BL Session 1 - Introduction To Body Systems and Investigative Techniques

Question 1

What is the normal range for body temperature ?

Answer 1

36.5 - 37.5 degrees C

Question 2

How can body temperature best be measured?

Answer 2

Using a tympanic (ear) thermometer

Question 3

What is core temperature?

Answer 3

The temperature of the internal environment of the body.

Question 4

What are the therapeutic uses of hyperthermia?

Answer 4

• Therapeutic hyperthermia is an induced local or general body increase in temperature.
• It is a treatment sometimes used on tumours and infections

Question 5

What are the therapeutic uses of hypothermia?

Answer 5

• Therapeutic hypothermia is sometimes used to slow metabolic rate during surgical procedures such as heart surgery.
• Because metabolic rate is decreased, tissues do not require as much oxygen as normal and are less likely to be damaged.

Question 6

What is pyrexia?

Answer 6

Elevated body temperature.

Question 7

What is the association between pyrexia and infection?

Answer 7

• Molecules called pyrogens, produced by macrophages, act on the hypothalamus of the brain causing an increase in body temperature.
• This temperature rise is protective as higher body temperature can kill / reduce the effectiveness of bacteria

Question 8

What is rigor?

Answer 8

• Rigor is shaking or exaggerated shivering that is associated with fever and infection.
• This is due to the pyrogens acting on the hypothalamus by making the body feel cold, hence shivering results to raise the body to the new hypothalamic temperature.

Question 9

What is a febrile seizure?

Answer 9

A seizure associated with a high body temperature without any serious underlying health issue.

Question 10

What three substances are needed in light microscopy?

Answer 10

• Formalin is needed to preserve the tissue
• Paraffin is needed to embed the substance so it can be sliced thinly
• Haematoxylin and Eosin are needed to stain the tissue (H&E)

Question 11

What is a frozen section?

Answer 11

• A surgical specimen is frozen rapidly to -20 - -30 degrees C.
• A cryosection occurs with a cryostat and the specimen is cut frozen then stained with H&E

Question 12

Describe the principles of fluorescent microscopy

Answer 12

• It resembles a light microscope
• The specimen observed has fluorophores attached to it.
• Fluorophores emit light when the are irradiated by a specific wavelength of light.
• Allows various colours to be observed for different components in a cell or different cell types within a tissue.

Question 13

Describe the advantages of confocal microscopy

Answer 13

• It eliminates out-of-focus glare
• It collects serial optical sections from thick specimens
• It allows for the imaging of live specimens.
• A major application involves imaging of either fixed / living cells and tissues that have been labelled with fluorescent probes.

Question 14

Describe the principles of autoradiography.

Answer 14

• A photographic emulsion is used to visualise molecules labelled with a radioactive marker.
• The marker is injected into the live animal / cell culture
• The histological section is coated with the emulsion.

Question 15

Describe the advantages of MRI

Answer 15

• A non-invasive and non-destructive diagnostic tool for imaging soft tissues such as the brain, heart and muscles and for discovering tumours in many organs
• It is an application of NMR spectroscopy - an analytical tool of chemists in laboratories worldwide

Question 16

Describe the principles of SEM.

Answer 16

• Scanning Electron Microscopy

- The electrons are reflected from the surface and received by a cathode ray tube.

Question 17

Describe the principles of Freeze Fracture Electron Microscopy.

Answer 17

• The tissue is frozen to -160 degrees C and fractures by hitting it with a knife edge.
• The fracture line passes through the plasma membrane exposing its interior which can then be imaged.

Question 18

Describe the principles of TEM.

Answer 18

• Uses an electron beam generated in a vaccuum
• Greater resolution than light microscopy
• Greater magnification than light microscopy
• The electron beam passes through the tissue. Those portions that the beam has passed through appear bright, those portions that have absorbed or scatter electrons appear dark.

Question 19

Describe the principles of medical ultrasounds.

Answer 19

• A diagnostic imaging technique based on the application of ultrasound.
• It is used to see internal body structures such as tendons, muscles, joints, vessels and internal organs.
• Its aim is often to find a source of a disease or to exclude any pathology.
• Ultrasound is sound waves with frequencies which are higher than those audible to humans (>20,000 Hz).
• Ultrasonic images also known as sonograms are made by sending pulses of ultrasound into tissue using a probe.

Question 20

Describe the body water distribution in a 70 kg human being.

Answer 20

• 70 kg human = 60% water = 42 litres total body water
• 2/3 is intracellular water = 28 litres intracellular water
• 1/3 is extracellular water = 14 litres extracellular water
  I. 11 litres = interstitial water
  II. 3 litres (+ 2 litres of red blood cells) = circulating blood volume