Musculoskeletal system Flashcards
ligament
Connect the articulating bones at a joint
CARTILAGE
Supports body structures
Connects bones
Maintains the shape of body structures
Resists compression
Has tensile strength
FUNCTIONS OF BONES
support
protection
storage of minerals & triglyceride
blood cell production
movement
axial skeleton
- skull
- vertebral column
- rib cage
APPENDICULAR SKELETON
upper limb
lower limb
shoulder girdle
pelvic girdle
bone shapes
long-humerus & clavicles
short-tarsals, carpals, patella
flat- sternum, ribs, scapula,
skull bones
irregular-vertebra, hip bones
passageways for blood vessel, nerves and sounds
foramen & canal or meatus
OSSEOUS TISSUE
Is a connective tissue - contains specialised cells and an
extracellular matrix
matrix has ground substance, collagen fibres, and calcium
phosphate crystals
collagen fibres:
provide flexibility & tensile strength calcium phosphate crystals:
make our bones hard & provide compressive strength
Specialised Cells
Osteoprogenitor cells-differentiate into osteoblasts
Osteoblasts-produce & secrete
collagen fibres & ground substance
Osteoclasts- break down the
matrix and release stored minerals
Osteocytes- mature bone cells that maintain the matrix
compact bone
Osseous tissue is arranged
into osteons=heavy
shaft of long bones
Resists forces applied to the ends of a bone.
spongy bone
Osseous tissue is arranged into trabeculae
can resist force in call direction and very light
found the proximal & distal epiphysis
Contains red bone marrow and is a site of haematopoiesis.
interstitial growth
New cartilage forms at the top of the epiphyseal plate. Bone replaces old cartilage at the bottom of the plate
Diaphysis lengthens
appositional growth
Osteoblasts occurs on bone
surface= compact
bone=bone widens
In long bones, osteoclasts occurs in inner surface= enlarges medullary
cavity= lighter bones
REGULATION OF BONE GROWTH
bone growth requires GH, TH,
testosterone & estrogen= growth spurt
End growth [the rate of bone formation exceeds the rate of cartilage formation
cartilage eventually replaced entirely by bone epiphyseal plate becomes epiphyseal line
BONE REMODELLING
rate of bone deposition
equals the rate of resorption However when u age resorption is higher
fractures
closed fracture-broken bone does not break the skin
comminuted fracture- bone fragments into three or more pieces
compression fracture- bone is crushed
greenstick fracture-incomplete break
spiral fracture- excessive twisting
forces are applied to a bone
avulsion fracture-tendon or ligament pulls off a fragment of bone
pathological fracture- disease that weakens bone structure
Colles fracture- distal end of the radius
scaphoid fracture- carpal bone
Pott’s fracture- a break in the medial malleolus of the
tibia and/or lateral malleolus of the
fibula
fracture repair
Haematoma forms- burst of blood
Fibrocartilaginous callus forms- fibroblast and chondroblasts
Bony callus of spongy bone form-spongy bone forms & bone ends firmly united
Bone remodelling- compact bone replaces spongy bone, osteoclasts.
Osteomalacia (adults) and Rickets (children)
bones are poorly mineralised
- lack calcium phosphate crystals
Osteogenesis imperfecta
disorder that affects
the quantity and/or quality of
collagen fibres
Osteoporosis
bone resorption outpaces bone
deposition= bones are porous,
light, fragile & easily fractured
CLASSIFICATIONS OF JOINTS
(functionally)
synarthrosis - immovable joint
amphiarthrosis - slightly movable joint
diarthrosis - freely movable joint
structurally
Fibrous joints have connective tissue that unite articulating bones, Joint cavity absent
CARTILAGINOUS JOINTS cartilage unite articulating bones, Joint cavity absent
synovial joint articular cartilage cover Articulating bone ends, joint cavity present
synovial joint features
Articular capsule:
- tough outer fibrous layer - stabilises articulating bones
- inner synovial membrane - produces synovial fluid
Joint cavity: separates articulating bones
& contains synovial fluid
Synovial fluid: shock absorption, reduces friction, supplies oxygen and nutrients to articular cartilage cells & remove waste
Articular cartilage: covers the ends of each articulating bone, shock absorption & reduces friction
Reinforcing ligaments stabilise joint
Sensory neurons detect pain and
monitor proprioception & blood vessels mainly supply synovial membrane
Menisci: shock absorption, reduces friction & stabilise joint
Muscle tendons: stabilise joint
Bursae and Tendon sheaths: bags of synovial fluid reduce friction
Fat pads: cushion & protect joint structures
TYPES OF SYNOVIAL JOINTS
allows rotation proximal radioulnar &
atlas-axis joints]
Plane Joint allows gliding movements
[intercarpal & intertarsal joints]
Condylar joint allows flexion, extension, adduction, abduction & circumduction [metacarpophalangeal (knuckle) & wrist joints]
Saddle joint allows flexion, extension, adduction, abduction & circumduction
[carpometacarpal joint of the thumb]
Hinge Joint allows flexion & extension
[elbow, knee, ankle &
interphalangeal (finger) joints]
Ball and Socket joint allows flexion, extension, adduction,
abduction, circumduction &
rotation [shoulder and hip joints]
SKELETAL MUSCLE STRUCTURE
Are surrounded by three connective tissue sheaths Endomysium, perimysium & Epimysium
Myofibrils: Extend the entire length of a muscle fibre. Composed of contractile units called sarcomeres
Sarcomeres: Composed of contractile proteins called thick and thin myofilaments
Thick myofilaments are composed of the protein myosin
¨ Thin myofilaments are composed of the protein actin
SKELETAL MUSCLE CONTRACTION
-Somatic motor output, in the form of an action potential, travels along the axon of a lower motor neuron to the axon terminals
-Voltage-gated Ca2+ channels open and
Ca2+ enters the axon terminal.
-Ca2+ entry causes synaptic vesicles to
release ACh into the synaptic cleft.
-ACh, diffuses across the synaptic
cleft and binds to chemically-gated
ion channels (nicotinic receptors)
on the sarcolemma.
-Ion channels open influx of Na+ ions
sarcolemma depolarises graded potential produced.
-Graded potential opens
voltage-gated Na+ channels in
the sarcolemma action potential produced.
-The action potential travels along the
length of the sarcolemma.
-The action potential travels down the T tubules deep into the muscle fibre.
-Action potential stimulates sarcoplasmic
reticulum Ca2+ release channels to open.
-Ca2+ flows into the cytoplasm of the
Ca muscle fibre.
-The binding of Ca2+ to troponin pulls tropomyosin away from the actin active
sites.
-Myosin heads bind to the active sites, forming cross bridges and contraction
begins.
THE PROCESS OF CONTRACTION
Myosin heads bind to actin active
sites on the thin myofilaments.
Myosin heads pull the thin myofilament
towards the center of the sarcomere (M-line)
and then detach.
ATP breaks the attachment
of myosin and actin
Cycle repeats:
Myosin heads bind to next actin
active sites on the thin myofilaments.
Myosin heads pull thin myofilament
closer towards the M-line and then
detach.
