Heart Flashcards
Cardiac
Heart
Network of capillaries that carry blood to/from the heart
Vascular system
Which side receives O poor blood
Right
Which side receives O rich blood?
Left
Where does O rich blood get pumped to?
Systemic arteries and organs
Is cardiovascular system open or closed system
Closed
Vessels that carry blood away from heart
Arteries
Only artery that carries O poor blood
Pulmonary artery
Where does pulmonary artery carry o poor blood to?
Lungs
What carries O rich blood from lungs to heart?
Pulmonary veins
Bottom right of heart is called?
Apex
What makes up most mass of the heart?
Ventricles
Systemic veins that drain O poor blood from upper or lower body
Superior and Inferior Vena Cava
Where do superior/inferior vena cava drain blood to?
Right atrium
Blood from right ventricle enters into what?
Pulmonary trunk
What does pulmonary trunk branch into
Right and left pulmonary arteries
Where do where do pulmonary arteries go?
Lungs
Where does blood from pulmonary veins enter into the heart
Left atrium
After O rich blood goes from left atrium to left ventricle, where next?
Ascending aorta
Where does blood go after ascending aorta?
Aortic arch
Where does blood go after aortic arch
Thoracic aorta
Name 3 branches on top of aortic arch
1) brachiocephalic trunk
2) left subclavian artery
3) left common carotid
Where do 3 branches on top of aorta mainly bring blood?
Head and brain
Blood vessels that bring and remove blood from heart muscle itself
1) coronary arteries (R&L)
2) circumflex artery
3) LAD
True/False: Artria contract at same time
True
True/False ventricles contract at same time
True
Muscular wall that separates right and left sides of heart
Interventricular septum
What does nervous tissue in interventricular septum create
Action potential to pump heart
Which side of the heart is more muscular
Left
Why is left side of heart more muscular
Must generate more force to overcome aortic pressure
What ensures one-way flow in the heart
Valves
What is valve in left ventricle
Aortic valve
What valve is under right ventricle
Pulmonary valve
Valves from artria to ventricles
AV valves
What is left bicuspid AV valve also called
Mitral valve
What is base of AV valves
Ring of cartilage
What is each cusp of an AV valve anchored to the ventricle by
Chordae tendinae
What do chordae tendonae attach to in the ventricle wall
Papillary muscles
What are aortic and pulmonary valves also called
Semi-lunar valves
What causes the cups of semi-lunar valves to fill with blood and seal off the valve
Decrease in ventricular pressure
What phase does the heart fill with blood
When at rest
When the heart is at rest and has zero pressure, what have high pressure that cause the valves leading to the heart to seal
Aorta and pulmonary arteries
Are AV valves open or closed when the heart has zero pressure
Open
What is it also called when heart contracts
Ejection phase
What closes AV valves
When ventricles fill with blood
Where does blood go from heart in ejection phase
Aortic and pulmonary valves
What is the serous membrane of the heart
Pericardial cavity
What cushions the heart and reduces friction
Pericardial sac
What else is in pericardial sac that helps heart function
Nerve cells
Outside layer of pericardium
Fibrous
Pericardial Layer below fibrous
Parietal
Pericardial layer closest to heart
Visceral
What is the visceral layer also known as
Epicardium
Between parietal and visceral layer filled with fluid
Pericardial cavity
What produces the pericardial fluid
Parietal and visceral layers
Inside layer of heart chamber
Endocardium
Outside layer of heart chamber next to pericardial sac
Myocardium
Where is cardiac muscle located
Myocardium
What cause the muscle cells to contract as a unit
Intercalated disc junctions
What are the 2 type of intercalated disc junctions
1) Desmosomes
2) Gap
Protein adhesion that physically anchors cardiac muscle cells together
Desmosomes
Ion channels that allow ion flow from one cardiac muscle cell to the next
Gap junctions
Are Gap junctions active or passive in nature
Passive
Two cardiac cells types
1) contractile (99%)
2) auto rhythmic (1%)
Nerve tissue in heart that can generate action potential without direct nerve stimulation
Autorhythmic
Change in electrical voltage across membrane of cell
Action potential
Main ions that move across cell to create action potential
Na and K
Phase where heart is at rest, K+ is inside cell and Na+ outside
Phase 4
Charge of cardiac cell at phase 4
-70mV
Phase when fast Na+ ion channels open and Na+ floods into cell to depolarize
Phase 0
Phase when Na+ ion channels close
Phase 1
Plateau Phase when Ca++ goes into cell and K+ out
Phase 2
Phase when Ca++ channels close but K+ continues to flow out
Phase 3
What cells causes Phase 4 to Phase 0
Autorhythmic cells
True/False: Ca++ that enters one cell diffuses to next and triggers action potential in next cell
True
Phase whose main purpose is to recruit neighboring cells to contract as a unit
Plateau phase (2)
What charge of Autorhythmic cell opens Ca++ channels
-40mV
When positive charge of cell peaks and Ca++ channels close, what channels open
K+
What happens when K+ channels open and pull K+ out of cell
Charge decreases and cell becomes more negative
When cell charge becomes most negative, what happens
Repolarization
Autorhythmic node located in back of right atrial wall
Sinoatrial (SA) node
Fibers that go from SA node go to what
Left atrium and AV node
Where is AV node?
Junction of right atrium and ventricle
Two branches of AV node
1) bundle of his (R/L)
2) purkinje fibers
Fibers that move up from apex and penetrate deep into ventricle muscle on both sides
Bundle of His
Fibers that branch off bundle of his into ventricle walls
Purkinje fibers
Firing rate of SA node
70-80 action potentials/minute
Firing rate of AV node
40-60 AP/min
Bundle of His and Purkinje Fibers firing rate
20-40 AP/min
What determines firing rate
Time is takes to depolarize
Because SA node fires the quickest, also known as
Pacemaker
100ms time lapse between AV node and SA node firing
AV nodal delay
What allows enough time for ventricles to max fill with blood
AV nodal delay
When AV node fires, what happens
Ventricles contract
Systole
Contraction
Diastole
Relaxation
How many leads for ECG
12
On ecg, what signifies depolarization of both atria
P wave
On ecg, what signifies depolarizing of ventricles and beginning of contraction
QRS complex
ECG, what is repolarization of ventricles
T wave
What is a flat line in ecg
No electrical activity
What is usually happening when there is no electrical activity (flat line)
Mechanical events (pressure change, muscle contraction)
On ECG, what is AV nodal delay
PR interval
Time that atria are contracting and ventricles filling
AV nodal delay
Ecg, contraction and emptying of ventricles (ejection)
ST interval
Ecg, diastolic rest phase between cycles
TP interval
What does ECG track
Electrical activity of heart
What are mechanical events in the heart
Pressure measurements
Sound when ventricular pressure rises and AV valves close
Lub
Sound when semilunar valves close as ventricle pressure drops
Dub
Volume in heart doesn’t change and all valves shut
ISO volumetric ventricular contraction
What opens when ventricular pressure exceeds aortic pressure
Semilunar valves
What happens when semilunar valves open
Blood rushes from ventricles to arteries
Blood from right ventricle goes where
Pulmonary artery
Blood from left ventricle goes where
Aorta
When ventricular volume peaks and filling phase ends
End diastolic volume (EDV)
When blood is ejected at end of contraction
End systolic volume (ESV)
Amount of blood ejected from heart
Stroke volume
Stroke volume is calculated by
End diastolic volume in ventricles - End systolic volume in ventricles
EDV - ESV
On ecg, relaxation of ventricle also called
T-wave
What part of T wave does ventricular pressure drop below aortic pressure and semilunar valves shut
Middle of T wave
When semilunar valves shut and blood hits walls of valves to cause a blip
Dicrotic notch
Ventricles relax, valves shut and volume unchanged
Isovolumetric relaxation
When is ventricular pressure almost zero on ecg
End of t wave
What is volume of blood ejected from each ventricle per minute
Cardiac output
Volume of blood per beat is
Stroke volume
How is cardiac output calculated
Heart rate x stroke volume
Max heart rate
220 - age
Extent to which your heart can increase blood delivery into systemic circulation between max activity and rest state
Cardiac reserve
Cardiac reserve is calculated by
Max cardiac output - resting cardiac output
What is key to measuring cardiac performance
Cardiac output
What sets heart rate
SA node
Parasympathetic nerves do what to the firing of SA and AV nodes
Inhibit (slows heart)
What do sympathetic nerves do to heart
Speed it up
What controls stroke volume
Strength of muscle contraction by ventricles
2 mechanisms that change stroke volume
Intrinsic and extrinsic
Intrinsic control of SV is
Increased filling with more blood
Extrinsic control is
Effect of sympathetic stimulation to heart
When will cardiac muscle exert more force
When stretched (to a point)
The more blood that fills the heart, the more it will
Stretch
The more the heart stretches from increased volume, what increases
Stroke volume
High volume = high force = high SV
Frank-Starling Law
Sympathetic nerves cause heart to pump
Harder and faster (effect nodes and muscle contraction)
How many heart beats to move blood through entire heart
2 beats
(Enter in 1, leave in another)
Charge of cell membrane at peak of Phase 0
+30mV
What causes slow depolarization (less negative charge) of autorhythmic cells
Slow leak of Na+ into cell
What fires to cause the atria to depolarize
SA node
Resting pressure of aorta
~80mm Hg
Which has slightly greater pressure during heart at rest, left atrium or left ventricle
Atrium
What is significant about atrium having higher pressure than ventricle when heart at rest?
Means AV valves are open
What happens when ventricular pressure rises above atrial pressure
AV valves shut
What happens to ventricular volume during ejection
Decreases dramatically
Where on ECG does it show that ventricular pressure has peaked and is starting to go down
Beginning of T wave
When ventricular pressure falls below aortic pressure, what begins
Ventricular diastole
What percentage of ventricular filling is due to atrial contraction (“atrial kick”)
20%
