PSL 310 Unit 1: Tissue

Primary tissue types

Epithelial, connective, muscle, and nervous

How is a diploid zygote formed?

Haploid sperm cell fertilizes haploid ovum

How is a multicellular embryo formed?

Single-celled zygote divides into a multicellular embryo

What are the stages of embryonic development?

Hyperplasia, hypertrophy, and differentiation

Hyperplasia

Mitosis, cells divide

Hypertrophy

Growth, as cells divide they get bigger

Differentiaton

Around 100-cell stage, cells begin differential gene expression

Where is epithelial tissue found?

Skin, lining blood vessels

Where is muscle tissue found?

Muscle, arterioles (smooth muscle)

Where is nerve tissue found?

Everywhere you want muscles to contract/move, blood vessels (vasoconstriction/dilation)

Where is connective tissue found?

Bone (specialized connective tissue with ossified ECM), tendon, ligament, in skin, collagenous fibers, cartilage, blood is considered connective tissue

Three shapes of epithelial tissue

Squamous, cuboidal, columnar

Squamous

Flat, tile-shaped cells

Cuboidal

Cube-shaped

Columnar

More tall than wide

Simple

Single layer

Stratified

2 or more layers of cells

How is cell shape identified?

By the topmost layer

Simple squamous

Single layer of squamous cells

Stratified squamous

2 or more layers of cells with the top layer being squamous, nonkeratinized

Non-keratinized

Cells are all living, have nuclei

Keratinized

Cells don’t have nuclei, all dead, found in top layers of skin

Do epithelial cells have blood?

No, no blood supply or vessels, avascular

Pseudostratified

Looks stratified but not, really just simple

Ciliated

Have cilia

Cilia

Extensions of plasma membrane, not to increase surface area but to beat on the surface of the cell and move things

Goblet cell

Unicellular exocrine gland, only one in the human body, found commonly in pseudostratified ciliated columnar epithelium

Exocrine gland

Secretes product into a space

Simple columnar w/ microvilli

Common in entire small and large intestine, has goblet cells secreting mucus

Microvilli

Increase surface area for absorption

How are cilia and microvilli supported?

Cilia are supported by flexible microtubules, microvilli are supported by stiff actin filaments

Apical surface modifications

Microvilli (brush border), cilia, stereocilia

Stereocilia

Not supported by microtubules, not involved in absorption, long, involved in senses like hearing and equilibrium

Cardiovascular system’s role in tissue

Feeds every cell in body, moves nutrients, gases, waste

Capillary bed

System connecting arterioles and venules to feed cells

How does fluid exchange in capillary bed?

IVF/plasma ←→ ISF ←→ ICF

Arteriole end of capillary

Moves down, things leave blood and enter ISF and cells to feed them, enters through arteriole

Venule end of capillary

Things move upward, out of cell, into ISF, then into bloodstream, exit through venule

How close are all body cells to a capillary?

Within approx. 20 um of a capillary

What are body cells bathed in?

Interstitial fluid (ISF, aqueous fluid)