Question | Answer |
tissues | groups of closely associated specialized cells that are similar in sturcture and that perform related/limited functions |
primary tissue types | epithelial, connective, muscular, nervous |
epithelium | singular, sheet of cells that covers a body surface or lines a body cavity & glandular secretions |
functions of the epithelium | protection, sensory reception, secretion, absorption, ion transport |
cellularity | (special characteristic)epithelia is composed of abundant densely-packed cells and very little extracellular material |
specialized contacts | (special characteristic) epithelial cell junctions |
polarity | (special characteristic) apical and basal regions exist and differ in structure and function |
support | (special characteristic) underlying connective tissues |
apical surface | exposed surface that faces the exterior of the body/internal space |
basal lamina | sheet of proteins that act as a filter and as a scaffolding on which regenerating epithelial cells grow |
avascular | epithilia do not contain blood vessels, so these cells must obtain nutrients by diffusion or absorption |
support | (special characteristic) avascular but innervated (supplied with nerves) |
regeneration | (special characteristic) due to high mitotic rates and the presence of mesenchymal (stem) cells, epithelia can regenerate |
mesenchymal cells | stem cells |
apical surface features | microvilli, stereocilia, cilia |
microvilli | increase surface area and may anchor sheets of mucus |
sterocilia | long microvilli that cannot move |
cilia | move fluid (mucus) |
lateral surface features | cell junctions (desmosomes, tight junction, gap junction) |
basal surface features | basal lamina & basement membrane |
basement membrane | formed by the basal lamina plus some underlying reticular fibers |
neuroepithilium | specialized sensory epithelium |
gland cells | epithelial cells that produce secretions |
glandular epithelium | most of all of the epithelial cells produce secretions |
simple epithelia | one layer of cells |
stratified epithelia | 2 or more layers of cells, superficial/apical layer is used to classify the epithelial layer |
pseudostratified with cilia | simple epithelium that contains both short and tall cells, classification used mainly in one type |
squamous | flattened cytoplasm and nucleus |
cuboidal | spherical nucleus |
columnar | oval/elongated nucleus, usually located basally |
transitional epithelia | stratified and stretches and changes shape due to the expansion of their cells' lumens |
lumens | open spaces |
germinative | continual division of stem cells close to the basal lamina |
simple squamous epithelium (1) | (thin, flat and irregular) most delicate and lines aveoli, forms endothelium of blood vessels and the mesothelium of the ventral body cavity |
simple squamous epithelium (2) | molecules rapidly diffuse through delicate and thin layer of flat cells of this epithelium |
mesothelium | lines the ventral body cavities (pleura, peritoneum, pericardium) |
endothelium | lines the heart and blood vessels |
stratified squamous epithelium | located where mechanical stresses are severe (skin, lining of mouth, throat, esophagus, rectum, anus, and vagina) |
keratinized | (protein) that forms the epidermis of the skin because it is tough and water resistant |
non-keratinized | forms the moist linings of the esophagus, mouth, and vagina |
functions of the stratified squamous epithelium | protecting underlying tissues in areas subjected to abrasion, pathogens, and chemical attack |
simple cuboidal epithelium | (hexagonal boxes) occurs in thyroid gland, kidney tubules and in ducts/secretory portions of small glands |
function of simple cuboidal ep. | limited protection, secretion, and absorption |
stratified cuboidal epithelium | (relatively rare) occurs in largest ducts of sweat glands, mammary glands, and salivary glands |
functions of stratified cuboidal ep. | protection mainly, also secretion and absorption |
simple columnar epithelium | hexagonal in cross section, (taller rather than wider) and absorbges, secretes, and does ion transport |
non-ciliated simple columnar | lines the stomach & intestines, gallbladder and excretory ducts of some glands |
ciliated simple columnar | lines small bronchi, uterine tubes and some regions of the uterus |
stratified columnar epithelia | rare existance in the body (male urethra, pharynx, anus & large ducts of some glands) - protection & secretion |
pseudostratified columnar epithelium | cells appear to be stratified because of a mixture of cells which have nuclei situated at varying distances from the surface |
ciliated pseudostratified columnar | lines the trachea, and most of upper respiratory tract |
non ciliated pseudostratified columnar | lines the sperm-carrying ducts and ducts of large glands |
functions of the pseudostratified columnar | secretion(mucus) and propulsion of mucus by ciliary action |
transitional epithelium | stratified ep. with special characteristics that allow it to stretch and permit distension/recoil (ureters, bladder, and urethra) |
glands | many epithelial cells make and secrete a product (aqueous fluid containing proteins) |
endocrine glands | ductless glands that release their secretions directly into the intersitital fluids, lymph, or blood |
exocrine glands | secrete product onto skin or into body cavities |
serous glands | produce a watery solution that usually contains enzymes |
mucuous glands | produce viscous, sticky mucus |
mixed glands | produce both types of excretions (serous and mucus) |
unicellular glands | (goblet cells) are individual secretory cells that occur in epithelia containing scattered gland cells |
multicellular glands | occur as aggregations of gland cells that produce exocrine/endocrine secretions |
multicellular glands are classified by.. | their ducts (simple/compound) and by the structure of their secretory unites (tubular, alveolar/acinar, tubuloalveolar) |
tubular | cells arranged in a tube (intestines) |
alveolar or acinar | blind pocket or chamber |
tubuloalveolar | combo of two previous arrangements |
simple vs compound | does not branch vs does branch repeatedly |
modes of secretion | apocrine, holocrine, merocrine(eccrine) |
apocrine | portion of secreting cell's cytoplasm is lost during secretions (milk) |
holocrine | entire cell disintegrates to secrete its substance (sebaceous gland) |
merocrine (eccrine) | cells secrete their substances by exocytosis (mucus and serous glands) |
endocrine glands | ductless and secrete product (hormones) directly into the bloodstream |
connective tissues | most diverse and abundant tissue |
four classes of connective tissue | connective tissue proper, cartilage, osseous (bone), blood |
mesenchyme | common embryonic origin |
connective tissues have 3 basic components | specialized cells, extracellular protein fibers, fluid ground substance |
structure of connective tissues | cells separated from one another by a large amount of extracellular matrix |
exception to the structure... | blood |
connective tissue proper | extracellular fibers, viscous(syrupy) ground substance, and two classes of cells (fixed and wandering) |
fibroblast | most abundant cell type in connective tissue proper |
fibroblasts produce | fibers and ground substance of the extracellular matrix |
3 types of fibers in connective tissues | collagen, reticular, elastic |
collagen fibers | resist tension |
reticular fibers | provide structural support |
elastic fibers | enable the recoil of stretched tissues |
fixed cells | mesenchymal(respond to local injury) fibroblast(make of all connective tissue fibers-stars/stellate) fibrocytes (stellate & maintain connective tissue fibers of CTP) macrophages (eat hurt cells/pathogens) adipocytes (fat cells) melanocytes (store melanin) |
wandering cells | macrophages (front line defense) mast (histamine and heparin stimulate local inflammation) lymphocytes (repair tissue damage) neutrophils/eosinophils (infection/injury) |
ligaments | connect one bone to another |
loose connective tissue proper | packing material (fill space, cushion, support) |
loose areolar | underlies almost all epithelia and surrounds capillaries. ground substance/collagen, reticular and elastic fibers in the matrix surround fibroblast cells, fat cells, and defense cells |
loose areolar functions | support/bind other tissues with its fibers, hold tissue fluid in jellylike ground subs, fight infection, store nutrients in fat cells |
loose adipose | similar to areolar but contains more fat cells |
functions of adipose | increased nutrient storage, insulates |
white fat is abundant in... | hypodermis |
brown fat occurs in.. | babies (generates heat) |
loose reticular | similar to areolar but only fibers in the matrix are reticular (bone marrow, lymph nodes and spleen) |
functions of reticular | form networks of caverns that hold free blood cells |
dense connective tissue proper | contains exceptionally thick collagen fibers/resists tremendous pulling forces |
dense irregular | similar to areolar but collagen fibers are thicker and run in different directions, appearing wavy (resists strong tensions, occurs in the dermis/organ capsules) |
dense regular | all collagen fibers in the matrix run in the same direction, seperated by rows of fibroblasts, parallel to the direction of the pull (main component of ligaments, tendons, aponeuroses and fascia) |
elastic | similar to areolar but increased bundles of elastic fibers (arteries, bronchial tubes, certian ligaments) |
bone (osseous) tissue | hard, calcified matrix consists of inorganic calcium salts and collagen fibers - very well vascularized |
osteoblasts | secrete collagen fibers and ground substance of the matrix |
osteocytes | (mature) bone cells inhabit small pits or cavities called lacunae |
blood | atypical connective tissue bec of its structure, yet is is connective bec it originates from mesenchyme |
RBC & WBC | surrounded by non-living liquid matrix called blood plasma |
cartilage | avascular/not innervated, thin collagen, ground substance and increased tissue fluid |
chondrocytes | mature cartilage cells that reside in lacunae (cavities) |
hyaline cartilage | amorphous but firm matrix, collagen fibers predominate |
elastic cart. | more elastic fibers in matrix |
fibrocartilage | thick collagen fibers predominate |
epithelial and connective tissues form covering and lining membranes | epithelium plus an underlying layer of connective tissue, cover broad surfaces in the body, cutaneous membrane (dry and covers outer body), mucous membrane (moist, lines organs that open to exterior) serous membrane (slippery, lines closed cavities) |
perichondrium | fibrous layer (outer) and cellular layer (inner) sets cartilage apart |
appositional growth | repeated cycles of division for inner layer of perichondrium |
periosteum | assists in attachment of a bone to surrounding tissues and to associated tendons/ligaments (fibrous and cellular layers) |
transudate | fluid formed on the surfaces of a serous membrane |
muscle tissue | muscle cells containing myofilaments (actin and myosin), specialized to contract/make movement, extracellular matrix seperates muscle cells |
skeletal muscle | multinucleated cells w/ a cylindrical and striated (banded) apperance due to highly organiized arrangement of myofilaments |
cardiace muscle | branching cells look striated, one nucleus, presence of intercalated discs (special cellular junctions) |
fascia | layer of connective tissue that can be seen at gross dissection |
smooth muscle | no visible striatiopns, one centrally-located nucleus, spindle-shaped cell, usually functions in propelling substances through hollow organs |
nervous tissue | main component of nervous organs (brain, spinal cord and nerves) |
neurons | highly specialized never cells with extensions and processes that allow electrical impluse transmition |
neuroglia | supporting cells, non-conducting cells that nourish, insulate and protect the neurons |