Part 4 Flashcards
Structure of Bone
the structure of bone gives it strength, the ability to grow and repair itself.
also has the ability to serve as a reservoir minerals and cells needed elsewhere in the body
the bone dynamic’s nature is possible because it is living tissue containing cells, collagen matrix, and minerals
Histology of Bone
Osteocytes are star shaped cells that maintain bone and are able to sense physical stresses
Osteoblast make bone and osteoclast break it down
Mineral resorption
Performed by osteoclast and it removes calcium from bone so it can enter the bloodstream
Neurons use calcium to communicate with each other and rely upon its presence in extracellular fluid for normal muscle contraction inhibition
Low levels of plasma calcium causes tetany (an involuntary and continuous contraction of skeletal muscle).
Blood clotting and other vital metabolic reactions require calcium as well.
Osteoporosis
Osteoclasts liberate calcium from bone-bound reserves but when too much calcium is depleted from the bone osteoporosis results
causing bones porous of minerals and make them weak and brittle
Osteoblast
Osteoblast secretions allow mineralization in bones, a process that is inhibited elsewhere in the body
This mineral deposition is in the form of hydroxyapatite a calcium phosphate salt
Osteoblast produce a highly organized collagen matrix to which extracellular hydroxyapatite binds
Collagen
Collagen protein gives bone flexibility, while the minerals that encrust those fibers give them strength
brittle bone disease (osteogenesis imperfecta) results from the genetically based corruption of bone’s collagen matrix
The structure of Bone
In compact bone, the mineral-laden collagen matrix is organized into long concentric layers called lamellae, layers of bones, tissues or cell walls
Between each lamella are microscopic pockets or lacunae where bone cells reside
Canaliculi
Call communication between the lacunae occurs through microscopic tunnels (canaliculi) which transverse lamellae
Osteon
a grouping of concentric lamellae is called an osteon and contains a central canal within its innermost ring called the central (haversian) canals and perforating (Volkmann’s) canals.
Central (Haversian) Canals
are passageways for nerves and blood vessels
haversian canals and their contents, running parallel within the center of each osteon, connect by way of perpendicular and oblique perforating Volkmann’s canals.
Compact (dense) bone
bone that makes up bone plates of the skull and the periphery of most other bones
Spongy bone
has few osteons compared to compact (dense) bone
The spongy bone contained with compact bone allows bone to be lighter and serves as a location for bone marrow to reside
Bone marrow
A soft material within spongey bone and medullary cavity of long bones.
Red bone marrow
is a site of blood formation and plays a role in the immune system
Yellow bone marrow
presents within the medullary cavity of adult long bones is primary composed of adipose tissue
The longest long bone of the adult body is the femur, so it contains the largest amount of yellow bone marrow
Long Bones
Bones that have a pronounced longitudinal axis, provide the mechanical advantages of levers where they articulate with other bones.
Some of these points of articulation allow the associated bones to move in a hinge-like fashion relative to each other.
Examples of bones hinge like fashion
Hinge joint found in each elbow and knee allows flexion and extension of the more distal bone along only one plane
The shoulders and hips are locations where long bones articulate with other bones in ball and socket joints.
Ball and socket joints allow for abduction, adduction, circumduction, and rotation of the associated long bone
Short bones
ex. Bones of the wrist, ankles, and patella
short bones have a width similar to their hight and articulate as gliding joints
Flat bones
Flat bones are thin bones that have a plat-like shape such as bones of the cranium, connect with each other at fused joints called sutures
Irregular bones
Bones that dont fit flat, long, or short are irregular bones
How is skeleton articulation possible?
Articulation of the skeleton is made possible through its association with soft tissue: cartilage, tendons, ligaments and the periosteum that covers bones
Cartilage
the primary structural protein of connective tissue
Tendons
Tough connective tissue that attaches muscle to bone
Ligaments
a tough connective tissue that attaches bone to bone
Periosteum
A thin layer that surrounds bone and its surface for attachment of tendons and ligaments
Hyaline Cartilage
At the location in the skeleton where bones are involved in articulations, bone joint interfaces are protected by hyaline cartilage
as a result of trauma, cartilage can wear down to the point it offers insufficient protection.
Osteoarthritis
Inflammation and pain of a joint when joint wears down
Rheumatoid arthritis
causes joint inflammation and pain like osteoarthritis but is caused by an autoimmune reaction rather than wear and tear of the joint
Epiphyseal plate
also called the growth plate
hyaline cartilage is also involved in bone elongation that happens in the epiphyseal plate
here, newly generated cartilage is turned into bone
an epiphyseal line develops when the plate area stops producing cartilage and indicates termination of growth in that long bone that is seen in X rays.
Anchondroplastic Dwarfism is the resulting short stature of individuals when epiphyseal plate stops growing at a premature age
Human Skeleton’s two major division
Axial Skeleton and Appendicular skeleton
Axial Skeleton
consists of a skull that shields the brain, a thoracic cage of ribs and sternum that shelters the heart and lugs, and a series of verterbrae in which the spinal cord resides
in addition to protective functions, the axial skeleton plays a major role in metabolism and movement
Mastication
Chewing
in the skull, the mandible articulates with the temporal bone to allow for the motions of mastication
sinuses
Sinuses inside the frontal, sphenoid, ethmoid, and maxillary bones are mucous membrane-lined cavities connecting with the nasal cavity
Tiniest bones in the skull are?
The three auditory ossicles in the middle ears
Hyoid bone
is a point of tongue and larynx attachment, and it is unique in being the only bone that is not connected to the rest of the skeleton
Vertebral column
is made of three groups of similar shaped bones: the cervical, thoracic, and lumbar vertebrae
Cervical
on the cranial end of the vertebral column is cervical vertebra number 1 (C1) also known as the atlas
the atlas is the rocker between C2 and the occipital bone of the skull that allows for the yes motion of head
The C2 is called the axis and it contains a vertical projection into the atlas, a pivot that allows for the no motion of the head
has 7 cervical vertebrae
Sacrum
at the level of the hips, five vertebrae that fuse together by adulthood make up the sacrum, which is joined on either side by a left and right hip bone
Coccyx or tailbone is behind it
Upper Region Appendicular Skeleton
Arms and legs
Upper region of the appendicular skeleton includes the pectoral girdle made of a right and left scapula and clavicles
Upper limbs consist of the humerus and more distally a pair of bones called the radius and ulna that articulate with the carpals of the wrist
The metacarpals of the palm articulate with the phalanges of the fingers
Lower Region of the Appendicular Skeleton
Includes the left and right hip bones of the pelvic girdle
Lower limbs consist of the femur and more distally a pair of bones called the tibia and fibula that articulate with the tarsals of the food
Between the tarsals and the phalanges of the toes are metatarsals
