Histology with photos Flashcards
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Which stain was used on this slide?
Alcian Blue
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What is Alcian Blue commonly used to stain
Glycosaminoglycans (GAGs) rich things
Mucous
Mast Cells
Cartilage
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Which stain was used on this slide?
Eosin
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What is Eosin commonly used to stain and what substances are stained pink?
Colloidal proteins
Plasma
Basic/acidophilic substances (also called eosinophilic)
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What stain was used on this slide?
Iron Haematoxylin
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What is Iron Haematoxylin commonly used to stain?
Nuclei and elastic fibres (black)
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Which stain was used on this slide?
Periodic Acid Schiff
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What is Periodic Acid Schiff commonly used to stain?
Hexose sugars (complex carbs)
Goblet cell mucins
Cartilage matrix
Glycogen
Basement membranes
Brush border
(magenta)
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Which stain was used on this slide?
Romanovsky/Leishman’s
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What is Romanowsky/Leishman’s commonly used to stain and what are the corresponding colours?
BLOOD FILMS
Chromatin/nuclei and neutrophil granules - purple
Erythrocytes/eosin granules - red/pink
Lymphocyte/monocyte plasma - pale blue
Basophil granules - dark blue/purple
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Which stain was used on this slide?
Toluidine Blue
P.S. probably one of the less important ones
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What is Toluidine Blue commonly used to stain and what are the corresponding colours?
Nuclei/Ribosomes - dark blue
Cytoplasm - pale blue
Cartilage/matrix/mast cell/GAG rich - bright purple
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Which stain was used on this slide?
Van Gieson’s Trichrome with Haematoxylin Counter Stain
P.S. yeah this one is probably not v important too
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What is Van Gieson’s Trichrome with Haematoxylin Counter stain commonly used to stain and what are the corresponding colours?
Collagen - pink/red
Cell cytoplasm - yellow/olive green
Nuclei - black
Elastic tissue - dark brown
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Which stain was used on this slide?
Haematoxylin
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What is Haematoxylin commonly used to stain? What structures are stain blue in general
Nuclei and RNA
Basophilic Structures = blue
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What stain was used on this slide?
Silver Stain
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What is shown on this slide?
Neurons
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How big are neurons?
large - 26-60 microns
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How many dendritic processes do neurons normally have? Can you see all of them?
1-5
No because of the slide thickness
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List two properties of the structures in the image
Neurons - metabolically active and fully differentiated
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What does this slide show?
Lymphocytes
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How large are the structures in this image?
Lymphocytes - small, 5 microns
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List three properties of the structures in this image
Contain little cytoplasm - dormant and not fully differentiated
They are metabolically active
They contain minimal Rough Endoplasmic Reticulum
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Name the main 2 types of epithelia and their main properties and functions
Epithelium functions as a barrier
Simple:
- single layer
- absorption and secretion
Stratified:
- multi-layered
- protection
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What epithelium is shown in this image?
Simple columnar
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What are the main properties differentiating this epithelium from other types?
Simple columnar:
- taller than wide
- oval nucleus
- often microvilli or cilia at the apical membrane
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Where would you expect to find this type of epithelia?
In gut enterocytes and respiratory tract
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Where would you find this epithelium?
Intestines (intestinal epithelium)
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How would you differentiate between the epithelium of small and large intestines?
Large has more goblet cells
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What does this epithelium show?
Enterocytes with goblet cells and microvilli on the apical surface
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What is the role of the basement membrane?
It provides a permeability barrier between epithelium and connective tissue
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What is the brush border?
Microvilli on the apical surface
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What is the function of the brush border?
Increases surface area
Attachment of exo-enzymes
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What stain was used on this slide?
Periodic Acid Schiff and Haematoxylin
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What does this slide show?
Microvilli/Intestinal Epithelium
Microvilli w/ carbohydrate-rich glycocalyx
Goblet cells and basement membrane rich in hexose
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Which stain was used in this slide?
H&E and Alcian Blue
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What kind of epithelium does this slide show?
Ciliated simple columnar with golbet cells and cilia
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Where can you find this type of epithelium?
Ciliated simple columnar:
- nose
- larynx
- bronchial tree
- fallopian tubes
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How big are cilia and how do they move?
2 microns
Move by tubulin and dynein
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What kind of epithelium does this slide show?
Cuboidal epithelium
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What are the main properties of cuboidal epithelium?
square
round nucleus
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Where would you expect to find this type of epithelium?
Ducts of exocrine organs - sweat glands, salivary and pancreas
Kidney tissue
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What kind of epithelium does this slide show?
Simple squamous (serosa)
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Where would you expect to find this type of epithelium?
Simple squamous:
- Outer surface of most thoracic and abdominal organs
- Lining pleular and peritoneal cavities
- Air sacs of lungs (alveoli)
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What are the main properites of squamous epithelium?
Flattened (plate-like)
Cylindrical/Elliptical nuclei at base of cell
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What does this image show?
Alveoli - the air-blood barrier
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What does the septa of the air-blood barrier consist of and how thick is it usually?
capillaries covered up by simple squamous epithelium, usually 1 micron thick
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What is the overall thickness of the air-blood barrier?
5-10 microns
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What does the air-blood barrier consist of?
2x capillary endothelial cells
2 x Type 1 pneumocytes and capillary lumen
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What kind of epithelium is shown in this image?
Stratified squamous
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Where can you find this type of epithelium?
Stratified squamous:
- mouth
- throat
- oesophagus
- anus
- vagina
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How are cells replaced in stratified squamous epithelium?
There is a basal layer of stem cells (mitosis capable)
Cells are replaced from below
Dead cells are sloughed off from the top
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What are the two sub-types of stratified squamous epithelium?
Keratinising and non-keratinising
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What kind of epithelium is shown on this slide?
Keratinised squamous epithelium
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Where can you find this type of epithelium?
Keratinised squamous:
In the epidermis
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How is the keratin layer in keratinised epithelia formed?
upper layers synthesise a unique collection of proteins
upper layers interact with the cytoskeleton of the cell
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What is keratin and what are its main properties?
Dense protein that filld the cytoplasm of cells
It’s tough and waterproof
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What is present at the boundary between the living cells and the keratin layer?
A layer with blue keratohyaline granules
Stratum Granulosum
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Are there stem cells in keratinised stratified squamous epithelium? If so, where?
Yes, at the basal layers
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What kind of epithelium can you see in this slide?
Pseudostratified
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What are the main properties of pseudostratified epithelium?
Appears multilayered but every cell touches basement membrane - flattens when stretched
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Where would you expect to find this type of epithelium?
trachea and bronchi (and urinary tract)
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What kind of epithelium lines the urinary tract?
Specialised urothelium - pseudostratified
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How can you distinguish stratified epithelium from pseudostratified?
In pseudo:
- all cells are in contact with the basement membrane
- cells replaced by lateral migration rather than vertical
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What are cell junctions and what are the three main types?
Attachments between adjacent cells, bound tightly together to prevent macromolecule or fluid movement
Desmosomes, tight (adherent) and gap junctions
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What does this slide show?
Glands
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How do glands develop?
They have an epithelial origin - develop as ingrowths
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What is the role of ducts in glands
They connect the exocrine glands to the surface for product secretion
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What types of things can be secreted by these structures?
Glands:
fluids, lubricants and enzymes
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How could you distinguish between mucus and serous glands?
Mucus - separate acini from serous, occasionally mixed; are pale and contain a flattened nucleus at base of cell
Serous - are dark and contain round nuclei
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What is the role of collagen/elastin?
It provides an extracellular fibre scaffold
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What is collagen/elastin synthesised from?
Fibroblasts
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What is GAG and where is it synthesised?
Glycosaminoglycans - hydrophilic polysaccharide polymer in connective tissue matrix
Synthesised in epithelial cells, muscle, cartilage and bone
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List examples of fibrous connective tissue
collagen
elastin
reticulin
(black lines with silver stain)
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What are the main types of connective tissue?
Fibrous
Loose irregular
Dense irregular
Dense regular
Fatty
(can also be soft or hard)
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Describe the appearance of loose irregular connective tissue
few visible fibres with random orientation
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Describe the appearance of dense irregular connective tissue
large number of fibres with only a little matrix, long, go in many directions
fibres stain pink and can contain fibroblasts (w/ dark nuclei) alongside
fibres not uniform thickness
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Describe the appearance of dense regular connective tissue
large number of fibres in thick, long, parallel bundles of collagen
fibroblasts inbetween layers
compact and regular
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Describe the appearance of fatty connective tissue
Mainly fat cells with intervening capillaries
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What type of connective tissue is present in this slide?
Dense irregular
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Where would you expect to find this type of connective tissue?
Dense irregular: dermis of scalp
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Are dense irregular connective tissue fibres intra- or extracellular?
Extracellular
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What tissue can be seen in this slide?
Dense regular connective tissue
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Is dense regular connective tissue collagen elastric or contractile?
Neither
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Describe the structure of collagen
Overlapping linear strands of tropocollagen arranged to fibrins extracellularly
Overlapping gives rise to banding
3 linear polypeptide chains of tropocollagen in an alpha helix
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How is tropocollagen secreted?
From fibroblasts
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Where can you find Type 1 collagen?
Skin, bone, teeth and organ capsules
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Where can you find type 2 collagen?
Cartilage
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Where can you find type 3 collagen?
liver, kidney, spleen, arteries and uterus
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Where can you find type 4 collagen?
Basement membranes
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Where can you find type 5 collagen?
Placenta
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What connective tissue lines the penis erectile compartment?
Dense irregular - forms a capsule/sheath
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What kind of stain was used in this slide?
Silver stain
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What kind of collagen is present in this slide?
Reticulin - type 3 collagen
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How can you distinguish between type 1 and type 3 collagen?
Type 1 has coarser elements whereas type 3 has a fine framework
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How can you distinguish reticulin from other types of collagen?
reticulin forms branches fibres, most colalgens form linear fibres
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What is the function of reticulin?
it helps to maintain the shape and integrity of many organs by extracellular fibres
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This is a slide of a large elastic artery
Describe what can be seen on this slide?
Microfibres of fibrillin set in amorphous matrix of elastin
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How are these fibres arranged?
elastic - in fine fibres or sheets
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Which stain was used in this slide?
Van Gieson’s trichrome
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This slide is stained with Van Gieson’s trichrome, what can be seen on this slide in dark brown staining?
Elastic fibres
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Which type of connective tissue can be seen on this slide?
Adipose tissue
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What are the two types of adipose tissue?
White and brown
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Which of the fatty tissues is more abundant?
In adults: white
In new-borns: brown
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Describe the appearances of white and brown fatty tissue
White:
- large cells with a single fat droplet
- 60 microns
- usually alongside capillaries
Brown:
- multi-locular - multiple droplets of fat per cell
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What is the function of brown fatty tissue?
Generation of heat via fat oxidation
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What is the function of white fatty tissue?
Protection of vital organs and energy store (insulation and packing)
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Where can you find brown fatty tissue in an adult?
chest and shoulder blade
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Which cells produce myelin for nerves?
CNS - oligodendrocytes
PNS - Schwann cells
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Name structures A, B, C and D
A. schwann cell nucleus
B. axon with myelin sheath
C. unmyelinated axon
D. myelin sheath
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How many Schwann cells are there per 1 axon?
Myelinated: 1
Unmyelinated: several
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How do unmyelinated axons differ from myelinated?
Myelinated usualy larger with increased velocity of conduction
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What are the characteristics of myelin and sphingomyelin?
Myelin: membranous, bilipid, proteins inserted between layers
Sphingomyelin - predominantly phospholipid
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What is a mesaxon?
Where 2 limbs of schwann/oligo around axon fuse
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What does this slide show?
Peripheral nerves with mixed motor and sensory axons surrounded by Schwann cells
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What can be seen between the axons?
a connective tissue network of fibres and cells:
endoneurium, perineurium and exoneurium
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How can you distinguish between fibroblasts and Schwann cells?
Fibroblasts have a flattened nucleus, schwann have a round nucleus
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Which stain was used in this slide?
Osmium Tetroxide
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What does this slide show?
A trasverse section of an isolated peripheral nerve
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What happens to the myelin sheath during processing with osmium tetroxide? What colour does it appear?
The lipids get extracted but myelin sheath becomes insoluble
Brown/black
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What does a nerve fibre consist of?
Many axons, with perineurium
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What does a peripheral nerve consist of?
Many nerve fibres, with epineurium
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Which stain was used in this slide?
Osmium Tetroxide
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What does this slide show? What is the arrow pointing to?
A longitudinal section through an isolated peripheral nerve
The arrow is pointing towards the Node of Ranvier
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What is the Node of Ranvier?
A constriction - boundary between one Schwann cell and the next
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What is the speed of conduction for myelinated and myelinated axons? Which one has a larger diameter?
Myelinated - 10-100 m/s
Unmyelinated - 1-20 m/s
Mylinated has a diameter (100x larger)
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What does the image show?
An electron micrograph of a synapse
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What does a synapse contain?
A large number of neuro-secretory vesicles at the presynaptic space
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What kind of stain was used in this slide?
Silver stain
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What does the slide show?
A nerve cell body
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Where can you find nerve cell bodies?
in CNS or in discrete ganglia close to the spinal cord
in parasympathetic nervous system with clusters close to the organ innervated
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Why do neurons stain heavily with silver stain?
Silver stain has an affinity for cytoskeleton of cells, neurons have a developed cytoskeleton
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What do the oval shapes in the centre of the cell body in the slide show?
The pale, outer oval is the nucleus but nucleolus inside this is black
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How does the developed cytoskeleton aid nerves?
It’s made up of microfilaments (tubulin and dynein) which aids in axonal transport of vesicles
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What are the different types of neurons and how many processes do they have?
Unipolar - sensory
Bipolar - interneurons
Multipolar - motor neurons
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Which stain was used in this slide?
H&E
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What does this slide show?
Sensory cell bodies at the dorsal root ganglion (but realistically all you need to know is that these are sensory cell bodies)
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What are the main features of this cell body?
Sensory:
- large
- one axon
- one major dendrite
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How would you distinguish between a sensory nerve cell body and motor nerve cell body?
Sensory appears more rounded
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What is Nissl substance and what is its function?
alternative name for rough endoplasmic reticulum
synthesis of proteins for export from cell or inclusion in membrane
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What are satellite cells and what is their function?
cells around a nerve cell body
they play a supportive role - supply neuron with nutrients and growth factors
GI/Liver
What kind of epithelium is present in the mouth (lips to palatoglossal folds)?
Stratified Squamous Non-Keratinising epithelium
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Which kind of epithelium is present in the oropharynx?
Stratified Squamous Non-Keratinising epithelium
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What does this slide show?
Lip mucosa - Stratified squamous non-keratinising epithelium
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What connective tissue is present in this sub-mucosa?
Collagen and elastin
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What is present in the deeper layers of lips?
glands and striated skeletal muscle
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How are the lips kept moist?
By numerous small blood vessels in the sub-mucosa
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What does this slide show?
The transition from stratified squamous non-keratinising epithelium of the lips to stratified squamous keratinising epithelium of the skin
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What is this slide showing?
Lip
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What are Fordyce’s spots?
Sebaceous glands that open to surface of lip (rather than hair follicles)
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What is the red arrow pointing to? Where found you find this on the lip?
Hair follicle
Found on keratinised surface of the lip
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What does this slide show?
Tongue
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What epithelium/a is present in this structure?
Tongue:
Dorsal surface - stratified squamous keratinising (constant abrasion)
Ventral surface - stratified squamous non-keratinising
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What structures can be found within the tongue?
Extrinsic muscle fibres
Intrinsic muscle fibres
Mixed sero-mucous salivary glands
Lymph nodules
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Where can you find most lymph nodules in the tongue?
In the lingual tonsils; posterior 1/3
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What is shown in this slide?
Upper surface of the tongue
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What type of epithelium is in this slide?
Stratified squamous keratinising epithelium