Glossary of cardiovasc
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- what does the cardiovascular system consist of?
- what's the function of the heart?
- to allow the bulk flow of blood through pulmonary and systemic vascular systems.
- what's the function of the blood vessels?
- -blood transport
-blood pressure regulation
-exchange of gas/nutrients/wastes between cells and blood.
- what's the function of the blood?
- -gas/nutrient/waste transport
-protect from infection/cancer
- what is the
- peri = fibrous sac enclosing the heart
epi = fibrous membrane on the surface of heart
- what is between the epicardium and pericardium?
- water to lubricate it.
- what are the coronary arteries?
- aa.s that supply blood to the myocardium
- What ar the 4 requirements of the heart?
- -maintain constant activity over lifetime
-must be regulatable and flexible in motor activity.
-maintain balance btwn pulmonary/systemic circulation.
- what are the characteristics of cardiac muscle?
- -only in heart
-electrically/mechanically couple to contract together.
-branched cells, striated.
- what is unique about the junctions between cardiac muscle cells?
- -joined by intercalated disks
-desmosomes inside disks hold cells together
- what's the purpose of desmosomes?
- -myofibrils of adjacent muscle cells attach to them
- where are gap junctions in myocardium, and what are they for?
- adjacent to intercalated disks; allow contact between conducting system and muscle cells.
- why does myocardium have high mitochondria content?
- for good aerobic metabolism.
-cardiac muscle can't build up an energy debt.
- What does Functional Syncytium refer to?
- the mechanical AND electrical coupling of cardiac muscle cells.
- what supplies the
- mech: intercalated disks - strong.
elec: gap junctions - not strong.
- what is the SR like in cardiac compared to skeletal muscle?
What is its purpose?
- less extensive, but still releases Ca+ for contraction.
action potential causes it to release calcium inside the cell.
- what are gap junctions made of?
- membrane proteins - connexins - in adjacent membranes.
-when the connexins line up, it makes an ion channel through both membranes.
- how do gap junctions function as electrical junctions?
- when connexins lined up, ions can flow from cytoplasm of one cell to another, passing the action potential along.
- what accounts for the mechanical strength of connections between cardiac muscle cells?
- DESMOSOMES - proteins imbedded in the cells' plasma membranes.
- what are the implications of desmosomes?
- when one muscle cell contracts, it will mechanically pull on the cells on either side of it, making them contract too.
- what is a desmosome made of?
- -proteins imbedded in plasma membranes, anchored via
-Attachment plaque increases stability.
- what are the primary energy sources for cardiac muscle?
- -aerobic metabolism
- where does the heart get -lactate
- lactate - carb from skeletal muscle activity.
fatty acids - from stored fat degradation.
-ketone bodies, amino acids - from fat degradation.
- What is the PRELOAD?
- End-diastolic volume.
- what is end-diastolic volume?
- the volume of blood in the ventricles at the end of their filling (diastole).
- what is AFTERLOAD?
- the arterial pressures against which ventricles pump.
- what 3 factors affect contraction force?
-Sympathetic nervous system input changes
-Afterload (arterial pressure)
- what does the Frank-Starling mechanism refer to?
- the relationship between ventricular end-diastolic volume and stroke volume.
- what IS the frank-starling mechanism?
- Simple: as end-diastolic-volume increases, stroke volume increases.
More blood in, more blood out.
- why does more blood go out when end-diastolic volume is increased?
- because the ventricle muscles are more stretched, so their contraction generates more force.
- What is Cardiac output?
- the volume of blood pumped by EACH ventricle per minute
- what does cardiac output equal?
- Heartrate x stroke volume
HR x SV = CO
- What happens to stroke volume and heartrate after blood loss?
- Stroke volume decreases
- what is the purpose of the Septum in the heart?
- it provides electrical isolation between the two sides.
- what is normal blood flow in the heart?
- on which side of the heart is
-How can you tell?
- Both pressure and resistance are higher on the left side of the heart.
-Left side has much thicker ventricular wall.
- What is the function of the heart valves?
- -to permit unidirectional blood flow.
-to open/close based on pressure gradients.
- What are the two AV valves names
- -Tricuspid (right)
-Mitral (left)- only one with 2 cusps/leaflets.
- what is the annulus?
- a fibrous ring that encircles the valve
- what are chordae tendinae?
- fibrous ligaments that connect the leaflets to the papillary muscles.
- what are papillary muscles for?
- to stabilize the AV valves to prevent prolapse.
-Do NOT open/close valves.
- which valves have a simpler structure, AV valves or semilunar?
- what are the 2 semilunar valves?
- systole refers to what action of the ventricles and valves?
- ventricular contraction.
period between mitral closing and aortic closing
- during diastole what are the ventricles doing?
- relaxing - filling with blood.
- during isovolumetric ventricular contraction, how are the
- atria = relaxed,
ventric = contracting.
AV valve: closed
- during ventricular ejection, how are the
- atria: relaxed
aorta/pulm valves: open
- during isovolumetric ventricular relaxation, how are the
- atria and ventricles: relaxed
av valve: closed
aortic/pulmon. valves: closed.
- during ventricular filling, how are the
- atria: contracts after initial filling
av valve: open
aortic/pulmon. valves: closed.
- How many heart sounds are there?
- 4 - S2, S2, S3, S4
- what is the sound of:
- 1 = mitral valve closing - LUB
2 = semilunar valves closing - DUB
- if you can hear S3 and S4, what does that mean?
what are these sounds?
- it's indicative of disease.
s3 = rapid filling of ventricles
S4 = atrial systole (contraction), reduced filling
- how much ventricular filling is atrial contraction responsible for?
- only 20-30% - most just happens by ventricular relaxation.
- what is diastasis?
- atrial systole - reduced filling of that last 20-30% of ventricles. heard as S4 in heart sounds.
- what is a heart murmur?
2 types of causes:
- an abnormal sound caused by rapid blood flow.
2 causes: stenosis/insufficiency
- what is stenosis?
- -Narrowing of the valve opening.
-Causes pressure buildup behind the valve, so blood spurts out with more force -> more rapid flow.
- When during a cardiac cycle is a stenosis heard? Does it cause any other alteration to valve closing?
- when the valve is OPEN
no, the valve closes normally.
- what is insuficciency?
- when a valve doesn't close completely; it allows blood to regurgitate into where it came from.
- when is insufficiency heard?
- when the valve is closed (because blood is leaking back)
but the valve opens normally.
- what is louder,
a systolic murmer? or
a diastolic murmer?
- a systolic - that's when the ventricles are contracting and blood is pushed out the semilunar valves at a higher flowrate, big sound.
- what are the 2 systolic murmurs you might hear?
- Semilunar stenosis
- What are the 2 diastolic murmurs you might hear?
- AV stenosis
- what are the names of 3 types of stenosis pathologies?
- -bicuspid aortic valve
-senile aortic stenosis
- what is bicuspid aortic valve?
- abnormality in the aortic valve so it's bi inst. of tricuspid. cuases restriction of blood flow, is Congenital.
- What occurs in senile aortic stenosis?
- the cusps become calcified and the valves are stiff and inflexible.
- what is mitral stenosis?
what can be a cause?
- when the mitral valve doesn't open enough.
-may be due to bacterial inf. or rheumatic disease.
- what are 3 types of replacement valves for heart murmers?
- -normal valves
-porcine or cadaveric replacements - last 15 yrs
-artificial replacements - they click.
- what is the pacemaker of the heart?
- the SA node
- what is the SA node?
- sinoatrial node - the pacemaker.
- what pace does the SA node set?
- 60-100 beats per min
- what is the electrical link between the atria/ventricles?
- the AV node.
- what is the conductive nature of the AV node?
- slow - it conducts the action potental very slowly - about 0.1 sec - so the ventricles contract AFTEr the atria
- what are bundle branches?
what do they do?
- branches that come off the bundle of His; deliver impulse simultaneously to the R and L ventricles.
- how does contraction spread across the ventricles?
- from Bottom to Top
- what are purkinje fibers?
- large, branching fibers that conduct action potential from r/l bundle branches to the myocardium
- is myocardial conducting tissue Nerve tissue?
- no!!! it's specialized myocardial cells that exhibit automaticity.
- what is automaticity?
- the lack of need for stimulation that is seen in myocardial cells.
- how does electrical conduction spread through the heart during phase one?
- begins at the SA node by symp or parasymp stimulation; atria excite; stimulates AV node; atria DONE.
- how does electrical conduction spread through the heart during phase two?
- 1. atria done while AV node still depolarizing.
2. AV stimulates bundle of His; then branches, then to purkinje fibers.
- why are the atria done depolarizing by the time the ventricles start?
- because Action potentials pass very slowly through the AV node.
- what are Ina channels?
In what type of myocardium are Ina channels found?
- Channels that allow fast Na influx if depolarized. Inactivate rapidly
ONLY in working, contractile. Not in conductive tissue (SA or AV nodes).
- what are If channels?
In what type of myocardium are they found?
- funny channels that allow a slow leak of Na into the cell when they are hyperpolarized.
ONLY found in conductive tissue.
- what are L type Calcium channels?
- voltage-gated Ca channels that allow a long-sustained influx when depolarized.
- what are T type Calcium channels?
in what type of tissue?
- channels that allow a transient influx of CA when depolarized; only found in conducting tissue.
- what are inward rectifier channels?
- potassium channels that open at highly negative potentials to allow outflow
- what are delayed rectifier channels?
- potassium channels that allow a sustained outflow when depolarized.
- what are g-protein activated potassium channels?
- channels that allow K+ outflow when activated by AcH or adenosine; important for neural regulation of heart rate.
- what ion channel is the most important in functional beating?
- the Funny channel
- what are the two methods by which action potential can spread?
- -via conducting tissue
-via myocardium through gap junctions.
- which method does AP spread through the atria?
- only through gap junctions.
- what is the pacemaker potential?
- the gradual/slow depolarization of the SA node that brings it to threshold for an action potential.
- which 3 ion channels contribute to the pacemaker potential?
- -Delayed rectifier K+ channels
-Funny Na+ channels
-Transient type Ca2+ channels
- now what does automaticity mean?
- it refers to the fact that conducting cells don't have a resting memb. potential, but have a rythmic pattern of pot. alteration by different channels opening/closing.
- what type of channel accounts for most of the depolarization in a conducting cell AP?
- L-type Ca2+ channels opening
- what type of channel accounts for repolarization to end an AP in conducting cells?
- delayed rectifier K+ channels - allow K+ outflow
- what starts the pacemaker potential?
- delayed rectifier K+ channels closing
- what two other channels account for the continued depolarization to cause a pacemaker potential?
- -Funny channels allow Na influx when membrane potential is neg.
-T-type Ca channels allow CA influx top it off for the AP
- How many phases are in Cardiac Action Potential generation in cardiac MUSCLE (not conduct. tissue)?
0 - upstroke,
1 - small repolariz.
2 - Plateau
3 - Repolarization
4 - back to resting potential.
- what happens in phase 0?
- Upstroke; Na+ fast channels open - normal, causes depolarization.
- what happens in phase 1?
- Small repolarization due to:
-Na+ channels close
-inward rectifier K+ channels open
- what happens in phase 2?
- Plateau - L-type Ca2+ channels open and calcium flows in to balance a closing of potassium inward rectifier channels.
- what happens in phase 3?
- Repolarization - delayed rectifier potassium channels open and allow efflux of K+
- what happens in phase 4?
- back to resting potential; inward rectifier K+ channels finish the job of returning to negative potential.
- what is the purpose of the refractory period in cardiac muscle?
When is this period?
- to allow ventricles time to fill, and to prevent tetanus.
Time: from action potential until completely repolarized.
- what is
- EDV = volume in ventricle after ejection
ESV = volume in ventricle after filling
- what is stroke volume?
- the amount of blood ejected by EACH ventricle/beat, so
SV = EDV - ESV
- what is ejection fraction?
- SV/EDV x 100 - a percent.
Should be greater than 55%.
- What is Cardiac Index?
- the ratio of Cardiac Output to surface area.
- What are the 3 ways to Physiologically control heart rate?
- 1. Funny channels
2. Sympathetic nerv. system
3. Parasymp. nerv. system
- What are Funny Channels?
- Hyperpolariz.-activated cyclic nucleotide-gated channels. HCN
- How do funny channels control heart rate?
What stimulates them?
- they have the greatest influence on SA node firing rate, and so the heart rate.
Stimulated by cyclic AMP.
- how does the sympath. nerv system control heart rate?
- -Enhances funny and Ca+ channels
-Inhibits K+ channels
-Increases heart rate
-Increases slope of pacemaker potential so AP is reached faster.
- what neurotransmitters are used for the sympathetic control?
- Norepinephrine - nerves release
Epinephrine - adrenal releases
- what neurotransmitters are used for the parasympathetic control?
- Acetylcholine from vagus nerve
- How does parasymp nerv system control heart rate?
- decreases it by doing the opposite of sympathetic.
- what is
-normal heart rate
- normal = 60-100 beats/min
bradycardia is <60
tachychardia is >100
- why do endurance athletes have lower normal heart rates?
- their hearts are bigger stroke volume is higher and they don't need to pump as often.
- how is STRENGTH of CONTRACTION increased?
- by increasing
- How is Contractility increased in the heart?
- NOT by increasing EDV.
It is independent of EDV; use ionotropic agents.
- Is the heart at its optimal length when normally pumping?
- No - that's why increasing EDV increases Stroke Volume and the force generated with pumping.
- Without changing EDV, how will increasing Aortic Pressure affect contractility?
- It won't change contractility
- Without changing EDV and contractility, how will increasing Aortic Pressure affect the strength of contraction? Stroke volume?
- It will decrease both strength and stroke volume.
- What is contractility?
- The strength of contraction at any given end-diastolic volume.
INDEPENDENT of EDV.
- What affects Contractility?
- Ionotropic agents
- what are 4 positive ionotropic agents?
- 1. Catecholamines
2. Cardiac glycosides
3. High extracell. Ca2+
4. Low extracell Na+
- what catecholamines increase contractility?
- how do catecholamines affect contractility?
- Myocardial cells have beta-adrenergic receptors that open calcium channels when stimulated with these NTs.
- what are cardiac glycosides?
- for example digitalis
- how does digitalis increase contractility?
- by decreasing Na/Ca ATPase
Intracell. Na increases
Pumping of Ca out decreases, so
Intracell. Ca increases.
- What are the 5 steps in Cardiac Excitation-contraction coupling?
- 1. Plasma membrane depolarizes.
2. Vltg stimulates Ca2+ channels in T-tubules to open
3. Ca2+ binds SR calcium channels
4. SR releases Ca2+ to cytosol
5. Ca2+ binds troponin, causes a POWER STROKE.
- How is myocardial contraction terminated?
- -by Ca ATPase reuptake into SR.
-by Ca ATPase in plasma memb.
-by Ca/Na exchanger pump
By maintaining the Ca/Na gradient.
- What maximizes depolarization and contraction of the heart?
- Intracellular - cytosolic Ca2+.
Because the cells are mech. linked, cannot recruit cells.
Must use Ca2+ concentration
- What increases Myocardial Contraction Strength?
- Cytosolic calcium
- What are 3 negative ionotropic agents?
- -Calcium channel blockers
-High extracell Na
-Low intracell Ca
- What is a calcium channel blocker?
- what does Verapamil do?
- Decreases Ca2+ influx during the plateau phase of the myocardial action potential.
- What type of channel does Verapamil block?
- L-type Ca2+ channels.
- What happens to contractility as heart rate increases?
- Contractility increases because intracellular Ca2+ increases.
- SUMMARY: CO = HR x SV and
-HR is affected by
-SV is affected by:
- HR: sympathetic or parasymp nervous activity
SV: EDV or contractility
- what is cardiomyopathy?
- a group of diseases that affect heart MUSCLE and cause decreased contractility.
- What is cardiomyopathy in young athletes?
what causes it? What is the result?
- hypertrophic cardiomyopathy
-caused by thickening of ventricular walls and septum
-results in fibrillation.
- what is heart failure caused by?
- ventricular remodeling.
- how does the heart change in:
-diastolic heart failure
-systolic heart failure
- diast: hypertropied heart - walls thicken and SV is decr.
syst: dilated heart to compensate for diast failure; results in decreased SV
- what is the body's response to decreased SV in heart failure?
- to increase blood volume - retains fluid.
- How does heart failure affect EDV?
- severely decreased, even with fluid retention.
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