The Skeletal System Flashcards
connective tissue
connective tissue in adults comes in many forms. they link muscles and bones together to create a system capable of producing movement.
variety of them including - fat, collagen, fibrous tissue,, cartilage
fat (connective tissue)
packing and insulating substance capable of acting as shock absorber - protects bones and internal organs
fat is stored for this purpose under the heel, in the buttocks and palm of the hand (subcutaneous)
subcutaneous fat is divided into compartments by fibrous tissue that stiffens in response to the protective demands placed upon it
Collagen (connective tissue)
primary structural protein found in connective tissue and plays integral role in binding tissues together
about 25-35% of the body’s protein tissue is made from collagen which is arranged in 2 diff forms:
- irregular = fibres have a random arrangement and do not have parallel bundles. this is most commonly found in the skin
- regular = fibres are arranged in parallel bundles and can be further divided into white and yellow fibrous tissue
Fibrous Tissue (connective tissue)
found throughout body, particularly in the dermis of the skin, muscles, tendons and ligaments. there are two types:
- white fibrous tissue = has the most regular collagen fibres and is incredibly dense. this density provides considerable strength without compromising its flexibility and elasticity. white fibrous tissue forms ligaments, tendons and the perimysium which is the protective membrane surrounding clusters of muscle fibres
- regular = this has a predominance of elastic fibres which allows it to perform the highly specialised function of deforming and reforming. yellow fibrous tissue is primarily found in the walls of the arteries and a small number of spinal ligaments that assist the spinal muscles in maintaining an erect posture, particularly the ligamentum flavum
cartilage
supplementary to bone and is found where rigidity and strength are required. it is not as strong as bone tho. 2 types:
- articular cartilage
- fibrocartilage
bone
bone is hard tissue with great deal of resistance
interwoven mix of fibrous connective tissue that is saturated with mineral salts.
its connective tissue provides bone with toughness and elasticity, whilst mineral salts provide hardness and rigidity
the mineral component of bones is a readily available store of calcium that is continuously exchanged with bodily fluids
compact bone
sometimes called cortical bone
toughest of 2 bone forms
laden with minerals, bone cells, blood and lymph
accounts of approx 80% of skeletal mass
found most prominently along diaphysis of long bones
protected by dense layer of fibrous tissue known as periosteum
means can withstand high levels of stress during movement and impact
cancellous bone
sometimes called spongy or trabecular bone
found usually towards ends of long bones
also found in core of vertebra
inside is a complex arrangement of boney tissue called trabeculae
the trabeculae arrangement of the cancellous bone resembles that of lattice, running in many different directions to maximise its strength, whilst enabling it to stay light enough to move
multi-directional arrangement of the cancellous bone is designed to resist compressive, tensile and shearing forces.
bone marrow
primarily responsible for producing red and white blood cells
can be found in both red and yellow form
red is most prevalent in infants and towards puberty
much of red is gradually replaced with yellow fat marrow
yellow primarily found in medulla while red stored in cancellous bone
regulation of bone development
the hormones involved in the regulation of bone density are:
testosterone, oestrogen, calcitonin, parathyroid hormone
when these hormones are low, the bones ability to retain calcium is diminished and risk of osteoporosis is increased
osteoporosis risk factors
age bone structure (petite frame) family history specific diseases pregnancy (hormonal changes) history of fractures as adult smoking underweight (bodyfat <17%) white or Asian female sedentary lifestyle early menopause history of eating disorders high protein intake, especially animal protein excessive sodium intake alcohol abuse use of anabolic steroids high caffeine intake vitamin d deficiency
osteoarthritis risk factors
age family history women repetitive loading activities/posture repetitive loading from sporting actions smoking other medical conditions
5 primary types of bone
long bones short bones flat bones irregular bones sesamoid bones
long bones
act as levers - large range of movement required locations
recognised by distinct diaphysis and prominent epiphysis
eg femur and humerus
short bones
fine and precise movement areas
less strength than long bones
eg carpals and tarsals
flat bones
protect vital organs
attachment sites for skeletal muscles
eg cranium, pelvis, scapula and ribs
irregular bones
located in spine and face
protect vital organs and surrounding structures
gives unique facial structures
sesamoid bones
resemble sesame seeds
usually embedded in a tendon
eg patella, first metacarpal, first metatarsal
appendicular skeleton
all bones in arms and legs, scapula and pelvis and bones in the extremity
two primary components = pectoral (shoulder) girdle and pelvic girdle
axial skeleton
primary supporting structure of body
spine, ribs, sternum, cranium and hyoid bone
more rigid than appendicular
3 classifications of joints
fused, fibrous, immoveable
slight moveable, cartilaginous
freely moveable, synovial
fused, fibrous immoveable joints
no movement permitted - articulating bones are fused together by fibrous ligaments
protect vital areas of body
eg. fusion of flat bones in skull, joining of irregular bones in sacrum and coccyx.
cartilaginous - slightly moveable joints
bones are attached by fibrocartilage.
eg. joints between sternum and ribs, between each vertebra (except sacrum and coccyx), and pubic symphysis
permits small range of movement
dissipate stress and absorb shock
synovial - freely moveable joints
most common joint
allow free range of movement between articulating surfaces of bones
6 primary types - each restricts or permits certain movements
many differences and similarities between
types of synovial joints
hinge ball and socket pivot gliding saddle condyloid
diaphysis
/ ‘shaft’
compact bone tissue = provides strength and support to skeleton
hard outer layer
epiphysis
end of the bone
largely made up of cancellous bone (spongy bone tissue)
cancellous bone tissue fills bone space in latticework
spaces within lattice help reduce weight of bone and allow room for bone marrow and blood vessels
lattice also reduces strength = more prone to fractures
periosteum
hard outer casing of bones
attachment site for muscles
largely composed of dense, compact bone - much greater tensile strength
articular cartilage
smooth, white glossy tissue - furnishes end of bones
ensures smooth, fluid and lubricated movement between articulating bones
cartilage can also soak up synovial fluid which helps absorb shock
medullary cavity
within the central component which contains yellow bone marrow
towards epiphysis, internal structure become spongier or more cancellous - where red bone marrow is
epiphyseal plate
plate of hyaline cartilage - located between diaphysis and epiphysis
found exclusively in children and adolescents - in adulthood plate fuses and is replaced with epiphyseal line.
source of all bone growth during development
hinge joint
eg knee and elbow, joints between phalanges of fingers and toes
permits flexion and extension
in knee - very small amount of rotation is possible but only in flexed position
ball and socket
head of one bones articulates with cavity of another
eg shoulder and hips
permits most movement of joints
pivot
two articulating bones that move around each other in a rotating fashion
eg joints between radius and ulna (radioulna joint) and between cervical spine and cranium
gliding
when almost flat articulating surfaces glide over each other in opposite directions
eg carpals in hands and acromioclavicular joint (shoulder girdle)
permits extension, flexion, elevation and depression
saddle
convex shape of one bone fits into concavity of another
not v common
egs base of thumb or between sternum and clavicle
movement permitted = flexion, extension, adduction, abduction, rotation
condyloid
/ ‘ellipsoid joint’
modified form of ball and socket - ball of projecting bone is more oval shaped and depth of socket is much shallower
egs. wrists, between metacarpals and phalanges
modified version in sub-talar joint of foot
movement it permits == flexion, extension, abduction, adduction and circumduction
synovial fluid
thick, sticky fluid
acts as a lubricant with the joint
contains several vital nutrients that help to nourish the cartilage and surrounding structures
synovial joints rely on synovial fluid to keep joints healthy and nourished
