Exam 2 Flashcards
(189 cards)
Cardiac muscle doesn’t require a nerve impulse beca
the heart uses an intrinsic method of conduction
Cardiac reserve
amount of extra blood that can be pushed through the heart when we need it to be
Stroke volume
amount of blood pushed out the heart during each beat
Stroke volume
end diastolic- end systolic
Cardiac output
SV x HR
Factors effecting stroke volume
stretch of cardiac muscle
Contraction strength
arterial pressure
Stretch of cardiac muscle
pre load
- the more blood in ventricles, more stretch, and stronger contraction
-causes ejection of more blood
-starling law of heart
Contraction strength
neither pre or post
-muscles can change its permeability to calcium which causes increase in strength of contraction
Arterial pressure
after load
-if there is increased pressure in the vessels, the heart cant’t push blood out because it has to go from high to low pressure
Cardiac output is what kind of variable?
homeostatic
If stroke volume increase, heart rate
slows down
Factors affecting heart rate
Parasympathetic nervous activation
Sympathetic nervous activation
Adrenal Medulla production of norepinephrine
Thyroxine
BP changes
Ionic balances
Age
Sex Exercise
Temperature
Parasympathetic nervous activation
releases acetlycholine, which causes hyperpolarization of the SA node. Makes it harder to create a pacemaker potential. slows it down
Sympathetic Nervous Activation
-releases norepinephrine, which causes the heart rate to increase.
-changes the sa node so it depolarizes faster
-increase in contractibility of the muscle
Adrenal Medulla production of norepinephrine
releases norepinephrine as a hormone
-increase in heart
Thyroxine
-increases cellular metabolic activity
BP changes
-detected by special receptors called baroreceptors
-if BP goes up, less blood can get out of the heart, so the heart needs to speed up
Ionic balances
-speed up or slow down heart rate depending on what we have
Age
-heart rate declines as you age->you wont be able to raise heart rate as high
Sex
females have a faster heart rate than males
Exercise
will go up, but if you continue long term aerobic exercise program, your resting heart rate will decrease
Temperature
heart rate goes up when you have a fever
Vagal escape
when heart starts racing when it shouldn’t be-> issue with vagal tone
Tachycardia
abnormally high resting heart rate >100BPM