Flashcards in Chapter 6 (Lecture Objective 4) Deck (22):
What are the functions of the skeletal system?
The main functions of the skeletal system are support, protection, movement, mineral storage, blood cell production, fat storage, and hormone production.
How are bones classified based on their shape?
Bones are either classified as long, short, flat, or irregular bones. Short, irregular, and flat bones share a simple design of thin plates of spongy bone enclosed by compact bone. Long bones have a shaft, bone ends, and membranes.
Define the following: process, ramus, trochanter, tuberosity, tubercle, facet, fossa, foramen and fissure.
process: any bony prominence
ramus: armlike bar of bone
trochanter: very large, blunt, irregularly shaped process, only on the femur
tuberosity: large rounded projection, may be roughened
tubercle: small rounded projection or process
facet: smooth nearly flat articular surface
fossa: shallow, basin-like depression in a bone, often serving as an articular surface
What are the structural components of a long bone?
A long bone is composed of a shaft (diaphysis), bone ends (proximal and distal epiphysis), and a membrane called the periosteum.
What are the components of the bone matrix?
The bone matrix is made up of water, collagen fibers, and minerals that help with the stiffening of the bone such as calcium.
Compare and contrast compact bone with spongy bone.
compact bone:Dense or cortical bone, solid. In long bones, compact bone forms the solid external walls of the bone
spongy bone: trabecular bone, porous, like a sponge, located internally within the epiphyses
What is an osteon, and what are its components?
An osteon is the structural unit of the compact bone. It is composed of a canal, multiple lamellae which have collagen fibers running in different directions. Within the canal there is an artery with capillaries, a vein and a nerve.
What is the function of red marrow in the bones and how does it differ in adults and infants?
The function of red marrow is to produce red blood cells, white blood cells, and platelets. In adults red marrow is in the epiphyses of the long bones and in flat bones; the yellow marrow is stored in the diaphysis. Infants only have red marrow throughout their long bones and in flat bones.
Define the following terms: osteoblast, osteogenesis, osteoid, osteoclasts, osteolysis.
osteoblast: are cells with single nuclei that synthesize bone
osteogenesis: the process of forming new bone
osteoid: the unmineralized organic component of bone
osteoclasts: large multinucleate bone cell that absorbs bone tissue during growth and healing
osteolysis: the pathological destruction or disappearance of bone tissue.
How do osteocytes communicate?
Osteocytes are networked to each other via long cytoplasmic extensions that occupy tiny canals called canaliculi. The cytoplasmic extensions are used for exchange of nutrients and waste via gap junctions
Summarize the process of endochondral ossification (two paragraphs).
Endochondral ossification starts with a hyaline cartilage model of the bone.
Primary ossification center is in the middle of shaft. Bone collar forms around the diaphysis from primary ossification center. Cartilage in the center of diaphysis calcifies and then develops cavities. The periosteal bud invades the internal cavities and spongy bone forms. The diaphysis elongates and a medullary cavity forms.
Secondary ossification centers appear in the epiphyses. The epiphyses ossify (no medullary cavity forms; spongy bone remains). When completed, hyaline cartilage remains only in the epiphyseal plates and articular cartilages
What is the epiphyseal line?
The epiphyseal line is the remnants of the epiphyseal plate once it has stopped producing bone; this is when a person has reached their adult height.
What are the factors affecting bone remodeling?
The process of bone remodeling encompasses two main factors, bone deposition and bone reabsorption. In reabsorption, osteoclasts are destroying and absorbing bone, and in deposition osteoblasts are depositing the necessary components of new bone.
Describe the growth of a long bone; indicate what occurs in the 5 layers of the growth area.
There are five areas of a growing long bone. There are the resting zone, proliferation zone, hypertrophic zone, calcification zone, and the ossification zone. In the resting zone is the inactive cartilage on the epiphyseal plate facing the epiphysis, here there is no proliferation. In the proliferation zone, is mitotically active stacks of cells abutting the resting zone. In this zone cells are pushing the epiphysis away from the diaphysis lengthening the bone. In the hypertrophic zone, older cartilage cells are enlarging and dying leaving hollow spaces which then become the calcification zone. These enlarged hollow spaces harden with the deposition of mineral salts like calcium. In the ossification zone there are calcified spicules which become covered with new bone by osteoblasts and eventually becoming spongy bone. Their cavities also get filled with marrow from the medullary cavity. Overtime the spicules get modified and the medullary cavity lengthens as well. During lengthening the epiphyseal plate maintains constant thickness because the rate of cartilage growth on the epiphyseal side and the replacement of bone tissue on the diaphysial side is equal.
How do bones respond to mechanical stress?
According to Wolff’s Law bones remodel and grow in the areas where there is the most likely chance of buckling. Essentially they grow towards their stressors in a preventative fashion.
Describe the role of vitamins A and C in the formation of bones.
Vitamin A is necessary for growth and the formation of bones via stimulation of the osteoblasts. Vitamin C is required for the normal production of collagen and optimal functioning of the osteoblast cells responsible for making new hard bone
Define osteomalacia, rickets, and osteoporosis.
osteomalacia: softening of the bones, typically through a deficiency of vitamin D or calcium
rickets: a disease of children caused by vitamin D deficiency, characterized by imperfect calcification, softening, and distortion of the bones typically resulting in bow legs
osteoporosis: bones become brittle and fragile from loss of tissue, typically as a result of hormonal changes, or deficiency of calcium or vitamin D
What are the effects of thyroid and parathyroid hormones on blood calcium levels?
Parathyroid hormone causes osteoclasts to start reabsorbing bone which then increases the levels of calcium in the blood. Thyroid hormones modulate growth hormone during adolescence to make sure that bones growth proportionately, but there are no known effects of thyroid hormone on the serum calcium levels.
What are the three different cartilages in the body and where are they found?
The three types of cartilage are hyaline, elastic, and fibrocartilage. Hyaline cartilage is found in the costal cartilage of the ribcage, nose, and wall of trachea. Elastic cartilage is found in ear lobe. And fibrocartilage is found in the intervertebral spaces.
Which is likely to heal faster, a bone injury or a cartilage injury? Why?
A bone injury is likely to heal faster than a cartilage injury because bone is vascularized and therefore has the healing properties and nutrients of the blood supply at their disposal. Cartilage is avascularized and therefore it takes a long time to get the materials for renewal to the injured site.
What are the organic and inorganic components of the bone matrix, and what specific roles do they play?
The organic parts of the bone matrix are the bone cells, and the osteoid. The osteoid makes up 1/3 of the matrix is composed of ground substance, and collagen fibers. The organic components are in charge of providing the bone’s resistance to stretching and twisting. The inorganic components of the bone matrix are mineral salts, primarily calcium phosphates. These mineral salts provide the bone with the hardness necessary to resist compression.