Histology Flashcards
Describe skeletal muscle cells
Unbranced, multinucleate, nuclei are at periphery of fibre-just under sarcolemma
What is the name of the cell membrane in muscle cells?
Sarcolemma
What are the bundles that muscle fibres are grouped into called?
Fascicles
What is the connective tissue surrounding the muscle as a whole?
Epimysium
What is the connective tissue around a single fascicle?
Perimysium
What is the connective tissue around a single muscle fibre?
Endomysium
What happens to the axon of motor neurone as it nears termination?
It branches
Where does each branch of the axon of motor neurone end?
In a special type of synapse called the neuromuscular junction
What are the 3 types of skeletal muscle fibre?
Type I, IIA, IIB
Describe type I skeletal muscle fibres
Relatively slowly contracting fibres that depend on oxidative metabolism. They have abundant mitochondria, are resistant to fatigue and produce relatively less force. Often called ‘red’ fibres.
Describe type IIA skeletal muscle fibres
This is intermediate between the other two. They are relatively fast contracting, but are also reasonably resistant to fatigue. These fibres are relatively uncommon
Describe type IIB skeletal muscle fibres
Fast contracting fibres that depend on anaerobic metabolism. They have few mitochondria, fatigue relatively easily and produce relatively greater force. Often called ‘white’ fibres.
How are cartilage cells nourished?
Diffusion through the extracellular matrix
What are the cells found in cartilage?
Chondrocytes (chondroblasts when immature)
Where are chondrocytes found?
Lacuna- a space in the extracellular matrix
What is the relation between chondrocytes and the extracellular matrix?
They secrete and maintain it around them
What is the most common form of cartilage?
Hyaline
What is the make up of ECM in hyaline cartilage?
75% water, 25% organic material (of which 60% is type II collagen, 40% proteoglycan aggregates)
What are the 3 types of cartilage?
Hyaline, elastic, fibrocartilage
Describe the gross appearance of hyaline cartilage
Blue-white in colour and translucent
Describe the gross appearance and flexibility of elastic cartilage
Light yellow in colour, addition of elastic fibres makes it quite flexible
Describe the structure and gross appearance of fibrocartilage
Hybrid between tendon and hyaline cartilage. It has bands of densely packed type I collagen interleaved with rows of chondrocytes surrounded by small amounts of cartilagenous ECM. Appears white.
Where may you find hyaline cartilage?
Articular surfaces, tracheal rings, costal cartilage, epiphyseal growth plates, precursor in fetus to many bones
By the early twenties what parts of the skeleton are involved in blood production?
Axial and limb girdle
What is the composition of bone?
65% mineral, 23% collagen, 10% water, 2% non-collagen proteins
What is the outer shell of dense cortical bone that makes of the shaft?
Diaphysis
What bone occupies the ends of the bone ( the epiphyses)?
Cancellous or trabecular
What is the main difference between compact and trabecular bone?
Presence of spaces (marrow cavities) adjacent to trabecular bone
What are the lines that are often visible surrounding the osteon?
Cement lines
What are osteoprogenitor cells?
Located on bone surfaces, for example under the periosteum, these cells serve as a pool of reserve osteoblasts
What are osteoblasts?
Bone forming cells found on the surface of developing bone. They have plentiful RER and prominent mitochondria.
What are osteocytes?
Bone cell trapped within the bone matrix
What are osteoclasts?
Large (up to 40 microns or more) multinucleated cells. Found on surface of bone and are responsible for bone resorption
What is the name for the collection of osteoclasts/blasts that participate in the cutting cone process in a tunnel is drilled into the bone, in which a blood vessel grows into and the tunnel is lined with osteoblasts which lay down new lamellar bone?
Basic multicellular unit (BMU)
Until when does the cutting cone process involving the BMU continue?
Until only the space of a Haversian canal remains
What is the mineral that principally makes up bone?
Calcium phosphate crystals, particularly hydroxyapatite: (Ca10(PO 4)6(OH)2
What is collectively termed osteoid?
The osteoblast secretion of collagen, glycosaminoglycans (GAGs), proteoglycans and other organic components of the matrix
What bone is formed during development or following a break?
Woven bone
