MSK histology 03/10/18 Flashcards
What are the 3 muscle types?
Skeletal
Smooth
Cardiac
What are the characteristics of skeletal muscle?
Striated
Unbranched
Multinucleate - form a syncytium - multiple cells gather togeter and then give up their membranes and become one cell
How long is a skeletal muscle cell?
The length of the muscle
What is the largest skeletal muscle in the body?
Sartorium
Where are the nuclei found in skeletal muscle cells?
At the periphery of the fibre just under the cell membrane
What is the sarcolemma?
The cell membrane in muscle cells
What a fascicles?
Individual bundles of muscle fibres
What is the epimysium?
Connective tissue surrounding the fasicles
What is the perimysium?
The connective tissue around a single fasicle
What is the endomysium?
Connective tissue around a single muscle fibre
What is the breakdown of a muscle?
Whole Muscle> Group of fascicles> Single fascicle> Muscle cell> Myofibril> Sarcomere> Actin and myocin
Why are skeletal muscles striated?
The striations are an optical illusion as a result of the arrangement of the sarcomeres, these are in the same place in each fibre and lines up, giving the illusion of transverse stripes across the cell
Are muscle cells able to create action potentials?
Yes
What are the characteristics of Type 1 fibres?
slow Oxidative metabolism Abundant mitochondria and myoglobin Resistant to fatigue 'Red Fibres'
What are the characteristics of Type 2a fibres?
Relatively fast
Relatively uncommon
What are the characteristics of type 2b fibres?
Fast contractiing
Anaerobic metabolism
Few mitochondria and myoglobin
Fatigue easily and have relatively greater force
What are the two skeletal components?
Cartilage
Bone
What are the characteristics of cartilage?
Semi-rigid and deformble
Permeable
Avascular
Cells are nourished by diffusion through the matrix
What are the characteristics of bone?
Rigid
Non permeable
Cells within bone must be nourished by blood vessels that pervade the tissue
What are the cells found in cartilage and where are they found?
Chondrocytes
In the extracellular matrix known as the lacuna
What is ECM made of?
75% water
25% organic material
-60% type 2 collagen (fine and 3d)
-40% proteoglycan aggregates made up of GAGs
What are the characteristics of hyaline cartilage?
Blue-white
Translucent
Most common
What are the characteristics of elastic cartilage?
Light yellow
Elastic fibres makes it flexible
What are the characteristics of fibrocartilage?
Tendon and hyaline cartilage
Bands of densely packed type 1 collagen interleaves with rows of chondrocytes surrounded by small amounts of ECM
Where is hyaline cartilage found?
Articular surfaces Tracheal rings Costal cartilages Epiphyseal growth plates Precursos in fetus to many bones
What are the functions of bone?
support levers protection of internal organs Calcium store Haemopoiesis -Production of bone marrow
How does cauliflower ear come about?
Damage to the vasculature of the ear due to trauma which is replaced largely with scar tissue
What is the composition of bone?
23% collagen
2% non-collagen proteins
10% water
65% bioapatitie ( a form of calcium phosphate)
What colour of marrow produces blood, red or yellow?
Red
What are the two types of bone?
Cortical or trabecular bone
Where is cortical bone found?
Diaphysis
Where is trabecullar bone found?
Epiphyses
When does bone remodelling finish?
Never remodels throughout life
What makes up cortical bone?
Groupings of lamellar structures with a blood vessel (heversion) canal in the middle and volkmans canals across the bone
What are osteons?
Groups of lamellar bodies
Product of later remodelling of the bone
what do heversion canals carry?
Blood vessels and nerve fibres
What distributes blood vessels to the heversion canals?
Volkmanns canal
What are canalicculi?
Small cell processes of a cell that extends to the heversion canal and other cells allowing it to communicate with other cells
Keeps the cell alive
how are cement lines formed?
Hole is made in the middle of the future osteon and bone is layed in concentric rings out from the centre
Are heversion canals common in trabecular bone?
No as the cells are close enough already
What are 4 bone cells and where are they found?
Osteoprogenitor cells - bone surfaces - pool of reserved osteoblasts
Osteoblasts - bone forming cells
Osteocytes - bone cell trapped within the bone matrix
Osteoclasts - large multinucleate cells - found on bone surface
What bone cells are capable of destroying bone?
Osteoclasts
What cells begin the process of laying new lamella?
Osteoblasts
What do osteoblasts secrete?
Collagen
Glycosaminoglycans
Proteoglycans
What is the mineral of bone principally made up from?
Calcium phosphate crystals - biapatite
What are osteclasts derived from?
Macrophage lineage
What is an osteoid?
The osteoblasts secrete things which will become bone, entrapping the cells and becoming an osteoid
Where is bone built from?
Can only be built from a surface
What is woven bone?
The cells dont pay attention to the orientation of the collagen after a break or during development, so an unorganised bone occurs which is not as strong, but will be replaced by lamellar bone in the future
