Histology

epithelial tissue

covers surfaces and linings, also includes glands; functions in exchange, protection, and secretion

epithelial tissues features

polar, lacks ECM, avascular

polar

apical surface (top) is oriented differently than basolateral surface (bottom)

lack ECM

cells are held together with cell-to-cell junctions (specialized regions of the cell membrane which attach)

avascular

no blood supply - cell nutrients are received via diffusion

simple

single layer of cells

stratified

multiple layers of cells

squamous

cells are flattened

cuboidal

cells are cube-shaped

columnar

cells are taller than they are wide

simple squamous

lubrication, absorption, and secretion
found in: alveoli, serous membranes, blood vessels, portions of the kidney tubules

simple cuboidal

absorption and secretion
found in: glands and ducts (thyroid), kidney tubules

simple columnar

protection, absorption, and secretion
found in: linings of the stomach and intestine

stratified squamous

protection (physical)
found in: skin, linings of mouth, throat, vagina, and rectum

stratified cuboidal

protection, absorption, and secretion
found in: ducts (sweat and salivary gland ducts), rare

stratified columnar

protection
found in: short segments of throat, anus, urethra

pseudostratified

protection, movement of mucus via cilia, and secretion
found in: nasal cavity, walls of respiratory passageways

transitional epithelium

stretches
found in: bladder and uterus

connective tissue

diverse tissue type with a wide array of functions and structure, characterized by abundant ECM

collagen

series of protein fibers wound together like rope, straight, and unbranched; flexible but strong

elastin

series of branched and wavy fibers that return to their original shape when stretched

dense connective tissue

abundant protein fibers that fill ECM, generally either highly collagenous or highly elastic

fibroblasts

In connective tissue, cells that secrete the proteins of the fibers.

loose connective tissue

ECM has few protein fibers and the space is filled with fluid and ground substance

areolar tissue

loose network of fibroblasts, thick collagen fibers, and thin elastin fibers
cushioning between two other tissue types
found: underneath epithelial tissue

adipose tissue

cushioning and energy storage
found: deep to skin on sides, buttocks, breasts, around eyes

adipocytes

fat cells

reticular tissue

reticular network of fibers, surrounding fibroblasts
strong supportive network
found in: liver, kidney, spleen, bone marrow

reticular fibers

contain tightly wound collagen proteins but are arranged differently

cartilage

CT, chondrocytes within relatively rigid matrix

chondrocyte

cartilage cell

hyaline cartilage

provides stiff but flexible support, and reduces friction
found: end of bones, trachea, nose

bone

CT, cells and mineralized matrix, osteocytes located within lacunae in matrix

blood

CT, divided into RBC, WBC, and platelets

compact bone

riding and strong structure which forms scaffolding of the body
bone matrix is a mix of collagen fibers and calcium salts
found: outer portion of bones

osteocytes

bone cells

platelets

blood clotting

RBC

O2 transport

WBC

immune system

muscle tissue

specialized for contraction

skeletal muscle

voluntary body movements
straight fibers don't intersect, multinucleated, striated
found in: large muscles

cardiac muscle

circulation of blood (involuntary)
cells branch and intersect, mononucleated, striated
found in: heart

smooth muscle

elasticity, contractility, support (involuntary)
spindle shaped, mononucleated, not striated
found in: walls of visceral organs

nervous tissue

specialized for conduction of electrical impulses from one region to another

neurons

primary cells of the nervous system, receive information from other neurons or specialized cells and respond accordingly

neuroglia

several kinds of support cells; provide nutrients and repair to neurons

motor nerve cells

cell bodies with dendrites

nerve

cross section of axons

astrocytes

main glial cell of the brain