The Skeletal System Flashcards
A bone is an organ made up of what different tissues?
-Bone (osseous) tissue
-Cartilage
-Connective tissue, Epithelial tissue
-Adipose
-Nervous tissue
-Blood vessels, marrow
What are the functions of the skeletal system?
Support, protection, movement, triglyceride storage, mineral homeostasis, and hematopoiesis
How does the skeletal system provide support for the body?
structural framework for the body and provides attachment points for the tendons of skeletal muscles
What does the skeletal system protect?
protects important internal organs and tissues from physical damage
How is the skeletal system involved in movement?
skeletal muscles contract and pull on bones to produce movement
How does the skeletal system provide triglyceride storage?
yellow bone marrow is composed of adipose tissue - energy reserve
What part does the skeletal system play in mineral homeostasis?
storage and release of many different minerals, primarily calcium and phosphorus
How does the skeletal system perform hematopoiesis?
Red bone marrow, found in specific bones, is the site of production for formed elements. In newborns, all bone marrow is red. As we age, much it begins to convert to yellow
What is the diaphysis?
shaft or body of a long bone
What is the epiphysis?
proximal and distal ends to the bone
What is the metaphysis?
region between the diaphysis and epiphysis
What is the epiphyseal (growth) plate?
(Only in bone in early life)
cartilage that becomes bone once the patient stops growing
What is articular cartilage?
-specialized cartilage (hyaline) found where a bone articulates (joint) with another bone
-provides lubrication and absorbs shock
-avascular - minimal healing if damaged
What is the periosteum?
-dense, vascular connective tissue that surrounds the bone wherever it is not covered by articular cartilage
-protects and nourishes the bone, aids in repair, attachment point for tendons and ligaments
What is the medullary cavity?
hollow space within the diaphysis that contains yellow bone marrow and blood vessels
What are long bones?
-Greater length than width
-Variable number of epiphyses
-Slightly curved (helps provide strength and shock absorption)
-Composed mainly of compact bone tissue in their diaphysis and and spongy bone tissue in their epiphyses
What are examples of long bones?
femur, tibial fibula, humerus, ulna, radius, phalanges
What are short bones?
-Somewhat cube shaped (nearly equal in length and width)
-Composed mainly of spongy bone tissue with a thin layer of compact bone tissue close to the surface
What are examples of short bones?
carpal and tarsal
What are irregular bones?
-Complex shapes
-Vary in distribution of spongy and compact bone tissue
What are examples of irregular bones?
vertebrae, hip bones, facial bones, calcaneus (heel)
What are flat bones?
-Generally thin and composed of two plates of compact bone tissue enclosing a layer of spongy bone tissue
-Considerable protection and numerous sites for muscle attachment
What are examples of flat bones?
cranial, sternum, ribs, scapula
What are sutural bones?
Small bones located in sutures (joints) between certain cranial bones
What are sesamoid bones?
-Develop in locations where there is considerable friction, tension and physical stress
-Protect tendons from wear and tear, improves mechanical advantage of a joint
What are examples of sesamoid bones?
patella, palms, soles
What are bone markings?
-Bones have characteristic surface markings, structural features, adapted for specific functions
-They develop in response to tensions and certain forces on the bone surface
What are depressions and openings in bones?
allow for the passage of soft tissue (blood vessels, nerves, ligaments, tendons), or formation of joints
What are processes?
projections or outgrowths that either help form joints or serve as attachment points for tendons and ligaments
What is a fissure marking?
Narrow slit between adjacent parts of bones through which blood vessels or nerves pass
What is a foramen marking?
Opening through which blood vessels, nerves or ligaments pass
What is a fossa marking?
A shallow depression
What is a sulcus marking?
Furrow across bone surface that accommodates blood vessels, nerves or tendons
What is a meatus marking?
A tubelike opening
What is a condyle process?
Large round protuberance with a smooth surface articular at the end of the bone
What is a facet process?
Smooth, flat, slightly concave, or convex articular surface
What is a head process?
Usually rounded articular projection supported on neck of bone
What is a crest marking?
Prominent ridge or elongated projection
What is an epicondyle marking?
Typically roughened projection above condyle
What is a line marking?
Long narrow ridge or border (less prominent than crest)
What is a spinal process?
A sharp slender projection, the spinous process of the vertebrae
What is a trochanter marking?
Very large marking
What is a tubercle marking?
Variably-sized rounded projection
What is a tuberosity marking?
Variably-sized projection with a rough, bumpy surface
What is bone/osseous tissue?
A specialized connective tissue with an abundant extracellular matrix that surrounds widely separated cells
What is calcification?
Several different mineral salts combine together and crystallize into hardened tissue
What can the crystallization in calcification not occur without?
the presence of collagen fibres (high in quantity
within bone ECM)
What do crystallized mineral salts do?
provide the hardness of the bone
What do collagen fibers do?
provide the flexibility and tensile strength
What are the 4 types of cells present in bone tissue?
Osteoprogenitor Cells, Osteoblasts, Osteocytes, Osteoclasts
What are osteoprogenitor cells?
Bone stem cells that undergo cell division and become
osteoblasts
What do osteoblasts do?
-Bone building cells
-Secrete collagen fibres and their components of ECM.
-Initiate calcification process.
What are osteocytes?
-main cells in bone tissue
-maintain daily metabolism by exchanging nutrients and wastes with the blood
What do osteoclasts do?
breakdown ECM for normal development, maintenance and repair of bone tissue - bone resorption
What is compact bone tissue?
Strongest form of bone tissue found beneath the periosteum and makes up the bulk of the diaphysis of long bones
What does compact bone tissue do?
Provides protection and support
What is compact bone tissue composed of?
-repeating structural units called osteons
-the osteons run parallel with the length of the diaphysis and surround a canal that
contains blood vessels on nerves
-these structures help provide the tissue with the tensile strength to resist bending or
breaking
What is spongey bone tissue?
-Located beneath a layer of compact bone and does not contain osteons
-Cells are arranged in an irregular pattern of thin columns called trabeculae
What is between the spaces of the trabeculae?
Filled with either red or yellow bone marrow,
depending on the type of bone
How much of the bone does spongey bone tissue make up?
-Makes up most of the interior of short, flat, sesamoid and irregular bones
-In long bones, it forms the core of the epiphyses and surrounds the medullary cavity of the diaphysis
Why do bones have a rich blood and nerve supply?
to ensure a constant nutrient supply to the tissue
What can bones provide due to the rich blood supply?
-bones provide an alternate, and non- collapsible, route for infusions of medication, fluids or blood products (intraosseous)
-the IO injection goes directly into the bone marrow of spongy bone for rapid infusion to venous circulation
What is the process of bone formation called?
ossification or osteogenesis
In what 4 situations does ossification occur?
-Initial formation (embryo and fetus)
-Growth of bones from infancy to adulthood
-Remodeling (regular maintenance)
-Repair of fractures
What are the two main types of ossification?
-intramembranous ossification and endochondral ossification
-in both situations preexisting connective tissue is replaced with newly formed bone tissue
What is intramembranous ossification?
-formation of bone from embryonic tissue
-flat bones of the skull, facial bones, mandible, and clavicle
What is endochondral ossification?
-formation of most bones in the body by replacing cartilage with bone
What are the steps of intramembranous ossification?
Step 1: Development of the Ossification Centre
Step 2: Calcification
Step 3: Formation of Trabeculae
Step 4: Development of Periosteum
What are the steps of endochondral ossification?
Step 1: Development of the Cartilage Model
Step 2: Growth of the Cartilage Mode
Step 3: Development of the Primary Ossification Centre
What occurs in bone growth?
-The epiphyseal (growth) plate is a line of cartilage that remains in the epiphyses until final bone growth is completed (adolescence to adulthood)
-The cartilage gradually transitions into bone tissue and leaves a faint line called the epiphyseal line
What is bone remodelling?
The ongoing replacement of old bone tissue
What does bone remodelling involve?
-Bone Resorption - removal of minerals and collagen fibres by osteoclasts (destruction of ECM)
-Bone Deposition - addition of new minerals and collagen fibres by osteoblasts (formation of ECM)
What does bone remodelling do?
can help better strengthen and support different areas of bone based on chronic use and stress loads
What are the phases of fracture repair?
- Reactive Phase
- Reparative Phase
- Bone Remodelling Phase
What occurs in the reactive phase?
-Early inflammatory phase.
-Blood vessels are ruptured at the fracture site and a fracture hematoma develops.
-Nearby bone cells die.
-Neutrophils and osteoclasts remove dead/damaged tissue
What occurs in the reparative phase?
-Formation of fibrocartilaginous callus (composed of collagen fibres and cartilage) which eventually converts to a bony callus (composed of spongy bone)
What occurs in the bone remodelling phase?
Remodelling of the callus (spongy bone converted to compact bone)
How can calcium homeostasis be regulated?
Can be regulated by controlling the rates of calcium resorption (bone to blood) and calcium deposition (blood to bone)
How does parathyroid Hormone (PTH) help regulate calcium homeostasis?
- released when blood levels of Ca2+ are low
-triggers an increase in the number and activity of osteoclasts (increases calcium resorption).
-also causes the kidneys to increase reabsorption Ca2+
-stimulates formation of Calcitriol
What is calcitrol?
promotes GI absorption of Ca2+
How does Calcitonin (CT) help regulate calcium homeostasis?
-released, by the thyroid gland, when blood levels of Ca2+ are high
-Inhibits activity of osteoclasts and promotes calcium deposition
What is a joint (aka articulation or arthrosis)?
A point of contact between two bones, bone and cartilage, or bone and teeth
What are the three structural classifications of joints?
fibrous Joints, cartilaginous joints, and synovial joints
What are fibrous joints?
-no synovial cavity (space between)
-bones are held together by collagen rich connective tissue
What are cartilaginous joints?
-no synovial cavity
-bones are held together by cartilage
What are synovial joints?
-has a synovial cavity
-bones are connected by irregular connective tissue and accessory ligaments
What is the structure of synovial joints?
-Presence of a synovial cavity; the space between the articulating bones
-The bones are covered by articular cartilage within the joint to reduce friction between the bones during movement
- An outer fibrous membrane surrounds the synovial cavity and has dense bundles of fibres called ligaments
What is the synovial cavity filled with?
filled with synovial fluid; allows for considerable movement at the joint
What is the purpose of the articular cartilage within the joint?
to reduce friction between the bones during movement
What is a ligament?
dense connective tissue that connects bone to bone
What are articular discs (or menisci/meniscus)?
-Within some synovial joints, like the knee, are crescent-shaped pads of fibrocartilage
-divides the synovial cavity into two sections
What do the menisci functionally aid in?
-Shock absorption
-Combined movements
-Weight distribution
-Distribution of synovial fluid
What are bursae?
-Some synovial joints contain saclike structures to strategically alleviate friction
-Found in the shoulders and knees
-Bursae are not exclusive to synovial joints
What are plane (planar) joints?
-Permits back-and-forth and side-to-side movements between the flat surfaces of bones
-Eg. Intercarpal, intertarsal
What are hinge joints?
-Convex surface of one bone fits into the concave surface of another
-Eg. Knee, elbow, ankle
What are pivot joints?
-Rounded or pointed surface of one bone articulates with a ring, formed partly by another bone and partly by a ligament
-Eg. Radioulnar, atlanto-axial (shake head “no”)
What are condyloid (ellipsoidal) joints?
-Convex projection of one bone projects into a depression of another bone
-Eg. radiocarpal, metacarpophalangeal
What are saddle joints?
-Articular surface of one bone is saddle-shaped, and the articular surface of another bone fits into the “saddle” as a rider would on a horse
-Eg. Carpometacarpal
What are ball and socket joints?
-Ball-like surface of one bone fits into the cup-like depression of another
-Eg. shoulder, hip
What is the appendicular skeleton?
-Bones that make up the upper and lower limbs
-The girdles that attach the limbs to the axial skeleton
What is the axial skeleton?
-Bones that lie along the axial line of the skeleton
-Protect the major internal organs
What are the common major bones of the axial skeleton?
Ribs:
-12 pair (numbered superior to inferior), Sternum
Vertebral Column:
-26 bones (7 cervical, 12 thoracic, 5 lumbar, 1 sacrum, 1 coccyx)
Skull:
-Cranial bones (occipital, temporal, frontal, parietal)
-Facial bones (mandible, maxilla, zygomatic, orbits
What are the common major bones of the appendicular skeleton?
Pectoral Girdle:
-Clavicle, Scapula
Arm:
-Humerus, radius, ulna
Leg:
-Femur, tibia, fibula, patella
Pelvic (Hip) Girdle:
-Hip bones (coxal or pelvic bones)
-Ilium, Ischium, Pubis
-Pubic Symphysis (fibrocartilaginous joint)
-Sacrum, Coccyx
