Anaesthetics - Physiology

Question 1

what are dead spaces in the lungs?

Answer 1

areas where ineffective gas exchange occurs

Question 2

what happens in a shunt in the lungs?

Answer 2

ventilation fails to supply the perfused parts of the lungs

Question 3

difference between hypoxia and hypoxaemia?

Answer 3

hypoxia - tissues

hypoxaemia - blood

Question 4

what does CO = ??

Answer 4

HR x SV

Question 5

what is stroke volume?

Answer 5

volume of blood pumped out by the LV in each systolic contraction

Question 6

what is EDV?

Answer 6

volume of blood in ventricles before contraction

Question 7

what is preload?

Answer 7

volume that is stretching walls of the ventricles

Question 8

what = preload?

Answer 8

stroke volume (volume ejected from the heart per heartbeat)

Question 9

what does the frank starling mechanism say?

Answer 9

a higher EDV will lead to greater contraction of the ventricles and therefore an increase stroke volume

Question 10

what is afterload?

Answer 10

resistance the heart is pumping into

Question 11

what does stroke volume =?

Answer 11

SV = EDV - ESV

Question 12

what does MAP =?

Answer 12

MAP = CO x TPR

Question 13

how does muscle contraction occur?

Answer 13

Ca binds to troponin
this moves the tropmyosin complex off the actin binding site
myosin head binds to the actin filament

Question 14

what is S1 closure of? what does it indicate?

Answer 14

mitral (L)
tricuspid (R)

systole

Question 15

what is S2? what does it indicate?

Answer 15

aortic
pulmonary

start of diastole

Question 16

how does heart filling occur?

Answer 16

passively into ventricles
atria contract, filling ventricles, S1 (AV valves close)
pressure rises in ventricles
semilunar valves open, blood flows to aorta/pulmonary artery
ventricles contract
S2 (semilunar close)

Question 17

where are the baroreceptors found? what do these do?

Answer 17

aortic arch
carotid sinus

modify BP by vasoconstrict/dilate

Question 18

what does parasympathetic control do to the heart? how?

Answer 18

slows HR

ACh on M2

Question 19

what does sympathetic control do to the heart? how?

Answer 19

increases HR
decreases AV node delay

NA acting on B1 receptors
alpha cause vasoconstriction

Question 20

what causes vasodilation and vasoconstriction?

Answer 20

adrenaline on B1 (dilate)

adrenaline on alpha (constrict)

Question 21

what is FVC?

Answer 21

maximum volume that can be moved out during a breath

Question 22

what is RV?

Answer 22

maximum volume left in lungs after max expiration

Question 23

what is TV?

Answer 23

volume entering and leaving the lungs during a breath

Question 24

what is FEV1?

Answer 24

volume of air expelled in one second

Question 25

what is the haldane effect?

Answer 25

Hb decreases its affinity for CO2 if oyxgen is high in the lungs
facilitates removal of CO2

Question 26

what are the parasympathetic controls in the lungs?

Answer 26

ACh
M3

contraction
increase mucus

Question 27

what are the sympathetic controls in the lungs?

Answer 27

adrenaline
B2

dilation
decrease mucus

Question 28

what generates breathing control?

Answer 28

medulla

Question 29

how long should COCP be stopped before surgery?

Answer 29

2 weeks