Cardio vascular 3
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The amount of blood that is entered into the ventricles at the end of diastole
End diastolic volume; highest potential
The volume of the blood that is actually ejected out
the strock volume
how to calculate cardiac output
heart rate x stroke volume
How does the parasympathetic nervous system effect the heart
Decreases heart rate; decreases SA node and increase AV node delay ;sympathetic does the opposite
what specific thing does sympathetic nervous system do
contracts smooth muscle in the veins; greater end-diastolic volume -increase contraction of myocardiocytes
extrinsic mechanism
control the heart from the outside the sympathetic nervous sytem is an example
intrinsic mechanisms
dependant on natural characteristics of myocardiocytes and cardiac muscle
the more the myocardiocytes contract the___
higher the strock volume
what are the steps of the ferguson reflex
1.Fetus presses on the cervix 2.sensroy neurons in the cervix send information to the hypothalumus 3.oxytocin is relseased from the posterior pituittary 4.oxytocin stimulates uterine contraction in the smooth muscle 5.fetus presses on the cervix more vigiously contributes to labor and contraction
preload
the potential force generated in the ventricular wall due to cardiac muscle stretch; this increases the contraction capacity of the cardiac muscle
Afterload
The force against which the heart must contract to eject blood out of the semilunar values, particularly the aortic valve
Why is preload so important
allows for equilibrium between both sides of the heart; can compensate for more blood entering the left side
the tunica intima layer of the arteries and veins
large arteries and have an internal elastic layer
Tunica media
-smooth muscle (thicker in arterioles than in arteries) -large arteries have external elastic layer
tunica externa
connective tissue
Arteries are able to expand during systole and recoil during diastole
Helps to serve as a blood reservoir to keep blood moving forward
Mean aterial pressue (MAP)
Average of blood pressure generated throughout a whole cycle. COx TPR (arteriole total peripheral vascular resistance)
what are the function of arterioes
-regulate MAP by controlling total peripheral vascular resistance or the resistance in blood flow
Vasodilation
muscle radius get larger
the smooth muscle maintain muscle tone, what is that
They are always a little contracted
How do they maintain the muscle tone
-myogenic activity -persistent sympathetic stimulation
What does myogenic activity mean
the arteries and arterioes naturally contract when stretched; allows for a middle ground to adjust blood flow
What type of blood flow would occur with a MAP that has high resistance
no blood flow
Vessel stretch
increases vasoconstriction and myogenic activity -type of autoregulation