lecture 7 - cardiovascular changes Flashcards
what are the 2 parts of the circulatory system
heart
blood vessels - arteries, veins
what are the three main functions of the CV system
- transport of substances
- removal of waste
- protecting the body (immune function)
when does the heart start to beat?
around 3 weeks
how does the cardiovascular system differ in foetus to adulthood. and the two shunts in the heart?
placenta provides oxygen for the infant therefore the blood does not need to travel to the heart. the foetus has a foramen ovale which connects right and left atria. and a ductus arteriosus which connects the aorta and the pulmonary artery
- the left and right atrium have the same job in foetus whereas in adult they have different functions
what are the shunts in the foetus heart?
foramen ovale - connects right and left atrium
ductus areteriosus - connects aorta and pulmonary artery
are lungs needed in a foetus?
no as they get all the oxygen from the mother
what are the changes in the heart size of a foetus
left and right are the same in fetal life but once born the left will increase more than the right as it has to push blood around the body
what is left ventricular hypertrophy? is this good or bad?
the heart walls thicken due to blockages and then heart has to work harder - this is bad as the volume of heart does not change which means the left ventricle has shrunk
is an endurance athletes heart larger than a non athletes?
yes
what are the heart rates for an infant, adult male and female?
newborn = 140bpm
Adult male = 72bpm
adult female = 76bpm
what does HR mean?
Heart Rate = beats per minute
SV?
Stroke volume = volume ejected per beat
Q?
Cardiac output = HR x SV (ml/min) or (L/min)
how do you work out the cardiac output?
HR x SV = ml/min or L/min
what does it mean if there is a dot above a letter?? e.g Q (dot above)
the dot means per minute
what happens with the heart function from birth to adulthood
the heart rate drops while the stroke volume increases
what is systolic and diastolic?
systolic = highest pressure during contraction of left ventricle diastolic = lowest pressure during relaxation of the left ventricle
how is blood pressure recorded?
systolic over diastolic
what happens to blood pressure as we grow?
the pressure increases as we grow
does blood volume change over growth? and what is a newborn and adults
yes newborn has 300-400mls while adults have about 5L
what is the ratio of blood
55% plasma = 90% H2O, 7% plasma, 3% other
45% formed elements = 99% red blood cells, 1% white blood cells and platelets
what happens to haematocrit from newborn to adulthood?
newborn at 50% then drops to 30% at age 3 then increases throughout growth
PO2?
partial pressure of oxygen
PCO2
partial pressure of carbon dioxide
what is the PO2 and PCO2 of blood in neonate (infant less than 4 weeks old) from lung to muscle?
PO2 = 100 PCO2 = 40
what is the PO2 and PCO2 of blood in neonate (infant less than 4 weeks old) from muscle to lung?
PO2 = 40 PCO2 = 46
what happens in haemoglobin during growth?
increases - more in males than females as they are more active = more mass
what are the changes in the CV system in the aged?
- thickening of vessels and left ventricle
- increase stiffness in aorta = increased systolic blood pressure
- possible fragmentation (clots)
what happens to resting heart rate and max heart rate as we age?
- resting heart rate doesn’t seem to change
- max heart rate decreases 10bpm per decade and is inevitable
how do you calculate max heart rate in a healthy adult and in an over 40?
healthy = MHR = 220 - age
over 40 = MHR = 208-07 x age
why does heart rate decrease in the aged?
HR decreases due to a decrease in the SNS (sympathetic nervous system) and changes in cardiac conduction
why does stroke volume decrease in the aged?
SV decreases due to increased TPR (total peripheral resistance) and a decrease in the LV (left ventricle) contractility
why does cardiac output decrease in the aged?
Q decreases due to a decrease in HR and SV
