histology

Question 1

what is anatomy

Answer 1

study of the structure, shape, size, weight & location of all organs, tissues and cells of the body (includes macroscopic / microscopic anatomy)

Question 2

what is physiology

Answer 2

study of processes underlying the function of all body systems and their mutual relationships

Question 3

what is histology

Answer 3

study of the microscopic structure of cells and tissues of plants / animals and their composition and function

Question 4

what are the basic conversions

Answer 4

0.1 mm (human eye)
100 um (cells / organelles)
100000nm (bacteria)

Question 5

describe the 3 different types of microscopes

Answer 5

• 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)

Question 6

what is an artefact

Answer 6

• pseudo structure
• often have altered or misleading properties
• scratches, folds, foreign material

Question 7

how are slides prepared and stained and what are some issues that can occur

Answer 7

• 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)

Question 8

what are different types of histological H&E staining techniques

Answer 8

• 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)

Question 9

describe the rough scales given to organelles / cells

Answer 9

• 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)

Question 10

describe characteristics of arteries

Answer 10

• thicker walls (smooth)
• more compact
• nuclei in tunica media
• collagen fibres
• few connective tissue cell nuclei visible in tunica adventitia

Question 11

describe characteristics of veins

Answer 11

• thinner walls
• valves
• large diameter / lumen
• wall layers are not distinct
• not completely circular

Question 12

describe characteristics of capillaries

Answer 12

• very small (4-15 um)
• wall may be formed by single endothelial cell
• low blood flow
• large SA
• single celled

Question 13

describe differences between microvilli and cilia

Answer 13

• 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

Question 14

what are tissues and the main elements of organs

Answer 14

• T: groups or layers of similar specialised cells with common function
• O: two or more tissues
• parenchyma: functional element of organ
• stroma: supportive framework

Question 15

what are the primary tissue types

Answer 15

• epithelial (cover and protection)
• muscle (movement)
• connective (support)
• nervous (control and communication)

Question 16

what is epithelial tissue

Answer 16

• 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

Question 17

describe different types of epithelial tissue

Answer 17

• 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

Question 18

what is keratin

Answer 18

• 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

Question 19

what is muscle tissue

Answer 19

• smooth, skeletal, cardiac

- contract, highly cellular / vascular, myo-filaments

Question 20

describe different types of muscle tissue

Answer 20

• 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

Question 21

what is connective tissue

Answer 21

• very variable, extracellular matrix between cells
• ECM: fibres in ground substance (tissue fluid), scaffold, biochemical support
• support, protection, insulation / cushioning, transport, storage

Question 22

describe different types of connective tissue

Answer 22

• 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

Question 23

what is proliferation / differentiation (immature vs mature)

Answer 23

• proliferation: active / rapid mitotic division of embryonic cells, immature (chondroblasts)
• differentiation: specialisation of embryonic cells to perform a specific function, mature (chondrocytes)

Question 24

describe chondroblasts vs chondrocytes

Answer 24

• chondroblasts: immature, mitotic division, secrete ECM, become chondrocytes
• chondrocytes: mature, cells in healthy cartilage, produce and maintain cartilaginous matrix