Test 2 Flashcards
what kind of tissue is cartilage and what does it contain?
cartilage is a specialized connective tissue; it is avascular and lacks nerve fibers and contains cells, fibers, and ECM
what are the three types of cartilage?
hyaline cartilage, elastic cartilage, and fibrocartilage
describe hyaline cartilage
known for its “glassy” appearance and is the most common type; composed mostly of type II collagen
where can you find hyaline cartilage?
in places where it maintains a lumen/space open (nose, larynx, trachea, and bronchi), at articular surfaces of bones (ventral ends of the ribs that articulate with sternum, articulating surfaces of mobile joints such as femur), and at epiphyseal plates (“growth” plates of growing bones)
what are the functions of hyaline cartilage?
to maintain an open lumen/space, to act as a shock absorber, and to allow friction-free gliding between bones of moveable joints
what is the function of epiphyseal growth plates?
they allow long bones to grow in length; they start as hyaline and are eventually replaced completely by bone
describe the histogenesis of hyaline cartilage
mesenchymal cells retract their cell processes and become round-shaped cells. these cells form chondrification centers which are future cartilage sites. mesenchymal cells then differentiate into chondroblasts which synthesize more of this matrix in their surroundings, they become trapped in lacunae
what does “isogenous” mean?
isogenous cells are progeny of a single cell and are genetically uniform
describe the perichondrium
a connective tissue capsule that covers only hyaline and elastic cartilage; composed of 2 cell layers: the outer fibrous layer that contains fibroblasts and the inner cellular layer composed of chondrogenic cells
explain how cellular growth occurs in perichondrium
the perichondrium has vessels to provide oxygen and nutrients; the nutrients and oxygen can get into cartilage layer; when there isn’t enough diffusion, the cells in the hyaline cartilage layer break down and new cells form from the perichondrium and move inward
what are the 2 mechanisms of cartilage growth
interstitial growth (cartilage grows from within); appositional growth (cartilage grows on the surface)
where does interstitial growth occur?
during early stages of cartilage formation, in articular cartilage (does not have perichondrium), in growth plates, and deep within the cartilage
what makes up the hyaline cartilage matrix?
proteins (mainly type II collagen; cannot be seen with staining so that is why you see glassy), proteoglycans, glycoproteins, and extracellular fluid
what are the three different types of cartilage cells?
chondrogenic cells, chondroblast and chondrocytes
describe chondrogenic cells
arise from mesenchymal cells and differentiate into chondroblasts and osteoprogenitor cells
describe chondroblasts
differentiate from mysenchymal cells in the chondrification center and/or chondrogenic cells in the inner perichondrium; form matrix and fibers of cartilage
describe chondrocytes
“grown up” chondroblasts; have large nucleus and prominent nucleoulus; can go back to being chondroblasts; are trapped in lacuna, and monitor matrix composition; synthesize necessary molecules to maintain cartilage matrix
where would you find elastic cartilage?
pinna of the ear, internal and external auditory tubes, the epiglottis, and larynx
how is elastic cartilage different from hyaline cartilage?
it contains not only type II collagen, but also elastic fibers in the ECM and in the fibrous layer of the perichondrium; it also has larger chondrocytes than hyaline cartilage, is more flexible and elastic than hyaline cartilage, and is yellow in the fresh state
describe fibrocartilage
transitional form between dense connective tissue and hyaline cartilage; contains chondrocytes and type I collagen; lacks a perichondrium
where do you find fibrocartilage
in areas requiring tough, tensile strength; can be seen in intervertebral discs, pubic symphysis, articular dists, menisci of knee joints, and attached to bones (between tendons and bones)
how are fibroblasts and chondrocytes related
fibroblasts secrete proteoglycans that become surrounded by matrix and become chondrocytes
osteoarthritis
articular surface of bone where cartilage has degenerated, exposing the underlying bone; caused by the breakdown of hyaline cartilage which normally provides a slippery surface for articulating bones; most prevalent in older individuals
tell me some general things about bone
it is a specialized connective tissue; bone is mineralized, living tissue that is continuously being remodeled; bone serves as a storage depot for minerals; bone marrow is a blood-cell forming tissue; bone supports and protects
how does bone respond to pressure and tension?
pressure applied to bone results in born resorption(breakdown); tension applied to bone results in bone deposition (addition)
what defines a long bone
long bones have long, cylindrical shaft and 2 epiphyses on either end (the heads of the bone)
define metaphysis
angulation between the epiphyseal plate and diaphysis
define diaphysis
diaphysis is the long cylindrical shaft between two epiphyses
what is the periosteum?
the external connective tissue capsule of bone; the periosteum of an actively growing bone has 2 layers - an outer fibrous layer and an inner cellular layer (not defined when inactive)
describe the outer fibrous layer of the periosteum
the outer layer consists of dense collagenous CT; it contains blood vessels, lymphatic vessels, and nerves that supply the bone; it is anchored into bone via Sharpey’s fibers (bundles of collagenous fibers) so it does not slide or peel off of the bone
describe the inner cellular layer of the periosteum
if the bone is actively growing, the inner layer contains osteoprogenitor cells; if the bone is mature and not growing, it contains periosteal cells that have the ability to differentiate into osteoblasts if necessary (for repair); it plays a role in the repair of bone fractures; covers the outer surface of bone, except the articular surface
describe endosteum
internal CT capsule of bone; consists of a thin CT layer with a single row of osteoprogenitor cells that have the ability to differentiate into osteoblasts or bone-lining cells; the endosteum lines the bone marrow cavity
what are the 2 component of bone matrix?
inorganic component and organic component
what makes up the inorganic layer of the bone matrix?
minerals; hydroxyapatite crystals (calcium phosphate), bicarb, citrate, magnesium, sodium, potassium
what makes up the organic layer of the bone matrix?
fibers (type 1 collagen mostly), ground substance (proteoglycans, glycoproteins, growth factors)
define osteonectin
serves as glue between collagen and hydroxyapatite crystals
define sailoproteins
help bind cells to bone matrix; examples are osteopontin and sialoproteins I and II; sailoproteins also begin calcium phosphate formation
define osteocalcin
traps calcium from the blood and stimulates osteoclasts to remodel bone
define trabeculae
islands of bone
what are the 2 ways to form bone?
via intramembranous ossification or endochondral ossification
what forms first - spongey bone or compact bone
spongey bone forms first, but it can become compact bone
how do blood vessels end up in bone?
during bone development, bone grows around blood vessels
intramembranous ossification
bone forms directly within a membrane of highly vascular mesenchyme; the mechanism by which flat bones form (face bone, skull, clavicle)
endochondral ossification
bone forms in hyaline cartilage; mechanism by which long bones form; forms a cartilage mold to be filled by bone
what are the layers of the eye
fibrous layer (corneoscleral coat), vascular layer (uvea), and retina (neural layer)
what are the chambers of the eye?
anterior segment (anterior chamber and posterior chamber), and posterior segment (vitreous chamber)
what are the 5 layers of the cornea (outside to in)
corneal epithelium, bowman’s membrane, corneal stroma, Descemet’s membrane, corneal endothelium
explain Bowman’s Membrane
acellular, does not regenerate, terminates at corneoscleral limbus, contributes to strength of cornea, is barrier to infections
corneal stroma
collagen fibrils arranged in lamellae; adjacent lamellae are arranged at right angles to each other, this maintains the transparency of the cornea; AKA substantia propia
Descemet’s membrane (posterior basement membrane)
regenerates after injury, thickens with age, helps maintain the normal curve of cornea
corneal endothelium
simple squamous epithelium, joined by zona adherens, zona occludens, and desmosomes; limited proliferative ability; responsible for virtually all of the metabolic exchange of the cornea
sclera
white of the eyeball that gives the eye shape; provides attachment for eye muscles; made up of 3 layers - episcleral/Tenon’s space, substantia propria (Tenon’s capsule), and suprachoroid lamina
iridocorneal angle
apparatus for outflow of aqueous humor
ciliary processes
secretion and anchoring of zonule fibers, form suspensory ligaments of the lens; form blood-aqueous layer, produce aqueous humor
what is the flow of aqueous humor?
posterior chamber –> pupil –> anterior chamber –> trabecular meshwork –> Canal of Schlemm –> venous system
open angle glaucoma
vision is damaged gradually; may take place over the course of some years; caused by blockage of meshwork leading to the canal of schlemm
fovea centralis
point of retina with the greatest visual acuity
Retinal Pigment Epithelium (RPE)
attached through Bruch’s membrane to the choriocapillary layer of the choroid; mechanical separation at this point is known as a “detached retina”
name 2 photoreceptors
rods and cones
name 2 conducting neurons
bipolar cells and ganglion cells
name 3 supporting/neuroglial cells
Muller’s cells, microglial cells, astrocytes
what are cones responsible for?
color
what are rods responsible for
low intensity light
are rods or cones more abundant?
rods
what vitamin is associated with rods?
vitamin A: retinal
what defines a bipolar cell?
1 cell body in the middle with the dendrites and axon coming off of a long neck
what is the most common cause of blindness?
diabetic retinopathy; neovascularization of the retina