Anat Tissues Textbook

Histology

study of tissues and how they arranged into organs

Tissue

a group of similar cells and cell products that arise form the same region of an embryo and work together to perform a specific structural or physiological role in an organ

what are the four primary tissues

epithelial
connective
nervous
muscular

how do the primary tissues differ from each other

types and functions of their cells, the characteristics of the matrix that surrounds the cells, and the relative amount of space occupied by cells versus matrix

matrix

The extracellular material of a tissue

Epithelial Characteristics

tissue composed of layers of closely spaced cells; covers organ surfaces, forms glands, and serves for protection, secretion, and absorption

Epithelial Representative Locations

epidermis, lining of digestive tract, liver, and other glands

Connective Characteristics

Tissue with usually more matrix than cell volume; often specialized to support, bind, and protect organs

Connective Representative Locations

tendons, ligaments, cartilage, fat, bone, blood

Nervous system characteristics

tissue containing excitable cells specialized for rapid transmission of information to other cells

nervous Representative Locations

brain, spinal cord, nerves

Muscular characteristics

tissue composed of elongated, excitable cells specialized for contraction and movement

muscular Representative Locations

skeletal muscles; heart; walls of uterus, bladder, intestines, and other internal organs

nonliving matter secreted by the tissue cells

matrix

what is the matrix composed of

fibrous proteins, and usually clear gel known as ground substance or extracellular fluid (ECF)

histological sections

thin tissue slices, generally one or two cells thick that are mounted on microscope slides and dyed with various stains

describe microscopic images of tissue sections

shows three-dimensional object as a two-dimensional image

try to translate the microscopic image into a mental image of the whole structure

planes of section

cut at various levels

list of cell shapes

squamous
cuboidal
columnar
polygonal
spheroidal to ovoid
fusiform
fibrous

Squamous

a thin flat scaly shape

where are squamous cells

lining the esophagus and form the surface layer (epidermis) of the skin

Cuboidal

squarish and about equal in height and width

Examples of cuboidal cells

kidney tubules and liver

columnar

distinctly taller than wide

Columnar cells examples

inner lining cells of the stomach and intestines

polygonal

having irregular, angular shapes with four, five, or more sides

spheroidal to ovoid

round to oval

spheroidal examples

egg cells and white blood cells

Fusiform

elongated, which a thick middle and tapered ends

fusiform examples

smooth muscle cells

fibrous

long, slender, and threadlike

example of fibrous

skeletal muscle cells

epithelial tissue (epithelium)

consists of a flat sheet of closely spaced cells, one or more cells thick

where is epithelium

body surface, lines body cavities, forms the external and internal linings of many organs, and makes up most gland tissue

Do epithelia have blood vessels

no

How do epithelia get its nourishment and waste removal

it lays on a layer of loose connective tissue and depend on its blood vessels

List of functions of the epithelial tissues

Protection
Secretion
Excretion
Absorption
Filtration
sensation

Epithelial Function Protection

epithelia protect deeper tissues form invasion and injury

where does epithelial protect

epidermis of the skin (barrier to infection and water loss from the body)

Epithelial Function Secretion

epithelia produce mucus, sweat, enzymes, hormones, and most of the body's other secretions (glands)

Epithelial function Excretion

Epithelia removes wastes from the tissues

Examples of epithelial excretion

CO2 is moved across the pulmonary epithelium to be exhaled

Epithelial Function absorption

epithelia absorb material; nutrients

Epithelial function Filtration

all substances leaving the blood are selectively filtered through the epithelium that lines the blood vessels; all urinary waste is filtered through epithelia of the kidneys

Epithelial function Sensation

epithelia have nerve endings that sense stimulation such as touch on the skin or irritation of the stomach

basement Membrane

between epithelium and the underlying connective tissue and is composed mainly of protein

Roles of basement membrane

anchors the epithelium to the connective tissue, regulates the exchange of materials between the epithelium and the underlying tissues, and binds growth factors from below that regulate epithelial development and maintenance

basal surface

surface of a cell that attaches to the basement membrane

apical surface

upper surface that faces the body surface or the lumen of an organ

lumen

The internal space of a hollow organ such as a blood vessel or the esophagus, or a space surrounded by cells as in a gland acinus.

lateral surfaces

sides of the cell

epithelial cells often have

cilia, microvilli or both on their apical surface

2 categories of epithelia

simple and stratified

simple epithelium

every cell touches the basement membrane

stratified epithelium

some cells rest on top of other cells and do not extend to the basement membrane

how many layers of cells do simple epithelium have

one

Four types of simple epithelium

simple squamous
simple cuboidal
simple columnar
pseudostratified columnar

3 types of simple epithelia named for the shapes

simple squamous (thin scaly cells)
simple cuboidal (squarish or rounded cells)
simple columnar (tall narrow cells)

pseudostratified columnar

not all cells reach the free surface; the shorter cells are covered over by the taller ones, but all of them reach the basement membrane

what two simple epithelium produce a mucous coating and how is it secreted

simple columnar and pseudostratified

wineglass-shaped goblet cells

goblet cells

A mucus-secreting gland cell, shaped somewhat like a wineglass, found in the epithelia of many mucous membranes

Simple Squamous Epithelium microscopic appearance

single layer of thin cells, shaped like fried eggs with a bulge where the nucleus is located; nucleus somewhat flattened in the plane of the cell, like an egg yolk; cytoplasm may be so thin it is hard to see in tissue sections; in surface view, cells have angular contours and nuclei appear

Simple Squamous Epithelium representative locations

air sacs (alveoli) of lungs; glomerular capsules of kidneys; some kidney tubules; inner lining (endothelium) of heart and blood vessels; serous membranes of stomach, intestines, and some other viscera; surface layer (mesothelium) of pleurae, pericardium, peritoneum, and mesenteries

Simple Squamous Epithelium functions

allows rapid diffusion of transport of substances through membranes; secretes lubricating serous fluid

simple cuboidal epithelium microscopic appearance

single layer of squarish or rounded cells; in glands, cells often pyramidal and arranged like segments of an orange around a central space; spherical, centrally placed nuclei; often with a brush border of microvilli in some kidney tubules; ciliated in bronchioles of lung

simple cuboidal epithelium representative location

liver, thyroid, mammary, salivary, and other glands; many gland ducts; most kidney tubules; bronchioles

simple cuboidal epithelium functions

absorption and secretion; production of protective mucous coat; movement of respiratory mucus

simple columnar epithelium microscopic appearance

single layer of tall, narrow cells; oval or sausage-shaped nuclei, vertically oriented, usually in basal half of cell; apical portion of cell often shows secretory vesicles visible with TEM; often shows a brush border of microvilli; ciliated in some organs; may possess goblet cells

simple columnar epithelium representative locations

inner lining of stomach, intestines, gallbladder, uterus, and uterine tubes; some kidney tubules

simple columnar epithelium functions

absorption and secretion; movement of egg and embryo in uterine tube; secretion of mucus

pseudostratified columnar epithelium microscopic appearance

looks multilayered; some cells do not reach free surface but all cells reach basement membrane; nuclei at several levels in deeper half of epithelium; often with goblet cells; often ciliated

pseudostratified columnar epithelium representative locations

respiratory tract from nasal cavity to bronchi; portions of male reproductive tract

pseudostratified columnar epithelium functions

secretes and propels respiratory mucus; absorbs excess fluid from parts of the male reproductive tract

stratified epithelia

range from 2 cell layers to 20 or more

4 types of stratified epithelia

stratified squamous
stratified cuboidal
stratified columnar epithelia
transitional epithelium

3 types of stratified epithelia based on shape

stratified squamous
stratified cuboidal
stratified columnar epithelia

how was the transitional epithelium originally named

thought to represent a transitional stage between stratified squamous and stratified columnar epithelium- proven untrue

stratified columnar is

rare (occurring in short transitional zones where one epithelium type grades into another)

stratified squamous epithelium-keratinized microscopic appearance

multiple cell layers with cells becoming increasingly flat and scaly toward surface; surface covered with a layer of compact dead cells without nuclei; basal cells may be cuboidal to columnar

stratified squamous epithelium-keratinized representative locations

epidermis; palms and soles are especially heavily keratinized

stratified squamous epithelium-keratinized functions

resists abrasion; retards water loss through skim; resists penetration by pathogenic organisms

Stratified squamous epithelium-nonkeratinized microscopic appearance

same as keratinized epithelium but without the surface layer of dead cells

Stratified squamous epithelium-nonkeratinized representative locations

tongue, oral, mucosa, esophagus, anal canal, vagina

Stratified squamous epithelium-nonkeratinized functions

resists abrasions and penetration by pathogenic organisms while providing a moist slippery surface

stratified cuboidal epithelium microscopic appearance

Two or more layers of cells; surface cells squarish or rounded

stratified cuboidal epithelium representative functions

sweat gland ducts; egg-producing vesicles (follicles) of ovaries; sperm-producing ducts (seminiferous tubules) of testes

stratified cuboidal epithelium functions

contributes to sweat secretion; secretes ovarian hormones; produces sperm

Transitional epithelium microscopic appearance

Somewhat resembles stratified squamous epithelium, but surface cells are rounded, not flattened, and often bulge above surface, typically five or six cells thick when relaxed, two or three cells thick when stretched; cells may be flatter and thinner when epithelium is stretched (as in a distended bladder); some cells have two nuclei

Transitional epithelium representative locations

limited to urinary tract- part of kidney, ureter, bladder, part of urethra

Transitional epithelium functions

stretches to allow filling of urinary tract; protects deeper cells and tissues form damage by acidic and hypertonic urine

what is the most widespread epithelium

stratified squamous epithelium

Describe squamous epithelium cells

deepest cells are cuboidal to columnar and undergo continual mitosis

daughter cells push toward the surface and becomes flatter (squamous) as the migrate farther upward until the die and flake of (exfoliation)

exfoliation

the peeling off in flakes or scales of bark or dead skin

exfoliate cytology

study of exfoliated cells

2 kinds of stratified squamous epithelia

keratinized and nonkeratinized

keratinized epithelium

found in the epidermis, is cover with a layer of compact, dead, squamous cells. These cells are packed with durable protein keratin and coated with a water repellant (retards water loss from the body and resists penetration by disease organisms)

nonkeratinized

lacks the surface layer of dead cells

located in tongue, oral mucosa, esophagus, vagina, and other internal surfaces.

provides a surface that is abrasion resistant but also moist and slippery. Resists stress produced by chewing, swallowing, sexual intercourse, and birth

Transitional epithelium (urothelium)

found only in the urinary tract

protects the cells from the acidic and hypertonic urine. Umbrella cells- at the surface protect the deeper cells from urine

what is the most abundant primary tissue

connective tissues

functions of connective tissue list

Binding organs
support
physical protection
immune protection
movement
storage
heat production
transport