Tissues - principles

4 main types of tissue

epithelial, connective, nervous, muscle

tissues are a collection of

similar cells with specialised functions as well as matrix

what is epithelial tissue

an epithelium is a sheet of cells that covers a surface or lines a cavity

function of epithelial tissue

protection, absorption, secretion and filtration

what is the matrix made up of

ground substance and fibres

smooth muscle is in all organs except

the heart

where is epithelial tissue

skin surface (epidermis), lining of GI tract organs and other hollow organs

example of epithelial tissue

in the skin - provides protecting from injury and bacteria

special characteristics of epithelial tissue

high cellularity (ratio of cells to matrix)

specialised contacts (cells fit tightly forming continuous sheets/layers)

polarity (cells have one exposed and one unexposed face)

a-vascularity (epithelial cells are not directly fed by blood vessels)

basement membrane (anchoring point of cell layer)

regeneration (high regenerative capacity)

classification of epithelial - first name indicates

arrangement of cells (simple, stratified or pseudo-stratified)

classification of epithelial - 2nd name describes

shape of cells - squamous, cuboidal, columnar

simple epithelial arrangement and functions

single layer of cells

secretion, absorption and filtration

stratified epithelial arrangement and functions

multiple cell layers

main function is protection

arrangement of pseudo-stratified

single layer of cells but with different heights

what does a gland consist of

one or more cells that produce and secrete a particular product

where are glands mainly derived from

epithelia

endocrine glands function

produce hormones secreted directly into blood i.e. pituitary gland

exocrine gland function

secrete products via ducts into body cavities or surfaces i.e. sweat glands

parts of connective tissue

connective tissue proper

cartilage

bone and blood

connective tissue functions

support, binding, protection (bone and cartilage), insulation (fat), transportation (blood)

example of connective tissue

tendons attach muscles to bones

subclasses of connective tissue proper

loose - areolar, adipose, reticular

dense - regular, irregular, elastic

subclasses of cartilage

hyaline, elastic, fibro

subclasses of bone tissue

compact, spongy

special characteristics connective tissue - common origin

all derived from one type of embryonic tissue (mesenchyme)

special characteristics connective tissue - varies degrees of vascularity

some have no direct blood supply (i.e. cartilage) while others have a rich supply

ground substance - what is it

unstructured material filling extracellular spaces and supporting fibres

what are the 3 types of fibres

collagen, elastic, reticular

where are collagen molecules secreted

the extracellular space, where they assemble and bundle into thick collagen fibres which can be seen with a microscope

elastic fibre elements

stretch and recoil, rubber-like protein, elastin, form branching networks in the extracellular matrix

reticular fibres (support) function

surround the soft tissue of organs and blood vessels

mitotically active and secretory cells

blasts

mature cells

cytes

types of cells in connective tissue proper

fibroblasts

types of cells in cartilage

chondroblasts and chondrocytes

types of cells in bone

osteoblasts and osteocytes

type of cell in bone marrow

hematopoietic stem cells