Ch:23 Bone Flashcards
How many bones are in the human body and whats the hardest substance in the human body?
206 bones
Enamel is the hardest substance in the human body
What is the difference between cortical bone and cancellous bone?
80% of bone is cortical or compact bone: think strength!!!
20% of bone is cancellous or spongy bone (highly vascular), which provides space for the bone marrow where RBC’s WBC’s and platelets are produced
What are the 3 segments of the bone and give a brief description of each?
(DON DAT)
Epiphysis: end segment of a long bone where GROWTH occurs
Metaphysis: region that contains the growth plate, columns of spongy tissue are found
Diaphysis: body or shaft of bone
Red bone marrow is considered hemopoietic. What does that mean?
hemopoietic is the tissue that makes blood and blood cells
Bottom line for the DAT: what is the distinguishing feature of bone?
The distinguishing feature of bone is ground substance and its extracellular matrix of collagen
What is the difference between tendons and ligaments?
Tendons connect bone to muscle
Ligaments connect bone to bone
What is the functional unit of compact bone?
Osteon
Define each of the following terms that have to do with bone:
- Lamellae
- Canaliculi
- Lacunae
Lamellae: surrounds the Haversian canal
Canaliculi: cavities within bone matrix that serves as a passage for substances between the blood vessels and bone cells
Lacunae: contains osteocytes
What are the main differences between osteoblasts and osteoclasts?
Osteoblasts:
- found at bone surface
- MONOnucleated
- arise from MESENCHYMAL cells
- synthesize much of the organic matrix of bone, thus are abundant in rough ER and Golgi
Osteoclasts:
- member of the monocyte/macrophage family
- MULTInucleated
- abundant in lysosomes and mitochondria
Osteocytes, osteoblasts, and osteoclasts do NOT do _______.
“A COMMONLY ASKED EXAM PROBLEM”
Mitosis
What is the name of the cell that gives rise to osteoblasts and osteoclasts?
Osteoprogenitor cell
Where does bone growth occur?
Epiphyseal plate
In a young person, bone development exceeds bone breakdown. Once in adulthood, the epiphyseal plates close and bone growth has been attained, a balance occurs between growth and breakdown.
Bottom line: ___1___ break down some bone to “excavate” the area to form an absorption cavity… Bone reabsorption stops. ____2___ now take over to build new bone. This process of bone breakdown (resorption) followed by bone replacement is called _____3____.
- osteoclasts
- osteoblasts
- coupling**
“VERY IMPORTANT DAT TOPIC TO UNDERSTAND”
How are the thyroid and parathyroid involved with bone?
When Ca++ levels decrease… PARATHYROID hormone is secreted. This hormone activates receptors on osteoblasts stopping them from building any more bone. Chemical factors are then produced by osteoblast which induce osteoclast formation to break down bone and release Ca++.
The THYROID glands makes calcitonin, by decreasing Ca++ levels. How? When Ca++ levels increase… calcitonin activates receptors on osteoclasts, inhibiting them from breaking down bone. Osteoblastic activity occurs, and the Ca++ go into building bone mass.
What is the most abundant type of cartilage?
Hyaline
