histology Flashcards
what is anatomy
study of the structure, shape, size, weight & location of all organs, tissues and cells of the body (includes macroscopic / microscopic anatomy)
what is physiology
study of processes underlying the function of all body systems and their mutual relationships
what is histology
study of the microscopic structure of cells and tissues of plants / animals and their composition and function
what are the basic conversions
0.1 mm (human eye)
100 um (cells / organelles)
100000nm (bacteria)
describe the 3 different types of microscopes
- light: 200nm, entire animals (see through), strong light source, slice it, filters, 2D, colour, 500x max
- SEM: 2nm, surface topography, beam of electrons, 3D, colour, 50,000x max
- TEM: 2nm, beam of electrons, 2D, black / white, 50,000x max (viruses)
what is an artefact
- pseudo structure
- often have altered or misleading properties
- scratches, folds, foreign material
how are slides prepared and stained and what are some issues that can occur
- always in 2D
- different planes possible (longitudinal, transverse, ventral)
- slide material lost, fluid content usually not present (water / fat = white), nucleus squished on side
- cells (transparent) = stained to make contents visible, acidic / basic dyes (determines visualisation of organelles)
what are different types of histological H&E staining techniques
- eosin: stains pink, acidic, -ve, reacts with proteins, filaments in muscle cells, intracellular membranes and extracellular fibres
- haematoxylin: stains blue / black (nucleus), basic, reacts with DNA, RNA and RER, carbohydrates (cartilage),
- advanced: fluorescent antibodies / probes, visualise different fine structures (organelles / proteins)
describe the rough scales given to organelles / cells
- eukaryotic cell (10-100 um)
- nucleus (5-6 um)
- nucleolus (1 um)
- mitochondria (0.5-1 um)
- lysosomes (0.1-0.2 um)
- ribosomes (25-30 nm)
- degradative enzymes (pH 4.5-5.5)
describe characteristics of arteries
- thicker walls (smooth)
- more compact
- nuclei in tunica media
- collagen fibres
- few connective tissue cell nuclei visible in tunica adventitia
describe characteristics of veins
- thinner walls
- valves
- large diameter / lumen
- wall layers are not distinct
- not completely circular
describe characteristics of capillaries
- very small (4-15 um)
- wall may be formed by single endothelial cell
- low blood flow
- large SA
- single celled
describe differences between microvilli and cilia
- M: 1um x 90nm, parallel actin, cross-linking proteins, smaller, not embedded, absorption
- C: 10um x 0.2um, microtubules, basal body anchors microtubules, beating of cilia, larger, embedded, 9 + 2 core, movement / transport
what are tissues and the main elements of organs
- T: groups or layers of similar specialised cells with common function
- O: two or more tissues
- parenchyma: functional element of organ
- stroma: supportive framework
what are the primary tissue types
- epithelial (cover and protection)
- muscle (movement)
- connective (support)
- nervous (control and communication)
what is epithelial tissue
- outer layer of body, lines alimentary canals / hollow structures, glands
- secretion, barrier, absorption, protection, transport, compartmentalisation and sensing
- polar: lumen (white) + basement membrane (collagen + glycoproteins, anchors to loose connective tissue
- simple / stratified, highly cellular, avascular, nerve supply, can be ciliated
describe different types of epithelial tissue
- squamous: fast absorption, diffusion, thin membrane, squished, nucleus protrudes
- cuboidal: absorb nutrients, secrete, line ducts, nucleus = circular and central
- columnar: absorb nutrients, secrete, robust, nuclei = elliptical / basal
- stratified: many stacked layers, shape can vary, wear and tear (hands / feet), no absorption / diffusion
- pseudo stratified: fake layers, cells connect to basement membrane but not always lumen
what is keratin
- fibrous structural protein that protects epithelial cells from damage / stress
- adheres cells to each other, filament layer, tightly packed
- intermediate fibres connect via desmosomes, insoluble
- at lumen of epithelial tissue, extra layer of fibres
what is muscle tissue
- smooth, skeletal, cardiac
- contract, highly cellular / vascular, myo-filaments
describe different types of muscle tissue
- skeletal: striations, stripes, multiple peripheral nuclei, voluntary, ‘fused cells’
- smooth: fusiform (thin sides thick middle), central nucleus, involuntary, no striations / stripes, inner (circular) and outer (longitudinal)
- cardiac: striations, stripes, intercalated discs, branches, uni-nucleated, involuntary
what is connective tissue
- very variable, extracellular matrix between cells
- ECM: fibres in ground substance (tissue fluid), scaffold, biochemical support
- support, protection, insulation / cushioning, transport, storage
describe different types of connective tissue
- loose: stains dark, scattered (strings, dots, gaps), BV, internal organ support
- dense: regular (bundled, regular, parallel, fibrous, ligaments / tendons), irregular (matrix of irregular fibres, few gaps, dermis of skin, periosteum)
- hyaline cartilage: scattered circles, bubbles through glass, movement / reduces friction, bones, costal cartilage
- elastic cartilage: butterfly wings / web, support, elasticity, epiglottis, eustachian tube
- bone: compact (tree cross section, attachment) spongey (sponge, house bone marrow, ends of bones)
- adipose: bubbles connected loosely, lots of white, energy source, cushioning / insulation
- blood: RBC (red), WBC (purple), transport / protection
what is proliferation / differentiation (immature vs mature)
- proliferation: active / rapid mitotic division of embryonic cells, immature (chondroblasts)
- differentiation: specialisation of embryonic cells to perform a specific function, mature (chondrocytes)
describe chondroblasts vs chondrocytes
- chondroblasts: immature, mitotic division, secrete ECM, become chondrocytes
- chondrocytes: mature, cells in healthy cartilage, produce and maintain cartilaginous matrix
