Histology Flashcards
Week 1 Lecture 2
What is Anatomy
Study of the structure, shape, size, weight & location of all the organs, tissues and cells of the human body.
This includes macroscopicanatomyand the microscopicanatomy
What is Physiology
Study of basic processes underlying the function of all the body systems and their and their mutual relationships.
What is Histology
Histological image
Study of the microscopic structure of cells and tissues of plants and animals and the study of their composition and function
HI: image under a microscope
Light microscope
Magnifies
Suitable for
M: 500x
S: Entire animals only if they are see-through
Scanning Electron Microscope
Magnifies
How it scans
M: 50 000x
Scans: focused beam of electrons
Transmission Electron Microscopy
Limit of resolutions:
L: 2nm
Usually gre/black/white
Artefacts in histology
Examples
Artefact: Pseudo-structure
The tissue section is not always true
Chemical or physical alterations or contaminations before or during
Can hide structures and change tissue appearance
Examples: scratches, folds, foreign material
Why do we need staining
Most cells are transparent
Histological sections have to be stained to make cells and their contents visible -> can determine cell type, tissue, pathology
Staining with acidic and basic due = visualisations of different organelles
Histological H&E staining
Eosin
Haemotoxylin
Eosin: stains pink
- acidic dye, negatively charged but reacts with positively charges contents. Reacts with proteins, filaments in muscle cells, intracellular membranes, extracellular fibres
H: stains blue/black
- basic dye, positively charged but reacts with negatively charged contents
Reacts with DNA in nucleus, RNA in ribosomes and in touch endoplasmic reticulum
Carbohydrates in cartilage
Organelle length Eukaryotic cell Nucleus Nucleolus Mitochondria Ribosomes Lysosomes
E: 10-100 um Nucleus: 5-6 um Nucleolus: 1um Mitochondria: 0.5-1um R: 25-30nm L: 0.1-0.2um
Specialised structures: veins
Vein walls are thinner than walls of arteries
Can have valves
diameter is larger than arteries
Layering in the wall of veins is not very distinct compared to arteries
Specialised structures: arteries
Walls of arteries will be much thicker and more compact than the wall of veins
Smooth muscle cell nuclei are frequent in the tunica media
Collagen fibres and a few connective tissue cell nuclei are visible int he tunica adventitia
Specialised structures: capillaries
Functions
Very small vessels (4-15um diameter)
Wall of a segment of capillary may be formed by a single endothelial cell
Low rate of blood flow and large surface area
Functions: provide nutrients an oxygen to surrounding tissue
Absorption of nutrients, waste products and carbon dioxide
Excretion of waste products
Specialised structures: microvilli
1um in length, 90nm diameter
Contain bundles of parallel actin filaments held together into a bundle by cross-linking proteins
On enterocytes in SI to increase absorption
Specialised structures: cilia
About 10um long, o.2um diameter Made of microtubules 9 + 2 structure Basal body anchors microtubules Beating of cilia e.g. propel mucus along the trachea
