musculoskeletal system Flashcards
list the function of the skeletal system
support
storage - minerals, fats, salts
attachment - for bones to muscles
articulation - when 2 bones move around each other
protection
production - of RBCs
explain what the epiphyses is in the structure of a long bone
ends of the bone
explain what the diaphyses is in the structure of a long bone
the main shaft, hollow cylinder of compact bone surrounding a cavity
explain what compact bone is in the structure of a long bone
forms the cortex/hard outer shell of most bones
very dense and rigid
filled with tiny holes that hold blood vessels
protects spongey bone and bone marrow
explain what spongey bone is in the structure of a long bone
bone on the inside
porous and has large spaces filled with marrow
Red bone marrow in flat and long bones, produces RBCs, WBCs and platelets
explain what the medullary cavity is in the structure of a long bone
hollow cavity in the diaphyses, filled with yellow bone marrow for fat storage
explain what articular cartilage is in the structure of a long bone
Covers epiphysis for protection and cushioning
explain what epiphyseal lines are in the structure of a long bone
Bone growth areas
what is an osteoblast
Secrete bone matrix around themselves until nutrients struggles to reach osteoblast when matrix becomes dense and can’t diffuse
When oxygen is low enough, combines with chemical signals, the osteoblasts differentiate into an osteocyte
what is an osteocyte
Bone cell
Maintains bone tissue
what is an osteon
Basic unit of bone cells (whole individual circle in diagrams)
what is the Haversian canal
Centre of osteon, blood vessel run up it to deliver nutrients to osteocyte
what are the lamellae
Concentric layers surrounding central canal
Forms 3 layers
what are the lacunae
Spaces in lamellae where osteocytes live
what are the canaliculi
Small crevices moving nutrients between osteocytes from the central canal
Run across from lamellae
Deliver nutrients from lacunae to lacunae
what is the process of bone formation/growth called
ossification
what are the 2 types of ossification processes
endochondral ossification- long bones
intramembranous ossification - flat bones
explain the process of endochondral ossification
Chondrocytes secrete cartilage matrix
Chondrocytes within the cartilage absorb the surrounding cartilage matrix
The matrix calcifies and the chondrocytes die
Stem cells in the pericardium divide to form osteoblasts
The periosteal bud (consisting of capillaries) form the primary ossification centre
Bone development from the osteoblasts extends toward epiphyses
Same process is repeated in epiphyses second ossification centres formed
Calcified cartilage is replaced with spongey bone
Osteoclasts reabsorb bone in the diaphysis creating a hollow medullary cavity
Remaining cartilage is over epiphyses forming articular cartilage.
explain the process of intramembranous ossification
Mesenchymal cells differentiate into osteoblasts
Osteoblasts lay down osteoid – organic part of bone made of collagen fibres
Some osteoblasts become entrapped in the osteoid and becomes an osteocyte
The osteoid calcifies and forms a type of spongey bone called spicules
These aggregate in small connecting beams called trabeculae
As trabeculae thicken they form compact bone
The blood vessels on the outside of the cells condense to form the periosteum
what is a joint
A site where 2 bones come together
what are the 3 types of joints
fixed
cartilaginous
synovial
explain what a fixed joint is
no movement, held by fibrous connective tissue e.g. sutures in skull
explain what a cartilaginous joint is
slight movement, held in place by cartilage e.g. symphysis pubis, between vertebrae
explain what a synovial joint is
amount of movement only limited by ligaments, tendons and adjoining bones e.g. shoulder, wrist, knee,
list the different types of synovial joints
ball and socket
gliding
saddle
hinge
pivot
condyloid
explain what a ball and socket joint is
Form when the spherical head of one bone fits into a cup-like cavity of another
E.g. head of humorous into scapula, head of femur fit with pelvis
explain what a hinge joint is
Allow movement in one plane only
Form when the convex surface of 1 bone fits into the concave surface of another
E.g. elbow, knee, ankle
explain what a pivot joint is
Formed when the rounded, pointed or conical end of 1 bone articulates with a ring, formed partly by a bone and partly by a ligament
E.g. joint between the first vertebrae and skull, between radius and ulna
explain what a gliding joint is
Allow movement in any direction in a side-to-side or back-and-forth motion
Restricted only by ligaments of bony processes
E.g. between carpals, between tarsals, between sternum and clavicle
explain what a saddle joint is
2 bones forming the joint are both saddle shaped
They fit together in a way that allowed side-to-side movement and back and forth movement
E.g. where the thumb joins the palm of the hand
explain what a condyloid joint is
Have 1 surface of bone slightly convex that fits into a slightly concave depression of another
They allow for movement in 2 directions (up and down and side to side)
E.g. between radius and carpals between metacarpals and phalanges
what is the synovial cavity in a joint
The space between synovial joints
what is the articular capsule in a joint
Surrounds and encloses the joints
Fibrous capsule:
- Dense, fibrous connective tissue attached to
periosteum of articulating bones
- Holds bones together
- Flexible and strong
Synovial membrane:
- inner layer of capsule
- Loose layer of connective tissue
- Well supplied with blood vessels
- Lines joint cavity
- Secretes synovial fluid
what is the synovial fluid in a joint
Fills joint cavity
Lubricates joint and provides nourishment for cartilage cells
Contains phagocytic cells
Prevents articulating surfaces from touching
what is the articular cartilage in a joint
Covers articulating surfaces
Provides smooth surface for movement
what are the articular discs
Made of fibrocartilage
extends inward from the articular cartilage
Divides synovial cavity in 2 so fluid is directed to areas of greatest friction
what are the bursae in a joint
Little sacs of synovial fluid
Prevent frictions between bone and ligament/tendon or bone and skin
what are accessory ligaments in a joint
Holds bone together
explain the sliding filament theory in term of contracting the muscle
- Nerve impulses cause axon terminals to release acetylcholine
- Acetylcholine initiates an impulse that travels into the T tubules and then into the sarcoplasmic reticulum
- The sarcoplasmic reticulum is stimulated to releasee calcium ions
- Calcium ions activate myosin which breaks down ATP and remove tropomyosin-troponin complex from the blocking activation sites on actin
- Myosin heads attach to activation sites in actin, forming crossbridges
- Through powerstrokes, the myosin heads pull along the actin and they slide past each other
- This causes the sarcomere to contract
explain the sliding filament theory in terms of relaxing the muscle
- Acetylcholine is inactivated by acetylcholinesterase
- Calcium ions are transported back into the sarcoplasmic reticulum using energy from the ATP breakdown
- Low calcium ion concentration in sarcoplasm stops the enzyme activity of myosin
- ADP is resynthesised into ATP and binds to the myosin crossbridges
- Tropomyosin-troponin complex attached back to actin and myosin crossbridges separate
- Thin myofilaments return to original position
- Sarcomeres return to resting lengths, muscles fibres relax and muscles relax.
what is osteporosis
Loss of bone mass and density impairs the bone’s normal function
As bone density decreases, risk to bone fractures increases
Even minor bumps/falls can results in serious fractures
Most affected in ribs, vertebrae, pelvis
Treatment: adequate calcium intake in their diet, plenty of exercise
what is osteoarthirits
Gradual change in joints overtime
Causes: irritation of joints, abrasion and wear
Articular cartilage at joints deteriorates, bone surfaces are no longer protected
The exposed bone wears away and bony spurs may develop from the exposed ends
These spurs decrease space within the joint cavity and restrict movement at the joint
Treatment: hydrotherapy, stretching, exercise
