Exam 4 - CARDIAC Flashcards
MAP reflects what exactly ?
Left Ventricular Afterload
Where are the gap junctions located in the heart muscle ?
at the intercalated discs
What are the high surface areas of the cardiac muscle ?
Intercalated disc
Where are intercalated disc found ?
ONLY in the heart
what is the pattern of the cardiac muscle?
striated muscle - due to lover laying of actin and myosin
How many nuclei do cardiac cells have ?
ONE
What type of muscle is mutli nucliated ?
ONLY skeletal muscle
Sarcomeres of cardiac muscle is similar to skeletal sarcomere ? T o F ?
TRUE
look exactly the same as skeletal muscle
Natural STEM cells do what in our body ?
replace cardiac muscle cells but very slowly
Where are fibroblast found ?
In the heart
What do fibroblast do in the heart ?
Fibroblast lay down scar tissue anywhere that the stem cells cannot fix
What disease can fibroblast repair lead to ?
CHF
laying down of scar tissue unnecessarily
What drug can slow down Fibroblast and why would we want it to ?
ACEi - block growth hormone factor of renin angiotensin system
Fibroblast does not conduct like normal cardiac tissue/muscle.
What drugs do pregnant people not want to be around that helps with heart failure ?
ACE or ARB’s
What word describes the layers and directions of the heart muscle ?
multi-layered SYNCYTIAL
How are the layers of the heart muscle layered?
two distinct layers that move in two opposite directions
Whats included in the “top half” of the heart ?
Left and Right ATRIA
Whats included in the “lower half” of the heart ?
Left and Right VENTRICLES
Different types of the cells in the heart ?
Muscle tissue
How does muscle tissue produce alot of force ?
achieves force by having lots of myofibrils within each muscle cell
How are myofibrils arranged in the heart ?
stacked or laid on top of each other for the length of the cell which increases the force
What makes the conduction tissue of the cardiac muscle different from other tissue?
there is less “stuff” inside the conduction tissue, which increases the force/conduction of the cardiac tissue
Where is the endocardium ??
Deep 1cell-layer thick endotheiliel muscle the heart
What is the myocardium of the heart ?
Bulk of the muscle wall
Where is the epicardium ?
Outer layer of the heart
most superficial layer
Where do most of the major blood vessels sit on the heart ?
The EPICARDIUM
What does the Pericardium consist of ?
Connective tissue of the sac of the heart
Epicardium
Pericardial Space
Parietal Pericardium - Inner layer
Fibrous Pericardium - outer STIFF layer
What layer sits just outside the Epicardium ?
Pericardial Space
What does the pericardial space consist of ?
thin layer of fluid and mucus
what does the pericardial space serve for ?
allows for the movement of the heart without pain
-lubricates the heart muscles at they move
What can increase friction in the heart ?
loss of fluid or inflammation of the pericardial space
Which part of the heart is stretchy ?
Parietal Pericardium
Which part of the heart is leathery and difficult to stretch ?
Fibrous pericardium
Subendocardium means what ?
super deep muscle layer in the heart wall
Where would an MI likely occur?
deep in the subendocardium layer
Where are our pressure the highest in the heart ?
subendocardium - deep in the heart
What increases the liklihood of ischemia in the heart ?
clogged vessels and high wall pressure
How does the orientation of cardiac sarcomere differ from other sarcomeres ?
Cardiac sarcomere is not relaxed to optimum degree
no H band due to actin and myosin filaments slightly overlap (UNDER-STRETCHED when relaxed )
Purkinje Fibers serve what purpose in the heart ?
CONDUCTION
transmit action potentials
What is the resting membrane potential of the purkinje fibers ?
VRM = -90mV
What is the resting membrane potential of the ventricular fibers ?
VRM = -80mV
Ventricular muscle and Purkinje fibers are both permeable to what while resting ?
SODIUM
Is the permeability of Sodium in cardiac muscle constant ?
NO
cardiac ventricular muscle and purkinjie fibers bother have the ability to depolarize with enough
When will you see purkinje fibers or ventricular fibers depolarize on their own ?
When something is WRONG
What is the rate of self-depolarization for purkinje or ventricular muscle ?
VERY SLOW
What is the threshold potential of the purkinje fibers or ventricular muscle ?
- 70 mV
Why does it take a long time for a person to escape a complete heart block naturally ?
LAG time of self-depolarization of the purkinje fibers or ventricular muscles
What is the lag time of self depolarization with the first action potential ?
30 + seconds
What procedure can lead to complete heart block ?
EYE procedures
v + x
Five and dime
where is the trigeminal nerve (CN 5) ?
side of the face
cranial nerve 5 in charge of sensory perception in the eye socket
what is the X in the five and dime ?
cranial nerve 10 stimulating vagal response to decrease heart rate
Phase 4 Ventricular electrical is what ?
RESTING membrane potential
Phase 0 includes what ?
rapid upstroke due to FAST sodium current to influxx
Phase 1
FAST Ca+ current from T-Type Ca+ Channels
When do K+ channels start to close ?
End of phase 0 through phase 1 and 2
During action potential
When do K+ begin to open
end of phase 2 - beginning of phase 3
When do Slow type Ca+ channels open ?
PLATEAU Phase 2
Phase 3
K+ channels open to repolarize and reset the cell
How long is the action potential in the cardiac muscle ?
200 milliseconds
the duration of phase 2 suggest what ?
the duration of the muscle contraction
What is the only outward current in cardiac action potentials ?
K+
Depolarization of cardiac muscles are initiated by what?
Na+ influx
what sustains the depolarization in the cardiac action potential cycle ?
Ca+ influx
Does the influx of Ca make the heart muscle positive ?
not enough calcium coming in to make cell that positive - just sustains the contraction period
V = iR
Ohm’s Law
Voltage = Current x R
Ohm’s Law
Current = i
Resistance = R
Conduction tissue is found where in the heart ?
Purkinje fibers
Positive Deflections on EKG readings occur from what ?
Electrons moving toward positive electrode
Negative Deflections on EKG reading occur from what ?
Electrons moving away from positive electrode
Depolarization happens in which direction in the heart?
INside to the OUTside
endocardium to the epicardium
Re-polarization happens in which direction in the heart?
OUTside to the INside
Epicardium to the endocardium
Area of re-polarization receive current from where ?
depolarized areas transmit current to other areas
What happens if the tissue does not have enough energy
It cannot re-polarize - ischemia does not allow normal resetting
ischemia leaves tissue in what state?
depolarized constantly tissue - will not reset itself electrically and now conducts currents of injury
Currents of injury can give off what ?
currents of injury when there isnt supposed to be any
How does the use of leads help us find areas of injury ?
They offer different perspectives of where the injury current can be coming from
