Investigative Techniques

Question 1

In a 70kg human, what percentage of their body is water?

How many litres is that?

Answer 1

60%

42 L

Question 2

In a 70kg human, 60% water, how much of this is INTRACELLULAR?

Answer 2

2/3 of 42 L = 28 L

Question 3

In a 70kg human, 60% water, how much of this is EXTRACELLULAR?

Answer 3

1/3 of 42 L = 14 L

Question 4

In a 70kg human, how many litres of INTERSTITIAL water do they have?

Answer 4

11 L

Question 5

In a 70kg human, what is their circulating blood volume?

How much of this is plasma and how much is red cells?

Answer 5

5 L

3 L plasma, 2 L red cells

Question 6

What is haematocrit?

What is the haematocrit value for males and females according to UHL?

Answer 6

Red blood cells

Males 40-54%

Females 37-47%

Question 7

What is the cardiac output at rest?

Answer 7

Rate x stroke volume

e.g. 70 bpm * 70 ml

= 4900 mls/min = 5 L/min

HOW MUCH and HOW FAST

Question 8

How long does it take for the total blood volume to circulate once?

Answer 8

1 minute.

Question 9

I want to view some cells with a light microsope. What are the three processes I must carry out to prepare the sample?

Answer 9

Preserve with formalin

Slice it thinly after setting in paraffin

Stain with Haematoxylin and Eosin

Question 10

Which structures stain with haematoxylin?

Answer 10

Nucleus

Question 11

Which structures stain with eosin?

Answer 11

Cytoplasm

ECM

Question 12

I want to create a frozen section. Why and how?

Answer 12

E.g. in surgery for quick analysis

Frozen -20-30deg C

Cryostat (cold microtome)

Stain H&E

Question 13

I think my patient has gout. How might I distinguish this from pseudogout?

Answer 13

Polarised light microscopy

Gout: Monosodium urate: needle shaped, yellow; more common in big toe

Pseudogout: calcium pyrophosphate dihydrate: rod/rhomboid, blue; more common in knee

Question 14

I want to give my patient an ultrasound. What do I need to ensure a good resolution?

Answer 14

High frequency, short wavelength

Question 15

What is this?

Answer 15

Transmission electron microscopy image

Question 16

What is this?

Answer 16

Scanning electron microscopy image