!!!Week 3: Histology of Cartilage, bone and skeletal muscle Flashcards
Matrix of cartilage?
Fibres and ground substance (water holding molecules)
Matrix of bone?
fibres and ground substance (Hyroxyapatite)
Where are cartilage and bone arise from?
mesenchyme - lateral somatopleuric mesoderm of embryo
CLASSIFICATIONS of cartilage?
Hyaline, elastic, fibrocartilage
Hyaline cartilage features?
Type II collagen fibres, proteoglycans (GAGs) etc
Elastic cartilage features?
Elastic fibres, elastic lamellae, collagen, proteoglycans (GAGs) etc - DOES NOT CALCIFY W AGE
Fibrocartilage features?
Type I collagen fibres, fibroblasts, proteoglycans (GAGs) etc - NO PERICHONDRIUM
What type of cartilage is s precursor to most bone?
Hyaline
Where is hyaline cartilage found?
Respiratory tract, articular surfaces synovial joints
Features of active chondroblasts and chondrocytes?
Abundant rough ER, prominent golgi - pale area next to nucleus in light microscope
What does the perichondrium consist of?
Outer fibrous layer, inner cellular layer - resemble fibroblasts (chondroprogenitor), give rise to chondroblasts
What are the precursor cells to chondrocytes?
Chondroblasts or other chondrocytes
Adult, mature bone is called what? What are the types?
Lamella bone - compact (dense) or spongy (trabecula).
Types of compact bone?
Circumferential (inner, outer), Haversion (osteon) and interstitial
Outer component of bone? Parts?
Periostum - outer fibrous (fibroblasts, collagen etc), inner cellular -
Where are osteoprogenitor cells located?
Inner cell layer of periosteum, endosteum
What canal joints osteons?
Volkmans canals
T or F: The endosteum only has a single layer of cells and no outer fibrous layer
T
Osteoprogenitor cells. Location, shape
Bone surfaces, squamous
Osteoblasts. shape
differentiated bone forming cells - secretes collagen and matrix cells, calcifies bone matrix. cuboidal
Osteoclasts from which cell line
hemopoitic progenitor cell
Osteoclasts shape
large, dome shaped, multinucleated, ruffled border
What sits in Howship’s lacuna?
osteoclasts
What is unmineralised bone called?
Osteoid
Muscle acting concentrically
Shortening
Muscle acting isometrically
Generating force but not shortening
Muscle acting eccentrically
Generating force while lengthening
What CT are tendons made from?
Dense regular CT
What are the contractile cells in skeletal msucle called?
Extrafusal
What are red fibres?
Slow acting, aerobic
What are white fibres?
Faster acting, anaerobic
How does skeletal muscle form?
Fusion of myoblasts
Once formed, cam skeletal muslce divide?
NO
In ythe light microscope, what are the dark bands?
A bands
What is the A band composed of?
Thick (myosin) and thin (actin) filaments
What is the I band composed of?
THin filaments only
What is the H band composed of?
Thick filaments only
What does troomyosin do?
Attaches on actin - blocks actin binding sites
What does troponin do?
Binds calcium, actin and tropomyosin
What binds thick filaments to the Z line
Titin
T or F: The thick filaments are not bound to the Z line
False - connected via titin
What motor fibres activate contraction?
Alpha motor fibres, lower motor neurons
How many NMJ are there usually per cell?
1
What motor neurons innervate intrafusal fibres>?
Gamma
What is the transmitter at the NMJ?
Acetylcholine
What activates the actin-myosin interaction?
Calcium
How is the activation of skeletal muscle reversed?
By calcium pumps - return calcium to SR
Where are Triads located?
Adjacent to A band and I band
Where do germinal cells reside in epiphyseal plate?
Reserve zone - near epiphysis
