Histology - A&P I

Four basic tissues

epithelial, connective, muscle, and nervous tissues

characteristics of epithelial tissue

High rate of mitosis, apical and basal surfaces, tightly packed cells, avascularity with innervation, and a basement membrane

epithelial tissue location

lining of GI tract organs and other hollow organs and skin surface (epidermis)

simple squamous tissue

a type of epithelial tissue composed of one layer of tightly packed, diamond shaped cells

simple squamous function

filter or exchange membrane

endothelium

simple squamous tissue found in capillary walls and lining larger blood vessels

mesothelium

simple squamous tissue found in pericardial, pleural, and peritoneal membranes

alveoli

air sacs of the lungs; composed of simple squamous

simple cuboidal tissue

a type of epithelial tissue composed of one layer of square shaped cells

simple cuboidal tissue function

used for secretion (eg. sweat glands)

simple cuboidal tissue locations

found in most glands and the kidney tubules

simple columnar tissue

a type of epithelial tissue composed of one layer of rectangle shaped cells

simple columnar tissue function

complex absorption or secretion

simple columnar tissue location

lining of stomach, small intestine (microvilli), and fallopian tubes (cilia)

microvilli

special structure found in small intestine; increase surface area

cilia

special structure found in fallopian tubes; provide movement for eggs

goblet cells

special structures found in the digestive tract; secrete mucus to protect from acid

stratified squamous tissue

a type of epithelial tissue composed of multiple layers of squished, diamond shaped cells

stratified squamous tissue function

protects against abrasion

stratified squamous tissue location

layer next to lumen (apical surface)and layer resting on basement membrane (basal layer); found in skin, oral cavity, throat, and esophagus

pseudostratified ciliated columnar tissue

a type of epithelial tissue composed of one layer of columnar tissue that appears to be stratified; all cells have contact with the basement membrane but are different lengths

transitional tissue

a type of epithelial tissue composed of multiple layers of cells designed to stretch and protect from urine in the bladder

Characteristics of connective tissue

Many different types of cells, large extracellular matrix, and vascularity

Types of connective tissue proper

Loose and dense connective tissues

Types of loose connective tissues

Areolar and adipose tissue

Areolar tissue

A loose connective tissue that has all three fiber types and lots of ground substance

Function of areolar tissue

Works as a “packing material” that holds internal structures in place; binds the epithelium to underlying structures

Adipose tissue

A loose connective tissue that hardly has any extracellular matrix; does not have closely packed fibers

Function of adipose tissue

Provides protection, insulation, and excess fuel storage

Location of adipose tissue

Under skin, around abdomen, and around organs

Adipocytes

Fat cells that are filled with lipid

Fascia

Tight, packing tissue that holds muscles and tissues in place; grey looking

Elastic fibers

Fibers that allow a tissue to stretch and recoil like a rubber band

Collagen fibers

The strongest of the three fibers; allows connective tissue to resist forces while providing structure

Reticular fibers

Fine fibers that form form networks and function as a scaffolding; provides structure and form for soft tissues and organs

Ground substance

An aqueous solution that contains mainly dissolved solutes; surrounds cells in tissue

Extracellular matrix

Part of connective tissues that surround cells; built by blast cells; contains fibers and ground substance

Dense connective tissues

Tissues that contain closely packed fibers either very little ground substance; includes dense regular and dense irregular tissue

Dense regular tissue

A type of connective tissue in which the collagen fibers are arranged parallel to each other; has poor vascularization

Location of dense regular tissue

Located in ligaments and tendons

Function of dense regular tissue

Attaches muscle to bone and bone to bone; provides high tensile strength in one direction

Dense irregular tissue

A type of connective tissue in which fibers are randomly seen in multiple directions; has poor vascularization;

Location of dense irregular tissue

Located in dermis of skin and the organs

Function of dense irregular tissue

Provides structural strength and allows tissues to withstand tension in many directions

Supportive connective tissue

Type of tissue that is considered “heavy weight”; contains cartilage, osseous tissue, and blood

Cartilage

A supportive connective tissue that is strong yet flexible; serves as a shock absorber and reduces friction in joints; has avascularity (which limits ability to self repair); includes hyaline, elastic, and fibrocartilage

Hyaline cartilage

A type of connective tissue that contain collagen fibers; provides rigidity but some flexibility; the weakest of the three types of cartilage

Function of hyaline cartilage

Provides resilience under pressure; gives smoothness to joints

Location of hyaline cartilage

Joints, nose, larynx, trachea, and ribs

Fibrocartilage

The toughest of the three types of cartilage; contains collagen fibers in matrix that alternate between rows of lacunae

Function of fibrocartilage

Acts as a shock absorber and resists extreme pushes

Location of fibrocartilage

Intervertebral discs, pubic symphysis, and menisci of the knees

Elastic cartilage

Highly flexible cartilage; contains numerous elastic fibers in extracellular matrix

Location of elastic cartilage

External ear, epiglottis, and auditory tube in middle ear

Function of elastic cartilage

allows tissue to recoil to original place and shape

Osseous tissue

bone tissue

function of osseous tissue

weight-bearing; provides structure to the body and armor-like protection for vital organs; mineral storage

osteoblasts

bone building cells

osteocytes

bone-maintaining cells; highly vascular

osteoclasts

bone-destroying cells

materials of bone extracellular matrix

hard matrix; collagen fibers; calcium phosphate

Blood

A type of connective tissue that connects all body systems and provides substances needed for function, survival, and defense

Plasma

Blood’s liquid, nonliving extracellular matrix

Erythrocytes

The most abundant cells that transport exigen from the lungs to the body’s tissues and carry carbon dioxide back to the lungs; also called red blood cells

Leukocytes

Vital components of the immune system; protect the body by identifying and destroying pathogens, foreign particles, and cancer cells; also called white blood cells

Thrombocytes

Cell fragments that play a vital role in blood clotting by sealing damaged blood vessels; also called platelets

Formed components of blood

Erythrocytes, leukocytes, and thrombocytes

Function of blood tissue

Transports gases, wastes, and nutrients throughout the body

muscle tissue

Tube-like cells that allow for movement and contraction; highly vascularized; cells are numerous and tight with little extracellular matrix; contain myofilaments; cannot regenerate; includes skeletal, cardiac, and smooth muscle

skeletal muscle

muscle tissue that is found attached to bones via tendons and ligaments; is striated and voluntary; arranged in fascicles

function of skeletal muscle

provides bodily movements, maintains posture, stabilizes joints, and generates heat

cardiac muscle

muscle tissue found only in the heart; is striated but involuntary; contain branched fibers and intercalated discs

function of cardiac muscle

to pump blood through the heart and into the circulatory system

smooth muscle

type of muscle in the walls of organs; is non-striated and involuntary

function of smooth muscle

to propel substances through internal passageways; control the width of blood vessels and airways

nervous tissue

the main component of the nervous system; located in the brain, spinal cord, and nerves; includes neurons and glial cells

function of nervous tissue

to regulate and control body functions

neurons

the basic functional and structural units of the nervous system; send and receive electrochemical signals; enable perception, sensation, movement, emotions, memory, and reasoning

glial cells

supportive and non-conducting cells that support, insulate, and protect neurons

chondrocytes

mature cells found in cartilage

chondroblasts

cartilage-building cells

fibroblasts

fiber-building cells; create ground substance

basement membrane

a double-layered structure that is between the epithelium (above) and the connective tissue (below)

apical surface

the “free surface”; exposed to the external environment; found in epithelial tissue

basal surface

the “bound” surface; bound to underlying tissue; found in epithelial tissue