Lab 8 Flashcards
Functional syncytium of muscle fibers, and the individual cells are electrically coupled
Cardiac Muscle
Impulse in a cardiac muscle is
all or none
the cardiac muscle contract more forcefully when stretched within limits
Starling’s law
cardiac muscle is made up of bulk of
myocardium
cells that contract without external stimulus
autorhythmic
the rate at which a heart beat is determined by what part of the heart? located at the rear of the heart
SA node
normal heart beat
70-75 times/minute
factors that influence the cardiac muscle contraction
nervous input, chemical & metabolic change, temperature
coordination of heart beat is due to the specialized conduction pathways located where?
in and between the atria and the ventricle
one feature of the path
delay of the AV node
allows the atria to complete their contraction before the ventricles begin to contract
delay of the AV node
(pacemaker) due to changes in the membrane channel conductances of
K, Ca, Na
ionic fluzes are modified by autonomic inputs, rate and force of contraction of heart can be
increase, decrease
frog heart has ___ chambered
3 (2 atria and 1 ventricle)
human heart has ____chambers
4 (2 A and 2 V)
where deoxygenated blood arrives
RA
where oxygenated blood arrives
LA
after passing in the atrium it goes to the
Ventricles
During ventricular systole the blood leaves through what?
truncus arteriosus
this prevents the mixing of deoxy and oxygenated blood
truncus arteriosus
heart is enclosed by
pericardium
ion that play important tole in excitation contraction coupling sequence
Ca
the excitation starts from __ to ___
atria to AV node
where electrical impulses travel
bundle of His and purkinje fibers
condition when the wave of excitation-contraction E-C can not proceed because of infarct or mechanical obstruction
heart block
atria is dependent on ventricle
true
cardiac influence extrinsic and intrinsic factors
neural hormonal. chemical, physical etc
change in heart rate can be applied by adding para and sympa stimuli
chronotropic effect
speed up the heart
epinephrine and norepinephrine
slows down the heart
acetylcholine
flow that keeps the pace of the heart..under the control via
tonic parasympathetic
vegal tone
this effects can also be seen after administration of drug, including receptors, or channels or blockers
chronotropic effects
use as a beta blocker, decreases heart rate
propanolol
induces faster heart rate by blocking muscarinic type of acetylcholine receptors
atropine
change in force, positive or negative, observed by altering the degree of stretch of the cardiac muscle fibers
inotropic effect
stretching the heart can achieved by
filling the heart more with blood during diastole
more Ca means
more availability of greater force
effect when epinephrine and norepinephrine are applied
inotropic effect
channel blockers used to decrease the force generated by the heart
Ca channel blockers
increase the chart speed and make a record of several bears
contractile sequence
recorded ventricular contractions under normal condition and effects of chemicals when applied
ventricular contraction
effects on the heart rate
chronotropic
effects on the force of contraction
inotropic
length of the cardiac fiber can be changed by
adjusting the tension
