BIO200INTRODUCTION TO TISSUES,

CLASIFICATION OF LIVING THINGS & ECOLOGY

TISSUES

ANIMAL TISSUES

RELECTION

DEFINITON OF TISSUE

• Groups of cells of similar appearance and a common function

• A group of closely associated, similar cells that carry out specific functions.

ANIMAL TISSUES

• 4 main categoriesi) epithelial tissueii) muscle tissueiii) connective tissueiv) nervous tissue

EPITHELIAL TISSUE

EPITHELIAL TISSUE

• Sheets of cells – covering the outside of the body and lines the organs and cavities within the body.

• Close packing of epithelial cells – involve in tight junction (function as a barrier against mechanical injury, pathogens and fluid loss) - example??

• Form active interfaces with the environment – epithelium lines the nasal passages

• Polarized – 2 different sides (apical & basal)• Apical surface – faces the lumen

cavity/outside of the organ- exposed to the fluid or air- often covered with specialized projections (e.g epithelial of small intestine – microvilli)

• Basal surface – attached to a basal lamina, a dense mat of extracellular matrix

• Separates the epithelium from the underlying tissue.

Figure 40.5ab

Apical surface

Basal surfaceBasal lamina

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Polarity of epithelia

• Types of epithelial cell shapes– Squamous (like floor tiles)– Cuboidal (like dice)– Columnar (like bricks standing on end)

• Type of epithelial tissue arrangement– Simple (single cell layer)– Stratified (multiple tiers of cells)– Pseudostratified (a single layer of cells

varying in height)

Simple squamous epithelium

• Simple squamous epithelium- thin and leaky- function in exchange of material by diffusion- Lines blood vessels and air sacs in the lungs (diffusion of nutrients and gasses is critical)

Simple squamous epithelium

Simple columnar and cuboidal

• Simple columnar and cuboidal- lines passageways- specialized for secretion and absorption- lines the intestines- secretes digestive juices and absorb nutrient

Simple cuboidal Simple columnar

• Stratified squamous epithelium- outer layer of skin- line passageways into the body- provides protection- regenerates rapidly by cell division near basal lamina. The new cells are pushed outward, replacing the cells that are sloughed off.- commonly found on surfaces subject to abrasion (outer skin, anus, vagina)

Stratified squamous epithelium

Stratified squamous

Pseudostratified ciliated columnar

• Pseudostratified ciliated columnar- lines passageways, protects underlying tissue- a mucous membrane that lines portions of respiratory tract

Pseudostratified ciliated columnar

MUSCLE TISSUE

Muscle Tissue

• Tissue responsible for nearly all types of body movement

• Consist of filaments containing the proteins actin and myosin

How many types of muscle tissue?

Types of muscle tissues

• 3 types of muscle tissue :- skeletal muscle- Cardiac muscle- Smooth muscle

Types of muscle tissue

Skeletal muscle

Skeletal muscle

• Attached to bones by tendons• Responsible for voluntary movements• Consists of bundles of long cells called

muscle fibers.• Also called striated muscle (the arrangement

of overlapping filament gives the cells a stripped appearance)

Skeletal muscle

Cardiac muscle

• Forms the contractile wall of the heart.striated like skeletal muscle, but

• Cardiac mus.- branched• End of cells – joined by intercalated disc

(relay signals from cell to cell during heartbeat, synchronize the heartbeat)

Cardiac muscle

Cardiac muscle

Cardiac muscle

Smooth muscle

• Named because lacks striations. Spindle-shaped cells lacking cross striations.

• Found in the walls of digestive tract, urinary bladder, arteries and other internal organ.

• Contract slowly thanskeletal muscle – but longer.

• Involuntary movement, such as churning of the stomach or construction of arteries.

Smooth muscle