Tissue #1 - Epithelial Tissue

Tissues

group of similar cells that work together to perform a specific structutral or physiological role

How many cell types are in the body

over 200

Histology

aka miscroscopic anatomy - study of tissues and how theyre arranged into organs

Four primary tissues

1. Epithelial

2. Connective

3. Nerve

4. Muscle

How do tissue types differ

Types and function, how much space cells and matrix take up

Matrix

extracellular material that is made of ground substance (fluid, ECF) and fibrous proteins

Tissue =

cells + fibrous proteins + matrix

Epithelial tissue

• covers body surfaces and lines body cavities (digestive tract, glands, BV)

• cells closely packed

• all cells bound to basement membrane

Functions of Epetheilial tissue (PPEAFS)

Produces and releases chemical secretions

Protects deep tissue

Excretes waste

Absorbs chemicals

Filter substances

Senses stimuli

Epethelial tissue structure

Apical surface, epethilial cells, basement membrane

Epethelial cells are classified by

1. cell shap (squamous, cuboid, columnar)

2. number of layers (simple, stratified, transitional, pseudostratified)

squamous

thin, flat

allows for rapid diffusion of substances

lungs and BV

cuboidal

square or round

allows for absorbtion and sectretions of substances

kidneys and glands

columnar

tall and pillar shaped

absorbtion of nutrients

intestines (GI)

Simple (layer)

one layer of cells

Stratified (layer)

ranges from 2-20 layers of cells. only lowest layer bound to basement membrane

psuedostratified (layer)

false appearance of multiple layers. all cells are bound to basement membrane

transitional (layer)

special type of layer found in organs that strech only (bladder)

Epithelial tisssue types

1. simple squamous

2. simple cuboidal

3. simple columnar

4. stratified squamous (keratinized/nonkeratinized)

5. pseudostratified

6. transitional

simple squamous

single row of thin cells

rapid diffusion of substances

secretes serous fluid

alveoli and serosa

simple cuboidal

single layer of cells

used for absorbtion and secretion of substances

found in liver, thyroid, bronchioles

simple columnar

talll pillar shape

oval nuclei in 2/3 part of cell

absorbtion and secretion

has microvili and goblet cells (secrete mucus)

GI, kidney, uterus

Pseudostratified

looks multilayerd but all cells touch basement membrane

nuceli scattered

has cilia and goblet cells

secretes and propels mucus

respiratory tract

stratified squamous

protects deep tissue

deepest layers undergo mitosis - cells pushed up towarsd surface, become flatter and eventually die and flake off (exfoliation or desquamation)

2 types keratinized and nonkeratinized

keratinized stratified squamous

multiple cell layers, cells become flatter at surface

resists abrasion and retards water loss thru skin

palms and soles of feet

nuclei present

non keratinized stratified squamous

same as keratinized without layer of dead cells

resists abrasion and penetration of pathogens

vag, tounge, oral cavity

Transitional/urothelium

multilayered, surface cells change from round to flat when streched

used in bladder

made to strech when filled

How to determine epithelial tissue?

1. cell shape

2. number of layers

3. if adjacent to apical surface looks white in tissue preparation