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123 Cards in this Set
- Front
- Back
Is the cardiovascular system a closed or open system?
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Closed
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What are the two types of capillaries in the body?
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Systemic capillaries and Pulmonary capillaries
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What type of blood do systemic veins bring back to the heart?
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Deoxygenated
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Oxygenated blood is carried by which types of vessels?
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Systemic arteries and pulmonary veins
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How many cardiac cycles does it take for the full path to be completed?
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2
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What does the circulatory system consist of?
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-The heart
-Blood vessels -The blood |
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What is the anatomy of the heart?
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-4 chambers
-2 atria and 2 ventricles -intraventricular septum |
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What is the name of the most inferior portion of the heart?
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the APEX
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The base of the heart lies where?
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Superior, towards the clavicles
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What valves separate the artia from the ventricles?
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the atrioventricular valves
-Tricupsid is right -Bicuspid/Mitral is left |
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What do the semi-lunar valves separate?
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the ventricles from the aorta and/or pulmonary arteries
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Do we have valves between the veins and the atria?
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NO!
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What is the purpose of valves?
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to prevent backflow of blood
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What structures help anchor the valves and prevent inverting of the valves?
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Chordae tendineae and Papillary Muscles
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What does the heart experience if a backflow of blood does occur due to a faulty valve?
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the heart has to work that much harder to pump the same amount of blood per beat
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Why are there no valves between the atria and the veins?
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-Atrial pressure is low
-When atria contract, they squeeze the veins closed |
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Where does the heart lie?
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Within a pericardial sac
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What are the two membranes surrounding the heart?
What is their function? |
Pericardial membrane
Epicardial membrane -produce fluid that surrounds them which helps reduce frictional forces against the heart with each beat |
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What are the two main types of cells in the heart?
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-Contractile muscle cells
-auto-rhythmic cells (ARCs) |
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What percentage of auto-rhythmic cells are in the heart?
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only 1%
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In what ways is cardiac muscle a unique form of tissue?
what function does it have? |
1. connected through intercalated discs (not in any other form of tissue)
2. They have branched structure -these allow them to be physically anchored and electrically connected to each other |
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What are the two types of membrane junctions involved in cardiac muscle?
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1. Desmosomes
2. Gap Junctions |
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What junctions are responsible for PHYSICALLY anchoring one plasma cell to another?>
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Desmosomes
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Describe Gap Junctions.
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-Electrical synapses
-allows for a depolarization to move from one cell to the next without having to physically depolarize each cell -allow heart muscle to contract in unison |
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Does the cardiac AP have a hyperpolarization stage?
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Not a dramatic one
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What is unique about the cardiac AP?
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It has a plateau phase.
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Describe the Cardiac AP
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What is responsible for the plateau phase of the cardiac AP?
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Sustained by the balance of Ca++ and K+ out.
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What is the advantage of the plateau phase of the cardiac AP?
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Allows for nearby cells to get on board and depolarize as a unit!
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In pacemaker cells, what direction is the membrane potential constantly drifting towards?
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Direction of depolarization
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Why are pacemaker cells constantly close to depolarization/
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Because Na+ is permeable and constantly slowing leaking INTO the cell!
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Which ion's permeability will remain the same in pacemaker cells?
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Sodium
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Which channels are triggered at the pacemaker cell gets close to threshold?
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Transient Calcium channels
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What channels are triggered once threshold is reached in pacemaker cells?
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L type Ca++ channels
L= long or latent because they stay open a little longer |
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What is pacemaker potential?
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Allow the cell to fire APs without any outside input in a spontaneous manner and with an intrinsically set pace.
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What type of activity does the membrane potential of ARC's display?
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pacemaker activity
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Can cardiac contractile muscle cells contract without stimulation?
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No, they must receive stimulation from pacemaker cells ARCs
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What factor decides which node is the pacemaker of the heart?
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the node that has the fastest natural firing frequency
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Which node is the pacemaker of the heart?
What is its pace? |
The SA node
-70- 100 APs pm |
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What is the pace of the AV node?
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40-60 APs per minute
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what is phase 4 of the cardiac cycle?
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Resting cell (where we start)
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What is the intrinsic pace of the Bundle of His and the Purkinje fibers?
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20--40 APs
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What do Purkinje fibers do?
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Connect the Bundle of His and send the AP to the ventricles
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Which node reaches threshold more quickly?
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SA node
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What are the 2 directions of AP sent from the SA node?
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1. interatrial pathway: to the left atrium
2. internodal pathway: to the AV node |
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What intrinsic property allows for the atria to contract before the ventricles, as well as encouraging maximal filing of the vents?
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The AV nodal delay.
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What is Systole?
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Ventricular Contraction
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Describe the Pacemaker AP
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What is Diastole?
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Ventricular Rest
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What are we recording in an EKG?
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The sum of the electrical actvity as it reaches the skin
-as it is conducted to the surface of the skin |
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What is the P wave?
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Atrial depolarization
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What is the PR segment?
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AV nodal delay
-during this time atria are contacting |
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What is happening during the QRS complex?
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Ventricular depolarization
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What does the ST segment signify?
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Time during which the ventricles are contracting and emptying
-ejection of blood into the arteries |
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What is the T wave?
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Ventricular REpolarization
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What is the TP interval?
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Time during which ventricles are relaxing and filling
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Why don't we see atrial repolarization in an EKG?
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Because it is masked by the ventricular depolarization
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Does the EKG give any mechanical information of the heart?
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No only electrical!
-But mechanical things are happening at the same time |
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What is considered an electrical event of the heart?
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The spread of depolarization from the atria to the ventricles
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What side of the heart are we considering during the cardiac cycle?
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The left side
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What happens before contraction?
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depolarization of the muscle
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What are the pressure ranges on the left side of the heart
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0-120
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What is the atrial kick?
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A little kick of blood into the ventricles as a result of atrial contraction.
-Tops of ventricular filling |
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When will the AV valve close?
At what point are we at in the EKG? |
When pressure in the vent is greater than pressure in the atria
-We are at he the QRS Complex |
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What happens to ventricular volume when the QRS complex spikes?
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It stays the same. Is in isovolumetric contraction.
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What is isovolumetric contraction?
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The time when no more blood in entering the vents, but they are contracting in order to generate pressure against the aorta.
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When will the Aortic valve open?
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When the pressure in the ventricle is greater than the pressure in the aorta
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What is the status of all of the valves during isovolumetric contraction?
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They are all closed
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Why does the aortic pressure line increase during ejection phase?
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Because the pressure in the aorta is also increasing
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Does the ventricular pressure stay above aortic pressure during ejection phase?
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Yes
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What happens to vent volume when the aortic valve opens?
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It drops rapidly
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What is stroke volume?
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the volume of blood ejected from each ventricle per systolic change
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What is End-Diastolic Volume?
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Volume of vents at the end of diastole (Larger number)
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What is end-systolic volume?
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volume of blood left over after ejection
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What is ejection fraction?
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The fraction of blood ejected from the heart per systole
-Healthy is 50-55% |
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Right around the time of T wave, what is happening to the vents?
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Parts of the vent are starting to relax
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Does all of the vent repolarize and depolarize at the same time?
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No, there can be both going on.
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Where does the AP spread from in the vents?
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From the apex, up the ventricles.
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What type of movement does the vent undergo when it contracts?
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It twists and rings itself out
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When the pressure in the vents falls below aortic pressure what happens?
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The aortic valve shuts (Dub)
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What is the dicrotic notch?
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Blip in aortic pressure. Reverberation of pressure against the aortic wall.
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Could the dicrotic notch be felt throughout the arterial tree? theoretically?
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Yes
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When does isovolumetric relaxation occur?
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when the pressure of vents is below aortic, but still above atrial.
-Continues until atrial pressure exceeds ventricular |
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Why do you get a rush of blood into the vents as soon as the AV valve opens?
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Because the atria were actually filling while the ventricles were contracting
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Why can the atria fill while the ventricles contract?
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Because of cardiac suction
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What is cardiac suction?
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When ventricles are twisting, the atria volume is being expanded and creating a negative pressure that sucks blood from the veins
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What is passive filling?
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It is the rush of blood into the ventricles without contraction of muscle
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What percent of ventricular filling happens during the atrial kick?
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ONLY 20%, So 80% of filling happens during diastole!!
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What is the equation for Stroke Volume?
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SV=EDV-ESV
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What is afterload?
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The resistance to ventricular ejection
-The workload that the heart has to meet and exceed to have ventricular contraction |
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What does the diastolic pressure of the aorta say about the work of the heart?
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It is based on the tone of the aorta (properties of the aorta and blood volume)
-The higher the pressure, the more work the heart has to do to imitate ventricular ejection |
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What is cardiac output?
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Volume of blood ejected from each ventricle per minute.
-Left should equal right |
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If the R Cardiac Ouptput (CO) > L CO, what could be happening?
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There may be some congestion in the pulmonary system
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What is the equation of Cardiac Output?
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Stroke Volume x Heart Rate
-~70 ml/beat = 5 liters/ min -At rest, our heart pumps out entire blood supply every minute |
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What is maximal HR a function of?
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Age
-Some individuals can reach a higher peak HR than what you would expect -Usually 220 - age |
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What is Max stroke volume dependent on?
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-Weight
-size -How in shape your heart is |
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What is your cardiac reserve?
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Max CO - resting CO
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What is your cardiac reserve a prediction of?
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Potential for physical performance
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What type of control contributes to increasing HR and Stroke Volume
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Autonomic Control
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What effect does the parasympathetic Pathway have on the HR.
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It will lower the firing frequency of the SA node thus slowing down HR
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What does it mean to have parasympathetic tone to the heart?
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You have low resting HR
-Your heart can put out the same CO with fewer beats -Thus you increase RESERVE!! |
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Which vagus nerve has greater innervation on the SA node?
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The R Vagus nerve
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The AV node is innervated predominantly by which vagus nerve?
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The Left
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What effect do the R and L Vagus nerves have on the heart?
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They decrease the firing frequency
-They also will increase AV nodal delay |
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What effect does an increase in AV nodal delay have on heart workload?
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This will bring about greater filling of the ventricles and thus your are pumping more volume per beat
-Thus allowing the heart to work less overall |
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What effect does the Sympathetic Pathway have on the heart?
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-Raise the firing frequency
-minor shortening of the AV nodal delay -Will bring cells closer to threshold |
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Does the decrease in AV nodal delay during sympathetic pathway compromise the filing of the vents?
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No it does not.
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What are the 2 mechanisms involved in altering SV?
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-Intrinsic control
-Extrinsic control |
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What does intrinsic control of the heart require
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Requires nothing but exploiting natural properties of the heart
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When you increase the stretching of the cardiac muscles, does this reduce contraction strength?
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No, it actually increases contractibility of the heart.
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What is the optimal length for contraction for skeletal muscle?
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The resting length of the muscle
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How do you increase the strength of contraction in the heart?
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You increase EDV by increaseing venous return (the amount of blod
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What is an inotropic agent?
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anything that effects contractility of the heart
-Positive: enhances contractility -Negative: decreases contractility |
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Describe a chronotropic agent
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Anything that changes HR
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Why is lengthening the cardiac muscle cell generate more force?
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Because the branches come in line with each other and thus can contract more!
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What is Frank-Starling Law of the Heart?
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It is the relationship between EDV, stroke volume and force
-Get more out than you've put in. -With Sympathetic added to it, you get more exaggerated Frank Starling relationship You have 2 mechanisms on top of each that stimulates stroke volume |
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What is extrinsic control of the heart?
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Sympathetic activity on the heart
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Which ways does sympathetic activity effect cardiac output?
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-Extrinsic control: + stroke volume= +CO
- +HR = + CO -+Venous return = increase EDV |
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Why is lengthening the cardiac muscle cell generate more force?
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Because the branches come in line with each other and thus can contract more!
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What is Frank-Starling Law of the Heart?
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It is the relationship between EDV, stroke volume and force
-Get more out than you've put in. -With Sympathetic added to it, you get more exaggerated Frank Starling relationship You have 2 mechanisms on top of each that stimulates stroke volume |
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What is extrinsic control of the heart?
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Sympathetic activity on the heart
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Which ways does sympathetic activity effect cardiac output?
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-Extrinsic control: + stroke volume= +CO
- +HR = + CO -+Venous return = increase EDV |
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Describe the cardiac Table
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