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cardiovascular system composed of
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subdivisions of cardiovascular system (3)
- systemic circulation
- pulmonary circulation
- lymphatic circulation
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components of conduction pathway
- sinoatrial node (SA)
- atrioventricular node (AV)
- bundle of his
- bundle branches
- purkinjie fibers
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fast response action potentials (3)
- cardiac muscle
- purkinje fibers
- bundle branches
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slow response action potentials (2)
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slow action potentials are associated with
automaticity
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T/F slow action potentials never rest
true
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SA node is affected, the sympathetic nerve activites are
increased rate of diastolic depolarization
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when the AV node is affected, the sympathetic nerve activites are
increased conduction rate
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when the artial muscle is affected, what is the sympathetic nerve activites
increased strength of contraction
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an increase in HR under sympathetic activity causes a release of
norepinephrine
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an increase in HR under parasympathetic activity causes a release of
acetylcholine
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when ACH binds to its receptors what 2 things happen?
increases K+ permeability and decreases Ca+ permeability
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what is the oxygen level of the cardiac muscle?
aerobic capacity
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cardiac muscle is innervated by
neurons of the autonomic branch of the peripheral nervous system
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T/F cardiac muscle has muscle fibers in a chamber to essentially contract in unison
true
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electrical synapses
communication site between cells or with different regions within a cell
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how is the electrical synapses message carried?
ions
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T/F electrical synapses have neurotransmitters
false
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intercalated disks
electrical synapses in the heart
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what 2 ways do intercalated disks enhance conductivity?
- allows action potentials to spread from:
- - one cardiac muscle fiber to an adjacent one
- - within a cardiac fiber
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where do all myofibers contract in unison?
atria or ventricles
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what is the contraction of cardiac muscle dependent on?
extra-cellular Ca+
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how does the extra-cellular Ca+ enter the cell? (2)
- via voltage regulated channels on the plasma membrane
- T-tubule
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by having the extra-cellular Ca+ in the cardiac muscle fiber, what does it extend?
- duration of action potential- ensures enough time for emptying the artia/ventricles
- absolute refractory period- cardiac muscle needs to fully relax before it can contract
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which valve is from the atria to ventricles?
AV valve
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which valve is from the right ventricle to the pulmonary artery?
pulmonary valve
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which valve is from the left ventricle to the aorta?
aortic valve
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when blood flows from the right atrium to the right ventricle, which valve needs to open?
right AV valve
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when blood goes from the right ventricle to the pulmonary artery, which valve has to open?
pulmonary valve
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when blood goes from the left atrium to the left ventricle, which valve has to open?
left AV valve
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systole
contraction of the heart
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diastole
relaxation of the heart
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temporal pattern
when atria are in systole, ventricles are in diastole
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what is phase 1 of the cardiac cycle called?
isovolumetric ventricular contraction
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what is phase 2 of the cardiac cycle called?
ventricular ejection which the aortic and pulmonary vavles are opened
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what is phase 3 and 4 of the cardiac cycle called?
isovolumetric ventricular relaxation
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what is phase 5 and 6 of the cardiac cycle called?
atrial contraction in which the AV valve is opened
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in what phase is the ventricular volume isnt changing?
1
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in what phase is the having rapid ejection?
2
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in what phase is the blood volume the same?
3 and 4
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in what phase the heart filling actively?
6
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in what phase can the heart have passive or active filling?
5
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cardiac output
the volume of blood ejected from the ventricles per minute
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what is the resting CO?
5 L
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what is the max CO?
20-40 L/min
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equation of SV
- EDV - ESV
- starting volume - final volume
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ejection fraction
fraction of blood ejected from the ventricles during ventricular stage
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equation for ejection fraction
(SV/EDV) 100
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3 things EDV can be influenced by
- time of ventricular diastole
- blood volume
- venus pressure
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venous return
volume of blood the returns to the right atrium
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ventricular filling is influenced by
heart rate
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time of ventricular diastole is
ventricular filling
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what is circulating blood volume proportional to (2)
- urine volume
- tissue fluid volume
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what is venous pressure around?
10mmHg
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veins have greater _____ compared to arteries? (2)
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diameter of blood vessels is influenced by (2)
- ANS
- skeletal and respiratory muscle contraction
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dense bodies are connected by
intermediate filaments
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what does calcium bind to for smooth muscle contraction?
calmodulin
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for smooth muscle contraction, the increase in sympathetic activity causes what? (2)
- increase in frequency and strength of contraction
- reduces the diameter of vessel
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when VP is increases, what else is also?
right atrial pressure
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when venous pressure is equal to right atrail pressure, what happens to venous return?
there is no VR
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frank starling law
the volume of blood that enters the ventricles is proportional to the volume of blood that is ejected from the ventricles
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increase in blood does what to sarcomeres?
increases the length
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an increase in sympathetic activity does what to ESV?
decreases it
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when MAP increases, what happens to the ESV?
increases which then decreases SV
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what is normal range for MAP?
90-100 mmHg
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an increase of sympthetic activity does what for smooth muscle contractions? (everything)
- increases: HR, EDV, CO, VP, VR, SV
- decreases: time of diastole, ESV, diameter of veins
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at rest, where is most of the blood distributed?
GI tract and renal
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left atrium and ventricle compose what artery?
left coronary artery
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when is there no blood flow to the heart?
systole
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what does the meta-arterioles connect?
arterioles to venules
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what does the meta-arterioles do?
opens new "capillaries" during relaxation
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an increase in metabolic activity increases blood flow how?
vasodilation
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when the precapillary sphincters are sensed with oxygen during an increase of metabolic activity, what happens?
they contracted which decreases blood flow
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an increase of CO2 does what to capillaries?
vasodilation which allows more blood flow
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why does blood pressure oscillate in arteries?
- in systole, the aortic valve opens letting blood in which expands in pressure and volume
- in diastole, the blood leaves and then there is an elastic recoil
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why does blood pressure drop as blood travels from the arteries to veins?
capillaries are between them which have more surface area and veins are more compliant
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equation of MAP
(CO)(total peripheral resistance)
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laminar flow
resistance to friction forces as blood travels over the walls of vessels
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an increase in radius does what to PRT?
decreases it
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what is MAP regulated by?
- short-term: nervous system
- long-term: endocrine and renal
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what 2 things regulate short-term regulation of MAP?
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where are the baroreceptors found?
- cartoid sinuses
- aortic arch
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where does the medulla send signals to?
- cardiac control center: regulates HR
- vasomotor center: regulates PRT
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