Histology practical 1 Flashcards
why are lymphocytes smaller than nerve cells
they aren’t yet differentiated, so are less metabolically active, once differentiated they become bigger and more metabolically active. Nerve cells are already differentiated
why do lymphocytes have relatively little cytoplasm compared to the size of the nucleus
they are a dormant cell type and are awaiting a stimulus and once challenged they become larger with more cytoplasm and more metabolically active
what does a fusiform cell look like
Spindle shaped/elliptical e.g. muscle cells
what is thin slice/section slide preparation
- thin slice/section - most common, fixed in aqueous solution of formaldehyde, then embedded in paraffin (extraction of water and number of other substances from tissue), thin slice = 4 microns thick, then stained, slices are smaller than cells so hard to imagine the 3D element (slices through the cells)
what is smear slide preparation
done with solids and liquids, whole cell instead of slice through cells. Slide cover is placed at an angle so the drop of e.g. blood is touching it, the slide cover is then moved in the direction of the obtuse angle
What does the dye haematoxylin stain
Stains nuclei blue and will also stain acidic substances e.g. RNA and DNA violet
What does the dye Eosin stain
Stains cytoplasm and extracellular fibres pink
What colour does watery extra-cellular jelly go when stained
it doesn’t stain so is just white
What does the dye Periodic acid shift (PAS) stain
sugars - stains them magenta
What does the dye Van Gieson stain
Elastic fibres - stains them brown (looks like brown bands)
what does trichrome dyes stain
Collagen - goes blue
Nuclei - go dark brown
Muscle tissue - goes red
cytoplasm - pink
what does the dye Alcian blue stain
Mucins - go blue
What are polygonal shaped cells
they are cells which have been squashed together and so are irregularly shaped
What are cuboidal shaped cells
they appear square in 2D and cuboidal in 3D
what are squamous shaped cells
they look like thin plates or fish scales under the microscope
what are columnar shaped cells
they are arranged in rectangular columns in 2D, in 3D they can be in hexagonal columns
what are bigger metabolically active or inactive
active
what is the life span of cells lining the gut
3-5 days
what is the life span of cells in the blood erythrocytes
120 days
what is the life span of cells in the skin
2 - 4 weeks
what is the life span of cells in the connective tissues
years
what is the life span of bone cells
10-50 years
what is the life span of skeletal muscle cells
can last your entire life but most don’t on average they last between 10-16 years
what is the lifespan of nerve and cardiac muscle cells
the organisms entire lifespan
what is the life span of germ cells
the organisms entire lifespan
what is chromatin and what are the 2 types
Nuclear DNA wrapped around proteins called histones to make nucleosomes, many nucleosomes in a chain make a chromatin fibre many chromatin fibres make chromatin. the two types are euchromatin and heterochromatin. Heterochromatin appears darker under the microscope and is transciptionally inactive, euchromatin appears lighter and is transcriptionally active
what does the nucleolus do and how big is it
1-3 microns in diameter and is the site of ribosomal RNA formation
what do the different parts and internal compartments of the mitochondria do
-outer membrane - lipid synthesis and fatty acid metabolism
-inner membrane - respiratory chain ATP production
-matrix - Krebs cycle
-Intermembranous space - nucleotide phosphorylation
-the mitochondria are the site of oxidative phosphorylation
what does the rough endoplasmic reticulum do
protein synthesis
what happens at the smooth endoplasmic reticulum
- lipid synthesis
- synthesised proteins are processed
what happens at the Golgi apparatus and what does it look like
- it processes macro-molecules which have been synthesised at the ER
- the cis face is nuclear facing and receives vesicles from the SER and phosphorylates some proteins
- the trans face is membrane facing and is the site of proteolysis and sorts macro-molecules into vesicles
- the Golgi is most prominent in plasma cells where it is a perinuclear Hoff
- the central part of the Golgi forms oligosaccharrides by adding sugars to lipids and peptides
what is the role of vesicles
- they are used for transport, storage and exchanging between compartments
what are the different types of vesicle
- cell surface derived pino and phagocytotic
- Golgi derived transport
- Lysosomes (contains acid hydrolases which degrade proteins)
- endolysosomes (hydrolase vesicles fuse with endosomes with the correct surface proteins), these can lower the pH of an environment and contain enzymes that work better at lower pH
- peroxisomes (enzymes for long chain fatty acids)
what is the order of filaments in the cytoskeleton
Microfilaments (actin) -> intermediate filaments -> microtubules (tubulin) arranged in groups of 13 to make hollow tubes
what protein is in epithelial cells
Cytokeratin
what protein is in muscle cells / myocytes
Desmin
what protein is in Astrocytic glial cells
Glial fibrillary acidic protein
what protein is in neurons
neurofilament protein
what protein is in the nucleus of all cells
nuclear laminin
what protein is in mesodermal cells
Vimentin
what is lipofuscin
Lipofuscin is the name given to fine yellow-brown pigment granules composed of lipid-containing residues of lysosomal digestion It is considered to be one of the aging or “wear-and-tear” pigments, found in the liver, kidney, heart muscle, retina, adrenals, nerve cells, and ganglion cells
what is the fluid inbetween cells called
interstitial fluid made up of water, salt, peptides and proteins
what are the different types of tissues
- Epithelia
- muscle
- Supporting/connective tissue e.g. cartilage, bone, tendons, blood
_nervous
what are the different types of tissue
- Epithelia
- Muscle
- Supporting/connective tissue
- Nervous
what are the different types of tissue
- Epithelia
- Muscle
- Supporting/connective tissue
- Nervous
what are germ cells
ova or sperm
what shape are the nuclei of simple columnar epithelia
Spheroidal - the longer axis is perpendicular to the base of the cell
what are the 2 specialisations that simple columnar epithelia can have on their apical surfaces
microvilli or cilia
where are microvilli found
on the apical surface of the epithelia in the gut
where are cilia found
on the apical surface of epithelia in the respiratory tract and in the fallopian tubes
what is a brush border
what intestinal villi are often referred to because they are too fine to be resolved individually
what is the average number of cilia per epithelial cell
300
what shape are cuboidal epithelium cells
they are square in profile with a round nucleus
what shape are simple squamous epithelial cells
the thinnest type consisting of a single layer of cells with cylindrical/elliptical nuclei whose long axis lie parallel to the bases of the cells
where are simple squamous epithelial cells found
they form the pleural and peritoneal membranes lining the chest and abdomen, similar cells line the air sacs of the lungs
where are simple cuboidal epithelial cells found
they form the ducts of many exocrine glands, they have a regular shape and a round nucleus
where are compound (stratified) epithelia found
they line the mouth, throat, oesophagus, anus and vagina (non-keratinised), in its kertainised form it also makes up the epidermal layer of the skin
what are the 3 types of junctions between epithelial cells and what are their roles
occluding (these link the cells to form an impermeable barrier, also known as tight junctions), anchoring (link cells to provide mechanical strength, also known as desmosomes) and communicating (allow movement of molecules between cells, also known as gap junctions)
what are the main types of secretory cells
simple tubular, coiled tubular, Acinus, branched tubulo-acinar
what intermediate layer in the epithelium stains blue and why
the granular layer because they contain large numbers of kerato-hyaline granules which are precursors to keratin
in which layer of the epidermis are desmosomes (anchor junctions) most promient
the prickle cell layer i.e. the layer directly above the basal layer – during tissue processing the cells shrink but they remain attached, so the attachment points look like spikes
what is the main purpose of tight (occluding) junctions in the epidermal lining of the gut
to hold the cells together to prevent large molecules from passing through and gaining access to the body, it creates a membrane which only selective absorption can occur across
what is the role of gap (communication) junctions in intestinal epithelia
they permit the quick passage of small molecules between cells, thereby synchronising the activity of the whole epithelium
