Exam 2 BIO 201 ASU Professor Sniegowski

There are "" trillion cells of "" different cell types

50; 20.

Four broad categories of tissues:

epithelial, connective, nervous, muscular

Organ

structure with discrete boundaries that is composed of two or more tissue types

Histology (microscopic anatomy)

the study of tissues and how they are arranged into organs.

Tissue

a group of similar cells and cell products working together to perform a specific role in an organ.

The four primary tissues (epithelial, connective, nervous, and muscular) differ from each other in:

-Types and functions of their cells

-Characteristics of the matrix (extracellular material)

-Relative amount of space occupied by cells and matrix

Matrix (extracellular material) is composed of:

-Fibrous proteins

-Clear gel called ground substance

Ground substance

-Also known as tissue fluid, extracellular fluid (ECF), or interstitial fluid

-Contains water, gases, minerals, nutrients, wastes, hormones4

The 3 primary germ layers:

ectoderm, mesoderm, endoderm

Ectoderm (outer)

Gives rise to epidermis and nervous system.

Endoderm (inner)

Gives rise to the mucous membrane lining digestive and respiratory tracts, digestive glands, among other things respiratory tracts

Mesoderm (middle) becomes a gelatinous tissue called "____________".

Mesenchyme.

Mesenchyme

-Wispy collagen fibers and fibroblasts in the gel matrix

-Gives rise to cartilage, bone, blood

Histological sections

tissue sliced into thin sections one or two cells thick.

"____________" prevents decay (formalin)

Fixative.

"_________" color the tissue, bind to different cellular components

Stains

"_______________" reduces three-dimensional structure to two-dimensional slice

Sectioning

Longitudinal section (l.s.)

tissue cut on its long axis

Cross section (c.s.)/transverse section (t.s.)

tissue cut perpendicular to long axis of the organ

Oblique section

tissue cut at an angle between cross and longitudinal sections

Smear

tissue is rubbed or spread across a slide.

-Examples: Blood and soft tissues like the spinal cord

Spread

tissues are laid out on a slide.

-Examples: Membranes and "cobwebby" tissues like areolar tissue

Epithelial tissue

sheet of closely adhering cells, one or more cells thick, with the upper surface exposed to the environment or internal space.

-Covers body surfaces and lines body cavities

-Constitutes most glands

-Avascular (does not have blood vessels)

"______________" is usually nourished by underlying connective tissue.

Epithelial tissue

functions of epithelial tissue:

Protection, secretion, excretion, absorption, filtration, and sensation.

Protection via epithelial tissue

protect deeper tissues from injury and infection

Secretion via epithelial tissue

produce and release mucus, sweat, enzymes, hormones, and other substances

Excretion via epithelial tissue

void wastes from the tissues

Absorption via epithelial tissue

absorb chemicals, such as nutrients

Filtration via epithelial tissue

all substances leaving the body are selectively filtered by an epithelium

Sensation via epithelial tissue

nerve endings in epithelia detect stimuli

General structure of epithelia:

-Avascular (no blood vessels).

-Cells close together, a small amount of extracellular material.

-High rate of mitosis in cells near connective tissue.

-Rest on a basement membrane.

Basement membrane

layer between an epithelium and underlying connective tissue

Composition of basement membranes:

Collagen, glycoproteins, other protein-carbohydrate complexes

"______________" anchors the epithelium to the connective tissue below it.

Basement membrane

Surfaces of epithelial cells:

apical, lateral, basal

Basal surface

surface facing the basement membrane

Apical surface

surface that faces away from the basement membrane

Lateral surface

surface between the basal and apical surface, the "sidewall"

Simple epithelia

have each cell anchored to basement membrane

Stratified epithelia

have cells on top of others, so not all contact the basement membrane.

A "________________" has a single layer of cells

Simple epithelium.

4 forms of simple epithelium:

-Simple squamous

-Simple columnar

-Pseudostratified columnar

-Simple cuboidal

Simple squamous

-Thin, scaly cells.

-Single row of thin cells

-Permits rapid diffusion or transport of substances

-Secretes serous fluid

-Locations: alveoli, glomeruli, endothelium, and serosa

Simple columnar

-Tall, narrow cells.

-Single row of tall, narrow cells

-Oval nuclei in the basal half of the cell

-Brush border of microvilli, sometimes ciliated, may possess goblet cells

-Absorption and secretion; secretion of mucus

-Locations: the lining of GI tract, uterus, kidney, and uterine tubes

Simple cuboidal

-Squarish/round cells.

-Single layer of square or round cells

-Absorption and secretion, mucus production and movement

-Locations: liver, thyroid, mammary and salivary glands, bronchioles, and kidney tubules

Pseudostratified columnar

-Not all cells reach the surface but all reach the basement membrane.

-Falsely looks stratified, some cells look taller than others.

-Nuclei at several layers

• Has cilia and goblet cells

• Secretes and propels mucus• Locations: respiratory tract and portions of male urethra

Goblet cells

wineglass-shaped mucus-secreting cells in simple columnar and pseudostratified epithelia

Stratified epithelia:

-range from 2 to 20 or more layers of cells

-Some cells rest directly on others; only the deepest layer attaches to basement membrane

The 4 types of stratified epithelia:

-Stratified squamous

-Stratified cuboidal

• Stratified columnar

-Urothelium

"______________" is unique to the urinary tract; previously called transitional epithelium

Urothelium

"____________" is rare, only in places where two other epithelial types meet other epithelial

Stratified columnar

"_____________" is most widespread.

Stratified squamous

Deepest cells are "" to "_" , include mitotically active stem cells.

Cuboidal; columnar.

exfoliation (desquamation)

-when cells die and flake off, resulting in their separation from the surface.

2 kinds of stratified squamous epithelia:

keratinized and nonkeratinized

keratinized/cornified

found on skin surface, abrasion resistant

Non-keratinized

found lining internal spaces, lacks surface layer of dead cells

Keratinized Stratified Squamous Epithelium

-Multiple cell layers; cells become flat and scaly toward the surface

• Resists abrasion; retards water loss through the skin; resists penetration by pathogenic organisms

-Locations: epidermis; palms and soles heavily keratinized

Non-keratinized Stratified Squamous Epithelium

-Same as keratinized epithelium without a surface layer of dead cells

-Resists abrasion and penetration of pathogens

-Locations: tongue, oral mucosa, esophagus, and vagina