Cardiovascular system Flashcards
Purpose of cardiovascular system
transport O2 and nutriets to tissue
removal CO2 wastes from tissue
regulation of body temp
During exercise 2 major adjustments of blood flow
increased CO
redistribution of blood flow from inactive organs to active muscles
Heart
creates pressure to pump blood
Arteries/arterioles
carry blood away from heart
distribution/resistance vessels
Capillaries
exchange O2, CO2 and nutrients with tissues
Veins/venules
carry blood towards the heart
capacitance
Pulmonary circuit
right side
pump deoxygenated blood to lungs via pulmonary arteries
return oxygenated blood to left side via pulmonary vein
Systemic circuit
left side
pump oxygenated blood to muscle via arteries
return deoxygenated blood to right side via veins
Wall components
smooth muscle
collagen
elastin
endothelium
Smooth muscle
change resistance
redistribute blood flow
Endothelium
blood flow over trigger response to dilate = more blood flow
Plasma
liquid portion of blood
contains ions, proteins, hormones
Red blood cells
erythrocytes
contain haemoglobin
White blood cells
prevent infection
Platelets
blood clotting
Hematocrit
percentage of volume of red blood cells
42%
Blood flow gradient
high pressure to low pressure
pressure generated by heart
Which side of the heart has lower pressure?
right
due to lungs
Resistance to flow
through vessel, caused by friction between blood vessel in wall
main resistance provided by arteries/arterioles
Total peripheral resistance
sum of resistances to flow in all individual organs
MAP = CO x TPR
Darcy’s law
blood flow = change pressure / resistance
Blood flow direction
directly proportional to pressure (p1-p2)
inversely proportional to resistance
Pressure direction
proportional to difference between MAP and right arterial pressure
Resistance depends on
length of vessel
viscosity of blood
radius of vessel
Resistance equation
length x viscocity / radius4
Poiseuille’s law
for a single vessel
resistance inversely proportional to radius4
Sources of vascular resistance
MAP decreases throughout systemic circulation
largest BP drop occurs across arterioles
Oxygen consumption equation
cardiac output x A-V oxygen difference
Arteriovenous difference
amount O2 taken up from 100ml blood
increase during exercise due to increase O2 uptake in tissues
used for oxidative ATP production
Fick equation
VO2 = Q (cardiac output) x a-vO2 difference
Central command theory
initial signal to drive cardiovascular system form higher brain centres
due to centrally generated motor signals at onset of exercise
Afferent feedback from
muscle mechanoreceptors
muscle chemoreceptors
baroreceptors
Exercise pressor reflex
peripheral feedback to medulla oblongata to amend CV response to exercise
Barorecptors
sensitive to changes in arterial blood pressure
Mechanoreceptors
muscle spindle/golgi tendon organ
sensitive to force and speed of muscular movement
Chemoreceptors
sensitive to changes in chemical environ
metabolites (H+ ions, lactic acid, CO2, pH)
Baroreflex
reset during exercise
curve shifted right
central command/exercise pressor reflex reset arterial baroreflex
Dual control
redundancy
Cardiac output direction
directly proportional to metabolic rate required to perform during exercise
HR
number of beats per minute
SV
amount of blood ejected in each beat
End diastolic volume
volume of blood in ventricles at end of diastole (preload)
venous return
frank starling mechanism (stretch of ventricles)
Average aortic blood pressure
pressure that heart must pump against to eject blood (afterload)
mean arterial pressure
Contractility enhanced by
circulating epinephrine/nor
direct sympathetic stimulation of heart
Double product
HR x systolic BP
Effect of aerobic training on sarcomeres
eccentric hypertrophy
Effect of resistance training on sarcomeres
concentric hypertrophy
During exercise time spent in diastole and systole
decreased
greatest decrease in diastole
Stroke volume during incremental exercise
increases to 40% VO2max
Contraction of left ventricle
bundle branches depolarise
ventricle contracts
ventricular pressure increases
blood exits the ventricle
How are electrical implulses conducted between heart muscle cells?
intercalated discs
