lecture 7 - cardiovascular changes

Question 1

what are the 2 parts of the circulatory system

Answer 1

heart

blood vessels - arteries, veins

Question 2

what are the three main functions of the CV system

Answer 2

• transport of substances
• removal of waste
• protecting the body (immune function)

Question 3

when does the heart start to beat?

Answer 3

around 3 weeks

Question 4

how does the cardiovascular system differ in foetus to adulthood. and the two shunts in the heart?

Answer 4

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

Question 5

what are the shunts in the foetus heart?

Answer 5

foramen ovale - connects right and left atrium

ductus areteriosus - connects aorta and pulmonary artery

Question 6

are lungs needed in a foetus?

Answer 6

no as they get all the oxygen from the mother

Question 7

what are the changes in the heart size of a foetus

Answer 7

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

Question 8

what is left ventricular hypertrophy? is this good or bad?

Answer 8

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

Question 9

is an endurance athletes heart larger than a non athletes?

Answer 9

yes

Question 10

what are the heart rates for an infant, adult male and female?

Answer 10

newborn = 140bpm
Adult male = 72bpm
adult female = 76bpm

Question 11

what does HR mean?

Answer 11

Heart Rate = beats per minute

Question 12

SV?

Answer 12

Stroke volume = volume ejected per beat

Question 13

Q?

Answer 13

Cardiac output = HR x SV (ml/min) or (L/min)

Question 14

how do you work out the cardiac output?

Answer 14

HR x SV = ml/min or L/min

Question 15

what does it mean if there is a dot above a letter?? e.g Q (dot above)

Answer 15

the dot means per minute

Question 16

what happens with the heart function from birth to adulthood

Answer 16

the heart rate drops while the stroke volume increases

Question 17

what is systolic and diastolic?

Answer 17

systolic = highest pressure during contraction of left ventricle 
diastolic = lowest pressure during relaxation of the left ventricle

Question 18

how is blood pressure recorded?

Answer 18

systolic over diastolic

Question 19

what happens to blood pressure as we grow?

Answer 19

the pressure increases as we grow

Question 20

does blood volume change over growth? and what is a newborn and adults

Answer 20

yes newborn has 300-400mls while adults have about 5L

Question 21

what is the ratio of blood

Answer 21

55% plasma = 90% H2O, 7% plasma, 3% other

45% formed elements = 99% red blood cells, 1% white blood cells and platelets

Question 22

what happens to haematocrit from newborn to adulthood?

Answer 22

newborn at 50% then drops to 30% at age 3 then increases throughout growth

Question 23

PO2?

Answer 23

partial pressure of oxygen

Question 24

PCO2

Answer 24

partial pressure of carbon dioxide

Question 25

what is the PO2 and PCO2 of blood in neonate (infant less than 4 weeks old) from lung to muscle?

Answer 25

PO2 = 100
PCO2 = 40

Question 26

what is the PO2 and PCO2 of blood in neonate (infant less than 4 weeks old) from muscle to lung?

Answer 26

PO2 = 40
PCO2 = 46

Question 27

what happens in haemoglobin during growth?

Answer 27

increases - more in males than females as they are more active = more mass

Question 28

what are the changes in the CV system in the aged?

Answer 28

• thickening of vessels and left ventricle
• increase stiffness in aorta = increased systolic blood pressure
• possible fragmentation (clots)

Question 29

what happens to resting heart rate and max heart rate as we age?

Answer 29

• resting heart rate doesn’t seem to change

- max heart rate decreases 10bpm per decade and is inevitable

Question 30

how do you calculate max heart rate in a healthy adult and in an over 40?

Answer 30

healthy = MHR = 220 - age

over 40 = MHR = 208-07 x age

Question 31

why does heart rate decrease in the aged?

Answer 31

HR decreases due to a decrease in the SNS (sympathetic nervous system) and changes in cardiac conduction

Question 32

why does stroke volume decrease in the aged?

Answer 32

SV decreases due to increased TPR (total peripheral resistance) and a decrease in the LV (left ventricle) contractility

Question 33

why does cardiac output decrease in the aged?

Answer 33

Q decreases due to a decrease in HR and SV