Histology Flashcards
Study of Tissues
tissue
similar cells that are specialized to perform a common function
adult tissue types
epithelial
connective
muscle
nervous
embryonic germ layers
ectoderm
mesoderm
endoderm
ectoderm
ET
NT
mesoderm
ET
CT
MT
endoderm
ET
extracellular fluid
surrounds all body cells
ECF functions
medium to dissolve solutes
transport
chemical reactions
ECF types
interstitial fluid
plasma
membrane (cell) junctions
hold layers of cells together
prevent intercellular leakage
allow for transport between cells
types of cell junctions
zonula occludens
macula adherens
gap junctions
hemidesmosomes
zonula occludens
tight, zipper like; prevent intercellular passage of materials; interlocking junction proteins; skin
macula adherens
desmosomes; anchoring junctions that hold adjacent cells together; linking proteins (cadherens); allow for movement between cells
gap junctions
transport (communicating) channels between adjacent cells; allow direct passage from to another via connexons
hemidesmosomes
anchor base of an epithelial cell to basement membrane
ET cellularity
tightly packed sheet of cells with little intercellular material between them
ET polarity
always has free (apical) surface which opens to outside or inside (lumen)
ET surface modifications
microvilli
cilia
ET basement membrane
anchored to underlying CT
malignant epithelial cells
fail to respect boundaries; loss of contact inhibition; invade/infiltrate
ET contacts
tight junctions
desmosomes
ET vascularity
avascular
nourished by nutrients that diffuse from underlying CT
ET regeneration
high regenerative capacity (assuming stem cells and intact BM)
ET nerves
innervated
ET location
cover all body surfaces inside and out
ET functions
secretion absorption filtration excretion protection
epithelial classification
according to shape and number of layers
simple
single layer of cells
stratified
many layers of cells
squamous
flattened cells
cuboidal
square shaped cells
columnar
elongated cells
simple squamous epithelium
single layer of flattened cells
allows for diffusion of substances
simple squamous ET locations
linings of air sacs of lungs
lining of capillaries
lining of lymph vessels
lining of body cavities
simple cuboidal epithelium
single layer of square shaped cells with centrally located nuclei; secretion & absorption
simple cuboidal ET locations
lining of kidney tubules
ducts of glands
germinal surface of ovary
thyroid parafollicular cells
simple columnar epithelium
single layer of elongated cells with basally located nuclei; protection, absorption, secretion
simple columnar ET locations
lining of digestive tract lining of uterus gallbladder oviduct epididymus
simple columnar ET modifications
microvilli (increase surface area) goblet cells (secrete mucus)
pseudostratified columnar epithelium
single layer of elongated cells with scattered nuclei; secretion, protection
pseudostratified columnar ET locations
lining of respiratory tract
lining of fallopian tube
pseudostratified columnar ET modifications
cilia (trap debris and beat upward) goblet cells (mucus)
stratified squamous epithelium
many layers of flattened cells: protection
stratified squamous ET location
Nonkeratinized: lining of mouth lining of throat lining of vagina lining of anus Keratinized: epidermis of skin
stratified cuboidal epithelium
usually 2 layers; rare
stratified cuboidal ET locations
ducts of adult sweat glands esophageal glands mammary glands lining of developing ovarian follicle seminiferous tubules
stratified columnar epithelium
usually 2 layers; transition areas between other epithelia; more rare
stratified columnar ET locations
pharynx
male urethra
epiglottis
transitional epithelium
many layers of cells that change shape in response to tension; distensibility
transitional ET locations
urinary bladder, ureters, renal pelvis
glandular epithelium
usually simple cuboidal or columnar; secretion
types of glandular ET
exocrine
endocrine
exocrine
secrete products into a duct which opens: external surface (sweat gland) internal surface (gastric gland)
endocrine
ductless; secrete hormones into blood
exocrine secretion classification
existence of cellular products or portions of glandular cells
eccrine (merocrine)
secrete fluid (99% water) through membrane into duct via secretory vesicle with no loss of glandular cells; sympathetic, cholinergic
apocrine
lose small portion of cells; sweat gland in axillary/anogenital region; mammary glands; ceruminous glands
holocrine
release entire cells; sebaceous glands
carcinoma
tumor originating from epithelial tissue
CT characteristics
common origin from mesenchyme
wide range of vascularity
CT structural elements
ground substance
fibers
cells
ground substance
amorphous material that fills space; functions as sieve; composed of interstitial fluid, cell adhesion proteins, proteoglycans
GAGs
glycosaminoglycans; more = stiffer; chondroitin sulfate, keratin sulfate, hyaluronic acid
fiber types
collagen
elastic
reticular
collagen
composed of the protein collagen
provide high tensile strength
stain pink
elastic fibers
composed of the protein elastin
provide rubbery resiliency to matrix (skin, lungs, vessels)
stain purple
reticular fibers
fine collagenous fibers
form delicate networks (capillaries, immune tissues)
basement membranes
stain purple
3 types of CT cells
fundamental
blast
migrating white blood cells
fundamental cells
aka parenchymal
osteocyte in bone
chondrocyte in cartilage
blast cells
undifferentiated that secrete matrix; convert to 'cyte' when complete fibroblast in CT proper chondroblast in cartilage osteoblast in bone hemocytoblast in blood
migrating white blood cells
respond to tissue damage; mast cells (basophils, monocytes, neutrophils)
connective tissue types
mesenchyme loose connective tissue dense connective tissue cartilage bone blood
mesenchyme
embryonic, gives rise to all other types of CT
loose CT
loose fibrous (areolar)
adipose
reticular
loose fibrous (areolar) CT
gel-like matrix with fibroblasts, macrophages, mast cells, collagen and elastic fibers
loose fibrous CT functions
wraps and cushions organs, inflammation, diffuse of nutrients and gases
loose fibrous CT locations
beneath epithelium, surrounds organs
adipose CT
closely packed adipocytes with nuclei pushed to one side with areolar matrix
adipose CT location
under skin, around kidneys, eyeballs, breasts
adipose CT functions
energy storage, insulation, protection
reticular CT
network of reticular fibers within loose ground substance and reticulocytes
reticular CT locations
basement membranes, lymph nodes, thymus, spleen
reticular CT function
support
dense connective tissue
dense regular (white fibrous) CT dense irregular CT
dense regular CT
primarily collagen fibers with few fibroblasts; poor blood supply, slow to no healing
dense regular CT locations
tendons
ligaments
dense regular CT functions
attachement; tensile strength
dense irregular CT
primarily collagen fibers randomly arranged
dense irregular CT location
dermis (below stratified squamous ET in skin)
heart valves
capsules around joints
dense irregular CT function
provides tensile strength
elastic CT
primarily elastin fibers; durability with stretch
elastic CT locations
lung tissue, wall of aorta
cartilage types
hyaline
elastic
fibrocartilage
hyaline cartilage
amorphous matrix that surrounds cells; avascular; support
hyaline cartilage locations
embryonic skeleton, costal cartilages, cartilage of the nose, trachea, larynx, glottis
elastic cartilage
same as hyaline with elastic fibers; maintenance of shape plus flexibility
elastic cartilage locations
external ear
epiglottis
fibrocartilage
less firm; tensile strength plus shock absorber
fibrocartilage locations
intervertebral discs, pubic symphysis, secondary cartilaginous
bone
hard, calcified matrix with collagen fibers and cells; highly vascular
bone functions
protection, support, movement, calcium storage, hematopoiesis
blood
RBC, WBC, platelets in plasma; transport of gases, nutrients, wastes
epithelial membrane
continuous multicellular sheet composed of an epithelium bound to a discrete underlying CT
epithelial membrane types
cutaneous
mucous
serous
cutaneous membranes
consists of keratinized stratified squamous epithelium firmly attached to dense irregular CT; skin
mucous membranes
line body cavities that open to the outside lining of digestive, respiratory, urinary; consist of epithelium (stratified squamous or simple columnar) firmly attached to a layer of loose areolar CT
serous membranes
consist of 2 layers with cavity between them; simple squamous ET on areolar CT
synovial membranes
are NOT epithelial membranes
muscle tissue
elongated cells; contractile
MT types
skeletal
cardiac
smooth
skeletal MT
long thin cells, multinucleate, striated, attached to bones, voluntary
cardiac MT
one centrally located nucleus, intercalated discs, striations, involuntary
smooth MT
spindle shaped, one central nucleus, no striations, involuntary
nervous tissue
neurons, neuroglia cells; no regeneration