Cardiac output is the volume of blood pumped by ______
By either ventricle per minute
cardiac out put
heart rate times stroke volume
What increases the contractility of the ventricle?
increased sympathetic impulses
T/F: temperature can affect heart rate
According to Sterling's Law of the Heart, Increased venous return will cause
an increase in stroke volume
what is the function of the serous fluid found between the visceral and the parietal layers of the pericardium?
act as a lubricant that reduces friction when the heart beats
The right side of the heart pumps blood through the ____ circulation and the left side pumps blood through the _____ circulation.
What separates the two functional syncytia in the heart?
hearts fibrous skeleton
What links the the two function syncytia in the heart?
What is autorhythmic tissue that depolarizes to threshold at the fastest rate in a normal heart?
T/F: in cardiac muscle, Ca++ ions that enter the cell from the ECF cause Ca++ release from the SR
In cardiac muscle, Ca++ ions that enter the cell from the extracellular fluid cause
Ca ++ release fromn the sarcoplasmic reticulum (SR)
part of the ECG that represents repolarization of the ventricles
What is "cardiac chaos"
If it occurs inn the ventricles it would be life threatening and requires treatment of exposing heart to an electrical current to re-establish a normal cardiac rhythm
During one complete cardiac cycle what occurs last?
opening of semilunar valves
Volume of blood ejected from the ventricle during one contraction of the ventricle (normal is 40-80ml)
When venous return increases, end diastolic volume increases and stroke volume increases due to what?
when venous return increases, end diastolic volume _____ and stroke volume _____ due to ______.
When length of cardiac muscle fibers affects stroke volume it describes...
-Ventricular diastole is the period during which the ventricles are relaxing, while atrial diastole is the period during which the atria are relaxing.
between the visceral and parietal layers of the pericardium there is _______.
Left side of the heart pumps blood through what?
Heart Valves allow for what?
one way flow of blood (prevent back flow)
What separates the two functional syncytia in the heart?
hearts fibrous skeleton
What is the normal pacemaker of the heart?
The S-A node (sinoatrial node) is often called the pacemaker of the heart.
Why is the SA node called the pacemaker of the normal heart?
It is the autorhythmnic tissue in the heart that depolarizes to threshold at the fastest rate
during the plateau of the cardiac action potential, the permeability of the membrane to ____ is increased, which causes the plateau.
What is responsible for cardiac Plateau?
slow Na & Ca channels.
The long plateau phase of the cardiac muscle action potential is due to
calcium channels remaining open
_____ is depolarization of the ventricles.
Depolarization of the ventricles
During one complete cardiac cycle which event would occur last?
first heart sound
Events that produce a single heartbeat:
-ventricles fill: pressure of blood in atria causes it to contract (~70% full), full-end of diastole
-ventricles contract: begin systole; all valves are closed; squeezing and building pressure
-ventricles eject: systole
-ventricles relax: beginning of diastole
When does most of the filling of the ventricle occur?
before atrial contraction
Heart muscle ______an action potential t cause contraction
Layers of the heart
Epicardium - surrounded by pericardium
- Outer layer: Parietal Paricardium
- Inner layer: Visceral Paricardium
- Pericardial Cavity: space between layers, filled with pericardial fluid.
visceral pericardium (epicardium)
Layer on the surface of the heart
Lines the fibrous pericardium - the sac around the heart
Function of serous fluid between the layers
Act as lubricant that reduces friction when the heart beats.
When the left side of heart pumps blood everywhere in the body but the lungs
When right side of heart pumps blood to the lungs
1. Right Atrium
2. Right Ventricle
3. Left Atrium
4. Left ventricle
"Hydrostatic Pressure" which is an outward force is greater than the "Osmotic Pressure" which is the inward force.
From systemic veins into right atrium
Deoxygenated blood flows from right atrium through right AV Valve (tricuspid) into the right ventricle
Whee is passes the right semilunar valve into pulmonary trunk
Which it travels by pulmonary artier is to the lungs to be oxygenated
Where it travels back to heart via pulmonary veins to the left atrium
where is passes the left AV valve (bicuspid or mitral valve) into left ventricle where it passes the left semilunar valve into aortas
which it then flows into systematic arteries to rest of body other than lungs
Lungs - Pulmonary vein - Left atrium - Left ventricle - Aorta - Body parts
Body parts - Vena Cava - Right atrium - Left atrium - Pulmonary artery - Lungs
Open and Close to prevent ackflow into wrong chambers
Help action potential to go from cell to cell so that muscle can contract as a unit as function syncytium
When a group of interconnected muscle cells which function mechanically and electrically as one unit.
The functional syncytia in the heart
1 in the atria
1 in the ventricles
separated by heart's fibrous skeleton
Link to the Ventricles
the heart itself are responsible for initiating the heartbeat
heart can rhythmically initiate own action potentials by pacemaker potentials
with nothing affecting HR except the heart itself
like when you have heart in hand it has no outside influences from body and simply acts on its own or a rate of 100pm
The normal heart rate is _____.
slowed by parasympathetic contrails that act as break on heart
What is pacemaker potential affected by?
Parasympathetic impulses, they decrease the slope of the pacemaker potential, making it flatter, longer to reach threshold, thereby decreasing heart rate.
What do parasympathetic division impulses do to heart rate?
Decrease slope of pacemaker potential
making it flatter, longer to reach threshold
thereby decreasing heartrate
What do Sympathetic Division Impulses do to heart rate?
Increase slope of pacemaker potential
Making it steeper and quicker to reach threshold
Thereby increasing the heart rate
Pacemaker of a normal heart because it fires first because it is quickest to get to threshold
IF SA Node damaged
The AV node takes over as the pacemaker and sets the pace at 50bpm
Cardiac Action Potential
A depolarization, a plateau and a repolarization
Occurs when he Na+ channels close and K+ stays the same and Ca2+ permeability increases to keep membrane depolarized at the plateau level.
Occurs when Ca2+ and K+ change back to permeabilities before the action potential and then K+ permeability goes higher
Depolarization (Na+ moves inside cell-> less neg)
Repolarization (restoration of neg. charge, K+ leaves cell)
Hyperpolarization (too much K+ leaves)
What are The effects of CA++ that enters the cell during the cardiac action potential?
The Ca++ that enters the cell induces more Ca2+ to be released from the SR to activate he contractile machinery and also the Ca2+ can directly activate the machinery.
What does an increase in Ca++ in cytosol do?
Increase the strength of cardiac muscle contraction.
parts of the heart's conducting system
SA node, AV bundle, and the AV node
Hearts Conducting System
consists of specialized muscle cells that transmit cardiac impulse to cause the contraction of the heart, allowing a faster transmission than regular cell to cell conduction.
Function of hearts conducting system
To make a coordinated contraction where 1st the atria contract together and the the 2 ventricles together
Location and Name of structures of Hearts Conducting System
SA node pacemaker of normal heart is near opening of the superior vena cava, it's a mass of specialized cardiac muscle cells which has an autorhythmicity of 1000pm but is held back to 70bpm by parasympathetic impulses
Location and Name of structures of Hearts Conducting System AV Node
Location- specialized cardiac muscle cells in right atrium near ventricle
Atrioventricular nnode - only link to ventricles so impulse can get to ventricles
Location and Name of structures of Hearts Conducting System AV bundles
Bundle of conductive tissue in ventricular septum
First a single bundle branches into right and left bundle branches
Location and Name of structures of Hearts Conducting System Purkinje fibers
After bundle branches
These fibers carry impulses to the thick myocardium causing a coordinated contraction of ventricles
SA node originated impulse when pacemaker potential reaches _____
Action potential moves throughout arterial myocardium through ________
1) SA node 2) Bachmann's Bundle 2)Internodal pathways 3) AV node 4) Bundle of His 5) Rt/Lft Bundle Branches 6) Purkinje Fibers
Where is cardiac impulse delayed
Impulse reaches AV node elayed 0.1 seconds
A stalling technique to give the trio time to contract and squeeze the blood into ventricles before the ventricle contraction
Contraction of myocardium or ventricle contraction
Depolarization causes contraction of myocardium what occurs with repolarization?
Withe depolarization you get
With depolarization you get
Importance of EKG as tool to help diagnose disease
because they can find electrical irregularities in the heart which indicate diseae
tool for evaluating electrical events in heart
Important because it can help diagnose disease - changes in electrical events in heart can indicate disease
Depolarization of atria causes the
Depolarization of ventricles causes the
Repolarization of ventricles causes
Repolarization of atria
Is NOT normally seen, is hidden or obscured by QRS complex
partial heart block
Some (half) impulses don't get though the AV node.
Slows or prolongs conduction in AV node
complex heart rate
No impulses get through AV node
NO correlate between P wave and QRS complex
Atria beat at own rate. Ventricles beat own rate
Some P waves are not conducted through AV node; hence more P than QRS waves are seen.
What is most likely the pacemaker for the ventricle in complete heart block and what would be the heart rate?
Part of the conducting system of the venrical
variation from normal heart ratre
Greater than 100bpm occurs in normal hearts during exercise; can occur in disease
Less than 60bpm not necessarily a problem -n highly conditioned athletes can have (pump more per beat so have decreased HR)
Can occur during disease (complete heart block)
Very Rapid but regular 250-300 bpm
At these rapid rates filling time is compromised (not enough time to fill with blood)
Person is in trouble if fluter of ventricles for more than 30 seconds - need medical intervention
Describe situation if ventricles are fibrillating
Ventricle looks like squirming worms in a bag
Are little areas of contracting and relaxing independently
Myocardium fails to contract as a whole (cells don't contract together)
Chambers cannot pump blood. If ventricles are fibrillating haver serious trouble - need medical attention
If ventricular fibrillation need to defibrillate the heart in order to reestablish a normal rhythm.
Expose myocardium to a strong electric current, to depolarize all cells at once.
Hope is that a "normal sinus rhythm" again and normal impulse conduction.
Describe cardiac cycle
1 complete heart beat
Systole and diastole, contraction and relaxation of atria and then ventricles. (i.e. ventricles contract while the atria are relaxing.
Milking action - squeezes blokk drom atria into ventricles then from ventricles not circulation
The cardiac cycle begins with atrial systole (T/F).
Define systolic pressure
Pressure at peak (or highest pressure) 120 mmHg
80 mm Hg
The lowest pressure just before the next peak near (6) before the SV is ejected.
occurs when the ventricles are relaxed. It is the lowest pressure against the walls of an artery.
end systolic volume
is amount of blood left in ventricles at end of systole
End Diastolic volume
Amount of blood in each ventricle at end of diastole
Stroke Volume (SV)
When the left ventricle contracts, it ejects blood into the aorta. (Amount ejected from the ventricle)
Difference between end systolic volume and end diastolic volume
What is Normal value for aortic systolic pressure
What is normal diastolic pressure
What is single difference in describing the cardiac cycles for the right side of heart compared to left side?
Right side is thinner and a lower pressure system compared to left side
Right ventricle ejects the SAME amount of blood as left ventricle.
Why is the right ventricle muscle much thinner than the left?
Because of low pulmonary pressure and there is less work done
Right ventricle ejects ______ amount of blood as left ventricle.
Amount of blood pumped by either ventricle per minmue
2 variable determine cardiac output
Heart Rate - # of time it beat or pumps
Stroke volume - how much the pump pumps per beat
CO = HR x SV
Normal Value for Cardiac Output at rest
5 L/min and in increase with activity to 7 L/min for walking and to a value of 25-30 L/min during exercise.
how is hr controlled by the ans
Mostly Heart rate is controlled by ANS ratio of impulses of parasympathetic and sympathetic impulses.
at hr lower than 100bpm, removal of parasympathetic activity, at hr higher than 100 bpm, hr is increased via increased sympathetic activity
Parasympathetic control of HR
Like a break on the heart, by secreting ACh, you can increase heart rate by decreasing parasympathetic impulses and decrease it by increasing parasympathetic impulses.
Sympathetic Control of Heart Rate
Like an accelerator
By secreting NE, you can increase HR by increasing sympathetic impulses and decrease it by decreasing parasympathetic impulses.
speeds heart rate and increases force of contraction.
Acts on the same B1 receptors that NE does to increase HR and increase force of contraction
Heart rate also affected by
Plasma electrolytes (especially K+
Usually less important than ANS, but could e important in disease/abnormal situations (cold)
2 normals ways to control SV
How is SV controlled
Can change the SV because always blood left in ventricle, never completely empty, can always empty more
the mechanism inherent to organ
Organ does it alone without help
the mechanism initiated outside or organ, control coming fomn outsie
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