MSK Flashcards
How many bones in adults
206
How many bones in infant
300
What are the 5 functions of skeleton
Shape and support
Movement
Protect vital organs
Hematopoietsis
Mineral hemeostais and storage (ca & ph)
Is bone a living organism
Yes
What is the structural elements of bone tissue?
Bone cells
Fibres (collagen)
Gelatinous material
Minerals (calcium)
What’s the function of bone cells
To grow, repair, synthesize new tissue and reabsorb old bone tissue
Fiber (collagen) function
To give bone it tensile strength
Gelatinous material of bone cell’s function
Medium between bone and blood
Bone Minerals (calcium) function
Provide rigidity
What are the 3 types of bone cells?
Osteoblasts
Osteoclasts
Osteocytes
Osteoblast
Immature cells that form new bone
Derived from mesenchymal cells
Form osteoids which mineralized to form new bone
Produce hormones (prostaglandins) ALP and other matrix protein
Bone shaped according to its function
What is osteoid
Protein mixture which mineralized to form new bone
What’s function is osteoclast
Function in bone reabsorption and remodeling
Xitcs
Large multinucleatedcwll ( ruffled borders)
Loosen from surface, become inactive and rest
Osteocytes function
Transform osteoblast to mature bone cells
Most abundant bone cells
Cell has dendrites, extend into canaliculi and secrete substances
Help to maintain bone by signaling osteoblast and osteoclasts to form and reabsorb bone
What’s the composition of bone matrix
Composition: 35% organic 65% inorganic 5% water
Organic component of bone
Collagen fiber ( provide bone strength)
Synthesized and secreted by osteoblasts
Inorganic component of bone is what?
Calcium
Phosphate minerals
Proteins
Carbohydrates- protein complexes
Proteoglycans
What’s the function of proteoglycans
Strengthen bone, form network fibrils
Help calcium deposit and calcify in bone
What’s the process of bone remodelling
- Activated osteoclasts scoop out bone and reabsorb it
- Osteoblasts lay down a new section of bones
- Osteocytes are spread throughout bone matrix
Transmit signal, recruit or inhibit osteoblast and osteoclast this influencing bone remodelling
What are the 3 phases of bone remodelling
Phase 1. Activation: a stimuli (ie physical stressor increased PTH secretion) activate osteoclast cell death (apoptosis)
Phase 2. Rrabsorption: osteoclast gradually digest bone minerals and leave behind a reabsorption cavity
Phase 3 formation : the layer down of new bone by osteoblasts line the walls of the reabsorption cavity
Successive layers (lamellae) in compact bone are then laid down until reabsorption cavity is reduced to a narrow Haversian canal
Process of bone remodelling takes how many months?
Reabsorption and new bone laid down to replace it takes 3-4 months
What regulates bone remodelling, bone integrity and bone mass
RANKL, RANK, OPG signalling pathway
What is the role of RANKL
It binds to RANK to activate osteoclasts and process of bone reabsorption
What is RANKL
It’s a transmembrane protein that is produced by osteoblasts,
It binds to its signaling receptor RANK on osteoclasts surface which activates osteoclasts and the process of bone resorption
What is Osteoprotgerin (OPG)
It’s a cytokine produced by osteoblast and act as a decoy receptor - inhibiting the binding of RANKL/RANK
Which protects the skeleton from increased bone resorption
What caused degenerative bone diseased?
Imbalance in the RANKL, RANK, OPG signalling pathway
What is the cause of osteoporosis and RA?
Imbalance between bone resorption and bone formation
In osteoporosis what do you find?
Bone formation is less than bone resorption
Bone formation < bone resorption
Which of the following best describe the xtics and function of osteoblasts
A. Synthesize the bone matrix and maintain skeleton
B. Found on bone surface and release enzymes which dissolve bone and connective tissues
C. Single nucleus cell derived from mature osteoclast and influence osteocyte activity
D. Found in the bone matrix and regulate bone mass and mineral homeostasis
Correct answer B
A. is describing osteoclasts
C incorrec
D describes osteocytes
The outer shell of all bones and shafts of long bones (femur) comprises of what % of skeleton
80%
What are the major structural elements of bone?
Bone cell- the grow, repair, synthesize, new tissue, and resorb old bones
Fiber (collagen) give bone it’s tensile strength
Gelatinous materials- medium between bone and blood vessels
Minerals - (calcium) provide regidity
What are the different types of bones
Compact bone
Spongy bone
Outer shell off all bones and shaft of long bones (femur) comprises of what percentage of skeleton
85%
What is the basic structural unit of compact bones
Osteon or Haversian system
Haversian canal is surrounded by what?
Rings of matrix (Lamellae)
Lacunae is located where
Between the matrix ring osteocytes
What is canaliculi?
Canaliculi are small channels that radiate from the lacunae to Haversian canal. It provide a passage through the hard matrix
What’s role of Haversian canal
Carries blood, lymphatic vessel and nerve branches
What are xtics of spongy bones
Less dense and softer than cortical bones
Comprises of 15% of skeleton
Makes up the interior of bone
No Heversian systems- consist of a network of trabeculae
Spaces between trabeculae filled with red bone marrow (hematopoietic stem cells)
Examples of spongy bones are?
Tubercular and cancellous bones
True or false- spongy bones have Haversian system?
False. No Haversian system
They have network of trabeculae
What is periosteum?
Covers all bones - except articulate cartilage in joints, small bones in hands and feet
Periosteum is made up of what?
Thin double layer of connective tissues
Made up of outer layer (fibrous) and inner layer (cellular)
What’s the function of periosteum
Supply blood and nutrients to bones
What are the different layers of periosteum and function?
Outer layer- fibrous)
- blood vessels, nerves, lymphatics
- blood vessels enter through channels (volkmann channels)
Inner layer (cellular)
- lies directly on bone
- contain osteoblasts that dilution in both growth and repair
What is the classification of bones?
Classified based on shape as
Long bones
Short (cuboidal)
Flat
Irregular
What’s xtics of long bones
Long bones- length is great than diameter, thin, have a long shaft, primarily consist of compact bones
E.g Fermur Tibia
What’s the xtics of short (cuboidal) bones
Small, cube shaped, their length is similar to width; primarily consist of spongy bone
E.g wrist, ankle
Flat bones xtics
Thin, flattened, slightly curved
E.g cranium, scapula, ribs
Irregular bone xtics
Complex shapes and cannot be classified as above, primarily consist of spongy bones
E.g spinal vertebrae, sacrum, coccyx
What are joints
Joint is where two or more bones come together
Function to provide stability and mobility
Classified based on structure and degree of movement
What is the classification of joints
Structural classification
- fibrous
- cartilaginous
- synovial
Degree of movement
- immovable (synathro Long bones- length is great than diameter, thin, have a long shaft, primarily consist of compact bones sis)
-slight or semi- movable (amphiarthrosis)
- freely movable (diarthrosis)
Classification of joint based on structure is what?
Structural classification
- fibrous
- cartilaginous
- synovial
Classification of bone based on movement
Degree of movement
- immovable (synathro Long bones- length is great than diameter, thin, have a long shaft, primarily consist of compact bones sis)
-slight or semi- movable (amphiarthrosis)
- freely movable (diarthrosis)
Classification
Scull - firbrous, immovable (synarthrosis)
Vertebrae- cartilaginous- semi movable(amphiarthrosis)
Hip joint- synovial - freely moveable (Diarthosis)
Which is the most movable joints
Synovial joints
What are the types of synovial joints?
Plane
Hinge joint(elbow)
Pivot (top of neck)
Conduloid (wrist)
Saddle
Ball and socket (shoulder and hip)
What is joint capsule?
Connective tissue that covers the ends of bones where they meet in the joint
Parallel interlacing bundles of white fibrous tissue
Supplied with nerves, blood and lymphatic vessels
What’s synovial memebrane
Synovial membrane is the inner lining of joint capsule and has 2 layers
Vascular layer- subintima
Cellular layer - intima
Synovial membrane has rich supply of blood and lymphatic vessels
What are the 2 layers of synovial memebrane
- Vascular(subtintima) - Fibrous connective tissue, elastin fibres, flat cells, fibroblast, macrophages and mast cells
- Cellular layer- (intima) rows of synovial cells
- Type A: ingest and remove bacteria/debris via phagocytosis
- Type B: secrete hyaluronate ( gives synovial fluid it’s viscous quality$
What is joint cavity?
Joint cavity (joint space)
Fluid filled space between articulating surfaces of 2 bones
Surrounded by synovial memebrane
Enable bones to move against one another
Filled with synovial fluid (clear viscous) super filtrate plasma from blood vessels in synovial membrane
What’s function of synovial fluid
Lubricates joint surfaces
Contain free floating synovial cells and leukocytes
Articulate cartilage function
Reduces friction in joints and distributes force of weight bearing
It’s made up of hyaline cartilage covered end of bone (2-5mm thick$
What’s the composition of articular cartilage
Chondrocytes (cartilage cells)
Intercellular matrix (collagen, protein polysaccharides water
Articular cartilage
Surface - collagen fibres runs parallel to joint surface (compacted into a dense protective mat)
Middle layer - fivers are tangential to surface to absorb force of weight bearing
Bottom layer - Fibers are perpendicular to surface to resist shear force
Is articular cartilage sensitive to pain
No
It has no blood or lymph vessels or nerves
(Insensitive to pain; regenerate slowly)
What is a ligament
Ligaments- fibrous tissue which connects bone to bone, provide stability to joints
What is tendons
Tough fibrous connective tissue which connect muscles to bone, withstand tension
What is cartilage
Flexible connective tissue
Made up of chondrin (elastic firm matrix)
Types of cartilage - Elastic (outer) hyaline (wall of trachea) and fibrous
What are the types of cartilage
Types of cartilage - Elastic (outer) hyaline (wall of trachea) and fibrous
Which of the following correctly describes the features of cuboidal or short bones
A- sesamoid shape with thick outside layer of compact bone
B- thin small shaft with rounded ends and primarily consist of compact bones
C- the length is similar to the audits and mostly consist of spongy bone
D. Vary in shape, often flattened and consist mostly of compact bones
Answer C
What’s the range in length of muscles
2-60cm
Muscle make up with percent of adult weight
40%
What’s the composition of muscle
75% water,
20% protein
5% organic/inorganic compounds
Muscles are shaped according to their function, what are the shapes
Fusiform: spindle shaped with tapered end( ie biceps)
Pennate: Broad, flat, fan shaped (ie hand muscles)
What are the types of muscles
Skeletal muscle
Smooth muscles
Cardiac muscles
What’s the xtics if skeletal muscles
Striated
Multi- nucleus
Not branched
Voluntary control ( controlled by CNS)
Skeletal muscles
What’s xtics I’d smooth muscles
Non- striated (organized sarcomeres)
Spindle shaped
Single central nucleus
Not branched
Involuntary control
(Autonomic nervous system ANS)
Blood vessels, glands, internal organs
What’s the xtics of cardiac muscle
Striated
Single nucleus
Branched with intercalated discs and gap junctions (cellular depolarization)
Involuntary control (autonomic nervous system ANS)
Myocardium only
What is fascia?
Casing of thick connective tissue that surrounds and separates each muscle, holding it in place (over the epimysium)
What are the 3 layers of connective tissues
Epimysium
Perimysium (middle layer)
Endomysium
Epimysium
Wraps surface of muscles (below fascia) and extends inwards; tapers at each end to form tendon
Perimysium
Continuation of epimysium into muscle, groups muscles fibres into bundles of fascicles
Endomysium
Surrounds and wraps each fascicle
Xtics of muscle fibres
Muscles are made up of myocytes and these cells contain chains of myofibrils (muscle fibre)
Myofibrils consist of actin(thin filaments) and myosin (thick filaments)
Myofibrils is made up of what?
Myofibrils consist of actin(thin filaments) and myosin (thick filaments)
What is the name of the contractile unit of myofibril
Sarcomere (basic unit of muscle)
What’s the composition of sarcomere
Proteins actin, myosin, titin and nebulin
What are the 4 step process of muscle contraction
Excitation
Coupling
Contraction
Relaxation
What happens in excitation stage
The spread is an action potential from nerve terminal to neuromuscular junction
Rapid depolarization of membrane initiates a muscle fibre action potentially
Action potential spreads along sarcolemmal membrane to T tubules
Triggers receptors in a wall of T tumble to open channels releasing calcium for SR( sarcoplasmic reticulum)
Coupling stage
Migration of calcium to myofilaments
Calcium affects the muscle proteins troponin and tropomyosin
Troponin: is a globular protein located on thin filament, Troponin in presence of calcium promotes actin-myosin activation
Tropomyosin is a thing filament protein, blocks binding sites on actin, prevents cross bridge formation and muscle contraction
Muscle contraction
contraction (cross bridge theory)
Calcium combines with troponin
Actin ( thin filament) slides onto myosin (thick filament)
Myosin heads attach to actin muscles, forms a cross-bridge (actin myosin complex)
ATP (cellular energy) release from actin-myosin complex when cross bridges attach
Sarcomere shortens and cause tension
Muscle contraction process
Step 4. Relaxation
ATP pumps move calcium out of sarcoplasm back into SR
Breaks link between actin and myosin(thick)
Cross bridge detach
Muscle loses its tension, Sarcomere lengthens and relax
All the following are correct regarding the role of tropomyosin in muscles contraction except
a. It is a rope like structure that prevent cross bridge formation
b. A globular protein found on myosin (thick filament) and combines with calcium
c. Blocked myosin binging site on actin and prevents muscle contraction
d. A major component of the thin filament in skeletal muscle
Answer B
Structural classification of bones
Fibrous - e.g skull
Cartilagenous - e.g spine bone
Synovial - e.g hip bone
Joint classification based on movement
Immovable (synathrosis) e.g skull
Slightly or semi movable (amphiarthrosis)- e.g spine joints
Freely moves me (Diarthrosis) .eg hip joint
