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27 Cards in this Set

  • Front
  • Back

autorhythmicity

1. self-generated action potential


2. 15-20% of heart cells are autorhythmic



sinoatrial node

1. pacemaker cells, upper right of right atrium


2. 120-140 beats/minute


3. action potentials originate in this node



prepotential

1. similar to threshold w/skeletal muscle tissue


2. the heart is always ready to pump again

Atrioventricular (AV) node

1. electrically connects atrial and ventricular chambers


2. electrical signal travels from SA node to AV node



Atrioventricular (AV) bundle

1. embedded in myocardium


2. conductive fibers in septum between the 2 ventricles


3. bundle branches

Purkinje fibers

1. smaller fibers that carry impulse to all cells in myocardium of the ventricles


2. reach papillary muscles which operate valves

electrical stimulation path in heart

1. SA node


2. AV node


3. AV bundle


4. bundle branches


5. Purkinje fibers

EKG or ECG: P wave


1. atria depolarization


2. atria systole


3. contraction





EKG or ECG: QRS Complex

1. depolarization


2. ventricular systole


3. contraction


EKG or ECG: T Wave

1. repolarization


2. relaxation


3. diastole

end systolic volume

amount of blood left in left ventricle after contraction

If a person exercises

1. left ventricle can accommodate more blood


2. heart grows, so it can handle larger volume


3. walls of chamber have to get thicker -- denser muscle needed to push extra blood out

enlarged heart

large heart but myocardium can't accommodate extra blood -- not thick enough

cardiac output

how much blood is flowing through left ventricle

mean arterial pressure

collective pressures of body

stroke volume

amount of blood left ventricle pumps each time

CO = SV x HR

1. CO: cardiac output


2. SV: stroke volume


3. HR: heart rate

venous return

amount of blood flowing back to heart

cardiac reserve

amount of blood heart could pump at optimal conditions (at rest or exercise)

intrinsic regulation -- preload

stretching walls of heart in order to contract maximally

intrinsic regulation -- reload

resetting

vagus nerves

1. release ACH onto nervous tissue


2. inhibits heart rate and contractions


3. extrinsic regulation

cardiac nerves

1. secrete epinephrine


2. increase heart rate


3. increase contractions


4. extrinsic regulation


5. long-term regulation

baroreceptor reflexes

1. pressure receptors located in aorta and carotid arteries -- short term regulation


2. vagus and cardiac nerves respond to baroreceptor to adjust blood flow

short term regulation of heart functions

tell yourself to calm down, breathe deep

cardioregulatory centers

medulla oblongata has a visceral reflex

adrenal medullary mechanism

1. increases blood pressure and heart rate


2. increases epinephrine, part of endocrine system