Skeletal System Flashcards
What composes the axial skeleton?
80 bones including the skull, spinal column, and ribcage + hyoid bone and ear ossicles.
What composes the Appendicular skeleton?
126 bones; all bones of upper and lower libs and pectoral and pelvic girdles
How are bones classified?
Based on their shape
What are long bones?
Cylindrical shaped bones where length is greater than width.
Which bones function as levers and move muscles when they contract?
Long bones
What bones provide stability and support?
Short bones
What bones are cube like in shape and are found in carpals of wrist and tarsals of ankles?
Short bones
What bones are attachment points of muscles and often protect internal organs?
Flat bones
What are examples of flat bones?
Skull bones, shoulder blades, sternum, and ribs.
What bones have a spongy interior
flat bones
What is the function of irregular bone?
Complex shapes help support spinal cord from compressive forces.
What is the function of seamoid bones?
protect tendons by helping them overcome compressive forces, patellas are the only bones found in common.
Sutural/Wormian bones occur where?
Within a joint of the skull
What are the two forms of bone classification based on internal structure?
Trabecular Bone
Compact Bone
What is trabecular bone?
50-90% porous and metabolically active
What is Compact bone?
10% porous and provides strength an support
constitutes 80% of adult skeleton
What is the ephysis?
Wider section at ends of bones (red bone marrow)
What is the diaphysis?
tubular shaft that runs between each ephysis (yellow bone marrow)
What is hematopoiesis and where does it occur?
The production of red blood cells, white blood cells and platelets that occurs in the red marrow
What type of tissue does yellow marrow contain?
Adipose tissue
Where does ephysis and diaphysis meet?
metaphysis
What is contained in the metaphysis?
Epiphyseal plate (growth plate) and a layer of hyaline cartilage in growing bone
What happens to metaphysis is adulthood?
The cartilage is replaced by osseous tissue and the ephyseal plate becomes an epiphyseal line.
Where is compact bone found?
In the diaphysis of long bones
What is the microscopic structural unit of compact bone and what is it composed of?
Osteon; rings of calcified matrix called lamellae.
What does the canaliculi of the lacuna do?
Connects to one another so that nutrients and wastes can be transported to and from osteocytes.
Permits communication between osteocytes.
Where are osteocytes located?
Within the lacuna
What is the Haversian canal?
A canal that contains blood vessels, lymphatic vessels, and nerves.
What is the periosteum
Outer sheath that contains blood vessels, nerves, and lymphatic vessels that nourish compact bone.
Where do tendons and ligaments connect to on the bone?
periosteum
What cells are in the periosteum?
Osteoblasts, fibroblasts, and osteogenic cells (skeletal stem cells).
Osteocytes trapped in matrix.
What cells are in the endosteum?
Osteoblasts, skeletal stem cells, and osteoclasts.
How is spongy bone arranged?
With trabeculae that form a matrix of spaces that provide support and strength.
How is blood and nerves supplied to the spongy bone?
Blood nutrients enter and leave through nutrient foramen
What types of cells are found in bone tissue?
Osteoblasts
Osteocytes
Osteogenic Cells
Osteoclasts
What are the steps to form a osteocyte?
Osteogenic cell to osteoblast to osteocyte
What do osteoblasts do?
Synthesize and secrete collagen matrix and calcium salts, once the outside calcifies, it becomes an osteocyte.
Where do osteoclasts originate from?
Monocytes and macrophages (WBC)
What cells break down old bone, while what cells form new bone?
Osteoclast break down and osteoblast form new bone.
What is intramembranous ossification?
Flat bone formation where compact and spongy bone develop from sheets of mesenchymal areolar connective tissue
What do mesenchymal cells differentiate into?
Specialized cells such as capillaries or osteogenic cells then fibroblasts.
What is the ossification center?
Where early osteoblasts cluster
What is the result of intramembranous ossification?
Osteoid results in trabecular matrix while osteoblasts on the surface of spongy bone become periosteum.
What is endochondral ossification?
After 6-8 weeks after conception, some mysenchemal cells differentiate into chondrocytes (cartilage cells) that form the precursor to bones
What is the perichondrium?
Membrane that covers cartilage
As more matrix is produced, what happens to chondrocytes?
As chondrocytes in center of cartilaginous model grow in size, the ones that are far in don’t receive nutrients and die.
When blood vessels invade the spaces chondrocyte what happens?
The spaces eventually become the medulalry cavity and the penetration of capillaries initaites transformation of perichondrium to bone producing periosteum.
How does bone keep growing?
Chondrocytes and cartilage continue to grow at the ends of the bones (future ephysis).
