anatomy - week 1

histology

branch of anatomy which deals with the microscopic study of tissues in animals and plants which intertwines with other disciplines such as biology, physiology and pathology

microscopy

all slides are in 2D either transverse or longitudinal and suitable only if the tissue is transparent if not try a stronger light source, slice it thinner or use filters

staining

basic cell components like cytoplasm, proteins, filaments in muscle cells, intracellular membranes and collagen/elastic are stained with acidic dyes while, acidic cell components like nucleus, DNA, ribosomes of RNA and carbohydrates in cartilage are stained with basic dyes

two types of stains

giemsa stain and haematoxylin and eosin stain

two types of stains - giemsa

stains the nucleus dark purple, cytoplasm pale blue and erythrocytes pink and excellent for identifying blood cells (basic dye: methylene and acidic dye: eosin and azure)

two types of stains - haematoxylin and eosin

stains the nucleus blue/purple and the cytoplasm and extracellular matrix pale pink and excellent for identifying structure, pathology and inflammation (basic dye: haematoxylin and acidic dye: eosin)

artefacts

some tissue components are lost during tissue processing, especially soluble or easily dissolvable substances, like fat, plasma and ground substances, causing structures to appear empty or distorted eg. scratch, fold or foreign material

tissues

group of specialised cells with a common function

four main tissue types

muscle for movement, connective for support, neural for communication and epithelium for protection and coverage

three types of muscle tissue

cardiac, smooth and skeletal tissue

three types of muscle tissue - skeletal

straited: alternating light and dark bands
multinucleated: each muscle fibre contains multiple nuclei for efficient protein synthesis
peripheral nuclei: located just beneath the cell membrane
voluntary control: movement consciously controlled by the nervous system

three types of muscle tissue - smooth

no striations
single and central nucleus: one per cell
spindle shaped cells: tapered at both ends becoming narrower
two layers: inner circular layer wraps around the lumen and outer longitudinal layer runs the length of the organ
involuntary control: found in the walls of hollow organs

three types of muscle tissue - cardiac

striations: alternating light and dark bands
uni/binucleated: 1 to 2 central nuclei per cell
intercalated discs: specialised connections for synchronised contraction
branched cells: creates a network for coordinated contraction
involuntary control: contracts automatically to pump blood

muscle tissue - functions

contraction which enables movement by shortening in response to a stimulation

muscle tissue - features

highly vascularised: requires large blood supply to meet high metabolic demands
highly cellular: composed primarily of long, cylindrical, spindle shaped cells

connective tissue - features

highly variable: vascularised or avascularised

connective tissue - functions

support, protection, insulation, transportation and energy storage

connective tissue - structures

cells: fibroblasts producing fibers and ground substances
fibers: embedded in ground substances eg. collagen, reticular and elastic fibers
ground substances: gel like matrix composed of water, proteoglycans and glycoproteins which allow for hydration, nutrient diffusion and tissue support

three types of connective tissue

connective tissue, fluid connective tissue and supportive connective tissue

two types of connective tissue

loose and dense

two types of fluid connective tissue

blood and lymph

two types of supportive connective tissue

bone and cartilage

two types of connective tissue - loose

loosely arranged fibers
highly vascularised and flexible
bins and supports other tissues and provides protection
contains fibroblasts and immune cells
subtypes: areolar, reticular and adipose

two types of connective tissue - dense

regular: collagen fibers align and run parallel and highly unidirectional forming resistance to stress
irregular: collagen fibers randomly interwoven and resistant to distension in all directions

two types of fluid connective tissue - blood

lacks structural fibers
contains erythrocytes, leukocytes and platelets
transportation, regulation and protection
extracellular matrix is the plasma composed of water, proteins, hormones, nutrients and waste

two types of supportive connective tissue - bone

support, protection, storage, blood cell production and muscle attachment
cell types: osteoblasts, osteocytes, osteoclasts and osteoprogenitor cells
spongy (cancellous): inner porous network containing red blood cells
compact (cortical): dense outer layer and structural units are osteons

two types of supportive connective tissue - cartilage

composed of chondrocytes in a gel like matrix, all surrounded by perichondrium except fibro and avascular
hyaline: fine collagen fibers which provide flexible, support and reduce friction
elastic: fine collagen and elastic fibers which allows flexibility whilst maintaining shape
fibro: thick bundle fo collage fibers which are resistant to compression and tension

neural tissue - functions

specialised for electrochemical communication

neural tissue - features

highly cellular: minimal extracellular matrix

neural tissue - structures

ganglia: clusters of neuron cell bodies in the PNS
nuclei: clusters of neuron cell bodies in the CNS
lamina: layers of neurons organised in sheets in the CNS
glia: maintain homeostasis, form myelin and defend and nourish neurons
neurons: cell body, axon and dendrites

epithelial tissue - functions

covers/lines surfaces through the body, secretion, absorption, barriers, protection, transcellular transport and sensation

epithelial tissue - features

polarity: apical surface facing the lumen/external environment and basal surface attached basement membrane
highly cellular: densely packed cells
avascular
innervated: containing nerve endings
cell to cell contact: strong due to no gaps
cell layers: simple, stratified or pseudostratified
cell shape: squamous, cuboidal and columnar

epithelial tissue - structures

cilia: transport mucus and debris along surfaces
microvilli: increase surface area for absorption
keratin: fibrous and tough structural protein
basal membrane: made up of collagen and glycoproteins, anchors epithelium to loose connective tissue and forms scaffolding for structural support

three types of simple epithelium tissue

squamous, cuboidal and columnar

three types of simple epithelium tissue - squamous

single thin layer of flat cells
rapid absorption
facilitates diffusion

three types of simple epithelium tissue - cuboidal

single layer of cubed cells as tall as they are wide
absorption and secretion
may be ciliated: aid movement of mucus/fluid
nucleus is spherical and central

three types of simple epithelium tissue - columnar

single layer of tall column cells
absorption and secretion
may be ciliated: aid movement of mucus/fluid
nucleus is oval and located in basal lamina

stratified squamous epithelium tissue

keratinised: composed of a superficial layer of numerous dead squamous cells, lack nuclei but filled with keratin which protects from damage, stress and evaporation
non-keratinised: has nuclei and white spaces

pseudostratified columnar epithelium tissue

appears multi-layered but all cells sit on the basement membrane
nuclei at varying heights giving the illusion of multiple layers
may be ciliated: aid movement of mucus/fluid