across those valves is what opens and closes them
Pressure in ________ has to be higher than ________ to keep valves closed
What opens the semilunar valves
ventricles contracting (systole) and creating more pressure than the great vessel pressure
What closes the AV valves
when ventricle pressure from contraction (systole) exceeds atrial pressure
What closes the semilunar valves
diastolic great vessel pressure exceeds diastolic ventricular pressure
stops blood flow from heart into circulation
What opens AV valves
(diastole) atrial pressure exceeds ventricular diastolic pressure
What is a major resistant point within the system
arterioles, they have a big pressure drop
CO = ∆P/SVR
Q = (P1-P2)/R
Q= flow = cardiac output (mL/min) = CO
(P1-P2) = ∆P = change in pressure
R = resistance = systemic vascular resistance = SVR = Peripheral vascular resistance = PV
How can you have uninterrupted blood flow with an intermittent pump?
because of the elastic recoil of aorta and vascular tone
Sensors of the CV system
baroreceptors sense blood pressure
chemoreceptors sense tissue needs
Effectors of CV system
sympathetic nervous system
parasympathetic nervous system
local and humoral modulators - modulate heart rate, cardiac muscle contraction, blood flow, vascular resistance, and blood pressure
What is the CV system driven by?
muscular pump connected to a vascular circuit (closed system)
Circulatory system is two circulations in ______
There is a ____________ flow through the heart and circulatory system
Flow through the system is ___________ driven with _____________ vascular flow
CV system is __________ and precisely controlled
Components of the cardiac conduction system
The wave of depolarization through the conduction system helps coordinate what?
action of the working cardiomyocyte cells
What does the impulse move fast through
SA node is made of
What does SA node allow for
spontaneous depolarization and sinus node depolarization sets heart rate which is variable
group of cells in the right atrium where the electrical signal is generated that establishes the heartbeat
Interconnect the SA Node with the AV Node, conducts impulses through to the atrial working cells.
relays electrical impulses from atria into ventricles
End of the conduction system; sends impulses through the ventricles, causing them to contract
What is the cardiac conduction system coupled to and why?
the working myocytes to support muscular pumping
The unique action potential of the sinus node allows for what?
How does spontaneous depolarization occur?
movement of positive ions into specialized myocyte
How does the cardiac conduction system coordinate muscular contraction?
SA node sets the heart rate
AV node allows for sequential atrial then ventricular contraction
internodal pathways/purkinje fibers cause rapid spread of depolarization for near simultaneous contraction of the chamber
Structural features of specialized cardiomyocytes
almost no contractile filaments
increased gap junctions for transmission of impulse except for AV node which has reduced gap junctions to slow transmission of impulse
What are gap junctions responsible for?
impulse from on cell to the next
What does the number of gap junctions dictate?
how fast impulse will move from one to another
Internodal and purkinje fibers are ____________, and the AV node is __________
Different action potentials of cardiac conduction system
SA node has spontaneous depolarization and changes value
Ventricular working myocytes stay the same, has -85 true resting membrane potential ; they plateau
Which comes first in the heart, electrical or mechanical activity?
electrical, starts at SA node
Sequential depolarization and contraction of atria and ventricles, pathway
1. sinus node depolarizes, slow response AP
2. internodal pathway/atrial depolarization/contraction
3. AV node depolarize, slow response AP
4. Purkinje/ventricular depolarization/contraction, fast response AP
What does an ECG represent?
the electrical activity that follows the contract-relax events of the myocardium (not mechanical)
stop at AV node
can be pointed up or down
PQ (or PR) wave
interval between start of p-wave and start of q-wave
atrial and AV node depolarization
What is the reason for a long gap after a T-wave
sinus node didn't fire, there was no atrial depolarization
______ time is longer than _________ time in a patient at a normal heart rate
when atria contract
when ventricles contract
What happens during a heart murmur
it is created by turbulent blood flow
it fills the space between heart sounds and can occur in through systole, through diastole, or both
How does the cardiac cycle relate to heart rate?
cardiac cycle duration (sec/beat) = 60 sec/min / heart rate (beats/min)
How long does it take for 1 systole + 1 diastole
longer cardiac cycle =
Where would you place a catheter to measure heart pressure?
on the right, you have to pass catheter into super vena cava to right atrium and through tricuspid valve to right atrium
on left, you have to cathetarize through aorta; access via carotid/femoral/etc
PPT 4 slide 9
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