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Heart Acts as a Pump to Push Blood through Two Major Circulatory Routes:
What are they?
Where do they pump to?
- 1. Pulmonary circulation - to the lungs and the right heart pumps to this
- 2. Systemic circulation - to the body and the left heart pumps to this
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Coronary circulation goes to the ......
Heart wall
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What are the 3 walls of the heart?
Endocardium covers inner most layer of heart, covers heart valves & tendons.
Myocardium is the thick middle layer, pumps blood into aorta & pulmonary trunk.
Epicardium is outer most layer and contains an inner layer called the Visceral Pericardium
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How many nucleus per cell does cardiac muscle have?
One
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Does cardiac muscle have troponin?
Does smooth muscle have troponin?
Does skeletal muscle have troponin?
Yes
?
?
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Does the cardiacmuscle have T-tubules?
Does the smooth muscle have T-tubules
Does the skeletal muscle have T-tubules
Yes
?
?
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Fibers in the cardiac muscle are connected by ______ ______.
Which contain ______ & ______
- Intercalated discs
- Desmosomes and Gap Junctions
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What do Desmosomes and Gap Junctions do?
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Does cardiac muscle contain pacemaker cells?
Yes
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Certain normal atrial cells secrete a hormone called ____ which is a family of ____ hormones and is made in the ____ & Brain.
In the brain it acts as a ....
Neuromodulator or neurotransmitter
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Stretching of specialized atrial cells causes them to release -____
ANP
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Action of ANP in the heart is....
- Acts as hormone to increase Na+ excretion.
- Inhibits renin, aldosterone, and ADH
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kidneys excrete _____ (natriuresis) and _____ (diuresis) which will decrease blood volume
What 3 things happens?
GFR...
NaCl & H2O.....
Lowers...
Salt & water
- GFR increases by widening filtration slits
- NaCl & H2O reabsorption in collection duct
- Lowers BP by dialating aterioles.
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Contraction speed of all three muscle types. Slowest to fastest.
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Excitation-contraction coupling is similar to skeletal muscle except......
- AP from Na+ voltage gates doesn't open Ca2+ channels of S.R.
- Ca++ voltage gates in the membrane open and Ca++ diffuses into cell and that opens Ca2+ gates in S.R.1. called calcium-induced calcium release process2.
- Ca++ removed from cytosol by Ca2+/ATPase pumps in S.R. and sarcolemma and by Na+/Ca2+ transport or antiport pumps in sarcolemma.
- b. Contractions are more graded than skeletal.
- 3. Cardiac cells have Na+/K+ ATPase pumps in the sarcolemmaB.
- Fibers are Stimulated to Contract by Depolarization of SA Node Fibers
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Pacemaker Potential: Cardiac
Potassium channels which open during _____ are now ____.
F-Type (funny) Channels are open, when stimulated by a _____ charge. _ and _ pass through but _ inflow exceeds _ outflow. As voltage change moves towards threshold, the Na channels ____ and some __ channels open briefly continuing the depolarization.
Ca+ T-Type Channels open at ______ of ______ _____ when threshold of _____ is met, many Ca+ ____-__ channels open ________ occurs and AP is produced.
L-Type Ca channels close at peak and slow K+ channels open. Repolarization due to outflow of K+. Ca+ is also pumped into S.R or ECF. When K+ channels close, the cycle starts again.
Repolarization / Closing
- Negative / K+ and Na+
- but Na+ inflow exceeds K+ outflow.
- Close / Ca+
- Middle of Pacemaker potential
- -40mV / Type-L
- Depolarization
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Is an AP of cardiac muscle produced to Calcium influx or sodium influx?
Due to Calcium influx
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What is gradual depolarization known as?
Pacemaker potential.
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SA node depolarizes on its own _-__ times ina minute
80-100
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A.N.S affect upon SA node fibers:
Parasympathetic division causes an increase in the permeability if the cell membrane to..... thus...... inhibits..... thus....
Why (2 reasons)
to K+ thus making cells diastolic potentials negative and inhibits F-Type Sodium channel opening thus slowing depolarization.
- 1. slows down the pacemaker rate by activating muscarinic receptors
- 2. inhibits Ca2+ permeability
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A.N.S affect upon SA node fibers:
Sympathetic N.S. _____ leakage of Ca++ into the _____ and opens ________ channels too:
Act on _______ ____
NE causes opening of ___ & ___ channels to ______ the pacemaker potentials, slope of pacemaker becomes steeper.
Speeds up / Cytosol / F-type Na+ Channels
- Act on B-1 receptors
- Na+ and Ca+ / Speed up
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Resting fiber:
Resting potential of ventricular fiber = __-__mV
Ventricular fibers are more permeable to __ than to ___
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Atrial Fibers - Impulses Travel __-___ m/sec
Do they have a long plateau?
AV Node - Impulses Travel __-___ m/sec
Conduction through AV node is ________
Take approx ___ because the fibers are ___ in diameter
Sypmatethic N.S ________ the conduction rate on AV node impulses.
AV Node impulses travel 0.03-0.05 m/sec
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AV Node impulses can depolarize __ - ___times/min
If SA node is not working, cells in the _____ _ ___take over _________ job.
- 25- 40
- Bundle of HiS / Pacemaker
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Purkinje fibers - Impulse Travels __ m/sec
5m/sec
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Average pulse rate is _-_ beats/min. (__ beats if you want one number)
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< 60 beats/min. =
Bradycardia
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100 beats/min. =
Tachycardia
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What does an ekg MEASURE?
the Electrical Events of the Heart Using Electrodes to Sense the Minute ElectricalChanges on the Skin
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Clinical ECGs:
a. lead I - reading between
b. lead II - reading between
c. lead III - reading between
d. avF - unipolar
e. avR - unipolar
f. avL - unipolarg. 6 chest leads
NEED TO FINISH
- a. lead I - reading between left and right arms - bipolar
- b. lead II - reading between left leg and right arm - bipolar
- c. lead III - reading between left leg and left arm - bipolar
- d. avF - unipolar
- e. avR - unipolar
- f. avL - unipolar
- g. 6 chest leads
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Starts from SA NODE -->
PR INTERVAL: Signal enters AV Node / Enters bundle HIS
QT INTERVAL: Time it takes for de-repolarization of venticals
PT INTERVAL
QRS INTERVAL: Ventricular depolarization
T: Ventricular repolarization
PQ:
ST: Period where Ventricals are Depolarized ( walls relaxed)
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Average Heart Axis = _____ degrees
Normal range of heart axis is from _ - _ degrees.
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The left ventricle goes through two major phases, what are they?
Systole: Pressure of artery during left ventricle contraction.
&
Diastole: Pressure of artery during right ventricle contraction.
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Volume of blood ejected = ____ ____
Stroke volume
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at 72 beats/min, average ejection volume is ____mL?
70% - 80% of ventricle fillling is ______ does and does not need the ______!
Ejection Fraction at rest = ~ __%
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Cardiac Output for Left Ventricle Equation:
CO = HR x SV (stroke volume)
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What three things affect stroke volume?
Sympathetic Input - NE & E which attach to B1 - adrenergic receptors --> stimulate Adenylyl Cyclase --> increases force of contraction & not dependent on end diastolic volume.
- changes in end-diastolic volume:
- Frank Starling's law of the heart: as ventricular end diastolic volume goes up, stroke volume goes up
- a. cardiac cells do not rest near optimum length but are too short.
- b. depends on venous return and also makes troponin's affinity to Ca2+ go up
- c. the greater the end-diastolic volume, the more the heart muscle is stretched.
- Afterload:
- an increase in arterial pressure tends to reduce stroke volume
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Heart rate:
If heart rate exceeds 200 beats/min. There is not enough time ......
for ventricles to fill
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2 things that affects heart rate
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Left ventricle contracts and goes to lungs via pulmonary trunk
RIght ventricle contracts and goes to body via aorta
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