Tissues and Membranes

Define epithelial tissue

Tissue that covers exposed surfaces, lines internal passage ways/chambers and forms glands

Describe functions of epithelial tissue

Protection (abrasion, dehydration, chemical/biological agents), absorption (oxygen and nutrients), filtration, excretion, secretion

Has a high rate of mitosis to continuously replace damaged cells

How is epithelium tissue classified (name all types of epithelium tissue)

Classified by cell shape and number of cell layers

• simple squamous

• simple cuboidal

• simple columnar

• stratified cuboidal

• stratified squamous

• stratified columnar

• pseudostratified columnar

• transitional epithelium

Describe general structure of epithelial tissue

Many cells tightly packed together with little to no extracellular matrix (ECM)

• avascular (without blood vessels)

• sit on a basement membrane which transfer nutrients/waste between basal layer of epithelium and capillaries of underlying CT

Describe function of cilia and microvilli in some epithelial tissues

Cilia contract in union to sweep substances across the cell surface

Microvilli greatly increase surface area for secretion or absorption

Describe functions of connective tissues

• supports and binds other tissues

• structural framework for body

• transport of fluids/dissolved material

• storing energy in adipose tissue

• protecting organs

• insulation

• protective sheath around skeletal muscles

Describe general structure of connective tissue

Large amount of extracellular matrix, composed of a ground substance (material between cells) and protein fibres (collagen)

• highly vascular (exception is cartilage, tendons and ligaments)

Name types of ground substance and describe the general function

Fluid - blood or lymph

Solid - cartilage or bone

Gelatinous - loose CT

Stores water and supports cells by binding them together using proteoglycans and adhesive proteins (fibronectin)

How is connective tissue classified

According to physical properties

• connective tissue proper (tendons)

• fluid connective tissue (blood and lymph)

• supporting connective tissue (bone, ligaments and cartilage)

What are the structural components of CT proper and supporting CT

Contains specialised cells, extracellular protein fibres and ground substance

What cells build connective tissue

“Blast” cells build CT

Fibroblasts = loose/dense CT
Chondroblasts = cartilage

Osteoblasts = bone

Mature into “cyte” cells which surround themselves in ECM to maintain ECM

Describe functions of muscle tissue

• specialised for contraction

• facilitate movement

• maintain joint stability

• structural control

• produce heat

Name classifications of muscle tissue

Smooth, cardiac and skeletal

Describe functions of nervous tissue

Primary function is communication

Describe structure of nervous tissue

Main component is neurons (nerve cells) and neuroglia (support cells)

Describe function of neurons and neuroglia

Neurons = generate/conduct electrical impulses

Neuroglia = support/repair neural tissue and supply nutrients to neurons (neurons have limited ability to replicate/repair)

Name age-related changes in epithelial tissue

Gets thinner (fewer layers = greater chance of skin damage)

Skin becomes dryer (less secretion of oils = increased damage)

Name age-related changed in connective tissue

Becomes more fragile

Decrease in collagen produced/reduction in quality (decrease in tensile strength and flexibility)

Elastin fibres fragment

Wrinkles develop

Name age-related changes in nervous tissue

Brain mass/weight reduces

Reduce biochemical activity

Name age-related changed in muscle tissue

Atrophy of muscle tissue (loss of strength at smooth, cardiac and skeletal muscle)

Constipation may develop (slowing of smooth muscle contraction)

Define membrane

Sheets of flexible tissue (composes of an epithelium plus underlying connective tissue) that line or cover a part of the body

Define cutaneous membrane

Membrane that covers the entire surface of body

• Epidermis (superior layer of keratinised, stratified, squamous epithelium)

• Attached to dermis (deeper, thicker layer of dense CT and areolar CT)

Define mucous membrane

Membrane that lines all body cavities that open to the outside of the body (e.g. digestive, respiratory, urinary, reproductive tracts)

• moist membrane

• various types of epithelial tissue lined directly over a layer of areolar CT

• absorption/secretion

• specialised cells produce mucus to prevent cavity from drying out/trap particles

Define serous membrane

Membrane that lines organs within cavities that do not open directly to the exterior

• visceral layer (covers organ)

• parietal layer (lines cavity)

• Layers separated by lubricating serous fluid

• Layers consist of simple squamous epithelium resting on thin layer of areolar CT

Define synovial membrane

Membrane that lines the cavities of synovial joints

• lack epithelium

• layer of CT (areolar and adipose CT)

• discontinuous layer of cells that secrete synovial fluid for lubrication