CV5 Flashcards
as force of contraction increases, _________ increases
stroke volume
what are the 2 forces that determine the force generated by cardiac muscle
the contractility of the heart
the length of the muscle fibres at the beginning of contraction
what determines the length of muscle fibres at the beginning of contraction
the amount of blood in the ventricle (EDV)
what is the contractility of the heart
the strength of the muscles contraction when it receives a signal to beat
what is contractibility controlled by
nervous system and endocrine system
what is a chemical that affects contractibility called
inotropic agent
what is an inotropic agents influence referred to
inotropic effect
what are chemicals that would increase contractility of the heart? what kind of effect is that
epinephrine
it would be a positive inotropic effect
whats the main determinant of contractility
the sympathetic branch of the autonomic system
does cardiac muscle like to be stretched or no
it likes to be stretched because it generates the most force when it is stretched
increasing sarcomere length in cardiac muscle increases __________
stroke volume
what is the frank starling law of the heart
stroke volume increases with increasing end diastolic volume
what is preload
the degree of myocardial stretch prior to contraction
what is EDV normally determined by
venous return
what is venous return
the flow of blood back to the heart through the veins
what are the three factors affecting venous return
- skeletal muscle pump
- respiratory pump
- sympathetic contraction of veins
what is after load
the resistance that the heart must overcome in order to open the aortic valve (overcoming the pressure in the aorta)
also applies to pulmonary
what does bigger after load cause
hypertrophy of the heart (causes your heart to work harder)
does blood flow ever stop
nope
what is considered the pressure reservoir
systemic arteries
what controls the blood flow when your ventricle is relaxing
recoil of large arteries
what can arterioles do
they can change resistance and redirect blood flow
what is there the greatest number of in your circulatory system
capillaries
where does exchange between blood and cells (interstitial fluid) happen
capillaries
