Lab 7 Flashcards
The pacemaker region of the heart is the
SA Node
The conducting tissue of the heart located in the inter ventricular septum is the
Bundle of His
P Wave
Depolarization of Atria
ORS Complex/Wave
Depolarization of Ventricles
T Wave
Repolarization of Ventricles
The electrical synapses between adjacent myocardial cells called
gap junctions
An abnormally fast rate of beat
Tachycardia
An abnormally slow rate
Bradycardia
An abnormally long PR interval indicates a condition
1st degree heart block
Which ECG wave must occur before the ventricles can contract?
QRS
Which ECQ wave must occur before the ventricles can relax?
T Wave
What could cause an increase in the peripheral resistance in a blood vessel?
a clogged artery
ventricular contraction
systole
the amount of blood each ventricle pumps per minute
cardiac output
the amount of blood pumped to the body per contraction per ventricle
stroke volume
the volume of the blood in the heart at the end of ventricular contraction
end systolic volume
ventricular relaxation
diastole
contraction that occurs when the volume of blood in the ventricles remains constant
isovolumetric contraction
the volume of blood in the heart at the end of ventricular relaxation
end diastolic volume
the ejection of blood near the end of systole during which ventricular pressure rises and then begins to decline
ventricular ejection
Frank Starlings Law
When the rate @ which blood returns to the heart changes, the heart will adjust its output to match the change in flow.
What variable had the strongest effect on fluid flow?
Radius
What would occur if the left side of the heart pumped faster than the right side?
Blood would soon empty from the heart, and stroke volume would fall greatly.
The sympathetic nervous system releases the neurotransmitter
Norepinephrine
The PNS releases the neurotransmitter
Acetylcholine
The Symmpatheic NS _______ heart rate
increases
The PNS ________ heart rate
decreases
Autorhytmicity
the hearts ability to trigger its own contractions
SA node
the pacemaker of the heart, where the cardiac cells with the fastest contraction rates join together
Pacemaker cells
cells in the SA node
Vagus nerves
cranial nerve that delivers PNS input to the heart
Difference between cardiac muscle and skeletal muscle
Cardiac muscle displays autorhythmicity, skeletal muscle does not. Cardiac muscle has a relative long refactory period, skeletal muscle has a relative short refractory period.
Epinephrine
increases heart rate and strengthens contractions
Pilocarpine
decreases heart rate, mimics AcH
atropine
increases heart rate, inhibits AcH
Digitalis
decreases heart rate, blocks conduction of atrial impulses to the ventricles
Ca2+
induces irregular heart rate, increases strength of contraction
Na+
induces irregular heart rate; decreases strength and rate of contraction
K+
intially causes heart rate to decrease then causes it to become irregular; weakens contractions
SA Node
Pacemaker of the heart, origin of electrical signal causing heart to contract
AV Node
delays the AP’s before sending the AP to the bundles of HIS (ensures atrias have fully contracted before the ventricles)
R & L bundle branches
Directs the AP to base of the ventricles (lay within the interventricular septum)
Purkinje Fiber
Receives stimulus from bundle branches and stimulate the ventricles from bottom to top direction
Bundle of His
electrical connection between atrias and ventricles
Why is atrial repolarization masked by ORS complex
Because of mass differences between atrias and ventricles
What changes are normal between pre and post exercise ECG’s and what parameter should never change!
Heart Rate changes. Ventricular diastole: the time between the peak of the T wave to the next ORS complex (ventricles are compeltely relaxed - should change). PR should never change this represents how long it takes the signal from the Atria to ventricles
Systolic Pressure
Pressure generated by the contracting ventricles
Diastolic Pressure
Pressure in the system when the ventricles are relaxed
MAP
Diastolic Pressure + 1/3 (Pulse Pressure
Pulse Pressure
Systolic-Diastolic
The scientific term for insufficient blood flow to the heart is called …
Ischemia
