Histology Test Vocab

muscular, nervous, connective, epithelial, wound healing

EPITHELIA

• lining, covering, & glandular tissue of the body

• glandular — forms glands

• lining & covering — covers all free body surfaces; various versatile cells

• functions: protection, absorption, filtration, secretion

apical surface

free “outer” surface of an epithelium

basement membrane

structureless material that supports epithelial cells; secreted by epithelial & nearby connective tissue cells

simple epithelium

epithelium made up of one layer of cells

stratified epithelium

epithelium made up of more than one layer of cells

simple squamous epithelium

• functions: diffusion, filtration, secretion (serous membranes)

• locations: air sacs in lungs, capillary walls, serous membranes (line ventral cavity & cover organs)

simple cuboidal epithelium

• functions: secretion, absorption

• locations: glands, ducts, walls of kidneys, surface of ovaries

simple columnar epithelium

• functions: secretion, absorption; ciliated cells propel mucus et al

• locations: digestive tract (stomach to anus), mucus membranes

pseudostratified columnar epithelium

• like columnar except cells are different lengths & shapes; nuclei appear to be all over the place

• functions: absorption, secretion; ciliated cells propel mucus et al

• locations: respiratory tract (ciliated)

goblet cell

• epithelial cells that secrete mucus and look like goblets

• often found in conjunction with columnar & pseudostratified columnar cells

stratified squamous epithelium

• most common stratified epithelium

• usually consists of several cell types: squamous at free edges, cuboidal/columnar close to basement membrane

• function: protection!!

• locations: esophagus, mouth, superficial portion of skin

stratified cuboidal & columnar epithelia

• cuboidal: at least surface layer of cells are cuboidal

• columnar: surface layer of cells are columnar, basal cells vary in size & shape

• quite rare in the body; if present, largely found in large ducts (protection)

transitional epithelium

• highly modified stratified squamous

  • basal cells are cuboidal/columnar; apical cells vary but are all dome-like

• cells characterized by ability to slide past one another & change shape

• functions: protection, allowing for stretching

• locations: urinary bladder, ureters, urethra (all urinary system)

glandular epithelium

• function: secretion

• locations: glands

endocrine vs. exocrine glands

ENDOCRINE

• no connection to the surface; no ducts

• secretions diffuse directly into the bloodstream

• ex.: thyroid, adrenal, pituitary

EXOCRINE

• ducts connect them to the surface

• secretions move through ducts

• ex.: sweat, oil, & salivary glands

SECRETION

• process by which substances are produced & discharged from cells, glands, or organs

• secretion pathway in gland cell: endoplasmic reticulum —> golgi complex —> secretory vesicles —> secretion

merocrine secretion

secretory process in which secretions are released from secretory vesicles at the surface of the gland cell by exocytosis

(merocrine = maintain)

apocrine secretion

secretory process in which the apical surface (part of cytoplasm & membrane) of the gland and the associated secretory vesicles are shed; the cell then grows and repairs itself before releasing additional secretions

(apocrine = apical)

holocrine secretion

secretory process in which superficial cells in glandular epithelia form secretions, increase in size, and then burst; the basal cells undergo constant division to replace lost cells

(holocrine = whole)

CONNECTIVE TISSUE

• connects body parts

• distinguishing factors: variations in blood supply, extracellular matrix

• functions: protecting, supporting, binding

• locations: everywhere in the body; most widely-distributed tissue type

extracellular matrix

• distinguishes different connective tissue types from each other

• produced by connective tissue cells & secreted to exterior

• made up of two main components: structureless ground substance & fibers

  • ground substance: largely made of water, proteins, & polysaccharide molecules

  • fibers: type & amount vary based on tissue type; incl. collagen (strength; secreted by chondrocytes), elastic, reticular (fine collagen fibers; structure)

osseous (compact bone) tissue

• composed of osteoblasts and osteocytes (bone cells), which live in little cavities called lacunae

  • osteoblasts at the center, surrounded by lacunae containing osteocytes

• matrix: very hard, contains lots of calcium salts & collagen fibers

• function: protect & support other body organs

hyaline cartilage

• most widespread type of cartilage

• less hard & more flexible than bone

• limited blood supply

• matrix: slippery, rubbery, glassy, “smooth”

• locations: supporting structures of larynx, connecting ribs to sternum, medium- and low-stress joints (fingers, elbows, etc.)

fibrocartilage

• stronger and stiffer than hyaline cartilage; highly-compressible

• limited blood supply

• matrix: lots of collagen, looks kind of fibrous

• locations: spinal discs, between high-stress joints (hips, knees, etc.)

elastic cartilage

• elastic; pretty self-explanatory

• limited blood supply

• matrix: chondrocytes, proteins, looks sketchy/fiber-y

• locations: external ear, tip of nose

dense regular fibrous connective tissue

• ideal for areas that need uniform structure

• matrix: very dense, many collagen fibers that run more or less parallel to one another, fibroblasts crowded between collagen fibers

• locations: tendons, ligaments

cancellous (spongy bone) tissue

• matrix: open spaces, a lot less dense than compact bone

• locations: marrow (inside bones)

dense irregular fibrous connective tissue

• matrix: like dense regular but the fibers inside of it aren’t parallel, they’re running in all different directions

• locations: dermis, eyeball’s protective coating

areolar (loose) connective tissue

• most common connective tissue in the body

• cushions & protects body organs; also holds them in place

• loose, fluid matrix acts as a reservoir for water & salts; nearly all body cells get their nutrients from & release waste into the matrix

  • when a region of the body is inflamed, surrounding areolar tissue soaks up excess fluid & causes swelling

• matrix: soft, pliable, cobweb-like; long elastic fibers running throughout; collagen fibers & fibroblasts throughout

  • micrographs look kind of like a big jumble of stuff

• locations: beneath epithelium of skin & mucus membranes, between muscles, around blood vessels & joints, etc.

adipose (fat) tissue

• protects, cushions, insulates, acts as energy store

• matrix: ground substance surrounding large fat-containing vacuoles; looks like it has big empty rings in it

• locations: subcutaneous tissue, around some organs, fat deposits, behind the eyes

reticular (lymphatic) tissue

• makes up stroma (internal framework) in lymphoid organs

• matrix: large, thick reticular fibers throughout which are surrounded by reticular cells & white blood cells

• locations: lymph nodes, spleen, bone marrow

vascular tissue (blood)

• fluid connective tissue

• “connects” different parts of the body by travelling all over and carrying around waste, nutrients, hormones, water, etc.

• matrix: plasma (clear-ish fluid) surrounding red blood cells (little circles w/ light centers), white blood cells, and fibers (present themselves during clotting)

• locations: inside blood vessels

MUSCLE TISSUE

highly specialized tissue whose primary function is to contract in order to produce movement

skeletal muscle

• formation/organization process: myoblasts —> fuse to form one cylindrical, multinucleated muscle fiber (myofibril) —> come together to form fascicles (surrounded by perimysium; like bridge cables; large “fiber” chunks you actually see) —> come together to form an even larger muscle (surrounded by epimysium; whole thick proper muscles)

• very obvious striations

• fibers are arranged parallel to one another

• 99% of movement is voluntary; only muscle type to be able to do so

• found all throughout the body, allows for movement, gives the body shape

cardiac muscle

• found only in the heart

• contracts —> changes size of space inside heart —> pumps blood out/lets blood flow in

• short, branching cells with one nucleus each; cells run in many different directions

  • space between them is bridged by intercalated discs

• lightly striated

• 99% of movement is involuntary

visceral (smooth) muscle

• no visible striations; i mean, it looks smooth

• spindle-shaped cells with lots of space in between

• found in walls of hollow organs (stomach, intestines, uterus, blood vessels)

• contracts (slowly) —> changes size of space inside organs —> propels fluid through organs

  • ex.: peristalsis keeps food moving through digestive system

• 99% of movement is involuntary

NERVOUS TISSUE

highly-specialized tissue that is made up of neuroglia and neurons

neuroglia

supporting cells in the nervous system; insulate, support, and protect neurons

neurons

• highly-specialized cells that receive and conduct electrical impulses in order to communicate quickly

• can vary from a few mm to over 3ft in length

• locations: brain, spinal cord, scattered throughout the body (nerves)

dendrites

• LIGHT YELLOW

• conduct impulses towards the soma (AFFERENT)

• will only send an impulse if the stimulus passes the threshold; it’s a fire/no fire process, no half-impulses

• help increase the surface area of the neuron so that stimuli can be received with better accuracy and in higher volume (if there are enough dendrites)

soma

• LIGHT GREEN

• cell body of the neuron

• stimuli being received by dendrites kind of collect within the soma; once there’s enough to meet the threshold, the impulse generates

axon

• RED

• conduct impulses away from the soma (EFFERENT)

• length of axon determines speed at which impulses are sent

  • longer axons must transport impulses over greater distances —> it takes longer for them to send impulses —> they tend to get more myelin

• wider/thicker axons conduct faster than thinner axons

• made up of axoplasm inside axolemma (outer membrane)

myelin sheath

• ORANGE

• “insulation” covering the axon that helps limit resistance, which speeds up transmission of impulses

  • works kind of like covering on wires; prevents impulses from “jumping off” axon, protects from outside interference, etc.

• made up of myelin lipids

nodes of Ranvier

• BLUE

• small gaps in the myelin sheath

• facilitates saltatory conduction — impulses “jump” between nodes of Ranvier bc impulses can only be conducted (ion exchange) directly on non-myelinated axon

  • speeds up transmission of impulses bc they don’t have to travel the entire length of the axon

axon terminals

• DARK YELLOW

• discharge impulses from the neuron once they’ve travelled through the axon (EFFERENT)

• form synaptic contacts with other neurons (continuing chain of communication) OR effector cells (carry out actions)

telodendria

• PINK

• little branching ends of the axon, lead into axon terminals

neuroglial (Schwann) cell

• DARK GREEN

• specialized cells that create the myelin sheath

• grows into big sheets that wrap around the axon over and over; nucleus remains on the outside (little bump)

  • neurilemma — the sheet itself (Schwann cell membrane)

nucleus

• LIGHT RED

• contains the genetic information for a particular neuron

axon hillock

• BROWN

• impulses generate here once enough stimuli have been received by the dendrites

WOUND HEALING

the process by which an injury to a tissue or group of tissues is recognized, responded to, and healed

inflammatory response

• generalized, non-specific way to minimize damage and prevent further injury

• involves participation of mast cells & macrophages

immune response

• antigen-specific attack against recognized invaders (germs, fungi, etc.)

• involves participation of white blood cells (specifically lymphocytes), which produce antibodies against a specific threat

regeneration

• the process by which damaged cells in injured tissue are replaced with new cells via mitotic cell divison

• new tissue retains functionality

fibrosis

• the process of using dense fibrous connective tissue in scar formation

• new tissue is nonfunctional

chondrocytes

mature cells that “live” in lacunae and help maintain cartilage