lab 7 Flashcards
cardiac cycle
involves sequential contraciton of atria and ventricles
hearts rhythmical contraction sequence
triggered from action potentials from myocardial cells
body fluids are
good conductors of electricity and able to be easily recorded at the surface
electrocardiogram
electrical currents associated with depolarization and repolarization of the heart that are measured as electrical potential across the body surface by placing electrodes on opposing sides of the heart
myocardial cells
where electrical signals to initiate vertebrate heart contraction originate
excitation and inhibition of the heart accomplished by
changes to contraction rate and various other parameters associated with myocardial contraction
T-P interval
time between beats
P-T interval
overall time that a complete depolarization/repolarization occurs
arterial system
receives blood from the heart and distributes it throughout the body
pressure resevoir for arteries
the amount of blood flood is directly related to the pressure difference along an artery
increased heart function
increases centralized blood pressure
signals from autonomic nervous system control
the degree of contraction of smooth muscles found in walls of arteries
vasoconstriction
increase centralized blood pressure
vasolidation
decrease centralized blood pressure
autonomic nervous system effects alter
how much blood goes to various organs
Fight or Flight
autonomic nervous system releases epinephrine from adrenal glands which bind to heart and cause it to be faster
after fight or flight
parasympathetic system releases acetylcholine from vagus nerve that binds to receptors on heart causing it to beat slower
peripheral feedback loops
simultaneously coordinate heart activity, arterial blood pressure and overall blood flow in the body
baroreceptor reflex
ensures central arterial blood pressure is maintained but not so high that arterial blood vessels are ruptured and there is excess fluid leakage
diving bradycardia
heart rate is substantially reduced to ensure blood pressure in central arteries does not exceed safe levels
diving causes
selective peripheral vasoconstriction (significant increase in blood pressure to central arteries
and sharply reduced blood flow to limbs gut and skin
(sensures blood is deliverd to organs with highest need for blood)
