HISTO
cells responsible for the special function of an organ
parenchyma
cells that act as supporting role in the organ
stroma
- composed of closely aggregated polyhedral cells adhering strongly to one aonther and to a thin layer of ECM
- forms cellular sheets that line the cavaties of organs and cover the body surface
- line all external and internal surfaces of the body
- all substances that enter and leave the organ must cross the epithelium
epithelial tissue
underlies the epithelia lining the organs of the digestive, respiratory and urinary system
lamina propia
small evaginations projecting from the connective tissue into the epithelium(skin and tongue)
papillae
region in contact with ECM and connective tissue
basal pole
region facing the surfaces
apical pole
- branching strands in the membrane around each cell's apical end
- restricts the movement of membrane lipids and proteins at the apical cell surface into the lateral and basal surfaces
- seals adjacent cells to one another
tight junction (zonula occludens)
- located immediately below the tight junction
- transmembrane proteins
adherent junction
- resembles a single "spot-weld" and does not form a belt around the cell
- disc-shaped structures at the surface of one cell that are matched with identical structures at an adjacent cell surface
- provides points of strong intermediate filament coupling
desmosome (macula adherens)
- half-desmosomes
- adhesive structures that resembles desmosome ultra structurally
- transmembrane proteins bind primarily to laminin molecules in the basal lamina
hemidesmosome
- mediate cellular communications
- transmembrane proteins are arranged in circular patches in the plasma membrane
gap junction
- non-motile
- enriched with receptors and signal transduction
primarily cilium
- motile
- abundant on cuboidal or columnar cells
- rapid beating patterns that move a current of fluid and suspended matter in one direction along the epithelium
secondary cilia
- organized into one or more layers
- cover the surface or line the cavities of an organ
covering epithelium
mainly to produce and secrete various macromolecules
secretory (glandular) epithelium
- one layer of squamous cells
- facilities movement of the viscera
- active transport by pinocytosis
- secretion of biologically active molecules
simple squamous epithelium
- one layer of cuboidal cells (tall as wide)
- thick cytoplasm allows the cell to be rich in mitochondria and other organelles > active transport across the spithelium
simple cuboidal epithelium
- one layer of columnar cells ( more tall than wide)
- lining of intestine and gallbladder
simple columnar epithelium
- excretory salivary glands
- sweat glands
- secretion
stratified cuboidal epithelium
- conjunctive lining the eyelids
- protection
- mucus secretion
stratified columnar epithelium
- special type of cuboidal epithelium
- "balloon" or "umbrella" cells
transitional epithelium
- tall, irregular cells attached to the basement membrane
- nuclei are different levels
pseudostratified epithelium
cells that mainly function to produce or secrete various macromolecules
secretory epithelium and glands
- contractile cells located at the basal ends of the secretory cells
- long processes of these cells embrace the secretory acinus
- bound to the hemidesmosomes and connected to the other epithelial cells by both gap junctional and desmosomes
- rich in actin filaments and myosin
- storng contraction of these cells propel secretory products from acini into ductal system
exocrine glands
- lack of myoepithelial cells
- protein (exocytosis) or steroid hormone (diffusion through cell membrane for uptake by bindiing proteins outside the cells)
- cytoplasmic staining for RER or SER
- involves hormone transport in the blood to the target cells throughout the body
endocrine glands
- provides a matrix that supports and physically connects other tissues and cells together to form the organs of the body.
- interstitial fluid gives metabolic support to cells as the medium for diffusion of nutrients and waste products
connective tissue
- a tissue developing mainly from the mesodorm
- consist of largely viscous ground substance with few collagen fibers
embryonic mesenchyma
are cells of the embryonic mesenchyme
mesenchymal cells
- key cells in the connective tissue proper
- synthesize and secrete collagen and elastin to form fibers
- also synthesize the ground substance of ECM
- responds to stimuli of growth factors which influence cell growth and differentiation
fibroblasts
- fat cells
- store lipid as neutral fats to produce heat
- serves as a cushion and insulate the skin and other organs
adipocytes
- oval or irregularly shaped cells filled with basophilic secretory granules that contain heparin, histamine, serine proteases and other enzymes
- release of enzymes mediates allergic reactions
mast cells
- derived from blood cells called lymphocytes
- produce and secrete antibodies
plasma cells
- thinner that type I collagen fibers
- form sparse networks interspersed with collagen fibers in many organs
- have a rubber-like properties that allow tissue to be elastic
- seen in the wall of large blood vessels
- composed of fibrillin
elastic fibers
typically contains cells, fibers, and ground substab=nce in roughly equal parts
loose areolar connective tissue
have similar components with loose areolar connective tissue but fewer cells and clear predominance of type I collagen fibers over ground substance
dense connective tissue
- bundles of collagen fibers that appear randomly interwoven with no definite orientation
- provides considerable resistance to stress from all directions
dense irregular connective tissue
consist mostly of type I collagen bundles and fibroblast aligned in parallel for great resistance to prolonged or repeated stresses form the same direction
dense regular connective tissue
characterized by abundant fibers of type II colagen called "reticulin" which are produced by modified fibroblasts known as reticular cells
reticular tissue
- forms a delicate network supporting various types of cells
- located in hematopoietic tissue and some lymphoid organs
reticular tissue
- represents the principal component of the fetal umbilical cord known as Wharton's jelly
- have abundant ground substance composed chiefly of hyalluronan
mucoid (mucous) connective tissue
stimulates glucose uptake by adipocytes and accelerates its conversion into triglycerides, inhibits hormone-sensitive lipase reducing fatty acid release and stimulate lipid synthesis
insulin
released in the adrenal gland activities hormone-sensitive lipase that breaks down triglycerides at the surface of the stored lipid droplets
noreprinephrine
"satiety factor", regulates appetite and participates in regulating the formatio of new adipose tissue
leptin
- a tough, resilient type of connective tissue
- structurally support soft tissues in the respiratory tract and joints
cartilage
growing cells which synthesize and secrete the organic components of the matrix
osteoblasts
- cells found in cavities or lacunae
- cytoplasmic processes that extend to the matrix
osteocytes
- giant multinucleated cells
- responsible for removing calcified bone matrix and remodelling bone tissue
osteoclasts
cancellous bone covered by thin layer of compact bone
epiphyses
- cylindrical part
- mostly dense compact bone with thin region of cancellous bone on the inner surface around the marrow cavity
diaphysis
region in between diaphysis and epiphysis
metaphysis
- multiple layers of lamellae of calcified matrix
- organized as parallel sheets or concentrically around a central canal
lamellar bone
- non-lamellar
- random disposition of type I collagen fibers
- first bone to appear in embryonic development and fracture repair
woven bone
osteoblasts differentiate directly from mesenchyme and begin secreting osteoid
entramembranous ossification
preexisting matrix of hyaline cartilage is eroded and invaded by osteoblasts, which begin osteoid formation
endochondral ossification
- are regoins where adjacent bones are capped and held together firmly by connective tissues
joints
- bones are united only by bone tissue
- no movement takes place
synostoses
- join bones by dense connective tissue only
syndesmoses
- ligaments and a capsule of dense connective tissue maintain proper alignment of the bones
- articular surfaces are made of hyaline cartilage that lacks the usual perichondrium
diarthroses
enclosed by the capsule
joint cavity
an ultrafiltrate of plasma that contains high concentration of hyaluronan produced by the synovial membrane, as lubricant of
synovial fluid
a specialized connective tissue that lines the joint cavity
synovial membrane
ability to shorten is inherent to all cells (actin)
contractility
blood vessels
pericytes
exocrine glands
myoepithelial cells
muscle tissues. It exhibits the greatest degree of contractility
myocytes
mesodermal in origin
muscle tissue
- differentiate by a gradual process of cell lengthening with abundant synthesis of myofibrillar proteins: Actin and Myosin
- elongated cells that are individually enveloped by a basal lamina
muscle tissue
- bundles of very long, multinucleated cells with striations
- contractions are quick, forceful, and usually voluntary
skeletal muscle
- striated, elongate,branched cells bound to one another by intercalated discs
- contraction is involuntary, vigorous, and rhythmic
cardiac muscle
- collections of fusiform cells that lack striations
- contractions are slow and often involuntary
smooth muscle
- striated muscle fibers
- long, cylindrical multinucleated cells
- nuclei are elongated and located peripherally
skeletal muscle
- myoblasts that did not fuse and differentiate into myotubules
- remain as mesenchymal cells to produce new myocytes after injury
satellite cells
an external shealth of dense connective tissue that surrounds the entire muscle
epimysium
a thin connective tissue layer that immediately surrounds each bundle of muscle fibers fascicle
perimysium
located inside the fascicles and surrounds individual muscle fibers. it is a thin layer of reticular fibers and scattered fibroblasts
endomysium
- bifringent in polarized microscope
- myosin fibers at the middle of the sarcomere
- ends of actin fibers that are attached to the myosin
A band (Anisotropic band)
- does not display bifringence in polarized microscope
- transected by Z-disc, which holds the actin filaments
I band (Isotropic band)
- consist of two identical heavy chains and two pairs of light chains
- heads bond both actin and ATP > catalyzing energy release
myosin filaments
- helical structure with binding site for myosin
actin filaments
- lighter zone at the center of A bands
- corresponds to a region with only rodlike portions of the myosin and no actin filaments
H zone
- bisects the H zone
- contains MYOMESIN, a myosin-bind protein that holds the myosin filaments in place
- also contains creatine kinase, an enzyme for ATP production
M line
- oxygen-binding proteibn that is responsible for the brownish discoloration of the muscle
- present in the sarcolemma of muscle fibers
myoglobin
depolarization causes release of calcium in he sarcoplasm
sarcoplasmic reticulum
invaginations of sarcolemma that penetrate deeply into the sarcoplasm and encircle each myofibril
transverse tubules (T-tubules)
commands for contraction originates from the CNS, carried to the muscle by myelinated nerve fibers of somatic (efferent neurons)
nerve supply
somatic motor neuron + muscle fiber
motor unit
point of contact between somatic neuron and the muscle fiber
motor endplate
a space in between axon and muscle
synaptic cleft
- stretch detectors
muscle spindles
- detects changes in tension
- located within tendons
- inhibit motor nerve activity if tension becomes excessive
golgi tendons organs
-occurs exclusively in the heart
- fibers consist of separate cells in a series joined at interdigitating regions
cardiac muscle
- specialized for slow, steady contractions under the influence of autonomic nerves and various hormones
- elongated, tapering, and un-striated cells (lack T tubules)
- centrally located single nucleus
- linked by gap junctions
smooth muscle
major muscle components of visceral organs
visceral muscles
- actin and myosin crisscross the sarcoplasm obliquely
- actin filament are not associated with troponin and tropomyosin
smooth muscle