Exam 2- Chapter 17 Flashcards
cardiac muscle cells
contain myoglobin (protein that carries oxygen)
how does the heart contract
gap junction
cardiac muscle cells rapidly spread electrical activity via electrical synapse
conduction system
- SA nose
- Intermodal pathways
- AV node
- AV bundle
- Bundle branches
- Purkinje fibers
positive chronotropic agents
anything that increases HR
negative chronotropic agents
anything that decreases HR
how does the sympathetic NS increase CO (which effects HR)
-sympathetic NS intervates the heart via sympathetic nerves
-sympathetic nerves release norepinephrine which increase CO with positive chronotropic agents
how does the parasympathetic NS decrease CO (which effects HR)
-intervates the heart by left + right vagus (X) nerve
- Vagus (X) nerve releases acetylcholine which decreases CO generation
where does the heart get energy for contractions
myoglobin in cardiac muscle cells & mitochondria in cytoplasm of cardiac muscle
P wave
atrial depolarization (systole)
QRS complex
ventricular depolarization (systole)
(masking atrial repolarization)
T wave
ventricular repolarization (diastole)
R-R interval
entire duration of heartbeat
used to take heart rate
P-R interval
duration of atrial depolarization
av node delay
Q-T interval
duration of ventricular action potential
S-T segment
ventricular pleatau phase
- ventricular filling phase
-blood drains atria –> ventricles
-AV valves open in high pressure in atria & close in high pressure in ventricles
-after atria systole, 120 ml of blood is in ventricles (end diastolic volume)
- isovolumetric contraction phase
-ventricle systole begins
-AV valves & systole valves close while pressure builds in ventricles
- ventricular ejection
-pressure in ventricles open semilunar valve and blood ejects into pulmonary artery or aorta
-70 ml of blood from each ventricle
- 50 ml remain after ventricular systole (end systolic volume)
- isovolumetric relaxation phase
-semilunar valves close bc pressure builds in ventricles
“lub” or S1
AV valves close
“dub” or S2
semilunar valves close
cardiac output
amount of blood the heart pumped in 1 min
stroke volume
amount of blood in 1 heartbeat
average heart rate
average of 60-80 bpm
__ + ___ = HR
SV + CO = HR
positive chronotropic agents that influence HR
-norepinephrine
-epinephrine
-glucagon
-aldosterone
-antidiuretic
negative chrontropic agents that influence HR
-acetylcholine
-ANP
factors that contribute to HR
-age
-physical fitness
-exercise
coronary artery disease
build up of fatty material (plaques) in coronary artery
-decreases blood flow (oxygen) to myocardium –>myocardial ischemia
symptoms of coronary artery disease
chest pain –>angia pectoris
most dangerous consequence of coronary artery disease
heart attack –> myocardial infarction
