Tissue (Epithelial)

Question 1

What does epithelial tissue do

Answer 1

-protects tissues from mechanical and thermal injury

-provides immune defenses, physical barriers, and prevents invasion by microorganisms

Question 2

What are the additional functions of the epithelial

Answer 2

-Secretion: forms glands that produce hormones and oils; secreted into blood or ducts

-Transport into other tissues: selectivity permeable membrane; substances can cross through passive or active transport and enter other tissues

-Sensation: rich nerve supply; detects changes in internal and external environment

Taste buds are an example of specialized epithelial cells

Question 3

What do epithelial tissue consist of

Answer 3

-consists of tightly packed cells linked by tight junctions and desmosomes

This makes cells impermeable and resistant to physical stresses and mechanical injury

Question 4

Are epithelial tissue vascular or avascular

Answer 4

It is avascular (lacks blood vessels); it obtains nutrients and oxygen by diffusion from deeper tissue; limits thickness

Question 5

Epithelium components: what does the basement membrane consist of?

Answer 5

Basal lamina - ECM is created by epithelial cells and has collagen fibers and ground substance

Reticular lamina - created by underlying connective tissue and has reticular fibers and ground substance

These two glue epithelial tissue to underlying connective tissue; anchor underlying blood vessels in place; provides barrier between epithelia and underlying tissues

Question 6

What is the epithelium classified by?

Answer 6

It is classified by the number of cells and the shape of cells in the layers

Simple epithelial - single cell layer

Stratified epithelial - more than one cell layer

Question 7

What are the classifications of the simple epithelial layer

Answer 7

Squamous cells - flattened

Cuboidal cells - short

Columnar cells - tall and elongated

Question 8

Describe simple epithelial

Answer 8

-one layer thick

-adapted for transportation of substances between different tissues (some have microvilli for increased surface area, some have cilia for moving substances through hollow organs)

Question 9

Describe this type of simple epithelial: simple squamous epithelium

Answer 9

-thin single layer of cells

-fried egg appearance

-rapid diffusion of substances (ions, oxygen, carbon dioxide, fluids) in air sacs of lung

-specific segments of kidney, tubules, and lining blood vessels

Question 10

Describe simple cuboidal epithelium

Answer 10

-single layer of cube-shaped cells

-is thin so substances can diffuse across rapidly

-lines structures where diffusion is needed (certain kidney tubules, respiratory passages, the ducts of many glands, and thyroid gland

Question 11

Describe simple columnar epithelialum

Answer 11

-single layer of rectangular-shaped cells

-has nuclei in basal portion of cell

-microvilli (small intestine) or cilia (uterine tubes and segments of respiratory tract) on apical plasma membrane

Question 12

Describe pseudostratified columnar epithelium

Answer 12

-looks layered because nuclei is at various heights

-one layer thick with basal plasma membrane in contact with basement membrane

-in segments of respiratory tract and nasal cavity

-ciliated

Question 13

What are the two transport processes in the epithelia

Answer 13

Paracellular transportation - substances leak in epithelial membrane; limited due to tight junctions that makes spaces between cells nearly permeable

Transcellular transportation - substances enter cell by crossing plasma membrane; diffuses across cytosol; exists cell through plasma membrane at opposite side

Question 14

What is stratified epithelium

Answer 14

-more than one layer of cells

-protective barrier where subjected to high degrees of mechanical stress

Question 15

What are the types of stratified epithelium

Answer 15

Keratinized stratified squamous epithelium

Nonkeratinized stratified squamous epithelium

Stratified cuboidal epithelium

Stratified columnar epithelium

Question 16

What is transitional epithelium

Answer 16

It is a subtype of stratified epithelium; only found in urinary system; lines kidney, ureter, bladder, urethra; has cuboidal basal cell layers; ability of apical cell layers to flatten allows tissues to stretch

Question 17

Describe glandular epithelial

Answer 17

-structure of epithelial; creates and secretes product from secretory cells

-is from epithelial tissue that migrated to underlying connective tissue

-classified by shape or how product is released

-is released by endocrine and exocrine

Question 18

Describe exocrine glands of grandular epithelial

Answer 18

-products released onto surface of epithelium or lines hollow organ

-is secreted through epithelial lined duct

-local effects on cells in grand vicinity

Question 19

Describe endocrine glands in epithelial

Answer 19

-secretes products, usually hormones; directly into bloodstream with or without ducts

-allows products to have systemic effects on other distant cells

Question 20

What are the exocrine glands that help secrete products

Answer 20

Merocrine, Holocrine, Apocrine

Question 21

What does merocrine do

Answer 21

Merocrine - used by majority of exocrine glands; products packaged by secretory vesicles for release by exocytosis into ducts

Question 22

What does holocrine do

Answer 22

Holocrine - used by sebaceous gland in skin to secrete sebum; releases product when cell ruptures and dies; mitosis in gland base

Question 23

What does apocrine do

Answer 23

Apocrine - rare secretion; parts of cytoplasm pinched off; lactates mammary gland

Question 24

Describe keratinized stratified squamous epithelium

Answer 24

Keratinized stratified squamous epithelium - apical cellular layers are dead; no nuclei; has protein keratin; tissue is rough and resistant to friction; adapted for outer layers of skin

Question 25

Describe Nonkeratinized stratified squamous epithelium

Answer 25

Nonkeratinized stratified squamous epithelium - apical cellular layers has nuclei; subjected to mechanical stresses where surface must remain moist; mouth, throat, esophagus, anus, vagina

Question 26

Describe stratified cuboidal epithelium

Answer 26

Stratified cuboidal epithelium - rare in humans; two cell layers; lines ducts of sweat glands

Question 27

Describe stratified columnar epithelium

Answer 27

Stratified columnar epithelium - rare in humans; part of certain exocrine glands; underlying basal lamina