Histology Flashcards
Describe the structure of skeletal muscle fibres
striated
unbranched
multi-nucleated
Muscle fibres are grouped into bundles called…?
Fasicles
Name for the connective tissue surrounding the muscle as a whole
Epimysium
Name for the connective tissue surrounding a single fasicle
Perimysium
Name for the connective tissue surrounding a single muscle fibre
Endomysium
Unit of contraction of a muscle cell
Sarcomere
Sarcomeres are placed end-to-end to form..?
Myofibrils
Motor unit definition
One motor neurone and all the fibres that it innervates
Types of skeletal muscle fibres
Type I
Type IIa
Type IIb
Describe Type I skeletal fibres
slow contracting
abundant in mitochondria
slow to fatigue
“red fibres”
Describe Type IIa skeletal fibres
relatively fast contracting
reasonably resistant to fatigue
uncommon
Describe Type IIb skeletal fibres
fast contracting fibres few mitochondria fatigue easily produce great force "white fibres"
What are chondrocytes
Cells found in cartilage
Name for immature chondroctyes
Chondroblasts
Where are chondrocytes found
Lacuna - space in the extracellular matrix
What does the Extracellular Matrix (ECM) consist of
- 75% water
- 25% organic material
a) 60% Type II collagen
b) 40% proteoglycan aggregates
What are Haversian Canals
minute tubes in bone which form a network in bone and maintain blood vessels
What are Volkmann’s Canals
the small channels in bone that transmit blood vessels from the periosteum into bone, and lie perpendicular to and communicate with the Haversian canals
What are osteons
a central canal containing blood capillaries and the concentric osseous lamellae around it occurring in compact bone
What are the lines surround osteons called
cement lines
What is the mineral of bone made from
Hydroxyapatite
What are osteoprogenitor cells
cells located on bone surfaces - reserve pool of osteoblasts
What are osteoblasts
Bone forming cells
What are osteocytes
a mature bone cells trapped within bone matrix
What are osteoclasts
Bone resorption cells - break down bone and release the minerals
Describe process of bone remodelling
Osteoclasts drill down into bone forming a tunnel.
A blood vessel grows into the tunnel bringing with it osteoblasts which line the tunnel and begin laying down new lamellar bone.
This process continues until only the space of a Haversian canal remains.
What are osteoclasts derived from
macrophages
Osteoid definition
collective term for the secretions of osteoblasts
