The musculoskeletal system Flashcards
What are the 5 functions of bone and the skeletal system?
- support (provides a structural framework for the body)
- protection (protects many internal organs from injury)
- assistance in movement (provides skeletal muscle attachments)
- mineral homeostasis (bone tissue stores several minerals including calcium and phosphorus)
- blood cell production (connective tissue red bone marrow produces red + white blood cells and platelets)
What are the 4 types of bones in the body?
-long bones
-short bones
-flat bones
-irregular bones
Describe long bones and give some examples of them
-greater length then width
-somewhat curved for strength
-include femur, tibia and fibula, humerus ulna and radius and phalanges (thigh, leg, arm, forearm, fingers and toes)
Describe short bones and give some examples of them
-cube shaped and nearly equal in length and width
-e.g most wrist and ankle bones
Describe flat bones and give some examples of them
-thin
-afford considerable protection
-provide extensive surfaces for muscle attachment
-e.g cranial bones which protect the brain, sternum (breast bone) and ribs which protect organs in the thorax
Describe irregular bones and give some examples of them
-complex shapes that can’t be grouped into any other category
-e.g the vertebrae and some facial bones
What are the 2 divisions of the skeletal system?
-the axial skeleton
-the appendicular skeleton
What is the axial system composed of?
- the skull
-22 cranial bones
-8 facial bones - the vertebral column
-separated by intervertebral discs
-made up of 5 different types of vertebrae - the thorax
-sternum
-ribs
What are the 5 types of vertebrae that makes up the vertebral column?
-cervical
-thoracic
-lumbar
(they get bigger in size due to a greater load carrying capacity)
-sacrum
-coccyx
What is the appendicular system composed of?
- pectoral (shoulder) girdle
-clavicle
-scapula - upper limb
-humerus
-ulna
-radius
-carpals
-phalanges
-metacarpals - pelvic (hip) girdle
- lower limb
-femur
-patella
-tibia
-fibula
-metatarsals
-phalanges
What are the parts of a long bone?
-proximal epiphysis (end)
-metaphysis (area between epiphysis and diaphysis)
-diaphysis (main section)
-metaphysis (area between epiphysis and diaphysis)
-distal epiphysis (other end)
What type of bone does the epiphysis and diaphysis have?
-epiphysis= spongy bone
-diaphysis= compact bone
What are the 2 different types of cells within bones?
- osteoblasts= build bone making extracellular matrix which builds bone
- osteoclasts= break the bone down to release calcium and phosphorus
-both maintain blood calcium levels (hypercalcemia and hypocalcemia)
What is the role of parathyroid hormone?
Receptors in parathyroid gland (in neck) detects blood calcium levels, so when low, releases parathyroid hormone which triggers the osteoclasts to break down the bone and to raise the calcium levels in blood so once back to normal release of parathyroid hormone is down regulated (switched off) =negative feedback
What are the 3 different types of joint?
-cartilaginous
-fibrous
-synovial
What are the properties of fibrous joints?
-typically immobile
-mainly found in the skull and teeth
-held together by dense connective tissue which prevents movement
What are the properties of cartilaginous joints?
-allow a small degree of movement
-fibrocartilaginous connection between 2 bones allows a small degree of movement when compressed
-cartilaginous joints between the ribs and the sternum facilitates movement in the ribcage essential during inspiration/ expiration
-intervertebral discs joining the vertebrae in the spine, allow a small degree of movement at each individual joint to collectively enable full movement of the spine
What are the properties of synovial joints?
-most prevalent in the human skeleton
-the most mobile enabling vast movement
-all are held together by ligaments, rather then connective tissue or cartilage
-all have synovial membrane and contain synovial fluid within the joint cavity
Give some examples of synovial joints
-ball and socket
-gliding
-hinge
-pivot
-saddle
-condyloid
Explain how the ball and socket joint of the shoulder enables movement
-round end of one bone articulates with a socket shaped articulation of another bone
-vast range of movement in all directions
-most mobile
Explain how both the pivot and hinge joint in the elbow enables movement
-pivot allows a rotational movement, centred around a single axis
-hinge allows flexion and extension like a door-hinge
What 6 synovial joint structures are there?
-articular cartilage
-synovial membrane and fluid
-capsule
-intra and extra capsular structure
What is articular (hyaline) cartilage (one of the six synovial structures)?
-a thin layer of specialised connective tissue covers articulating bone surfaces
-role is to protect the bone and reduce friction during movement
What are the intra-capsular structures (one of the six synovial structures)?
-additional structures are specific to individual joints
-e.g in the knee bursae and fat pads act as shock absorbers, meniscus acts as a buffer between the joint surfaces in the knee
What are the extra-capsular structures (one of the six synovial structures)?
-ligaments connect the joint externally to create stability
-tendons use bony points as attachment sites which enables muscle control and movement across the joint
What is the outer layer of the capsule (one of the six synovial structures)?
-a dense fibrous tissue, strong, protective, provides rigidity but also flexible enough not to inhibit joint movement
What is the inner layer of the capsule, the synovial membrane (one of the six synovial structures)?
-made from epithelial cells
-covers all non-weight bearing exposed areas within the joint that are not covered by hyaline cartilage
-secretes synovial fluid to fill the joint cavity
-provides core nutrients to lubricate the joint
-promotes joint stability to protect against trauma
What are the roles of tendons?
-need strength flexibility and elasticity
-transmit force generated by muscle to bone
-act as a shock absorber
-have a nerve supply and contain sensory receptors called Golgi-tendon organs which detect changes in muscle tension
-limited blood supply which can impact capabilities to heal
-tensile strength is related to the tendon thickness and collagen content
-made of type 1 collagen which has strength as its biggest property
What are the roles of ligaments?
-coomprised of dense bundles of a fibrous protein called collagen
-parallel across a joint from their origin to their insertion, attaching directly to the bone
-much better blood supply and nerve supply so increased capacity to heal
-primary responsibility is stabilisation whilst under load during movement
-receptors in the ligament sense stretch and tension which passes information to the brain and appropriate muscle responses are activated
What are the roles of cartilage?
-highly specialised connective tissue
-no specific blood or nerve supply and exhibits some rigidity
-no capacity to regenerate and repair
-contains a significant amount of water which is essential to its function
-it has a class white gloss appearance
What is hyaline cartilage?
-lines the bony articular surfaces in joints
-the smooth glossy exterior and strength (hyaline cartilage) is good at protecting the joint surfaces as well as reducing friction during movement
What is fibre cartilage?
-strong and slightly thicker/ spongy e.g menisci in the knee
-the strong but spongy physiological characteristic of the menisci enables it to protect the joint from impact and potential damage acting as a shock absorber
What % of bone strength is due to its mineral content and its architecture?
-75-80% is mineral content (calcium and phosphorus)
-20% is architecture
What are the effects of physical activity on bone density?
-skeleton responds in a site-specific manner to mechanical loading, so density increases when greater stress
-exercise in childhood or adolescence is critical to optimise maximum bone mass density
-normal forces in daily activities in older adults is not enough to sustain critical bone mass
What is bone remodelling and how long does this process last?
-bone has the ability to adapt by changing its size shape and structure to the mechanical demands placed on it
-remodelling is a cyclical balanced process which happens throughout life
-the whole process takes between 4 and 8 months
-over a 10 year period the majority of the skeleton will undergo some level of remodelling
-reabsorption= 10 days
-matrix formation= 10-20 days
-mineralisation= 3-4 months
Give an example of what might cause disruption to the balance of a healthy skeletal system
if more bone is reabsorbed (due to smoking, aging, alcoholism, drugs) than is laid down, this results in structural weakness and fragility
What is osteoporosis?
-low bone mass and structural deterioration of bone tissue
-increased reabsorption of the spongy bone structure means it looses its structural integrity and strength, becomes more porous, weaker, and gaps widen
-a low-level impact or minor fall would be sufficient trauma to cause a fracture in pathologically weak bone
What groups of people are at high risk or potential risk for developing osteoporosis?
At risk:
-all women over age of 65
-all men over age of 75
At potential risk:
-women under 65 and men under 75 with additional risk factors such as
-a history of falls
-low body mass index
-smoking
-alcohol above recommended units
-previous fragility fracture
What is the scientific study of muscles?
myology
What are the 3 types of muscular tissue?
-skeletal muscle
-cardiac muscle
-smooth muscle
Describe skeletal muscle
-mostly attached to bones
-striated and voluntary
Describe cardiac muscle
-forms most of the wall of the heart
-it is striated and involuntary
Describe smooth muscle
-located in viscera
-it is non striated and involuntary
What are the 5 key functions of muscular tissue?
- producing body movements
- stabilising body positions
- regulating organ volume
- moving substances within the body
- producing heat
What is the sarcolemma and endomysium part of a muscle?
-sarcolemma is muscle cell membrane
-endomysium surrounds the sarcolemma
What is the facicle?
Bundle of muscle cells
What membrane surrounds the fascicle?
perimysium
What membrane surrounds the muscle?
Epimysium
What forms the tendon?
The epimysium which connects the muscle to the bone
What are the thick and thin filaments of a muscle?
-thick= protein called myosin
-thin= protein called actin
What are the 2 additional proteins to actin?
-troponin
-tropomyosin
What triggers muscle contraction?
an action potential travelling through a motor neurone across a neuromuscular junction
Explain the process “sliding filament theory” in the contraction and relaxation of muscles
- myosin heads break down ATP into ADP and become energised
- myosin heads bind to myosin-binding site on actin, forming cross-bridges
- myosin cross-bridges rotate toward centre of sarcomere
- as myosin head bind to ATP, the cross-bridges detach from actin
What 2 things need to be present to allow contraction cycle to continue?
-ATP
-Calcium levels in sarcoplasm is high
Explain how the bicep and tricep muscles work antagonistically
As bicep muscle relaxes, tricep muscle contracts and vice versa
