L14: Cardiac Output & Blood Flow to Muscle Tissues Flashcards
cardiac output definition
quantity of blood pumped into the aorta each minute by the heart
other CO definitions
- quantity of blood that flows thru the circulation
2. sum of all blood flow to all tissues of body
cardiac index
CO per square meter of body surface
calculating CI
normal human = 70kg
body surface = 1.7
CO = 5 L/min
CI = 5/1.7 == 3 L/min/meter squared
cardiac index by age
decreases with age
CO and O2 consumption w/ exercise
both increase w/ exercise
used to calculate blood flow thru an organ
flick principle of blood flow
also for blood flow thru entire body
CO = O2 consumption / (O2pul vein - O2pul art)
how to measure pulmonary vein [O2]
in systemic arterial blood
how to measure pulmonary artery [O2]
in systemic mixed venous blood
using flick principle to calculate CO
= rest O2/ (art - venous)
using flick principle to calculate SV
= CO / HR
what is the determining factor that controls how much blood the heart pumps out?
–the amount of blood that is returned to the heart is what gets pumped out
–the heart pumps out whatever blood it gets
the heart is a _____ pump
demand
pumps out what the tissues demands
the cardiovascular system consists of two ____ and two ____ connected in ____.
2 pumps
2 circuits
connected in series
pumps of the cardiovascular system
left and right ventricles
circuits of the cardiovascular system
pulmonary and systemic circuits connected in series
relate flow in both circuits
- flow is equal in both circuits
relate CO in both circuits
CO is equal
relate pressures of both circuits
systemic is always higher
relate chemical composition of both circuits
pulmonary venous composition = systemic arterial blood
systemic veins = pulmonary arterial blood
factors that directly affect cardiac output
- basic metabolism rate
- exercise?
- age
- size
normal values of CO
young = 5.6
women = 4.9
resting adult = 5.0 L/min
are peripheral or internal factors more important in controlling CO?
peripheral factors
frank-starling law of CO
heart automatically pumps whatever amount of blood that flows into the right atrium
stretching of heart causes…..
heart to pump faster and initiates Bainbridge reflex
ohm’s law of CO
any time the long-term level of total peripheral resistance changes, the CO will change in opposite direction
Bainbridge reflex
atrial stretch reflex
it responds to changes in blood vol. as detected by stretch receptors in right atrium
can control HR
baroreceptors
respond to changes in arterial pressure
for HR control
baroreceptors and Bainbridge reflex importance
not very important in humans