CARTILAGE & BONE BASICS
This specialized connective tissue is unusual because it contains neither blood vessels nor nerves, and its cells are embedded within a surrounding structure known as the perichondrium.
What is skeletal cartilage?
This type of osseous tissue forms the dense outer layer of a bone, while another type contains trabeculae and has spaces that can contain red or yellow marrow.
What are compact bone and spongy bone?
This general biological process describes how bone forms and includes stages involving bone formation, postnatal growth, and remodeling/repair.
What is ossification?
This process continuously replaces portions of existing bone and involves both adding new bone matrix and removing existing bone.
What is bone remodeling?
A fracture occurs, but the broken ends of the bone remain in their normal anatomical position. Which classification describes the position of the bone ends?
What is a nondisplaced fracture?
A patient needs a tissue that can withstand compression while also possessing considerable tensile strength. Based on the locations discussed in lecture, this tissue would most appropriately be found in structures such as the knee menisci or between the vertebrae.
What is fibrocartilage?
A bone contains an organized microscopic structural unit surrounding a central canal through which blood vessels and nerves travel. The unit is characteristic of one specific type of osseous tissue.
What is an osteon in compact bone?
A developing bone begins with mesenchyme and proceeds toward osteoblasts and bone without first creating a cartilage model. This process is particularly important for flat bones such as cranial bones and the clavicles.
What is intramembranous ossification?
A patient has cells that are actively breaking down bone tissue. These cells release lysosomal enzymes that digest the organic matrix. Which type of bone cell is performing this activity?
What are osteoclasts?
A patient experiences a fracture in which the bone breaks completely through, but the broken bone does not penetrate the skin. Which two classifications describe this injury?
What are a complete and closed fracture?
Although both of these cartilage-growth mechanisms increase the size of cartilage, one increases its thickness by adding matrix to the outside, while the other increases its length because chondrocytes divide and secrete matrix from within.
What are appositional growth and interstitial growth?
A researcher is examining spongy bone and notices a branching network of bony structures. However, they cannot find the osteons and central canals that they expected to see in compact bone. What structures are they observing?
What are trabeculae?
A long bone begins development using a hyaline cartilage model. Eventually, a bone collar forms, the cartilage calcifies, a periosteal bud enters the developing cavity, and secondary ossification centers appear in the epiphyses. Which type of ossification is occurring?
What is endochondral ossification?
Another patient is actively depositing new bone matrix. Unlike the cells responsible for bone resorption, these cells are responsible for building new bone tissue.
What are osteoblasts?
A physician decides that manually manipulating the patient's fracture is sufficient to return the broken bone ends to their proper alignment, rather than surgically inserting screws and plates. What type of reduction is being performed?
What is a closed reduction?
If a structure needs to provide support while still maintaining flexibility and resilience, rather than primarily maximizing stretchiness or tensile strength, the type of cartilage found in articular and costal cartilage would be the most appropriate choice.
What is hyaline cartilage?
Bone is strong enough to resist compression but also needs enough flexibility and tensile strength to resist stretching and twisting. Identify the two major categories of bone-matrix components responsible for these different properties.
What are organic and inorganic components?
-Organic → flexibility, framework, tensile strength
- Inorganic → hardness and compression resistance
A teenager's long bones stop increasing in length because the epiphyseal plate becomes thinner, is replaced by bone, and eventually the epiphysis and diaphysis fuse. What specific event has occurred?
What is epiphyseal plate closure?
A patient's blood calcium level falls below normal. The body responds by releasing a hormone from specific glands, increasing osteoclast activity and ultimately helping return calcium to the bloodstream. Identify both the hormone and the glands that release it.
What are parathyroid hormone (PTH) and the parathyroid glands?
A patient has soft, weak bones because osteoid is being produced but calcium is not being properly deposited into the bone. They experience bone pain particularly when bearing weight. Which condition best matches this description?
What is osteomalacia?
A student claims that all cartilage is essentially the same because it performs a supportive function. Explain why this statement is incorrect by identifying the three skeletal cartilage types and matching each one with its characteristic mechanical property or location.
What are hyaline cartilage, elastic cartilage, and fibrocartilage?
- Hyaline → support, flexibility, resilience
- Elastic → more stretchy because of elastic fibers
- Fibrocartilage → compressible with great tensile strength
Imagine that the tiny connections between adjacent spaces containing osteocytes were destroyed. The osteocytes would lose an important pathway for communication and exchange. What microscopic structures normally connect these spaces?
What are canaliculi?
A child has normal bones but experiences impaired longitudinal bone growth because a hormone responsible for stimulating the liver to produce IGF-1 is significantly reduced. Based strictly on the lecture material, which hormone is most directly responsible for stimulating epiphyseal plate activity?
What is growth hormone (GH)?
A person's plasma calcium concentration becomes abnormally high. Rather than continuing to deposit calcium into the bloodstream, the body activates a hormone that promotes calcium-salt deposition into bone. Which hormone is released, and which gland releases it?
What are calcitonin from the thyroid gland?
An older patient has decreased bone mass because the rate of bone resorption has exceeded the rate of bone formation. Although the bone matrix itself remains normal, the resulting bones are porous and fragile, increasing fracture risk. What condition is being described?
What is osteoporosis?