Heart / Cardiac
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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
Coronary circulation goes to the ......
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
How many nucleus per cell does cardiac muscle have?
Does cardiac muscle have troponin?
Does smooth muscle have troponin?
Does skeletal muscle have troponin?
Does the cardiacmuscle have T-tubules?
Does the smooth muscle have T-tubules
Does the skeletal muscle have T-tubules
Fibers in the cardiac muscle are connected by ______ ______.
Which contain ______ & ______
- Intercalated discs
- Desmosomes and Gap Junctions
What do Desmosomes and Gap Junctions do?
Does cardiac muscle contain pacemaker cells?
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
Stretching of specialized atrial cells causes them to release -____
Action of ANP in the heart is....
- Acts as hormone to increase Na+ excretion.
- Inhibits renin, aldosterone, and ADH
kidneys excrete _____ (natriuresis) and _____ (diuresis) which will decrease blood volume
What 3 things happens?
NaCl & H2O.....
Salt & water
- GFR increases by widening filtration slits
- NaCl & H2O reabsorption in collection duct
- Lowers BP by dialating aterioles.
Contraction speed of all three muscle types. Slowest to fastest.
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
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
Is an AP of cardiac muscle produced to Calcium influx or sodium influx?
Due to Calcium influx
What is gradual depolarization known as?
SA node depolarizes on its own _-__ times ina minute
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
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
Resting potential of ventricular fiber = __-__mV
Ventricular fibers are more permeable to __ than to ___
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
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
Purkinje fibers - Impulse Travels __ m/sec
Average pulse rate is _-_ beats/min. (__ beats if you want one number)
< 60 beats/min. =
100 beats/min. =
What does an ekg MEASURE?
the Electrical Events of the Heart Using Electrodes to Sense the Minute ElectricalChanges on the Skin
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
Starts from SA NODE -->
PR INTERVAL: Signal enters AV Node / Enters bundle HIS
QT INTERVAL: Time it takes for de-repolarization of venticals
QRS INTERVAL: Ventricular depolarization
T: Ventricular repolarization
ST: Period where Ventricals are Depolarized ( walls relaxed)
Average Heart Axis = _____ degrees
Normal range of heart axis is from _ - _ degrees.
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.
Volume of blood ejected = ____ ____
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 = ~ __%
Cardiac Output for Left Ventricle Equation:
CO = HR x SV (stroke volume)
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.
- an increase in arterial pressure tends to reduce stroke volume
If heart rate exceeds 200 beats/min. There is not enough time ......
for ventricles to fill
2 things that affects heart rate
Left ventricle contracts and goes to lungs via pulmonary trunk
RIght ventricle contracts and goes to body via aorta
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