it's what's inside that counts Flashcards
What is Renaissance?
rebirth or revival
What are major factors in Renaissance medicine?
-Reformation of the church
-the invention of the printing press
-the invention of the microscope
-the discovery of new lands (the Americas and Australia)
-Scientist like Andreas Vesalius, William Harvey, and Ambroise Pare
How the reformation of the church did affect medicine?
Destroy the ideas of Galen with the help of the printing press.
What were the wrong ideas of Galen?
-Humor theory
-Humor imbalance is the cause of illness
-Venous blood pumped by liver
-Arterial blood originated in the heart
-Blood was consumed by the organs
What were the benefits of the press print?
-quick communication of new discoveries
-printing of detailed anatomical drawings
-printing De Humani Corporis fabrica by Andreas Vesalius (7 books)
Who were barber surgeons?
-medical practitioner in medieval Europe
-Worked on wounded soldiers
-Conducted tooth extractions, bloodletting, and enemas
-barbers used blue and white poles and were prohibited from performing surgeries
-surgeons used red and white poles and were prohibited from cutting hair or shaving
What was Harvey’s blood volume idea?
-heart capacity 43ml
-heart pumps 1/6 of its volume with each beat
-heart beats 1000 times per half an hour
How did Harvey prove that blood circulates?
-Tying the veins cause the heart to empty
-Tying arteries cause the heart to swell
-The blood only flows one way with valves preventing back flow
Who developed the cautery iron used in surgeries?
Ambroise Pare
Why did most of the patient treated by Pare with the egg yolk, oil of roses, and turpentine survived while most of those treated with boiling oil died?
turpentine is an antiseptic
Who pioneered the use of prosthetics?
Ambroise Pare
What are the alternative methods to get anatomical info beside dissection and textbooks?
-Visible Human Server
-Gunther Von Hagens
What technique did Gunther use to preserve cadavers?
Plastination technique.
What were Gunther objectives?
-improving anatomy instruction
-improving awareness of medical issues
-popularising and developing plastination techniques.
What are the properties of visible human server?
-visualise the human anatomical slices.
-see 3D reconstructions of organ systems.
What is the definition of microscopes?
Instrument for viewing objects too small to be seen by naked eye.
Why the glass lens is the key feature of the microscope?
bends the light to enlarge the image we are viewing
What is one of the earliest reports of lens use?
burning lens created by Archimedes
What civilization was one of the first to experiment with glass lenses?
Romans
How did the Romans use lenses?
-Burning glasses: cauterise wounds in battle
-Image enlargement
How did the roman emperor Nero used Emerald?
Watch gladiator matches (First sunglasses?)
What is the first vision aid?
The reading stone by Abbas bin Firnas
Who invented the first wearable glasses?
Salvino D’Armate
What is the difference between simple and compound microscope?
Simple: single lens
Compound: 2 or more lenses (also known as light or optical microscope)
What are the components of the first compound microscope?
Extending tube (fully extended: 10x, at shortest: 3x)
2 lenses: objective and eyepiece
What was Galileo’s Microscope called?
Occhiolino
What magnification did Anthonie Van Leeuwnhoek achieve with his simple microscope?
270x
What did Van Leeuwnhoek observe with his microscope?
bacteria, yeast, red blood cells, spermatozoa
How did Robert Hooke improve the compound microscope?
Added a light source to illuminate and improve image quality of specimen.
What did Hooke’s work inspire?
-Schwann and Schleiden cell doctrine
-Rudolph Virchow cell theory (plagiarised Robert Remak work)
How does existing microscopes differ from pioneer’s microscopes?
-Improved focus mechanism
-Greater control/precision/design
-improved lens
-use of different types of glass
-employing more compatible lenses in compound microscopes
What is the difference between upright and inverted microscope?
Upright microscope: has light source below stage
Inverted microscope: has light source above stage
What is the path of light in light microscope?
1) light source
2) condenser lens: focuses light into specimen
3) objective lens: magnification and inversion of image
4) eyepiece: further magnification and reversion of image to correct way
5) human eye (retina)
What are different variations of light microscopy?
*Brightfield microscopy: 2D, lacks detail
*Phase contrast microscopy: 3D, better details
*DIC Microscopy: 3D, better detail
*Darkfield microscopy: good contrast, specific structures
How can magnification be calculated?
multiplying individual magnification of the lenses together.
What is the difference between Low-mid and Higher power magnification?
Low-mid power magnification: scanning broad aspects of the specimen
Higher power magnification: for increased details, but lose appreciation of some areas of the specimen
What is resolution?
The ability to separate and distinguish 2 individual points in a specimen viewed through a microscope
What is Abbe’s law? and why is it important in light microscopy?
“cannot distinguish objects smaller than 1/2 the wavelength of the light source”
light microscopy use white light = 0.55μm wavelength
*any objects smaller than 0.275μm will not be visible
*any 2 points separated by less than 0.275μm will appear as one
What is the resolving power?
Shorter wavelength increases resolution capabilities of the microscope
What are the challenges surrounding specimen preparation? and what are the solutions?
1) biological change- Fixation (kill cells, stabilises protein, creates biological snapshot)
2) tissue flimsiness- Embedding (embedding tissue in wax or resin to harden, so it can be sliced)
3) visibility of individual cells- Sectioning (using microtome to slice tissue block into thin sections
4) thin sections transparent- Staining (stained with organic dyes, provide contrast)
Is there an alternative way to prepare specimens?
Yes, “Snap-freeze” tissue in liquid nitrogen, doesn’t need to go through embedding because it’s already frozen solid, sectioned on a special frozen microtome called “cryostat”, and similarly stained.
What is the most used staining dye?
H and E combination:
Nucleus- purple/blue
cytoplasm- pink
collagen- pale pink
Can the sensitivity of microscopy be increased?
Yes
What is the visible wavelength range?
Approximately 400 to 750 nm
What is an example of something that increase microscopic sensitivity?
Fluorescence
How does fluorescence work?
-Absorb light of a given wavelength (excitation wavelength)
-Emit light at a different, longer wavelength (emission wavelength)
What is Fluorescence?
Emission of light in response to stimulation by electromagnetic radiation (the basis of fluorescence microscopy)
What are the components of fluorescence microscope?
1) specimen that contains fluorescent
2) filter that let light (from the source) of specific wavelength through
3) dichroic mirror that let light of particular wavelength range through and reflects the rest
4) filter that let light (before it goes to the eyepiece) of specific wavelength through
5) eye could only see specific light on a dark background from the eyepiece
What are the advantages of using fluorescence microscope over conventional organic dye staining?
- detection of specific molecules inside or outside cells
-dark background increase contrast and sensitivity
-endless flexibility in the types of experiment to do
What has longer wavelength, excitation or emission?
Always emission
What is the most important fluorescent molecule, an what is its emission wavelength and colour?
GFP, 500nm, green
How can we extend cell labelling?
-Use combination of fluorescent molecules
-But it can’t be represented in one go as each type of molecule requires its own unique set of filters, so each image is taken individually and then superimposed together
What is the source of GFP?
Jellyfish, glows green, excited with blue light
What fluorescent protein molecules derived from GFP?
CFP, YFP, RFP
What are some of the fields that GFP used on?
cloning technologies, molecular biology, transgenic animal studies
How does electron microscope differ from light microscope?
-has a shorter wavelength, hence higher resolution.
-1000x better than light microscope
-electron beam travels in vacuum
-magnetic coil focuses the beam rather than lenses in light microscope
-viewed on a screen or photographic film, not directly as in light microscope
what is the resolution of electron microscope?
- wavelength of electron beam at high velocity (around 0.004 nm)
-Theoretically= 0.002nm
-Realistically=0.1nm because of limitations
What are the properties of electron beam?
-travels in vacuum
-focused by magnetic coils
-passes through specially prepared specimen
-absorbed by more electron-dense areas of specimen (these areas appear lighter on image)
What are the types of electron microscopes?
-transmission electron microscope (TEM)
-scanning electron microscope (SEM)
What are the differences between SEM and TEM?
TEM:
2D picture
Higher in resolution
Measure electrons absorbed by specimen
SEM:
3D pictures
Lower in resolution (still very high resolution)
Measure electron off the specimen (by a detector)
Only examine the surface features
Who designed TEM?
Ernst Ruska
Who worked on SEM?
Max Knoll
but developed and commercialised by Charles Oatley
What are the differences between Light microscope, TEM, and SEM?
Light microscope:
-Typical max. magnification= 400x
-Typical max. resolution= 0.275μm
-Radiation type= light
-Limitations= resolution
SEM:
-Typical max. magnification= 20,000x
-Typical max. resolution= 10nm
-Radiation type= electron beam
-Limitations= can only study surface
TEM:
-Typical max. magnification= 1,000,000x
-Typical max. resolution= 0.1nm
-Radiation type= Electron beam
-Limitations= 2D
What are the ways of assessing a patient before the discovery of x-ray scanning?
-touch
-stethoscope (changes in the way sound travels through)
not very efficient
What paved the way for the discovery of x-ray?
Victorian photographic revolution
Who discovered X-ray?
Wilhelm Rontgen
How did Wilhelm Rontgen discover x-ray?
Accidently while he was working on cathode rays.
A phosphorescent-painted board away from Crooke’s tube illuminated (so, there is a ray that passed through the tube). he called it x-ray
What were the first uses of X-ray?
-used in the location of foreign bodies
-Treat skin disorders (or as cosmetic)
How are x-rays created?
1) Electrons pass through the cathode to the metal target in the anode in the tube
2) high-energy radiation released (x-ray)
Why do X-rays see through stuff?
- Dense objects like bones absorb x-ray photons
- Less dense objects like soft tissues allow x-ray photons to pass through
What are the ways in which x-rays are detected?
- Photographic plate
- Photostimulable phosphors: used in modern hospital (create x-ray digital image)
- Semiconductor detector: Allow moving x-ray images to be recorded.
What is radiology?
The specialised use of x-rays for diagnostic imaging
What are some of X-ray limitations?
-2D images, this can be overcome by CT scans (computer tomography) which reconstruct the X-ray images to be 3D
- Soft tissue imaging
What are other uses of x-ray in the medical sciences?
- X-ray microscopes
- Rontgen stereophotogrammetry
- X-ray crystallography (important in the discovery of many proteins and also in the discovery that DNA is double helix)
What are other imaging techniques?
MRI, fMRI, Ultrasound, Bioluminescence, Angiography
How does MRI work?
- the magnet excites H ions (nuclei) in water
- Radio waves with frequency specific to H is passed through which lead the nuclei to shift by 90 degree
-When the radio waves removed the nuclei return to their previous state releasing a small amount of energy which is recorded - A computer collates this information to construct an image
What is the name of the first full-body MRI scanner? and who developed it?
Mark-I, prof James Hutchison in Aberdeen
What is an fMRI?
Functional MRI identifies neuronal activity through the usage of O2 (Active cells= more O2 consumption)
-Information plot on top an MRI scan
Who used ultra sound for the first diagnostic application?
Prof Ian Donald in Glasgow
What method did Prof Ian Donald and Dr James Willocks use ultrasound for?
define the development and growth of the foetus
How does ultrasound imaging work?
Ultrasound pass through the soft tissue, but reflect to differing degrees by internal structure
What are some of ultrasound imaging derived techniques?
- 3D ultrasound ( not any better at identifying problems), just more detailed images
-Echocardiography (2D or 3D), identify problems with minimal invasive techniques using Doppler effect to monitor movement
How can the direction of blood flow be differentiated using Doppler ultrasound?
-If the blood moving away from the transducer - reflected wave would be longer than original wave
-If the blood moving toward the transducer - reflected wave would be shorter than original wave
what is Bioluminescent imaging?
the use of fluorescent proteins to identify structures.
Mainly used in medical sciences research rather than clinical use.
What is Luciferase? and how does it work?
An enzyme found in insects that emit light for communication purposes.
when the enzyme is mixed with specific substrate, the reaction emit light.
encoded in animals genes to produce transgenic animals.
What is Angiography?
uses x-ray technology to visualise blood vessels in real time in living tissues.
For what parts angiography is commonly used?
Heart, Brain, Kidney
What is the most common angiography procedure?
Coronary angiography (occlusions, thrombosis)
How does the coronary angiography procedure work?
- catheter (2-3mm wide) inserted into an artery of either the arm or groin
-Arteries injected with radiocontrast to visualise the blood vessels
-x-ray images recorded to position the end of the catheter (which has the balloon and the stent) at the blocked area
