MSK histology Flashcards
What are the three types of muscle?
Skeletal
Cardiac
Smooth
What is the plasma membrane of a skeletal muscle cell called?
Sarcolemma
Are skeletal muscles striated?
Yes
Are skeletal muscles branched or unbranched?
Unbranched
Are skeletal muscles multinucleate or uninucleate?
Multinucleate
Where in the skeletal muscles do the nuclei lie?
Peripherally
What is the epimysium?
The connective tissue surrounding a muscle
What is the perimysium?
The connective tissue surrounding a muscle fascicle
What do we call the connective tissue which surrounds a single muscle fibre?
Endomysium
What are sarcomeres?
Smallest contractile elements in skeletal muscle
What are myofibrils?
Structure formed when loads of sarcomeres form end to end
Muscle fibres are composed of what?
Myofibrils
Why does skeletal muscle appear striated?
Because of the alternating thick and thin filaments in the sarcomere
What is a motor unit?
One motor neurone (nerve) and all the muscle fibres which it innervates
What denotes fine muscle control in relation to the motor unit?
The smaller the number of muscle cells that the nerve innervates the more precise the control
What is the synapse between motor nerves and muscle cells called?
Neuromuscular junction
Describe the three subtypes of skeletal muscle cell
Type I (red) - slow contracting & aerobic, many mitochondria, low force, fatigue resistant
Type IIA - intermediate of other two subtypes, relatively fast contracting and fatigue resistant
Type IIB (white) - fast contracting & anaerobic, fatigue easily, minimal mitochondria, high force
Which of the three skeletal muscle subtypes is the least common?
Type IIA
Describe the vasculature of cartilage
It’s avascular
How does the cartilage receive nutrients?
Diffusion through the extracellular matrix
Is bone permeable?
No - it’s cartilage that is permeable
What do we call cartilage cells?
Chondrocytes
What do we call immature cartilage cells?
Chondroblasts
Where are chondrocytes found within the cell?
Lacuna
Nb - spelling similar to laluna but this is a structure found on your nail!
What is the major component of the extracellular matrix in cartilage?
Water
What type of collagen is found in cartilage?
Type II
What type of collagen is found in most connective tissues?
Type I
What are the three subtypes of cartilage?
Hyaline
Elastic
Fibrocartilage
Which is the most common subtype of cartilage?
Hyaline
List some common sites where cartilage is found
Articular surfaces Tracheal rings Costal cartilage Growth plates Pre-bone ossification bones are cartilage
List some functions of bone
Support Movement Protection Calcium metabolism Haemopoiesis
What is haemopoiesis?
Red blood cell production
In adulthood which bones remain involved in haemopoiesis?
Axial skeleton
Limb girdles
Which type of collagen is found in bone?
Type I
Which type of bone morphology can be seen at the diaphysis?
Cortical bone
Which type of bone morphology can be seen at the epiphysis?
Trabecular/cancellous
What is the difference between cortical and trabecular bone?
Presence of spaces
Is bone avascular or vascular?
Vascular
What do we call bone cells?
Osteocytes
Where are the osteocytes found within the bone?
Canals
Name the two types of canals found within bone and the difference between them
Haversion canal - longitudinal
Volkman canal - horizontal
How does bone transfer nutrients from blood from one osteocyte to the other?
Osteocytes possess dendritic cell processes which run in canaliculi
What are cement lines in relation to bone?
Visible lines surrounding an osteon
What is an osteon?
Functional unit of bone
What cells do bone cells derive themselves from?
Osteoprogenitor cells
What are osteoblasts?
Cells which produce new bone
What are osteoclasts?
Cells which reabsorb old bone
What are osteocytes?
Cells trapped within bone matrix
What is the basic multicellular unit?
Osteoclasts and osteoblasts which participate in bone remodelling
Describe bone remodelling briefly
Osteoclasts drill down into bone –>
Blood vessels form and bring osteoblasts –>
Osteoblasts begin laying down new bone in this drilled tunnel –>
Only haversion and/or volkmans canals remain
What do osteoblasts need a good supply of to function normally?
Calcium
What is osteoid?
Osteoblast secretion consisting of collagen, GAGs & other organic compounds which eventually becomes mineralised
What is woven bone?
Bone fibres which have been laid down in a haphazard manner in response to a break within the bone
What will woven bone eventually become?
Lamellar bone
