lecture 7 Flashcards
types of ciculation
1- pulmonary circulation
2- systemic circulation
contraction and relaxation phase
systole and diastole
heart rate
averages 60-80bpm
- highly trained athletes = 45bpm
- bradycardia = HR < 60bpm
- trachycardia = resting HR > 100bpm
how to calculate max HR
220 - age
cardiac cycle
1- ventricular diastole: passive filling - atrial contaction
2- ventricular systole: Av valves close - semilunar valves open, ventricules eject blood
ventricular filling
passive filling of ventricle = 70-80% of end disatolic volume. Atrial contraction tops up 20-30%
isovolumetric contraction
ventricles begin to contract but volume does not decrease until pressure exeeds that in the aorta and the semilunar valves open (increase and decrease in pressure)
ventricular ejection
semilunar valves open
- semilunar valves close when pulmonary pressures exeeds ventricular pressure
stroke volume
during systole blood is ejected from the left ventricle, the blood that gets pumped out is the stroke volume
stroke volume equation
SV = EDV - ESV
(EDV- the amount of blood filling the ventricles)
ESV- remaining blood after blood is ejected)
End diastolic volume
total amount of blood filling the LV
EDV is affected by:
1- filling time
2- filling amount
end systolic volume
amount of blood left following contractions ESV is affected by: 1- ventricular pre load 2- ventricular contractability 3- ventricular after load
frank starling law of the heart
force of contraction is related to the stretch of the ventricle
Baroreceptors
- located in the aortic and cartoid bodies
- change in BP stimulates baroreceptors which sends signals to the medulla
- the medualla corrects BP by modifying the ANS
baroreceptor feedback
decrease in BP: - error alert to the brain (medulla) - PNS inhibition - SNS activation increase in BP: - pressure error registered - PNS stimulated - SNS inhibited
