1A03 - TISSUES

Characteristics of Epithelia

- densely packed
- little matrix
- distinctive cell surfaces

Surfaces of Epithelia

apical, basal, lateral

Basement Membranes of Epithelia

- extracellular
- porous
- avascular
- regenerated
- attaches epithelia to CT
- acts as glue

Functions of Epithelia

- protection
- secretion
- absorption
- filtration
- diffusion

Epithelial Cell Surface Modifications

microvilli: increased surface area for absorption or secretion

cilia: move materials across cell surface

Functions of Simple Epithelial Cells

- diffusion
- blood filtration
- secretion
- absorption

Functions of Stratified Epithelial Cells

- protection

Functions of Pseudostratified Epithelial Cells

- secretion
- mucus movement

Functions of Squamous Epithelial Cells

- diffusion
- filtration

Functions of Cuboidal/Columnar Epithelial Cells

- secretion
- absorption
- may include goblet cells

Goblet Cells

produce and secrete mucus

Glands

- epithelium with supporting network of CT
- endocrine and exocrine

Simple Squamous Epithelia

- diffusion
- filtration
- secretion

- endothelium
- serous membranes
- alveoli
- bowman's capsule

Simple Cuboidal Epithelia

- secretion
- absorption

- kidney tubules
- glands+ducts
- ovary surface

Simple Columnar Epithelia

- movement
- secretion
- absorption

- glands
- bronchioles
- uterus + uterine tubes
- stomach
- intestines
- gallbladder
- ventricles of brain

Psudostratified Columnar Epithelia

- synthesize+secrete+move mucus
- absorption
- protection

- lining of most of upper respiratory tract (ciliated)
- male urethra and epidymis (non-ciliated)

Stratified Squamous Epithelia

- protection

keratinized: skin
non-keratinized: mouth, throat, esophagus, anus, vagina

Transitional Epithelia

- regulation (fluid volume)
- protection (against urine)

- lining of urinary system

Connective Tissue Characteristics

- abundant
- consists of cells separated by extracellular matrix
- mostly vascular
- supports extracellular matrix

Connective Tissue Functions

- encloses organs as a capsule
- connects tissues
- storage
- insulation
- transportation
- protection

Extracellular Matrix

protein fibres + ground substance

Extracellular Matrix - Protein fibres

collagen: strong, flexible, inelastic

reticular: fill space, fine collagenous, form branching networks

elastic: made from elastin, crosss linked

Elastin

protein surrounded by fibrillin (a glycoprotein)

Extracellular Matrix - Ground Substance

hyaluronic acid: reduces friction

proteoglycan: long protein core with many polysaccharides

adhesion proteins: fill in space, attach fibres (to cell walls and each other)

Loose CT

areolar: mostly collagen; fills in space

adipose: from adipose cells; store fat

reticular: from reticular fibres; form structures in lymphatic system

Dense CT

regular: fibres line up
irregular: fibres in many directions