Chapter 7 Flashcards
Bone Structure & Function
two forms of bone in the body
compact bone and spongy bone.
two main forms of cartilage within the skeletal system
hyaline cartilage and fibrocartilage.
Tendons are fibrous connective tissues that connect
muscles to bones.
Ligaments are fibrous connective tissues that connects
bones to other bones.
Compact bone is also known as
dense or cortical bone
Spongy bone is also known
cancellous or trabecular bone
compact bone makes up __% of total bone mass
80
spongy bone makes up __% of total bone mass
20
compact bone
spongy bone
where is hyaline cartilage found in the skeletal system?
costal cartilage
articular cartilage
epiphyseal growth plates
fibrocartilage is found where in the skeletal system?
intervertebral discs
pubic symphysis
menisci of the knee
four general functions of bone?
support/protection
levers for movement
hematopoiesis
mineral/energy storage
four classes of bone
long
short
flat
irregular
Long bones are found in
the upper and lower limbs
Short bones are found in
the wrist and foot.
Irregular bones are found in
the vertebrae, hip bones, some bones of the skull.
Flat bones are found in
the skull, scapulae, sternum, and ribs
Sesamoid bones are found
along tendons of some muscles and the kneecap
the diaphysis is
the shaft of the long bone
the medullary cavity is
the hollow cavity in the diaphysis
in children, the the medullary cavity contains
red bone marrow
in adults, the the medullary cavity contains
yellow bone marrow
the epiphysis is covered by
articular cartilage
the metaphysis is
the area where the bone widens from the diaphysis to the epiphysis.
in a growing bone, the metaphysis contains
the epiphyseal growth plate
in adults, the epiphyseal growth plate becomes the
epiphyseal line
the periosteum is
a tough sheath that covers areas of the bone that aren’t covered by articular cartilage
The periosteum is anchored to the bone via
perforating fibers
The endosteum is
a very thin layer of CT containing osteoprogenitor cells, osteoblasts, and osteoclasts. It covers all internal surfaces of the bone within the medullary cavity and assists in bone growth, repair, and remodeling.
Blood vessels enter bones from the
periosteum
the nutrient foramen provides space for
the single nutrient artery and vein that supplies the bone
Red bone marrow function
hematopoiesis
anemia is
condition where red blood cell counts are lower than normal, resulting in decreased oxygenation to cells
four cells found in bone
Osteoprogenitor cells
Osteoblasts
Osteocytes
Osteoclasts
Osteoprogenitor cells
stem cells that arise from mesenchyme. When they divide, another stem cell is produced along with an immature osteoblast (committed cell).
Osteoblasts
formed from osteoprogenitor cells. They are often positioned side-by-side on bone surfaces. Responsible for bone production.
Osteocytes
mature bone cells from osteoblasts that have been enveloped by the calcified osteoid. Responsible for maintaining bone matrix and sensing mechanical stress.
Osteoclasts
derived from fused bone marrow cells and are located in a depression of the bone surface, the resorption lacuna (Howship’s lacuna). Responsible for bone resorption.
The organic component of bone matrix is
osteoid
the inorganic component of bone matrix is
hydroxyapatite, a crystalline structure of calcium phosphate and calcium hydroxide
Bone formation begins when
osteoblasts secrete osteoid
Bone resorption is
a process where bone matrix is destroyed by substances released from osteoclasts into the extracellular space adjacent to bone.
Bone resorption can occur when
blood calcium levels are low.
Compact bone is composed of
osteons, small, cylindrical structures, also known as Haversian systems.
The central canal (Haversian canal)
the cylindrical channel that lies in the center of the osteon and runs parallel to it. This houses blood vessels and nerves that supply the bone.
Concentric lamellae
rings of connective tissue that surround the central canal and form the bulk of the osteon. Collagen fibers create an alternating pattern which gives the bone strength and resilience.
Lacunae
small spaces that house osteocytes
Canaliculi
tiny, interconnecting channels within the bone that extend from each lacuna, through the lamellae, and connect with other lacunae and the central canal. They house the osteocyte cytoplasmic projections that allow for intercellular contact and communication.
Nutrients, minerals, gases, and wastes are transported through these extensions, allowing exchange between the osteocytes and vessels within the central canal.
Volkmann (perforating) canals
resemble central canals but run perpendicular and help connect multiple central canals with different osteons
Circumferential lamellae
rings of bone immediately internal to the periosteum or immediately external to the endosteum.
Interstitial lamellae
components of bone that are between osteons or parts of resorbed osteons that contain no central canal.
trabeculae
open lattice structure found within spongy bone
The cells of hyaline cartilage
chondroblasts
chondrocytes
chondroblasts
produce cartilage matrix
chondrocytes
matured chondroblasts that occupy lacunae
Intramembranous ossification produces
flat bones of the skull, some facial bones, the mandible, and central part of the clavicle.
not testing over the steps of intramembranous ossification
:D
Endochondral ossification produces
bones in the skeleton, including upper and lower limbs, pelvis, vertebrae, and ends of the clavicle.
not testing over the steps of endchondral ossification
:D
How could a physician determine whether a person has reached full height by examining x rays?
open vs closed epiphyseal growth plates
interstitial growth is
when a long bone grows in length
Appositional growth is when
a bone growth in diameter within the periosteum
Bone remodeling is dependent on
oordination of osteoblasts, osteoclasts, and osteocytes.
Bone remodeling is a
constant, dynamic process by which old bone tissue is removed and replaced with new bone tissue
Bone remodeling is influenced by
hormones and mechanical stress.
Calcitriol is
a hormone, specifically an activated form of vitamin D
two primary hormones that regulate blood calcium levels
calcitriol and parathyroid hormone.
Parathyroid hormone (PTH) is secreted by the parathyroid glands in response to
low blood calcium levels.
Calcitonin is released from the thyroid gland in response to
high blood calcium levels or stress from exercise
PTH increases blood calcium levels by
increasing osteoclast activity
Calcitonin function
inhibit osteoclast activity and stimulate secretion of calcium into the urine.
Osteopenia is a condition in which
the bones of the skeleton are weak and thin, resulting in insufficient ossification.
Osteoporosis
is a condition characterized by reduction in bone mass sufficient to compromise normal function.
Stress fractures are
thin breaks caused by increased physical activity in which the bone experiences repetitive loads (can be seen in long distance runners)
Pathological fractures
occur in bone that has been weakened by disease.
Simple fractures
are when the broken bone does not penetrate the skin (closed fracture)
Compound fractures
are when one or both ends of the broken bone pierce the underlying skin (open fracture)
Bone fracture repair process:
A fracture hematoma forms. Blood vessels tear when a fracture occurs, causing bleeding. A hematoma forms from the clotted blood.
A fibrocartilaginous callus forms (that is soft). Blood vessels are regenerated and the callus brings the ends of the bone together. This usually lasts three weeks
A hard, bony callus forms. Osteoprogenitor cells become osteoblasts and produce trabeculae of bone. The fibrocartilage callus is replaced with this bone. It continues to grow and thicken for several months.
The bone is remodeled. Osteoclasts remove excess bony material from exterior and interior surfaces. Compact bone replaces primary bone. Sometimes a slight thickening can be detected via x ray but in most cases, there is no obvious bone thickening after repair.
