Spare Part Surgery

Question 1

Ethical Frameworks

Answer 1

characterise the thought process we go through, the reasons we give when deciding how to act in a certain situation

Question 2

Utilitarianism

Answer 2

believe the best course of action is the one giving way to the most happiness

Question 3

Divine Command

Answer 3

using religions writings to guide the decision

Question 4

Virtue Ethics

Answer 4

the right course of action is that which is considered ‘virtuous’ (morally correct)

Question 5

Rights and Duties

Answer 5

people have certain rights and other people have a duty to grant them this right (e.g. patient has right to treatment and doctor has to grant it to them)

Question 6

Good bone substitute

Answer 6

• material must be strong enough to withstand and exert forces involved in movement
• mechanical properties must be similar to those of real bone

Question 7

Smooth material

Answer 7

has a low friction surface

Question 8

Durable material

Answer 8

can withstand repeated loading and unloading

Question 9

Tensile stress

Answer 9

when the sample is pulled

Question 10

Compressive stress

Answer 10

when the sample is squashed

Question 11

Ultimate compressive/tensile stress

Answer 11

stress needed to break a material

Question 12

Strain

Answer 12

the ratio of compression/extension to the original length

Question 13

Young’s modulus

Answer 13

stress/strain

Question 14

limit of proportionality

Answer 14

when the two variables no longer create a straight line

Question 15

elastic limit

Answer 15

beyond this point the material will be plastically deformed so won’t go back to original shape/size

Question 16

What is the area under a force extension graph?

Answer 16

the elastic energy (1/2fx)

Question 17

What is the gradient of a stress strain graph?

Answer 17

Young’s Modulus

Question 18

What is the area under a stress strain graph?

Answer 18

energy density

Question 19

Yield point

Answer 19

dip on stress strain graph after elastic limit reached - after this point the material becomes plastic

Question 20

Ultimate tensile strength/stress

Answer 20

highest point on a stress strain graph - this is the maximum stress the material can take before breaking

Question 21

What are diffraction patterns used for?

Answer 21

to identify the structure of small materials

Question 22

Why are we looking into polymers for replacement body parts?

Answer 22

because they have similar properties to bones:

are strong and have an ultra high molecular weight

Question 23

Converging lens (Convex)

Answer 23

• brings light together at a focal point
• fattest in middle
• real image

Question 24

Diverging lens (Concave)

Answer 24

• spreads light out
• thinnest in middle
• virtual image

Question 25

Drawing ray diagrams

Answer 25

- draw a ray parallel to principle axis (from object to lens) - draw refracted ray from principle axis through focal point - draw undeviated ray through the middle of the lens from object - draw image where the two rays cross

Question 26

Object position: Outside 2F

Answer 26

- Image position: between F and 2F - real - inverted - diminished

Question 27

Object position: At 2F

Answer 27

- Image position: At 2F - real - inverted - same size

Question 28

Object position: Between F and 2F

Answer 28

- Image position: outside 2F - real - inverted - magnified

Question 29

Object position: At F

Answer 29

- Image position: at ∞ - real - inverted - at ∞

Question 30

Object position: Inside F

Answer 30

- Image position: -between F and 2F - virtual - upright - magnified

Question 31

What is a real image?

Answer 31

can be projected onto a screen (is on the other side of the lens from the object)

Question 32

Diverging lens image

Answer 32

- virtual - upright - diminished - closer to lens than object

Question 33

What sound frequencies can we hear?

Answer 33

20-20000Hertz

Question 34

Above 20000Hz

Answer 34

Ultrasound

Question 35

Below 20Hz

Answer 35

Infrasound

Question 36

Uses of ultrasound in medicine:

Answer 36

- check blood flow - break up kidney stones - pictures of developing foetuses

Question 37

Sound

Answer 37

- is a longitudinal wave - through air at 340m/s - can reflect, refract, superpose and form standing waves

Question 38

Ultrasonic probe

Answer 38

has a piezo-electric transducer

Question 39

Why is coupling gel used?

Answer 39

so the ultrasound doesn't reflect off the skin

Question 40

How does ultrasound work?

Answer 40

It will travel at different speeds in different materials so we measure the time taken for the echo to return. This will depend on the material as well as the distance. The wavelength of the ultrasound will change. At each boundary some of the ultrasound will reflect and some will refract

Question 41

Doppler Effect (Towards)

Answer 41

Moving source towards you means more waves per second so it has a higher frequency and higher pitch than the emitted ones. The wavelength received will be shorter than emitted

Question 42

Doppler Effect (Away from)

Answer 42

Moving source away from you means the wavelength will be longer than the emitted. This causes the frequency and pitch to decrease so they'll be lower than the original