msk Flashcards
what does the msk system consist of
bones, joints, ligaments, muscles, tendons, and connective tissues that support and bind tissues and organs together
ligaments vs tendons
Ligaments bind bones together at joints
ligaments = Connective tissue that attaches bone to bone at a joint; stabilizes joint and prevents movement beyond intended range of motion
Tendons attach muscles to bones
tendons = Connective tissue that attaches muscle to bone; tendon acts on bone when the muscle contracts to cause movement
skeletal bone provides
form, support, protection, stability, and movement to the body
Shape to the body
Physical support
Protection of organs
Stores minerals – calcium; and lipids
Responsible for blood cell formation
Muscle attachment sites – to facilitate movement
muscles
keep skeleton upright and facilitate body’s physical movement
attach to the bones of the skeletal system
- each muscle is a discrete organ composed of skeletal muscle tissue, blood vessels, tendons, nerves
- muscle tissue found in the heart, digestives organs, blood vessels
- ~ 700 muscles that account for half person’s body weight
how many bones in human body
206
-bones are formed from osseous tissue-provides structure and function to the body
nerves
- control the contraction of skeletal muscles
- interpret sensory information
- coordinate the activities of the body’s organ systems
osseous tissue composed of
composed of calcified connective tissue
Ground substance and 90-95% collagen fibers (ossein) create the bone matrix
Calcium and phosphorus stored in matrix adding strength and density
Osteocytes are contained in the matrix
cartilage
semi-rigid connective tissue deposited in areas where the bones need to move such as ribcage and joints
Soft connective tissue found between joints; shock absorber to reduce friction
structure of bone
Periosteum
Outermost layer of bone; protective sheath; thin tough membrane of fibrous tissue; provides support for tendons
Completely covers all bones except at joints where there is a layer of cartilage
Two layers: inner cellular osteogenic layer that forms new bone tissues and outer fibrous connective tissue layer for blood and nerve supply to bone
Osteogenic layer decreases in older bones
compact bone
under periosteum
hard outer layers of the bone; no spaces between lamellae
cancellous/spongy bone
under compact bone
lighter, softer, weaker, more porous but with greater surface area; spaces between lamellae; more vascular; “honeycomb appearance”
medulla
hollow cavity containing marrow within cancellous bone
bone development
Cartilage is the major component of skeleton when very young –provides greater flexibility and resiliency
Cartilage becomes harder with deposition of calcium phosphate in it
Some cartilage cells break loose and channels develop in the shaft of the bones
Blood vessels enter these channels and carry other connective tissue cells – some develop into osteoblasts and osteoclasts
Osteoblasts enter cartilage and form the layers of bone
Osteoclasts tear down old and excessive bone structures, allowing osteoblasts to rebuild with new bone – continuous process which slows down with age
osteoblasts
bone forming cells which secrete collage and substances to form the ground substance of bone
osteocytes
most common cell in mature bone
Responsible for bone growth and density
osteoclasts
cells that reabsorb bone tissue
lamellae
circular layers of bone matrix around the Haversian canal (osteon – functional unit of compact bone)
trabeculae
functional unit of cancellous bone; contain osteocytes but no osteons; receive nutrition from marrow tissue
bone marrow
Fills inner core of bones - the medullary cavity
Soft, gelatinous tissue – myeloid tissue
Red bone marrow for hematopoiesis OR yellow bone marrow filled with adipose tissue (or both)
red marrow
Primarily in central bones of adults – skull, vertebrae, sternum, ribs, pelvis, and upper thirds of long bones (humerus and femur)
In all bones until age seven – when need is high for new blood formation
yellow marrow
Primarily a storehouse for fats
Can be converted to red marrow under certain conditions (severe blood loss, fever)
Fill the cavities of other bones without red marrow
types of bone
endochondral and intramembranous long short flat sesamoid irregular
endochondral and intramembranous bones
Endochondral/intra-cartilaginous - ossification from centers arising in cartilage
Intramembranous – direct formation of bone on the mesenchyme (embryonic connective tissue) for formation of flat bones
ossification: formation of bone
Conversion of connective tissues into bone
Initiated at centers of ossification – points at which bone formation is started by osteoblasts through laying down of lamellae
Centers of ossification – primary or secondary
primary center of ossification
present before birth
first to start process of ossification
secondary center of ossification
usually appears after birth
process of ossification starts here after it has been started at the primary center
endochondral ossification
Embryonic mesenchymal cells develop into cartilaginous models which become ossified and form bone
Cartilage is gradually replaced by bone radiating out from the primary ossification center in the diaphysis to the epiphysis (secondary ossification center)
Cartilage remains at epiphysis as articular cartilage for joint movement
and as epiphyseal cartilage plate for bone
lengthening at junction with diaphysis
intramembranous ossification
Mesenchyme differentiates into osteoblasts which deposit osteoid (unmineralized matrix)
Then osteoblasts deposit calcium phosphate into the osteoid, and the osteoid is converted into a bony matrix called bony spicules
The osteoblasts transform into osteocytes
The spicules coalesce into layers (lamellae) which form around the blood vessels and develop into osteons (Haversian canal system); osteoblasts lay down lamellae at the surface of the developing bone forming compact bone
Mesenchyme differentiates into bone marrow
bone growth and remodeling
lengthening
growth in thickness
healing bone fractures
bone remodeling (bone metabolism)
bone lengthening
At diaphyseal-epiphysial junction where the epiphysial cartilages plate cells multiply, move towards diaphysis/shaft of bone, and become replaced by osteocytes
Is completed by puberty; growth in bone length stops [bone growth stops between ages of 18 and 30 years]
bone growth in thickness
Osteoblasts (bone forming cells) in periosteum (diaphysis/shaft) multiply continuously and form osteocytes, increasing the thickness of the bone
healing bone fractures
Cartilage laid down at edges of fracture
Endochondral process of bone replacing cartilage
bone remodeling (bone metabolism)
Purpose is to regulate calcium homeostasis, repair micro-damage to bones from everyday stress, and to shape the skeleton during growth
Lifelong, regulated process
Mature (old/defective) bone tissue is removed from the skeleton (bone resorption by osteoclasts) and new bone tissue is formed (ossification or new bone formation by osteoblasts)
types of muscles
voluntary involuntary striated skeletal smooth cardiac
voluntary muscles
muscle that can be consciously controlled
involuntary muscles
muscle that is controlled by the autonomic nervous system (not consciously controlled)
striated muscles
muscle tissue that has a striped appearance due to its fiber composition
skeletal muscle
voluntary and striated
attach to bones and control conscious movement
smooth muscle
involuntary and non-striated
in the hollow organs
cardiac muscle
involuntary and striated
only in heart and specialized to pump blood
each skeletal muscle is an organ
Composed of skeletal muscle fibers, blood vessels, nerve fibers, connective tissue
Enclosed by connective tissue – the epimysium
within each skeletal muscle
Bundles of muscle fibers/cells - fascicles
Enclosed by connective tissue – perimysium
Each muscle fiber/cell enclosed by connective tissue - endomysium
within each muscle fiber/cell
Multiple nuclei to produce large amounts of proteins and enzymes
Proteins organized into myofibrils
Hundreds to thousands of myofibrils within one muscle fiber/cell
Sarcoplasmic reticulum – store, release and retrieve calcium ions
within each myofibril
Thousands of sarcomeres
Sarcomeres – smallest functional unit of muscle fiber/cell
Each sarcomere - contains organized arrangement of contractile, regulatory and structural proteins
synovial fluid
synovia
lubricates the cartilage and reduces friction between the articular cartilages of the joints during movement
shock absorber by becoming more viscous under pressure to protect the joint from shocks
ATP required for
muscle contraction and relaxation:
ATP is stored in resting muscles